EM 1110-2-3600
10 October 201
7
U.S.
Army Corps
of Engineers
®
ENGINEERING AND DESI
GN
Management of Water Control Systems
ENGINEER MANUAL
EM 1110-2-3600
10 Oct 17
THIS PAGE INTENTIONALLY LEFT BLANK
DEPARTMENT OF THE ARMY
*EM 1110-2-3600
U.S. Army Corps
of
Engineers
CECW-CE
Washington, DC 20314-1000
Manual
No. 1110-2-3600
10
October 2017
Engineering and Design
MANAGEMENT OF WATER CONTROL SYSTEMS
1.
Purpose. This Engineer Manual (EM) provides guidance to field offices for water manage-
ment at all U.S. Army Corps
of
Engineers (Corps) owned and Corps-operated reservoirs, locks,
dams, and other water control projects
in
which water storage is managed and operated for multi-
ple authorized purposes such as flood risk management, navigation, and other uses.
It
also ap-
plies to Corps actions in developing water control plans and manuals or in operating non-Corps
reservoirs, locks, dams, and other water control projects
in
which water storage is managed and
operated for flood risk management or navigation, and which are subject to Corps direction pur-
suant to Section 7
of
the Flood Control Act
of
1944 or other law. This manual may also provide
guidance to the Corps in other cases where water resources infrastructure is similarly operated
for flood risk management or navigation and subject to Corps direction through the establish-
ment
of
water control or operational plans. Water management
of
these systems, however,
may
require special techniques beyond those used in the planning, design, and construction phases, to
analyze and regulate water conditions at individual projects
in
order to meet authorized water
management objectives. This manual incorporates, by reference, other USACE guidance docu-
ments, but unless expressly stated, this manual does not alter or supersede other USACE guid-
ance. Additionally, this manual does not alter or supersede any law or binding regulation, or de-
termine the authorized purposes
of
any USACE reservoir project, nor does it impose legal re-
quirements on any entity.
2. Applicability. This manual applies to all Headquarters, U.S. Army Corps
of
Engineers
(HQUSACE) elements, major subordinate commands (MSCs), districts, laboratories, and sepa-
rate field operating activities (FOAs) having civil works responsibilities and activities related to
or affecting water control management. This manual also applies to Corps actions in developing
water control or operational plans for projects not owned
by
the U.S. Army Corps
of
Engineers
(USACE), as defined in Para.
1.
3.
Distribution Statement. Approved for public release; distribution is unlimited.
FOR
THE COMMANDER:
~z~
3 Appendices
RICHARD L. HANSEN
(See Table
of
Contents)
COL, EN
Chief
of
Staff
*This manual supersedes
EM
1110-2-3600 dated 30 November 1987.
DEPARTMENT OF THE ARMY EM 1110-2-3600
U.S. Army Corps of Engineers
CECW-CE Washington, DC 20314-1000
Manual
No. 1110-2-3600 10 October 17
Engineering and Design
MANAGEMENT OF WATER CONTROL SYSTEMS
TABLE OF CONTENTS
Paragraph Page
CHAPTER 1. Introduction
Purpose.......................................................................................... 1.1 1-1
Applicability.................................................................................. 1.2 1-1
Distribution Statement. ................................................................. 1.3 1-1
References and Resources............................................................. 1.4 1-1
Authorities for the Corps Water Control Management
Role. ........................................................................................ 1.5 1-2
Scope of this Manual..................................................................... 1.6 1-3
CHAPTER 2. Objectives and Principles of Water Management
General Considerations. ................................................................ 2.1 2-1
Flood Risk Management. .............................................................. 2.2 2-3
Navigation..................................................................................... 2.3 2-9
Hydroelectric Power Generation................................................... 2.4 2-10
Irrigation........................................................................................ 2.5 2-14
M&I Water Supply Use. ............................................................... 2.6 2-16
Water Quality................................................................................ 2.7 2-17
Fish and Wildlife........................................................................... 2.8 2-18
Recreation. .................................................................................... 2.9 2-23
Erosion and Deposition Considerations........................................ 2.10 2-24
Aesthetic Considerations............................................................... 2.11 2-26
Cultural Resources ........................................................................ 2.12 2-26
CHAPTER 3. Water Control Plans
General. ......................................................................................... 3.1 3-1
Principles and Objectives.............................................................. 3.2 3-1
Flood Risk Management Regulation............................................. 3.3 3-5
Navigation Regulation. ................................................................. 3.4 3-12
Development of Water Management Operating Criteria.............. 3.5 3-13
Drought Contingency Plans .......................................................... 3.6 3-21
Monitoring and Revising Water Control Plans............................. 3.7 3-21
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Paragraph Page
CHAPTER 4 Operational Characteristics of Water Management
Facilities
General Considerations. ................................................................ 4.1 4-1
Spillways....................................................................................... 4.2 4-2
Outlet Works. ................................................................................ 4.3 4-5
Flood Risk Management Operation. ............................................. 4.4 4-8
Induced Flood Surcharge Storage. ................................................ 4.5 4-10
Outlet Works Releases. ................................................................. 4.6 4-20
Diversion and Bypass Structures. ................................................. 4.7 4-21
Hurricane or Tidal Barriers. .......................................................... 4.8 4-22
Interior Flood Risk Management Facilities................................... 4.9 4-22
Hydroelectric Power Generation Facilities. .................................. 4.10 4-23
Use of Water Management Facilities for Fishery
Enhancement........................................................................... 4.11 4-24
CHAPTER 5. Water Management Enterprise Systems
Overview....................................................................................... 5.1 5-1
Water Management Enterprise System Hardware. ....................... 5.2 5-3
Water Management Data............................................................... 5.3 5-4
Continuity of Operations Plan and WMES................................... 5.4 5-11
WMES Master Plan. ..................................................................... 5.5 5-12
CHAPTER 6. Water Management Techniques
General Considerations. ................................................................ 6.1 6-1
Analytical Methods in Modeling for Water Management. ........... 6.2 6-2
Meteorological Forecasts Used in Water Management. ............... 6.3 6-4
Simplified Analytical Procedures for Analyzing River
Response. ................................................................................ 6.4 6-8
Long-Range Predictions of Streamflow........................................ 6.5 6-8
Long-Range Analysis of Project Regulation................................. 6.6 6-11
Water Quality Forecasting. ........................................................... 6.7 6-12
Special Hydrologic Analyses. ....................................................... 6.8 6-14
CHAPTER 7. Real-Time Water Management
Basic Considerations..................................................................... 7.1 7-1
Appraisal of Current Project Water Management......................... 7.2 7-2
Performing System Analyses for Water Management
Activity Scheduling................................................................. 7.3 7-2
Water Management Decisions and Project Scheduling. ............... 7.4 7-5
Disseminating Water Management Activity Schedules................ 7.5 7-7
Water Management Activities during Emergency Events............ 7.6 7-9
Coordinating Flow and Water Level Forecasts............................. 7.7 7-11
ii
LIST OF FIGURES (CONTINUED)
EM 1110-2-3600
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Paragraph Page
CHAPTER 8 Administrative and Coordination Requirements for
Water Management
Administration of Water Management Activities......................... 8.1 8-1
Briefing Room Facilities............................................................... 8.2 8-3
Administration of Water Management Data Collection
Agreements. ............................................................................ 8.3 8-5
Interagency Coordination and Agreements................................... 8.4 8-5
Water Management Reports on Prevailing Conditions................. 8.5 8-11
Documents, Reports, and Records. ............................................... 8.6 8-12
CHAPTER 9. Preparation of Water Management Documents
Basic Documents........................................................................... 9.1 9-1
Water Control Manuals................................................................. 9.2 9-1
Water Control Plans. ..................................................................... 9.3 9-3
Standing Instructions to Project Operators for Water
Management............................................................................ 9.4 9-6
Related Water Control Documents. .............................................. 9.5 9-7
Coordination of Water Management Documents. ........................ 9.6 9-7
Vertical Datum Reference............................................................. 9.7 9-9
APPENDICES
APPENDIX A - References A-1
APPENDIX B - Water Management-Related Legislation B-1
APPENDIX C - Acronyms and Abbreviations C-1
EXHIBIT A: WATER CONTROL PLAN E-A-1
EXHIBIT B: STANDING INSTRUCTIONS TO THE PROJECT OPERATOR E-B-1
LIST OF FIGURES
Figure 3-1. Example of Water Management Guide Curve ................................................... 3-14
Figure 3-2. Example of a Water Management Seasonal Guide Curve .................................. 3-17
Figure 3-3. Wolf Creek Dam Guide Curve........................................................................... 3-18
Figure 4-1. Spillway Section Showing Surcharge ................................................................ 4-11
Figure 4-2. Gated Spillway Discharge Characteristics ......................................................... 4-12
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LIST OF FIGURES (CONTINUED)
Figure 4-3. Schematic Hydrograph ....................................................................................... 4-15
Figure 4-4. Spillway Gate Regulation, Schedule A
LIST OF TABLES
.............................................................. 4-17
Figure 4-5. Spillway Gage Regulation, Schedule B ............................................................. 4-18
Figure 5-1. Typical Example of CWMS AIS Integration into a WMES................................ 5-3
Figure 5-2. Typical Example of Data Transmission ............................................................... 5-6
Table 9-1. Categories and Characteristics of Water Management Projects............................ 9-2
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CHAPTER 1
Introduction
1.1. Purpose. This Engineer Manual (EM) provides guidance to field offices for water manage-
ment at all U.S. Army Corps of Engineers (Corps) owned and Corps-operated reservoirs, locks,
dams, and other water control projects in which water storage is managed and operated for multi-
ple authorized purposes such as flood risk management, navigation, and other uses. It also applies
to Corps actions in developing water control plans and manuals or in operating non-Corps reser-
voirs, locks, dams, and other water control projects in which water storage is managed and oper-
ated for flood risk management or navigation, and which are subject to Corps direction pursuant to
Section 7 of the Flood Control Act of 1944 or other law. This manual may also provide guidance
to the Corps in other cases where water resources infrastructure is similarly operated for flood risk
management or navigation and subject to Corps direction through the establishment of water con-
trol or operational plans. Water management of these systems, however, may require special tech-
niques beyond those used in the planning, design, and construction phases, to analyze and regulate
water conditions at individual projects to meet authorized water management objectives. This man-
ual incorporates, by reference, other USACE guidance documents, but unless expressly stated, this
manual does not alter or supersede other USACE guidance. Additionally, this manual does not al-
ter or supersede any law or binding regulation, or determine the authorized purposes of any
USACE reservoir project, nor does it impose legal requirements on any entity.
1.2. Applicability. This manual applies to all Headquarters, U.S. Army Corps of Engineers
(HQUSACE) elements, major subordinate commands (MSCs), districts, laboratories, and sepa-
rate field operating activities (FOAs) having civil works responsibilities and activities related to
or affecting water control management. This manual also applies to Corps actions in developing
water control or operational plans for projects not owned by the U.S. Army Corps of Engineers
(USACE), as defined in Para. 1.
1.3. Distribution Statement. Approved for public release; distribution is unlimited.
1.4. References and Resources.
1. Appendix A to this manual lists Engineer Regulations (ERs), Engineer Manuals (EMs),
Engineer Circular (EC), Engineer Pamphlet (EP), and other publications that define pol-
icy and basic methods directly related to water management activities by the Corps of En-
gineers, and that are cited in this manual.
2. Appendix B to this manual contains partial lists of Federal Water Resource Management
and Environmental Laws.
3. Appendix C to this manual contains a list that defines acronyms and abbreviations used in
this manual.
4. This manual contains two sample exhibits: a “Water Control Plan,” and “Standing In-
structions to the Project Operator For Water Control.”
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1.5. Authorities for the Corps Water Control Management Role.
1.5.1. The Corps is responsible for water control management at the reservoir projects it
owns and operates throughout the United States. These projects are referred to in this regulation
as Corps-owned projects. This responsibility is prescribed by laws initially authorizing construc-
tion of specific projects and any referenced project documents, by laws specific to projects that
are passed subsequent to construction, and by the flood control acts and related legislation that
Congress has passed that apply generally to all Corps reservoirs. Modifications to project opera-
tions may also be permitted under laws passed post-construction.
1.5.2. Corps-owned projects are operated for authorized purposes such as flood control, navi-
gation, hydroelectric power, irrigation, municipal and industrial (M&I) water supply, recreation,
low flow augmentation, water quality, and fish and wildlife conservation. Operations for these au-
thorized purposes may derive from the original project authorization, from appropriate revisions
within the discretionary authority of the Chief of Engineers, or from modifications permitted under
subsequent congressional acts or in compliance with Federal laws relating to the operation of Fed-
eral facilities. In addition, water control plans for projects owned and operated by USACE shall be
developed in concert with all basin interests that may be impacted by or influence project regula-
tion; public involvement in the development or significant revision of water control plans shall also
be provided as required under this regulation. These considerations should be addressed by a water
control plan and reflected in an approved water control manual. Questions requiring interpretation
of authorizations will be referred to HQUSACE, CECW-CE (USACE, Civil Works – Construction
and Engineering) for guidance and resolution, and should include review by District, Division, and
HQUSACE counsel. This manual does not determine or define the authorized purposes or legal
operating requirements of any USACE reservoir project.
1.5.3. The Corps is also responsible for prescribing flood control and navigation regulations
and providing operational guidance for certain reservoir projects constructed or operated by other
Federal, non-Federal, or private agencies; such projects are referred to in this regulation as non-
Corps projects. These projects include those subject to direction by the Corps under Section 7 of
the Flood Control Act of 1944 (which requires the Corps to prescribe regulations for the use of
storage allocated to navigation, or flood control at reservoirs constructed wholly or in part with
Federal funds) and related legislation, as well as those authorized by special acts of Congress, those
for which licenses are issued by the Federal Energy Regulatory Commission on the condition that
they be operated in accordance with Corps instructions, those covered by agreements between the
operating agency and the Corps, and those that fall under the terms of general legislative and ad-
ministrative provisions. This regulation establishes the general policies that the Corps shall follow
when developing water control management plans or operations for such projects. This manual
does not determine or define the purposes or operations of non-Corps projects, nor does it im-
pose obligations on any other entity.
1.5.4. For these non-Corps projects, the intent is to provide guidance to establish an under-
standing of the water control plan and responsibilities for flood control and navigation between
the project owner, operating agencies, and the Corps. Excepted non-Corps projects include those
under the jurisdiction of the International Boundary and Water Commission, United States and
Mexico; those under the jurisdiction of the International Joint Commission, United States, and
Canada; and those under the Columbia River Treaty.
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1.5.5. Appendix B to this manual contains more information about authorities prescribing
Corps roles and responsibilities for water control management.
1.6. Scope of this Manual. This manual covers water management activities related to the hy-
drologic/hydraulic aspects of completed projects. These activities include: data collection and
handling; determination of project inflow, and planning and implementing of operational deci-
sions, which include releases for flood risk management, hydropower, water supply, water qual-
ity, fish and wildlife, and other authorized purposes; and coordination and communication of wa-
ter management decisions. Water resource projects are regulated to meet water management ob-
jectives by operating spillway gates, sluice gates, pumping plants, etc. In this regard, the physi-
cal operation of structures, such as the manipulation of gates or recognition of structural con-
straints, is addressed only in terms of achieving the water management objectives. The term
“operation” is used interchangeably throughout the manual to mean “regulation” for water man-
agement such as project release scheduling as well as to mean the physical operation of projects.
The phrase “project operator” refers to the person who is responsible for the project’s physical
operation. Non-hydrologic/non-hydraulic aspects of project operation and maintenance are not
addressed herein. This manual includes a compendium of elements related to water management
systems, including discussions of:
1. Regulation of single purpose projects, multipurpose projects, and systems.
2. Preparation of water control plans and regulation schedules to achieve multipurpose ob-
jectives consistent with authorized purposes.
3. Collection, processing, and dissemination of data and information related to water man-
agement activities including real-time systems and use of automated data systems.
4. Analysis of river and reservoir systems on a real-time basis to inform water management
decisions, including use of automated techniques to simulate hydrologic systems.
5. Considerations related to environmental, social, economic, and aesthetic aspects of water
management.
6. Methods to support real-time water management decisions.
7. Development of water control plans and manuals for an individual project and for a system.
8. Coordination of water management activities with stakeholders and the public at a local,
regional, and national level.
1.6.1. Chapter 2 describes the objectives and principles for the management of water for var-
ious congressionally authorized project purposes. The specific requirements for any of these
purposes (functional, economic, environmental, social, and aesthetic) are unique to a given river
basin. The manual describes each element, insofar as the principles apply to projects generally,
and the necessity for considering all elements as well as the project’s safety and integrity. This
chapter is not intended to present detailed solutions.
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1.6.2. Chapter 3 addresses the technical aspects of developing water control plans, which of-
ten encompass multipurpose and multiproject systems. Even in the case of a single purpose pro-
ject, there are often important aspects to be accounted for in the overall management of a river
system. The manual provides guidelines for the formulation of detailed regulation criteria,
which are based largely on planning and design studies, together with the use of techniques for
water management to attain the overall goals. This chapter discusses the preparation of water
control diagrams, which include the regulating criteria in the form of guide curves and release
schedules. Section 3.2.5.2 deals with requirements contained in water control agreements for
non-Corps projects, as set forth in the revision of Title 33 of Code of Federal Regulations (CFR)
Section 208.11, published in the Federal Register, 47184, 13 October 1978, as amended at 46 FR
58075, 30 November 1981; 55 FR 21508, 24 May 1990; 79 FR 13564, 11 March 2014.
1.6.3. Chapter 4 briefly describes the design of hydraulic facilities at water management pro-
jects. These include spillways, spillway gates, regulating outlets, bypass and diversion struc-
tures, interior drainage facilities, navigation locks, hydropower facilities, fish passage facilities,
and special devices for regulating the quality of water released from a reservoir. Special empha-
sis is placed on the methods for controlling floods through the combined use of spillway gates
and/or regulating outlets in order to use flood surcharge storage in reservoirs. Also mentioned
are special water control management issues involved in the use of bypass structures, hydro-
power facilities, navigation locks and dams, and fish passage facilities.
1.6.4. Chapter 5 summarizes the methods available for collecting, processing, storing, and
disseminating basic data for project regulation. It discusses the relationship between a water
management enterprise system (WMES) and Corps Water Management System (CWMS). This
chapter presents methods for coordinating data collection with other organizations and the use of
cooperatively developed data systems. It also covers the importance and process for developing
solid continuity of operation (COOP) plans.
1.6.5. Chapter 6 includes methods of hydrologic analysis that are directly applicable to water
management systems. These include modeling to simulate the continuous natural response of
hydrologic and river systems, combined with the effects of project regulation on conditions of
streamflow and river stages. These simulations are used to evaluate the effects of alternative
conditions or assumptions in forecasting streamflows and project regulation. This chapter also
describes meteorological assessments and forecasts that are important to project regulation. Sys-
tems analysis techniques discussed in this chapter also include methods for analyzing and pro-
jecting long-term regulation of projects for several months to a year in advance. These projec-
tions are based on known or assumed conditions of stream and operating criteria. These analyses
are useful in evaluating alternatives in system regulation, and in adjusting the water control plan
for flood risk management, hydroelectric power generation, irrigation, navigation, water quality,
fish and wildlife, or other project purpose as needed to assess the particular observed and to as-
sess projected conditions of hydrology and project regulation on the overall water management.
Other aspects of hydrologic analysis include reservoir evaporation, effect of ice and wind,
streamflow determination, hurricanes, tsunami waves, tidal effects, artificial flood waves, ground
water effects, and effects of changing channel capacities downstream from projects.
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1.6.6. Chapter 7 presents the methods for integrating system guidelines for water manage-
ment, criteria and goals for scheduling water releases. The specific schedules are developed us-
ing all existing current information, hydrometeorological data, project data, and projections de-
veloped by simulation techniques. This chapter discusses organization and staffing recom-
mended to perform this function, methods of arriving at daily water management decisions, and
the way water management decisions may be disseminated and implemented at the project level.
It also discusses methods for coordinating releases, streamflow and regulation forecasts with
other interests. It describes requirements of regulation during floods or other emergency condi-
tions, as opposed to normal routine regulation, and methods for disseminating vital information
to the news media and the general public.
1.6.7. Chapter 8 presents the administrative and coordination requirements of the Corps for
water management systems, and discusses the role of the Corps in the regulation of international
rivers and the authority for regulating projects constructed by other entities in the United States.
Note that the content of this chapter that summarizes the requirements for administrative control
by the Corps is derived primarily from existing ERs.
1.6.8. Chapter 9 discusses the preparation of water control documents, and includes standing
instruction to project operators, water control plans, and water control manuals.
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CHAPTER 2
Objectives and Principles of Water Management
2.1. General Considerations.
2.1.1. Introduction.
2.1.1.1. This chapter defines the objectives and principles for water management by the Corps.
A primary objective for water management is to develop and implement water control plans that sup-
port the delivery of benefits consistent with congressionally authorized project purposes, functional
goals, and applicable legal requirements. The water control plan provides the basis for decisions on
the storage and release of water to meet project objectives.
2.1.1.2. This chapter describes fundamental objectives and project purposes that are generally
applicable to most projects. This chapter also addresses the principal water management considera-
tions and issues associated with each purpose. The water manager should take this information into
account when preparing a water control plan.
2.1.1.3. This chapter discusses various operational objectives, applicable authorities, and stand-
ard water management considerations for various types of single and multipurpose projects. In oper-
ating all its projects, regardless of their authorized purposes, the Corps always seeks to minimize risk
to public safety.
2.1.2. Congressionally Authorized Project Purposes, Related Legal Requirements, and Rele-
vant Case Law.
2.1.2.1. Water management activities are governed by authorized project purposes defined in au-
thorizing legislation and supporting reports, post-authorization legislation, and general legislation ap-
plicable to all Corps projects. Water management activities must also be consistent with other legal
requirements related to real estate, environmental principles, public use, and public safety. Appendix
B to this manual provides a summary of legislation relevant to water management. Water manage-
ment activities may also need to consider the advice of counsel, written legal opinions, and relevant
case law.
2.1.2.2. The Corps is responsible for water management at Corps projects and at Corps-oper-
ated projects throughout the United States. This responsibility is prescribed by laws initially au-
thorizing construction of specific projects, laws specific to projects that are passed subsequent to
construction, and flood control acts and related legislation that Congress has passed that apply to
all Corps projects. Congressionally authorized project purposes may include one or more of the
following:
1. Flood control.
2. Navigation.
3. Hydroelectric power generation.
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4. Irrigation.
5. Water supply (M&I).
6. Water quality.
7. Fish and wildlife.
8. Recreation.
9. Sediment control.
2.1.3. Single Purpose Project. In some cases, water resources projects are authorized for a
single purpose.
2.1.4. Multiple Purpose (Multipurpose) Project.
2.1.4.1. Projects authorized and operated for multiple purposes must balance multiple water
management objectives. The water control plan integrates the different project purposes, which are
characterized by the storage and release functions. The degree of compatibility among the various
project purposes depends on the characteristics of the river system, water use requirements, and the
ability to forecast runoff. Some degree of flexibility is needed to achieve the water management ob-
jectives. Management of water levels upstream and downstream from projects may achieve project
goals and also desires for public use, recreation, and fish and wildlife activities.
2.1.4.2. A project’s water control plan should seek to accomplish the project purposes by outlin-
ing regulation that benefits them to the greatest extent possible while seeking to minimize the risk to
public safety. ER 1110-2-8156, Preparation of Water Control Manuals, provides a format to docu-
ment the effects and benefits of project purposes, which may be used to improve the water control
plan and provide a basis for structural modifications.
2.1.5. System Water Management. Water management objectives may encompass a single
project or a system of projects. The system may consist of any combination of rivers, tributaries,
reservoirs, and a regional watershed. ER 1110-2-240, Water Control Management, requires that
an integrated water control master manual be prepared for system water management of Corps-
regulated projects in a drainage basin with interrelated purposes. For example, a master manual
may be necessary for projects interconnected hydraulically or with a hydroelectric power genera-
tion purpose. A number of the individual water control plans contained in the master manual
may include requirements that extend beyond a single river basin boundary and entail regional
flood risk management, water supply, or hydroelectric power generation requirements. A system
could contain water resource projects in series where project actions directly impact inflows or
releases to upstream or downstream projects. A system could also have parallel projects where
multiple projects may impact a common downstream control point.
2.1.6. Streamflow Objectives. Streamflow objectives are developed to serve the authorized
project purposes such as flood risk reduction, navigation, hydropower, and water supply. For
multipurpose projects or systems, operating to achieve one purpose may also satisfy other
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streamflow objectives. For example, water released for irrigation could also address other in-
stream water needs. Streamflow objectives should be documented in the water control manual
and supported by analyses that consider project and system benefits and impacts to optimize the
use of the water resource.
2.1.7. Climate Change.
2.1.7.1. The Corps Climate Preparedness and Resilience Policy Statement (27 June 2014), states
that the Corps will integrate climate change preparedness and resilience planning and actions in all
activities for the purpose of enhancing the resilience of our built and natural water-resource infra-
structure to reduce the potential vulnerabilities of that infrastructure to the effects of climate change
and variability.
2.1.7.2. As water control plans and water management are developed or updated, they should
include integrated strategies for adaptation (i.e., manage unavoidable impacts) and mitigation (i.e.,
avoid unmanageable impacts). Water control plans need to be reviewed periodically and updated as
needed to manage climate change and variability impacts. Data and models that support water man-
agement decisions must also be periodically reviewed and updated to provide reliable and current in-
formation to decision makers. Statistical analyses that relate hydrologic variables such as volumetric
runoff or streamflows to meteorological or current system states such as snowfall and snowpack will
be influenced if those relationships are changing. Physical or numerical models that have been cali-
brated to historic conditions may need to be re-evaluated within the context of climate change and
calibrated to current conditions as changes are observed.
2.2. Flood Risk Management.
2.2.1. Historical Perspective.
2.2.1.1. General. From the founding of the nation through much of the 19th century, flood risk
management activities were viewed as a responsibility of the states and local governments. In 1879,
the establishment of the Mississippi River Commission, which Congress tasked with developing
plans to improve navigation and prevent destructive floods, represented the first Federal attempt to
mature a coordinated plan of development of the Mississippi River. Hampered by restrictive legisla-
tion that prevented expenditure of Federal funds for the sole reason of protecting private property
from overflow, the commission focused its attention on improving the existing levee system as a
means of improving navigation. The passage of the 1917 Flood Control Act, however, fully commit-
ted the Federal government to flood control improvements in the Mississippi Valley. The act also
extended Federal flood risk management responsibilities to the Sacramento River, CA. Following
the disastrous flood of 1927, the Flood Control Act of 1928 authorized a comprehensive plan for
management of the Mississippi River and its tributaries. The Flood Control Act of 1936 and the
Flood Control Act of 1944 marked the beginning of Corps construction of flood risk management
projects throughout the nation. Appendix B to this manual provides a summary of relevant water
management-related legislation.
2.2.1.2. Evolution from Flood Control to Flood Risk Management. Although previous legisla-
tion and regulations have used the term “flood control,” in recent years, the Corps has transitioned
through the term “flood damage reduction” and now uses the term “flood risk management.” One
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reason for this change in terminology is that the term flood control has been misunderstood to denote
“flood elimination.” The term flood damage reduction was adopted in recognition of the fact that the
structures built for flood control can only reduce the level of flooding and subsequent damage, and
do not totally control all floods. Flood risk management recognizes that there are different levels of
risk in flood control projects and activities. The Corps manages risks associated with flood waters,
but cannot fully control or eliminate them. Projects described in subsequent sections have a limited
capacity to reduce flood risk, and decision makers must understand these limitations and operational
constraints. The more recent flood risk management terminology is used as appropriate in the re-
mainder of this manual. The terminology used in this manual does not result in any change in the
congressionally authorized purposes or operations of any project.
2.2.2. Flood Risk Management Measures.
2.2.2.1. Management of flood risk by structural remedies, such as reservoirs, levees, drainage
systems, and channel improvements, has long been a national objective. Nonstructural means, such
as flood plain zoning, flood proofing, and flood insurance have been incorporated into overall flood
risk management plans to augment structural operations. In the operational phase, the overall objec-
tive is to reduce flood risk in a given region to the extent reasonably possible. Most structural alter-
native measures require specific plans based on hydrometeorological conditions, flood risk manage-
ment objectives, and the capabilities of appropriate flood risk management facilities. Water control
plans must integrate the flood risk management information outlined above to best manage projects;
deviations from the water control plan must be approved in advance for alternate regulation (see ER
1110-2-240, Water Control Management).
2.2.2.2. Streamflow and reservoir forecasting is an important element in managing water during
floods, and timely preparation of flood forecasts facilitates the evacuation of people and property
from harm’s way. In general, Corps policy is to implement operational decisions based on water-on-
the-ground while planning and scenario analysis can include precipitation forecasts. Forecasted pre-
cipitation may be used in operational decision making as part of an approved water control plan. The
National Weather Service is the responsible Federal agency to provide weather, hydrologic, and river
stage forecasts, and warnings for the protection of life and property. Specific flood risk management
measures and objectives are discussed briefly in the following paragraphs. Types of water manage-
ment facilities are discussed in Chapter 4.
2.2.3. Runoff Management Using Dams. A principal structural remedy for flooding is to
manage streamflow and river levels by impounding runoff using dams. Planning studies to meet
flood risk management objectives using reservoirs may require analysis of historical and hypo-
thetical floods, comparison of alternatives that provide varying storage levels and structural loca-
tions, consideration of downstream flooding, consideration of inflows from uncontrolled areas
below the project, determination of downstream channel capacities, completion of flood damage
surveys, cost-benefit analysis, and preparation of a general plan of regulation. These planning
studies are used to determine the size and location of dams, the level of flood risk management to
be provided, and the multipurpose uses of projects. The studies are based on a comprehensive
evaluation of river basin development that considers economic, environmental, and social values.
In the design phase, the project studies are refined, and detailed studies are made to finalize hy-
draulic features and the water control plan for the project.
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2.2.4. Objectives for Reservoir Management of Floods.
2.2.4.1. General. Reservoirs cannot eliminate flooding, but do reduce risk. They are designed to
operate through a wide range of events including extreme floods. Many reservoirs have sufficient
storage to completely retain the local runoff from minor or moderate floods. The water control plan
should define the basic goal of regulation, relative to management of minor and major floods. The
water control plan should be designed to best use reservoir storage, considering both major and mi-
nor floods as well as consecutive rainfall events. Also, the amount of flood storage for a particular
project may be varied seasonally to improve benefits of multipurpose regulation. Decisions affecting
flood risk management can be planned for the longer term when reservoir inflows can be accurately
forecast several days or weeks in advance (e.g., runoff from snowmelt).
2.2.4.2. Operation Conflict. For multipurpose reservoirs, the projects are designed and operated
to balance multiple objectives. A project’s design and water control plan define the tradeoffs that are
to be made among purposes to reduce conflict. When the rules in the water control plan are formu-
lated, water managers should recognize opportunities for flexibility. Adjustments in priority during
different times of the year can and should be addressed during initial formation of a water control
plan or during a revision process. The water control plan should address any pressures to depart
from flood risk management regulations in the interest of other objectives. In operating all its pro-
jects, the Corps always seeks to minimize risk to public safety; other purposes should be considered
within the context of risk. If, in the attempt to maintain flexibility, water managers consider objec-
tives that fall outside the water control plan, they may follow the deviation process described in ER
1110-2-240, Water Control Management.
2.2.4.3. Evacuation of Flood Storage. Depending on reservoir storage and discharge capabili-
ties, a challenging component of reservoir management is the requirement for post-flood evacuation
of stored water. The flood storage should be evacuated as quickly as possible without exceeding the
safe rate of release. The water control plan must account for the release of flood storage, which may
vary between a rapid evacuation of stored water to provide flood storage for subsequent events and a
slow evacuation to allow downstream river levels to recede below bankfull as quickly as possible.
This may result in a long duration of downstream river levels at or near bankfull, or produce minor
damaging stages at downstream control points. Some projects may designate a portion of the flood
storage to meet other project purposes, which is outlined in the water control manual.
2.2.5. Reservoir Systems.
2.2.5.1. A multireservoir system is regulated generally to mitigate for flood risk both in interven-
ing tributary areas and at downstream mainstem damage areas or control points. The extent of reser-
voir regulation needed to mitigate risk in these areas depends on local flood conditions, uncontrolled
tributary drainage, reservoir storage capacity, and the volume and time distribution of reservoir in-
flows. Upstream or downstream impacts may influence reservoir regulation, but optimum regulation
is usually based on a combination of the two. Reservoir releases are based on the overall objectives
to manage flood risk at defined control points. The regulation must consider the travel times caused
by storage effects in the river system and the local inflows between the reservoir and control points.
Since each flood event is caused by a unique set of hydrometeorological conditions, the specific plan
of regulation for a reservoir system should be based on the analysis of the particular flood event.
This analysis is commonly conducted by modeling the runoff conditions and reservoir regulation to
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determine the releases at each project needed to meet the desired downstream targets and to achieve
the water management objectives at each reservoir or management structure. Water managers should
integrate the corporate tool, CWMS, to the extent possible for simulations including hydrologic, res-
ervoir, hydraulic, and flood inundation models.
2.2.5.2. System management may incorporate the concept of a balanced reservoir regulation,
with regard to filling the reservoirs in proportion to the flood risk management capability, while also
considering expected residual inflows and available storage. Flood water stored in a reservoir system
must also be evacuated on a coordinated basis to provide space for managing future floods while
managing downstream risks. Regulation criteria in the form of guide curves and regulation sched-
ules for individual reservoirs should be developed to define various amounts of storage as seasonal or
exclusive flood storage. The seasonal flood storage zone elevations could vary based on the time of
year and the associated risk of flooding along with the ability to forecast reservoir inflows (e.g.,
snowmelt runoff vs. thunderstorm rainfall runoff). The withdrawal objectives in the seasonal flood
storage zone should be determined to balance the need to conserve water for future use with the need
to reduce flood risk. The exclusive flood storage zone will typically be evacuated as quickly as pos-
sible to provide space for managing future floods while managing downstream risks.
2.2.6. Levees. Flood risk management of land and structures adjacent to rivers is often pro-
vided by levees. While most levee projects do not require daily water management decisions,
water managers should be informed of conditions along levee systems related to the management
of a water resources system. Particularly during major floods, the water management office
should be alerted to any signs of weakness in the levee system. The water management office, in
coordination with other offices, should disseminate an evaluation of flood hazard areas in con-
junction with the regulation of reservoirs or diversion structures. Also, flood fight activities,
which involve special precautions to ensure the safety and integrity of levees, require the coordi-
nated efforts of the water management office, Operations Division, Readiness and Contingency
Operations (RCO), and other appropriate organizational elements. The latest forecasts of river
levels and potential future flooding may be assessed and disseminated to the field. In some
cases, special requirements, such as placing temporary bulkheads at street or highway crossings
and sandbagging vulnerable locations to ensure the continuity of levee effectiveness, are incor-
porated into the design of levee systems. Since such requirements must be accomplished before
critical conditions or flood levels are reached, timely coordination of river level forecasts must
be made with appropriate Operations Division and RCO personnel.
2.2.7. Combined Reservoir and Levee Systems. Flood risk management is provided in many
river basins through the combined effects of reservoirs and levee systems. The system design
should be based on planning and engineering considerations in an analysis of river basin devel-
opment to provide a practical and economic flood risk management solution. Water managers
should be informed of conditions along levee systems related to the management of a water re-
sources system.
2.2.8. Flood Risk Management Projects Operated and Maintained by Non-Federal Interests.
In addition to Corps-operated dams and reservoirs, the Corps prescribes operations and mainte-
nance requirements, which may include water management requirements, for three categories of
projects operated and maintained by non-Federal interests: (a) Corps-constructed non-reservoir
projects, which usually fall under the responsibility of local interests or non-Federal sponsors for
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operations, maintenance, repair, rehabilitation, and replacement (OMRR&R), and which are sub-
ject to OMRR&R Manuals formulated by the Corps for such projects and to regulations in 33
CFR Section 208.10; (b) projects constructed by non-Federal interests that retain an Active status
under the Corps’ Rehabilitation and Inspection Program, pursuant to 33 USC 701n (generally re-
ferred to as the P.L. 84-99 program) and to 33 CFR Part 203 Subpart D.; or (c) non-Federal res-
ervoir projects that include flood risk management or navigation storage and that were con-
structed wholly or in part with Federal funds provided for such purposes, the storage of which is
operated pursuant to Corps regulations pursuant to Section 7 of the Flood Control Act of 1944
and to 33 CFR Section 208.11. Documentation guidance pertaining to water management re-
quirements is provided in Chapter 9.
2.2.9. Interior Drainage Systems.
2.2.9.1. Areas protected by levees often include the requirement to provide interior drainage for
levee seepage or storm runoff from local uncontrolled inflows that drain into the channels on the pro-
tected side of the levees. The design of drainage systems to manage these flows may be based on the
use of pumping plants, tide or “flap” gates, or temporary storage of water in low-lying areas or chan-
nels that are not subject to flood damage. Adequate channels must be constructed to convey the wa-
ter to the outlets or management structures. The design of the drainage systems may be determined
from studies of storm rainfall and associated runoff that reasonably occur while taking into account
flooding on the unprotected side of the levee.
2.2.9.2. The facilities constructed to manage flooding in interior drainage systems often operate
automatically and only require surveillance during times of floods. Most small pumping stations
used in evacuating interior drainage are operated and maintained by local entities. For large pumping
facilities that are operated by Corps personnel as part of interior drainage systems, the pumps and
gates may be manually operated according to established operating plans or standing instructions.
For inflows and water levels that are not described in these plans, water management staff may deter-
mine target flows or stages to facilitate operation of outlet structure gates. During high water periods,
water management staff should continuously monitor upstream and downstream conditions at these
structures and consult with pumping station operators as necessary.
2.2.10. Diversions, Bypass Structures, and Floodways.
2.2.10.1. Temporary diversions are often required during construction of projects. In some river
systems, however, excess flood water or water supply is diverted from the main river channel by a per-
manent diversion, bypass structure, or floodway and auxiliary channels to reduce flood flows and river
levels at main stem damage centers. These permanent structures are usually located in flood plains,
where river slopes are relatively flat, and adjacent to the main river channel to divert water into the aux-
iliary channels. Many structures are seldom used or pass only insignificant amounts of water, but sig-
nificant streamflow could be diverted during flooding. Diversions could be operated continuously.
The diversion of water may be managed through use of control gates, pumps, or other methods, or the
structure may be designed for uncontrolled operation, depending on the water level in the main river.
The capacity of the structure is determined by engineering studies of desired flood stage reduction and
downstream channel capacities in the main river and in the auxiliary channels, in connection with the
overall plan of flood risk management, which may include levees and impoundment projects upstream.
The auxiliary channels may be improved to provide the desired flow capacity without flooding adjacent
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areas, or may be left as unimproved natural overflow channels. The degree of improvement depends
on the frequency and extent of flooding, land use, and economic factors.
2.2.10.2. Diversions, bypass structures, and floodways may require gate operations to manage re-
leases. The timing and use of the structure for diverting flood flows must be based on the best forecasts
of river flows and flood conditions. In some cases, the auxiliary channels are designed to be used only
under maximum flood conditions to reduce adverse effects of flooding along the auxiliary channels.
These channels should be used only for design floods or other necessary conditions. Decisions to use
the structures should be based on the most complete basic data and technical evaluations available.
2.2.10.3. Diversion and bypass structures that have ungated spillways or sluices do not require
specific water management decisions since the flow of water through the structure is determined
solely by water levels in the river. The date and time that the facilities will be operated should be es-
timated sufficiently in advance to provide timely warnings to the people living along the auxiliary
channels and to take other necessary actions.
2.2.11. Hurricane and Tidal Barriers.
2.2.11.1. Hurricane and tidal barriers, which are located along the ocean coastlines, across tidal
estuaries, or along the perimeter of very large lakes with long fetches, provide flood risk management
against high water levels and surges resulting from hurricanes or severe storms. These projects con-
sist of rock-lined earthen dikes or concrete walls and structures that confine the water and thereby
mitigate flood risk caused by storm surges and wave action. Flooding resulting from such conditions
is usually of short duration, ranging from a few hours to a few days. Hurricane and tidal barriers are
generally designed to withstand an infrequent combination of strong winds and high tides.
2.2.11.2. The barriers protect low lying areas from inundation and wave action and the associ-
ated management structures permit drainage of interior runoff during non-flood periods. In estuaries,
a movable barrier (sector, Tainter, or flap gates) may be incorporated into the design to permit navi-
gation through the structure during normal conditions. During tidal flooding, this movable barrier
closes off the navigation channel to preserve the integrity of the barrier system. During closure, the
interior runoff is either discharged by pumps or temporarily stored behind the barrier. In most cases,
the Corps retains ownership and management of those barrier elements that contain navigation facili-
ties; however, local communities are usually responsible for the O&M activities for barriers that do
not contain navigation features.
2.2.11.3. The management of barrier systems requires a water control plan to regulate the struc-
tures, including pumping stations, vehicular gate openings, sewer lines, and sea water intakes. When
rivers or tributaries drain into estuarine channels, the water control plan may require management of
the entire river system to mitigate risk to the estuary. Forecasts of controlled or uncontrolled tribu-
tary inflows may be an important element in the plan, but operational decisions should be made
based on water-on-the-ground unless stated in an approved water control plan.
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2.3. Navigation.
2.3.1. Historical Background.
2.3.1.1. Improvement of national waterways for navigation was an early concern in the water
resources development of the United States. The first artificial waterways were built in the northeast-
ern United States in the late 18th century and early 19th century by private developers. Federal in-
volvement became a matter of national policy, because the waterways were used for interstate com-
merce, as well as for national and international trade. The Federal government, through the Corps,
has been involved in navigation improvements along some 22,000 miles of inland and coastal water-
ways. Types of navigation improvements include canals, locks, dams, and reservoirs; maintained
channels and estuaries; and bank protection, pile dikes, and other forms of channel stabilization. Re-
leasing water from reservoirs to increase river levels is another type of navigation improvement.
2.3.1.2. Navigation improvements along a particular river may involve several of the afore-men-
tioned methods. Although the requirements are related mainly to commercial navigation, navigation
needs may exist for small boat operation and recreational use by the general public. Commercial
needs range from intra-river transportation by small draft barges and tows to deep-draft ocean-going
vessels for general use.
2.3.2. Water for Navigation.
2.3.2.1. General. The complexity related to water management for navigation use varies widely
among river basins and types of developments. Dams, reservoirs, or other facilities with navigation
as a project purpose should be regulated to help provide appropriate flows, or to help maintain pro-
ject navigation depths. Navigation needs are integrated with other water uses in multipurpose water
resources systems. In the regulation of dams and reservoirs, efforts to accommodate navigation in-
terests typically involve managing water levels in the reservoirs and at downstream locations as well
as providing the quantity of water necessary for lock operation. Navigation constraints may be inte-
grated into the regulation of dams and reservoirs with regard to rates of change of water surface ele-
vations and releases. Numerous special navigation conditions may involve water management, such
as the presence of ice, undesirable currents and flow patterns, emergency precautions, and boating
events and launchings.
2.3.2.2. Water Requirements for Lockage and Controlled Canals. Navigation locks located at
dams on major rivers generally have sufficient water from instream flows to supply lockage flow re-
quirements. Usually, water released from reservoirs for navigation also fulfills other purposes, such
as hydroelectric power generation, water supply, water quality, enhancement of fish and wildlife, and
recreation. Seasonal or annual water management plans may be prepared to define the use of water
for navigation. The amount of water available for release depends on the quantity of water stored in
the reservoir system, downstream requirements or goals for water supply, and consideration of all
uses of the water in storage.
2.3.2.3. Water Releases for Navigation in Open Rivers. Navigation requirements for down-
stream use in open river channels may require flows to be managed over a long period of time (from
several months to years), to achieve a significant, continuous increase in water levels for boat, barge,
or ship transportation. Water released from reservoirs to increase long-term downstream flows for
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navigation purposes may be a major factor in managing a system that has hydroelectric power gener-
ation requirements. A water control plan that includes both hydroelectric power generation and navi-
gation should include analyses to support operating decisions that balance the uses between those
two purposes as well as other authorized purposes (e.g., water supply, flood risk management). Ex-
treme daily fluctuations in releases that would result from power peaking operations may need to be
prevented due to navigation demands to maintain minimum water levels at downstream locations.
These restrictions, which may apply to both daily and weekly fluctuations in streamflow and water
levels, are determined by other requirements (e.g., for navigation, boating) of the waterway.
2.3.2.4. Winter Navigation. Winter navigation poses a special concern for water management.
The goal of an effective winter navigation plan should be to manage ice accumulations to maintain
winter navigation as long as reasonably practicable. If a winter navigation management plan is de-
sired, then it should be a part of the water control plan for the entire system. However, basin condi-
tions may be such that a water control plan does not support winter navigation, and instead provides
for seasonal navigation based on normal winter conditions.
2.4. Hydroelectric Power Generation.
2.4.1. Hydroelectric Power in Corps Projects. Hydroelectric power generation is a major el-
ement of many Corps water resources projects. Geographically, about three quarters of Corps
hydroelectric power is generated in the Northwestern Division.
2.4.2. Hydroelectric Power Evaluation. The methods to evaluate hydroelectric power capa-
bilities, power values, and power system operation are provided in EM 1110-2-1701, Hydro-
power. ER 10-1-53, Roles and Responsibilities, Hydroelectric Design Center, designates the
U.S. Army Corps of Engineers District, Portland, Hydroelectric Design Center (HDC), as the
Mandatory Center of Expertise (MCX) for hydroelectric power engineering and design.
2.4.3. Types of Projects.
2.4.3.1. Most projects with a hydroelectric power purpose may be placed into one of two distinct
categories: (a) dams and reservoirs that have sufficient storage to regulate streamflows on a seasonal
basis and have a flood risk management authorized purpose, and (b) lock and dam (run-of-the-river)
projects with minimal storage capacity relative to the volume of flow that are either primarily author-
ized for hydropower, or that also include navigation as an authorized purpose. Other, less common
types of projects and features include off-stream diversions, pumpback facilities, and hydrokinetic
projects.
2.4.3.2. Hydroelectric power projects are usually multipurpose, with additional water uses that
may include flood risk management, irrigation, navigation, M&I water supply, water quality, fish and
wildlife, and recreation. Normally, a reservoir will include provisions for power production at the
site as well as for release of water for downstream purposes. A storage project may also be paired
with a downstream reregulating dam to allow the powerhouse to fluctuate discharge in response to
power demand and to use the reregulating dam to dampen the flow fluctuations to maintain more sta-
ble downstream conditions.
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2.4.3.3. Run-of-the-river hydroelectric power plants are usually developed in connection with
navigation projects. These projects have minimal storage capacity, often allowing for only a limited
operating range. Within the operating range, the projects pass inflow either through generating units
or through an alternate gated or spillway structure.
2.4.3.4. In addition, power facilities may be developed in off-stream water supply channels or
irrigation works. In high mountain areas, off-stream diversions may be used for high-head power
plants. Also, pumped storage plants may be used to pump water into a storage reservoir, using less
expensive electricity available during times of surplus energy and releasing the stored water to gener-
ate hydroelectric power during peak system power demands.
2.4.3.5. In certain conditions, hydrokinetic projects can be developed from wave action or tidal
fluctuations in bays or estuaries or from flowing water in large rivers. Many such projects in the
United States are in various stages of planning, permitting, and construction.
2.4.4. Integration of Federal Hydroelectric Power Systems.
2.4.4.1. The electrical power produced at Corps projects in the United States is integrated with
electric power produced by other utilities. Power produced by Corps projects is marketed to the utili-
ties and other direct service customers by four regional power marketing administrations (PMAs) of
the Department of Energy. In addition to marketing, some of the PMAs also provide transmission
and dispatching services. The regional electrical power networks in the United States are complex
and highly integrated systems, the operation of which is made possible through formal agreements
made between utilities or through informal working relationships to enhance the overall capability of
individual utilities.
2.4.4.2. The four regional PMAs are Bonneville Power Administration (BPA), Southeastern
Power Administration (SEPA), Southwestern Power Administration (SWPA), and Western Area
Power Administration (WAPA). All four PMAs market Federally-produced power from dams
owned by the Corps. The Tennessee Valley Authority (TVA), a Federally-owned corporation, also
markets and transmits power from Corps-owned dams.
2.4.5. Management of Federal Hydroelectric Power Systems. For Corps hydroelectric pro-
jects, schedulers from the PMAs coordinate hydroelectric power operations with Corps water
managers to ensure successful integration of the Corps water management operations into the hy-
droelectric power system. In many cases, the Corps water management operations are con-
strained (e.g., minimum release, maximum release, release pattern) and are simply communi-
cated to the power marketing agency. At some projects, enough flexibility exists in the Corps
regulation schedule to allow for increased input from the power marketing agency. The Corps
may prescribe operating limits, such as forebay and tailwater constraints, and allow a power mar-
keting agency to communicate flow changes directly to operating project personnel, while stay-
ing within the prescribed constraints. In a river basin with dams owned by both the Corps and
other entities, Corps water managers may also have agreements to coordinate water management
activities with other dam owners to maximize all hydroelectric power benefits from the system.
2.4.6. Non-Federal Development of Hydroelectric Power at Corps of Engineers Projects.
The Federal Power Act, as amended on 1 April 1975, delegates to the Secretary of the Army and
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to the Commander, USACE certain functions necessary for Federal Energy Regulatory Commis-
sion (FERC) administration of the act. ER 1110-2-1454, Corps Responsibilities for Non-Federal
Hydroelectric Power Development Under the Federal Power Act, provides policy and guidance
for review of preliminary permit and license applications for non-Federal development at or af-
fecting Corps projects.
2.4.7. Special Operating Issues. Issues associated with power operation vary widely among
projects and systems, depending on the importance of hydroelectric power generation in relation
to other project purposes, the methods of hydropower system control, and the system integration
of power regulation with other multipurpose water management requirements. The water man-
ager is concerned with two basic types of issues, both of which result in a large degree of coordi-
nation with all users:
1. Seasonal project and system regulation, in which power is a consideration in the water
control plan.
2. Power regulation scheduled on a daily, weekly, or monthly basis to meet the power needs
in conjunction with the other water uses.
2.4.7.1. Seasonal Reservoir Regulation for Hydroelectric Power Generation. An annual operat-
ing plan (AOP) is generally developed on the basis of yearly hydrologic conditions, system power
requirements, and multipurpose requirements and goals for reservoir regulation. The studies required
for developing the AOP should be coordinated with other power interests and local or regional
groups that have an interest in the multipurpose aspects of water regulation.
2.4.7.2. Coordination. Coordination between the Corps and the PMA must occur in formulating
power production and power marketing strategies and integrating the operation of power facilities
within the regional power grid. This coordination involves many aspects of project operation and
reservoir regulation at Corps projects, including the development of the operating plan to achieve the
hydroelectric power generation operating objectives, scheduling reservoir releases, and dispatching
power under normal and emergency conditions. The coordination requires administrative proce-
dures, technical evaluations, and detailed working arrangements to ensure that the responsibilities of
the two agencies are met. This is generally accomplished by executing formal memorandums of un-
derstanding (MOUs) that define specific duties and responsibilities, establish coordinating groups
composed of agency representatives that oversee the operations, and form work groups assigned to
specific tasks.
2.4.7.3. Scheduling and Dispatching Power. Scheduling and dispatching power from Corps pro-
jects are performed according to the basic operating strategies and criteria contained in the AOP and
water control manual. The AOP consists of guide curves and other operating guidelines generalized
from power operation studies performed on the basis of mean monthly historical streamflow data and
estimated load and resource evaluations. The actual operating schedules must also be based on cur-
rent and forecasted hydrologic and power data. For small or relatively simple systems, the schedules
can be determined manually from analysis of current data and forecasts of operations. For large inte-
grated power systems, however, the schedules are usually determined from simulations that provide
current analyses of all hydrologic and power generation data, load forecasts, interchange require-
ments, and real-time plant and unit status conditions, and that conform to the constraints of operating
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rule curves. Forecasted simulations range from several days to weeks or months in duration, and
more general projections may be made for periods that extend multiple years. The actual operating
schedules are derived from the simulations of project operation. The daily operating schedules are
forwarded to the project office for plants not on centralized control or are inserted into the system
controller at the power control center. The schedules may indicate hourly generation values for
block loaded plants and anticipated plant loadings, unit status, and “break point” settings for plants
operating under automatic generation control (AGC) equipment.
2.4.7.4. Power Dispatchers.
2.4.7.4.1. The continuous operation of the power system is managed by the power dispatchers,
who monitor all aspects of plant and system operation. The dispatchers should be in frequent com-
munication with plant operators who manage the operation of hydroelectric facilities. The plant
operators are responsible for the plant operation according to the operating schedules and other op-
erating criteria that may affect water regulation and the operation of the physical facilities.
2.4.7.4.2. Corps water managers may need to communicate with dispatchers regarding regu-
lation schedules, transmission and generation constraints, emergencies; or to provide project up-
dates. This includes dispatchers for agencies transmitting power from Corps-owned dams, as
well as dispatchers for dams operated by other entities for which the Corps directs flood risk
management operations or has reservoir regulation responsibility.
2.4.7.5. Constraints on Peaking Operation at Hydroelectric Power Plants. Many hydroelectric
plants are designed to meet peaking and intermediate load requirements that result in a low load factor
operation. Some plants generate only at times of peak loading, generally for less than 8 hours per day,
and the generation is scheduled to help meet the morning or afternoon peak loads. Other plants are
scheduled for a more continuous operation, but still respond to daily variations in system loads. While
many advantages are obtained from operation for peak-only loading conditions, fluctuating outflows
resulting from this operation may cause water regulation issues. Environmental considerations, such as
the effect of fluctuating water levels on fish and wildlife, aesthetics, navigation, and public safety are
considered in the planning, design, and operation of peaking power plants. In some cases, water fluctu-
ations related to peaking operation are reduced by constructing reregulating reservoirs immediately
downstream from peaking power projects. At locations where construction of reregulating reservoirs is
impractical, specific operating limits for fluctuations in power production or water level in the river sys-
tem below the projects are developed on the basis of studies made during the design phase. Pondage
projects, which are developed in tandem on a major river, are operated as a system with regard to peak-
ing power operation. The total system output is shaped to meet the fluctuating power loads, so that all
plants share in loads and fluctuations of reservoir and tailwater water levels. The analysis of this type
of system operation is accomplished through use of the various computer models. In actual operation,
requests for restrictions in peaking operation may be made, beyond those set forth in the design or oper-
ational studies. Generally, these requests are a result of changed environmental conditions or other un-
anticipated conditions and should be carefully analyzed.
2.4.7.6. Departure from Normal Hydroelectric Power Operations.
2.4.7.6.1. During operation, circumstances may require minor departures from the operating
plans to satisfy unanticipated needs or desires for river regulation. In some cases, departure from
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operating plan schedules and guidelines may affect the ability to meet one or more of the water
management goals, and the issue may have to be referred to an appropriate administrative level
for resolution. The water manager must be informed immediately of any large scale interruption
of the power system and take actions as necessary to preserve the water management goals and
alert others regarding the emergency conditions.
2.4.7.6.2. The PMA may coordinate with Regional Transmission Organizations (RTOs) or
independent system operators (ISOs) to ensure the efficient and reliable delivery of power across
large areas. Occasionally, power market or regional transmission issues can influence the timing
of hydroelectric power releases or the method of releases by requiring water to be released
through outlet tunnels or spillways rather than to be used for hydroelectric power generation.
2.5. Irrigation.
2.5.1. Historical Background and Agency Roles. In the arid and semi-arid regions of the
western United States, the use of water to irrigate arable lands has been a major factor in devel-
oping water resources systems. The seasonal nature of precipitation and the lack of rainfall in
the growing season led to the development of agricultural water supplies following the turn of
the century. Initially, development of irrigation projects using surface water depended on diver-
sions from the flow of the rivers. As the developments increased in size, reservoirs were con-
structed to increase the dependable flow of the rivers, thereby assuring water supplies on an an-
nual or multiyear basis when the instream flow was insufficient to meet demands. As the com-
plexity of the developments increased, it became necessary to institutionalize these arrange-
ments. This originated first at the local and state levels of government, but Federal action was
initiated by the Carey Act of 1894.
2.5.1.1. U.S. Bureau of Reclamation (USBR). Reclamation law establishes irrigation in the West
as a national policy. For purposes of reclamation law, the West is defined as those 17 contiguous
states lying wholly or in part west of the 98th meridian. The Secretary of the Interior is authorized to
locate, construct, operate, and maintain works for the storage, diversion, and development of waters
for the reclamation of arid and semi-arid lands in the west. In these 17 western states, in conformity
with reclamation law, the repayment arrangements and agreements for irrigation water from Corps
reservoirs is administered by USBR.
2.5.1.2. Corps of Engineers. Section 8 of the Flood Control Act of 1944 provides that Corps res-
ervoirs may include irrigation as a purpose upon the recommendation of the Secretary of the Interior
and approval of the Secretary of the Army, after authorization by Congress under the reclamation
laws. This provision applies only to Corps reservoirs in the western states. Congressional authoriza-
tion would also provide the U.S. Department of the Interior (DOI) with the authority to construct, op-
erate, and maintain the additional irrigation works and to contract for the storage. In addition, Sub-
section 103(c)(3) of the Water Resources Development Act of 1986 (WRDA 1986) establishes a
35% non-Federal share of construction costs for Corps projects authorized for agricultural water sup-
ply. Section 931 of WRDA 1986 amends Section 8 to provide that, for any Corps reservoir project,
the Secretary of the Army may allocate to irrigation purposes, for an interim period, storage included
in the project for M&I water supply that is not under a repayment agreement.
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2.5.2. Water Diversions and Return Flows.
2.5.2.1. Water Duty.
2.5.2.1.1. The amount of water needed to meet the demands for growing crops for the entire
season is termed the water duty. This is equal to the total amount of water supplied to the land
by means of gravity diversions from rivers or reservoirs or pumped from rivers, reservoirs, or un-
derground sources of water. Net duty is the amount of water delivered to individual farm units,
considering losses in canals, laterals, and waste from the point of diversion to the point of appli-
cation on the land. In the western United States, the water duty averages about 2 acre-feet of de-
livered water per cultivated acre of land per year, and ranges from about one to as much as
6 acre-feet per cultivated acre.
2.5.2.1.2. Irrigation water diverted from reservoirs, diversion dams, or natural river channels
is controlled in a manner to supply water for the irrigation system as necessary to meet the water
duty requirements. The requirements vary seasonally, and in most irrigated areas in the western
United States the agricultural growing season begins in April or May. The diversions gradually
increase as the summer progresses, reaching maximum amounts in July or August. Then they
recede to relatively low amounts by late summer. By the end of the growing season, irrigation
diversions are terminated except for minor amounts of water that may be necessary for domestic
use, stock water, or other purposes.
2.5.2.1.3. The return flow of water from irrigated lands is collected in drainage channels,
where it flows back into creeks and natural river channels. This return flow augments the pre-
vailing river flow, and depending on water rights and quality, the return flow may be reused for
downstream irrigation or to supply some other water use function. Continued improvements in
irrigation practices have made higher efficiencies in consumptive, on-farm water application
more practical; however, these practices may result in lower return flows and higher net con-
sumptive use from a basin perspective.
2.5.2.1.4. USBR annually completes and provides western Corps projects with a depletion anal-
ysis. Depletions are defined as removal of water from a river or reservoir for a specific man-induced
activity, such as irrigation of cropland. The depletion estimates are used by the Corps in long-term
model simulations as well as calendar year runoff projections. As resource development continues, a
growth in depletions can be expected. While increasing depletions likely benefit the flood risk man-
agement function, it is evident that they may have adverse effects on other authorized purposes, such
as irrigation, that are dependent on the availability of a continuing water supply.
2.5.3. Water Management for Irrigation.
2.5.3.1. Corps reservoir projects have been authorized and constructed primarily for flood risk
management, navigation, and hydroelectric power generation. However, several major Corps multi-
purpose reservoir projects include irrigation as a project purpose. Usually, water for irrigation is sup-
plied from reservoir storage to augment the available streamflows to meet irrigation demands in
downstream areas. In some cases, water is diverted from the reservoir by gravity through outlet facil-
ities at the dam that feed directly into irrigation canals. At some run-of-the-river power or navigation
projects, water is pumped directly from the reservoir for irrigation.
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2.5.3.2. The general mode for regulation of multipurpose reservoirs to meet irrigation demands is
to capture all runoff in excess of minimum flow demands and rule curve levels to refill the reservoirs
before the irrigation demand season. The water is held in storage until the instream flow recedes to the
point where it is insufficient to meet all consumptive and instream demands. At that time, the release
of stored water from reservoirs begins and continues on a demand basis until the end of the growing
season, or when flow augmentation is no longer needed for water quality or fish and wildlife. During
the late fall and winter, projects release water for instream flows, stock water, or other project purposes,
such as to evacuate for flood risk management during the annual flood season.
2.6. M&I Water Supply Use.
2.6.1. Basic Considerations.
2.6.1.1. Many Corps reservoir projects supply water for M&I use as an authorized purpose.
M&I water users must separately acquire all necessary water rights. At Corps reservoir projects,
M&I water supply is typically managed according to long-term water storage agreements between
the Corps and nonfederal entities pursuant to the Water Supply Act of 1958. These agreements au-
thorize the use of reservoir storage of water supply to meet demands commensurate with the esti-
mated yield of that storage space, and they require that the water supply users share in the costs to
construct, operate, and maintain the project.
2.6.1.2. ER 1105-2-100, Planning Guidance Notebook, describes the objectives, policies, alloca-
tions of storage, repayments, obligations, and other aspects of plan formulation involved in incorpo-
rating water supply for M&I use into Corps reservoirs projects. The policies stem principally from
the Water Supply Act of 1958. While certain water withdrawals may be accommodated under other
authority, such as limited uses under approved shoreline management permits, in general, withdraw-
als or releases of water from Corps reservoir projects for M&I use must fall under a project-specific
authority, the Water Supply Act of 1958, or Section 6 of the Flood Control Act of 1944. Questions
regarding the authority for water supply withdrawals should be directed to the office of counsel.
2.6.2. Other M&I Water Supply Considerations.
2.6.2.1. Storage rights of the user are defined in the current agreement format in terms of an un-
divided percentage of usable conservation storage space, including the estimated acre-feet of storage
at the time of agreement execution. When storage is available, the user generally has the right, sub-
ject to relevant conditions, to withdraw water from the reservoir or to order releases to be made
through the outlet works. Availability of storage may be subject to periodic accounting based on pro-
portional sharing of inflows and losses, and to certain rights that are reserved to the Government with
regard to the project’s overall regulation.
2.6.2.2. Estimates of reliable yield for local users based on their available storage space may de-
crease over time due to changing hydrologic conditions or sedimentation. Such findings should be
communicated to the local users for use in their own planning and operations. Typically, water storage
agreements require that, when findings of a sediment survey indicate that the storage available for M&I
water supply has been affected by unanticipated sedimentation, the sediment reserve storage will be eq-
uitably redistributed among all of the project purposes, and the total remaining storage space in the pro-
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ject will be divided among the purposes in the same ratio as the original storage agreement to the origi-
nal authorization of other purposes. The resulting change in storage allocated to the M&I user will be
described in an exhibit to the storage agreement and update to the water control manual.
2.6.2.3. In times of drought, special considerations may guide the regulation of projects with re-
gard to water supply. ER 1110-2-1941, Drought Contingency Plans, provides policy and guidance to
prepare drought contingency plans. Drought contingency planning requires close coordination among
all Federal, state, and local interests to maintain reasonable expectations regarding project water levels.
2.7. Water Quality.
2.7.1. General.
2.7.1.1. Corps policy for water quality management at Corps civil works projects is outlined in ER
1110-2-8154, Water Quality and Environmental Management for Corps Civil Works Projects. Alt-
hough water quality control may not be an authorized project purpose at all projects, the Corps tries to
protect and enhance the quality of water and land resources at its projects as a matter of policy.
2.7.1.2. Water quality benefits may accumulate slowly, but become quite substantial over time;
this contrasts with the substantial benefits that may quickly accrue from a single flood risk management
operation. Potential considerations to address water quality include selective withdrawal, run-of-the-
river releases, variable minimum flows, temperature management, and routing of sediments.
2.7.2. Releases for Downstream Management.
2.7.2.1. Water quality releases for downstream management have both quantitative and qualita-
tive aspects. One of the most common measures of water quality is flow. At many projects author-
ized for water quality management, a minimum flow at a downstream control point is the water qual-
ity objective. However, flow alone does not ensure a sustainable downstream habitat for aquatic life.
2.7.2.2. The qualitative aspects relate to Corps policy and objectives to meet Federal, state, local,
and tribal water quality standards and to maintain a sustainable downstream habitat for aquatic life.
The stream and reservoir water temperature annual cycle of warming in the spring and cooling in the
fall is an important consideration in managing the water resources project, as temperature is critical
to life cycles in the aquatic community. Dissolved oxygen is related to temperature, and aquatic
communities require continuous supplies of dissolved oxygen. Satisfactory average dissolved oxy-
gen concentrations are not sufficient to sustain an aquatic community; for example, a single, brief an-
oxic project release may cause a fish kill. Reservoirs may stratify during parts of the year creating a
potential for anoxic releases. Monitoring the oxygen levels in a reservoir and outlet channel, re-aera-
tion in the stilling basin and downstream area, monitoring the oxygen demand of release water, and
use of appropriate intakes and outlets can help to reduce anoxic occurrences.
2.7.3. Monitoring.
2.7.3.1. Water quality should be monitored continuously for effective water management of en-
vironmental resources. Data collection guidance and reporting requirements are contained in ER
1110-2-8154. A comprehensive treatment of all aspects of water quality monitoring and data analy-
sis can be found in EM 1110-2-1201, Reservoir Water Quality Analysis. Data collection programs
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should be adapted to each water resources project, as documented in the water control plan, to ensure
that project purposes are not compromised and to monitor effects of project regulation on reservoir
and outlet channel water quality.
2.7.3.2. As part of the Clean Water Act, states are required to establish total maximum daily
loads (TMDLs) for specific parameters on some streams. TMDLs may have a direct impact on man-
agement of a Corps reservoir project, and a coordinated effort to establish TMDLs is important.
2.7.3.3. Known or suspected issues such as harmful algal blooms (HABs) or priority contami-
nants require special and often intensive data collection efforts. As appropriate, districts should de-
velop HAB response plans coordinated with the division office, as HABs may have devastating con-
sequences on project purposes such as recreation, water supply, and fish and wildlife. Districts re-
sponsible for navigation channel maintenance must coordinate with regulating agencies regarding
priority contaminants.
2.7.4. Selective Withdrawal for Water Quality Management. Most impoundments exhibit
some degree of temperature stratification. Due to water quality variations in the reservoir water
column, the primary means of managing the quality of reservoir releases is to provide facilities to
withdraw water from various levels in the reservoir, such as multilevel intake structures, when
available. Managing the quality of releases through selective withdrawal structures requires suf-
ficient data to coordinate daily decisions. Withdrawing water from any one reservoir elevation
layer, based on a water quality vertical profile, may be insufficient to meet all water quality ob-
jectives. Detailed technical guidance for selective withdrawal is provided in EM 1110-2-1201.
2.7.5. System Regulation for Water Quality.
2.7.5.1. Water quality maintenance and enhancement beyond the discernible beneficial effects of
a single project may also be achieved through coordinated system regulation. System regulation for
water quality may be of value during low-flow periods, when available water should be managed
carefully to avoid degrading reservoir or river quality.
2.7.5.2. Differences between series and parallel systems and associated downstream impacts
should be understood. In series operation, upstream projects release water into downstream projects,
directly impacting the water quality in the downstream project. In cases where the system is com-
prised of parallel projects, water released from multiple projects may impact a common downstream
control point.
2.8. Fish and Wildlife.
2.8.1. Authority. Corps projects may be specifically authorized for fish and wildlife. Appen-
dix B to this manual lists several important Federal laws and executive orders that also influence
how the Corps manages projects with respect to fish and wildlife. Regardless of the authority, the
Endangered Species Act (ESA) requires the Corps to ensure that its discretionary operations do not
jeopardize the continued existence of any Federally listed threatened or endangered species. If op-
erations are likely to adversely affect an endangered or threatened species a Biological Assessment
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and consultation with the appropriate Federal agency is required, usually the National Marine Fish-
eries Service or the U.S. Fish and Wildlife Service. A Biological Opinion may be issued outlining
actions and measures to be implemented to avoid jeopardizing the listed species.
2.8.2. General.
2.8.2.1. Fish and wildlife management opportunities and issues related to water management
vary widely depending on the project’s geographical location, management objectives, and opera-
tional capabilities. Each project’s water control manual should contain specific information regard-
ing how the project should be regulated to meet the fish and wildlife objective.
2.8.2.2. Most large water management projects are authorized and designed for multiple pur-
poses and water control plans may contain enough flexibility to permit some manipulation of water
levels and reservoir releases for fisheries management and other wildlife considerations. Water man-
agers may work with relevant stakeholders to understand how pool level fluctuations and the quality,
quantity, and timing of project releases impact fish and wildlife.
2.8.2.3. Developing guidance to creatively manage projects for fisheries is complicated by con-
sideration of the wide range of hydrometeorological events that may occur and the effects of regula-
tion to meet project authorized purposes. Further complexity is introduced by the fact that habitat
requirements for spawning, incubation, and emergence times vary greatly among species.
2.8.2.4. While the project’s structural design may limit the flexibility of regulation strategies, ob-
jectives and priorities for fish and wildlife management should be identified and coordinated with ap-
propriate fish and natural resources agencies. The agencies may include the U.S. Fish and Wildlife
Service, the National Oceanic and Atmospheric Administration (NOAA) National Marine Fisheries
Service, state fish and wildlife agencies, and tribal groups.
2.8.3. Reservoir Fisheries.
2.8.3.1. One of the most readily observable effects of reservoir regulation is reservoir pool fluc-
tuation. Periodic fluctuations in reservoir water levels present both issues and opportunities to the
water manager with regard to fishery management. The seasonal fluctuations that occur at many
flood risk management reservoirs and the daily fluctuations that occur with hydroelectric power gen-
eration may eliminate shoreline vegetation, thereby leading to shoreline erosion, water quality degra-
dation, and loss of riparian and aquatic habitat, and physical disruption of spawning and nests.
2.8.3.2. Fishery management techniques may include managing pool levels to force foraging
fish out of shallow cover areas and into areas more susceptible to predation, maintaining appropriate
pool levels during spawning, and minimizing fluctuation in pool levels. Wave action from slowly
lowering pool levels can help maintain clean gravel substrates, which are favorable to some target
fish species. Alternatively, bank erosion and slumping that removes substrate and prevents establish-
ment of vegetated littoral zones can occur in some reservoirs.
2.8.3.3. The success of each management technique varies regionally and by individual reservoir.
The variability in physical, biological, chemical, and operational characteristics and uncontrolled envi-
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ronmental influences create difficulty in predicting the results of changes in reservoir levels and re-
leases on fisheries. Reservoir design, mode of operation, and developmental requirements of target fish
species affect water management strategies. Manipulation of water levels to enhance fisheries is often
based on the timeliness of flooding or dewatering shoreline vegetation. For recommended seasonal
flooding of shoreline vegetation, fishery management plans may include lowering water levels during a
portion of the growing season to permit regrowth of vegetation. By regulating the timing and duration
of flooding, water level management schemes can be developed for a reservoir to encourage the estab-
lishment of desirable, innocuous macrophytes and to reduce nuisance aquatic plants.
2.8.3.4. Water-level management in fluctuating warm-water and cold-water reservoirs generally
includes raising water levels during the spring to enhance spawning and survival of young predators.
Pool levels are lowered during the summer to permit regrowth of vegetation in the fluctuation zone.
Fluctuations may be timed to benefit one or more target species; therefore, several variations in oper-
ation may be desirable.
2.8.3.5. Fall, winter, or summer drawdowns are often recommended for shallow reservoirs that
support large stands of water plants (aquatic macrophytes). The drawdowns are effective in concen-
trating prey species and controlling aquatic vegetation. Drawdowns that reduce surface area by as
much as 50% may be desirable in some cases. As with other basic approaches to water-level man-
agement, numerous variations have been applied and drawdowns for macrophyte and rough fish
management are sometimes combined.
2.8.3.6. In addition to small pool fluctuations, periodic major drawdown has been used effec-
tively for fishery management. This procedure includes a drastic lowering of a reservoir pool for an
extended time period (at least one growing season) to permit vegetative regrowth in the dewatered
zone. This step may be augmented by seeding plants to establish desirable species. Some objectives
may be accomplished by selectively removing or killing various fish communities. Finally, the reser-
voir is refilled during the spring, fish are restocked, and a high water level maintained through the
summer. This technique is effective for stimulating production of desirable sport and prey fishes, alt-
hough authorized reservoir purposes must be taken into consideration.
2.8.3.7. Water-level management in some cold-water reservoirs has been oriented toward the
production and enhancement of salmonoids, with anadromous species receiving primary considera-
tion. Management issues related to production of salmonoids include maintaining access to tributary
streams for spawning, controlling releases to facilitate passage of anadromous species, limiting losses
of important sport fishes, and stabilizing reservoir pool levels during the extended periods of egg and
larval development of certain species.
2.8.4. Downstream Fisheries.
2.8.4.1. Guidelines to meet downstream fishery management potentials may be developed for
each project based on project water quality characteristics and the water management capabilities.
An understanding of the reservoir water quality regimes is critical for developing the water manage-
ment operating criteria to meet the objectives. For example, temperature is often a major constraint
of fishery management in the downstream reach, and water managers should understand the tempera-
ture regime in the reservoir pool and downstream temperature goals as well as the project’s capability
to achieve a good balance between uncontrolled inflows and project releases. Releasing cold water
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instead of warm water to meet fishery management objectives may be detrimental to the downstream
fishery. Conversely, releasing warm water may impact a cold-water downstream fishery.
2.8.4.2. Water management activities can also impact reservoir water temperatures by changing
the volume of water available at a particular temperature. In some instances, cold-water reserves
may be necessary to maintain a downstream temperature objective in the late summer months. For
some projects, particularly in the southern United States, water management objectives include main-
taining warm-water sports fisheries in the reservoir, and in some cases, cold-water fisheries in down-
stream reaches. In other instances, fishery management objectives may include the maintenance of a
two-tier reservoir fishery, with a warm-water fishery in the surface layer, and a cold-water fishery in
the bottom layer. To meet such an objective, water managers should endeavor to regulate the project
to maintain the desired temperature stratification and sufficient dissolved oxygen in the bottom for
the cold-water fishery, dependent on the location of intake gates. Also, the water manager should
have an understanding of operational effects on seasonal patterns of thermal stratification and the
ability to anticipate thermal characteristics. The ability to analyze these effects depends on relevant
data being collected throughout the season.
2.8.4.3. Rapid changes in release volumes can have positive or negative downstream effects. In-
creasing releases from near zero to very high magnitudes, such as those that result from flood regula-
tion or hydroelectric power peaking regulation, are sometimes essential to maintain downstream
gravel beds for species that desire this habitat. However, rapidly decreasing releases can be detri-
mental to downstream fish and other aquatic organisms by stranding fish in relatively low-gradient
areas of the channel or in pockets or side channels, dewatering eggs incubating in streambed gravels,
increasing bird predation, elevating water temperatures, and reducing the benthic macroinvertebrate
population. Other important factors to consider in managing releases include river channel morphol-
ogy, channel substrate type, time of day, season, water temperature, flow level, and fish species and
life stage. Maintaining minimum releases and incorporating reregulation structures are two options
available to mitigate adverse effects.
2.8.4.4. The Corps is responsible for providing established minimum releases from water manage-
ment projects to maintain downstream fisheries and the health of the downstream aquatic environment
as specified in the water control manual. The release influences the downstream food supply, water
velocity, and depth. Water managers often maintain minimum releases for this purpose along with
minimum flow requirements for other instream purposes. Minimum instream flows are often required
by state laws to maintain biological productivity, to provide spawning and rearing habitat, to decrease
fish vulnerability to predation, and to support necessary oxygen and temperature conditions.
2.8.4.5. In some instances, fishing in an outlet channel is at a maximum during summer week-
ends and holidays and at times when power generation may be at a minimum and project releases
near zero. Maintaining minimum releases during weekend daylight hours may improve the recrea-
tional fishing, but may reduce the capability to meet peak power loads during the following week be-
cause of lower water level (head) in the reservoir. In this instance, water managers may be particu-
larly challenged to regulate the project for hydroelectric power and downstream fisheries.
2.8.4.6. The development of downstream total dissolved gas supersaturation, which can occur as
water is released over a spillway or through a regulating outlet, may impact the aquatic biota. Man-
aging this phenomenon is discussed in Chapter 4.
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2.8.4.7. Opportunities to modify reservoir regulation increase with the complexity of the reser-
voir river system (e.g., Columbia River, Missouri River, White River, and Lower Ohio River basins),
in which reservoir regulation is highly integrated. Reservoirs regulated primarily for flood risk man-
agement generally provide greater water level management flexibility than do hydroelectric power
generation projects.
2.8.5. Fish Migration.
2.8.5.1. Another concern, particularly in the Pacific Northwest, is the maintenance of successful
migration of anadromous fish such as salmon; similar objectives exist in the northeastern United States
and in places that other anadromous fish, such as striped bass, have become established. Declines in
anadromous fish populations have been attributed to dams from physical or thermal blockage of migra-
tion, alteration of normal streamflow patterns, habitat modification due to inundation, blockage of ac-
cess to spawning and rearing areas, delays in migration rates, and changes in water quality.
2.8.5.2. Regulation for anadromous fish is particularly important during certain periods of the
year. Generally, upstream migration of adult anadromous fish begins in the spring of each year and
continues through early fall, and downstream migration of juvenile fish occurs predominantly during
the spring and summer months. The reduced water velocities in reservoirs in comparison with pre-
project conditions may greatly lengthen the travel time for juvenile fish to travel downstream through
the impounded reach. In addition, storage for hydroelectric power reduces spillage, and as a result,
juvenile fish pass through the turbines or a constructed fish bypass system. The longer travel time
subjects the juvenile fish to greater exposure to birds and predator fish, as well as delay in physio-
logic development required to enter the ocean. Passage through the powerhouse turbines may in-
crease fish mortality. To improve juvenile survival, storage has been made available at some projects
to augment river flows, to increase spill rates, and to divert flows from the turbine intakes into collec-
tor dams. Barges or tank trucks can be used to transport juveniles from the collector dams to release
sites below the projects. Other Corps projects have been modified to allow for juvenile fish passage
through ice and trash sluiceways or newly constructed surface flow weirs.
2.8.5.3. Catadromous fish, such as eels, may also have migration flow needs. In addition, inva-
sive anadromous species, such as sea lamprey in the Great Lakes region, may need to be limited to
support catadromous fish populations.
2.8.5.4. Regulation to allow for adult fish passage may include selective operation of power
units and spillway bays to manage downstream flow patterns to attract adult fish to ladder entrances.
Chapter 4 discusses water management facilities to protect and enhance anadromous fisheries.
2.8.6. Reservoir and Downstream Wildlife.
2.8.6.1. Drawdowns to manage wildlife may allow for the natural and artificial revegetation of
shallows for waterfowl, the installation and maintenance of artificial nesting structures, the manage-
ment of vegetative species composition; and may ensure mast tree survival in greentree reservoirs.
Wildlife benefits of intentional, temporary, and non-damaging inundation could include inhibition of
the growth of undesirable and perennial plants, creation of access and foraging opportunities for wa-
terfowl in areas such as green tree reservoirs, and management of water levels in stands of vegetation
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to encourage waterfowl nesting and reproduction. In the central United States, managers frequently
recommend small increases in pool levels during autumn for waterfowl management.
2.8.6.2. Water level manipulations without regard to effects on wildlife habitat may result in
many impacts, including the destruction of emergent and terrestrial vegetation, permitting access of
predators to otherwise inaccessible areas, abandonment of active nest sites, and rendering soils with
iron oxides unproductive. Downstream riparian, floodplain, and wetland habitat may also benefit
from periodic flow augmentation from dams.
2.9. Recreation.
2.9.1. Historical Background. In many cases, the use of reservoir projects for recreation stems
from the Flood Control Act of 1944 and the Federal Water Project Recreation Act of 1965 (gener-
ally referred to as PL 89-72). Regulation of reservoirs for reservoir and downstream recreation in-
terests should be balanced against meeting the other project purposes, such as flood risk manage-
ment, navigation, or others. Many projects, including those for which recreational facilities may
have been included under general provisions of the Flood Control Act of 1944, as amended, do not
have separable storage costs for recreation. In these cases, recreation is of secondary importance as
an authorized purpose to project functions for which storage was formulated.
2.9.2. General Considerations. The general public uses reservoirs for recreational activities.
Also, river systems below dams are frequently used for recreational boating, swimming, fishing,
and other water-related activities. Recreational activity is a source of income for businesses cater-
ing to water-related recreational pursuits, as well as for service establishments located near the
river. Water control plans should consider the effects of streamflow and water levels on recrea-
tional activities at the project site, in the reservoir area, and at downstream locations.
2.9.3. Water Management Considerations.
2.9.3.1. Recreational use of reservoirs may extend throughout the year. Under most circum-
stances, reservoirs yield the optimum recreational use when they are at or near full multipurpose pool
during the recreation season. The degree to which this objective can be met varies widely, depending
on the regional characteristics of water supply, runoff, and the basic objectives of water management
for the various water use functions. Reservoir facilities for recreation may be designed for use under
the planned reservoir regulation guide curves, which reflect the ranges of reservoir levels that are to
be expected during the recreational season. In low-runoff years, or years in which the runoff is de-
layed because of weather conditions, maintaining full pool reservoir levels during the recreational
season may not be possible.
2.9.3.2. In addition to the seasonal regulation of reservoir levels for recreation, regulation of pro-
ject outflows could enhance the use of downstream channels and ensure the safety of the general
public recreating downstream of a project.
2.9.3.3. Biological opinions to benefit threatened or endangered species may also influence res-
ervoir management. A summer drawdown for downstream flow augmentation or water quality en-
hancement during the peak of the recreational season is an example of a change to a historic pattern
of resource use that may not be supported by the local population.
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2.9.4. Water Management for Downstream Recreational Use. Water levels needed to maintain
or enhance river recreation are usually much smaller than those needed for other major project
uses, but specific objectives could be included in the water control plan to benefit recreation in
downstream rivers. The objectives may be to provide minimum project outflows or augmented
streamflows at times of special need for boating or fishing. Also, since river drifting is becoming
an important recreational use of some rivers, management opportunities may exist to provide this
use for relatively short periods of time. Releases should be adjusted gradually and communicated
to the public in order to help avoid dangerous or abrupt changes in downstream water levels.
2.10. Erosion and Deposition Considerations.
2.10.1. General. Interruption of the natural sediment processes of a stream generally results
in deposition of sediment in the upstream reservoir area, and corresponding erosion and degrada-
tion of the streambed and banks immediately downstream from the project. The location of de-
posits in the reservoir is a function of the size of the reservoir; the size, composition type, and
quantity of the sediments being transported; and the pool level at the time of significant inflow.
The amount of bank and shoreline erosion is closely related to the rate and magnitude of the pool
level fluctuations. Erosion and deposition may impact many project-related functions and should
be recognized, considered, and carefully monitored throughout the life of a project.
2.10.2. Downstream Considerations.
2.10.2.1. Large reservoir projects frequently trap and retain suspended sediment and bed material
load within the upstream pool, thus releasing sediment-free water. These releases, which often vary
from zero to maximum capacity within a very short time period, may erode both the bed and banks of
the stream immediately downstream from the outlet structure. The amount and rate of this erosion is
related to the composition of the bed and bank material, the volume and rate of water released on an
annual or seasonal basis, vegetation along the banks, and the manner in which the flow is released.
Fluctuating releases often result in initial bank erosion, and this loss is closely related to the magnitude
of the stage fluctuation. Bank erosion causes a loss of riparian vegetation into the adjacent channel.
This vegetative debris can cause channel blockages or shoaling. Bank recession is generally highest
following initial project operation and usually stabilizes in the first few years of operation as the bed
slope adjusts to a revised flow regime. Once an equilibrium bed profile has been achieved, the bank
erosion processes may return to conditions similar to those of a natural channel. Periodic wetting and
drying of the banks through fluctuating releases may increase bank erosion. Significant reservoir re-
leases may also result in further lowering of the streambed, with the maximum amount of lowering oc-
curring immediately downstream from the outlet protection and decreasing in the downstream direc-
tion. This degradation process continues until an equilibrium slope is reached or the bed becomes natu-
rally armored. Armoring occurs when removal of the fine sediment exposes the coarser, less-erodible
bed materials. Once the bed becomes naturally armored, future lowering of the streambed is usually
insignificant unless an excessively large release has sufficient energy to disrupt the armor layer.
2.10.2.2. Small- and medium-sized reservoir projects often have downstream channels that aggrade
over time, much different from the downstream channels of large projects described above. Projects that
make only intermittent releases over short periods of time, or low-level releases over extended periods of
time may result in extensive downstream deposition and subsequent vegetative encroachment. Aggrada-
tion tends to continue, and once established, the process may be difficult to reverse. Annual flushing
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flows, capable of removing deposits near the mouth of tributaries, are often replaced by low-level non-
erosive releases, contributing to the loss of channel capacity and future operating flexibility.
2.10.3. Upstream Considerations.
2.10.3.1. Shoreline Erosion. Reservoir shorelines, which are subject to a number of forces con-
tributing to instability, frequently undergo major changes throughout a project life. Fluctuating pool
levels saturate previously unsaturated material, resulting in slides when the pool level is drawn down
to lower levels. Reservoir banks are also subjected to attack by both wind and waves, which tend to
remove bank material and undercut the banks.
2.10.3.2. Reservoir Deposition. Reservoir sediment deposits may impact not only the reservoir
storage capacity over the life of a project, but also many project purposes both adjacent to the pool
and in the backwater reach immediately upstream from the pool. Sediment deposits are not restricted
to the lower reservoir zone typically reserved as a sediment pool. Deposition often occurs in the mul-
tipurpose or flood pool zones in the form of large deltas and may cause a multitude of issues and con-
cerns as the project matures. Major sediment deposits can reduce the storage reserved for flood risk
management to such an extent that an adjustment in the flood pool level must be made to maintain
the flood storage capacity. The deposits may also have a significant impact on the backwater profile
of reservoir inflows over time, resulting in increased groundwater and surface water levels and flood-
ing concerns in the areas immediately upstream from the reservoir pool. The location of the sedi-
ment deposits may also affect and contribute to ice accumulations and jams, which become opera-
tional constraints during certain times of the year. The impact of sediment accumulations in the res-
ervoir should be recognized and accounted for in the planning, design, and operation of the project.
2.10.4. Monitoring.
2.10.4.1. Water management may include balancing inflow, storage, and release of water from a
reservoir or system of reservoirs and the effects in downstream channels. Sediment erosion and dep-
osition in a reservoir can alter system response over time, requiring water managers to adapt manage-
ment practices to maximize project benefits. Water control plans should be revised as needed to re-
flect changes in project storage from sediment accumulation that affect operational criteria and man-
agement decisions.
2.10.4.2. Sediment monitoring programs may be expensive and should be based on individual
project needs, purposes, and conditions, but should generally include the requirements identified in
EM 1110-2-4000, Sedimentation Investigations of Rivers and Reservoirs. Considerations for dry
reservoirs and those with sediment pools are discussed in EM 1110-2-4000.
2.10.5. Operating Guidelines. Water managers should be aware of the impacts that project
operations have on erosion and deposition and should operate to manage both upstream and
downstream impacts to the extent reasonably possible in consideration of other project purposes.
Problem areas and the potential impact of alternative regulations may influence project operating
decisions. Although much of the erosion and deposition may be beyond the control of water
management, certain precautions may significantly reduce concerns. These include:
a. Lowering the rate of reservoir pool drawdown.
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3. Avoiding sudden increases in project releases and subsequent downstream stage fluctuations.
4. Avoiding sudden cutbacks in hydroelectric power generation and flood risk management
releases and resultant stage fluctuations.
5. Keeping reservoir pool levels as low as possible during known periods of high sediment
inflow to encourage sediment depositions in the lower zones of the pool.
6. Raising pool levels sufficiently to inundate existing sediment deposits and preclude the
establishment of permanent vegetation and subsequent increased sediment deposition in
the backwater reaches entering the pool.
7. Scheduling periodic releases through the outlet works to preclude sediment accumula-
tions in and near the intake structure and in the downstream channel.
8. Recognizing conditions that may impact erosion and deposition, such as ice jams, tribu-
tary inflow, shifting channels, and local constraints, and adjusting regulation criteria to
reduce impacts.
2.11. Aesthetic Considerations. The effects of water management on the aesthetics of a river
system are closely related to the public use of reservoirs and rivers and may be considered in op-
erating decisions. Good management may mitigate harm to the aesthetics and the general beauty
of the riverine environment. Such mitigation may include establishing minimum streamflows
and related river levels, minimizing the duration of exposure of unsightly reservoir shoreline re-
sulting from reservoir drawdown, or releasing water for special aesthetic purposes. Many water
management projects may be unable to fully compensate for such effects and still meet author-
ized project purposes. For some projects, water control plans may be adjusted to partially miti-
gate these effects. The relative importance of aesthetic considerations varies widely, and the ad-
justment of water control plans to meet aesthetic goals is based on judgment and knowledge of
all water management functions.
2.12. Cultural Resources
2.12.1. As defined in 36 CFR 800, cultural resources (also referred to as historic properties)
include any prehistoric or historic site, district, building, structure, or object, as well as properties
of religious and cultural significance to Indian Tribes, that are listed in or eligible for listing in
the National Register of Historic Places. Appendix B to this manual includes relevant laws.
Corresponding Corps regulations include ER 1130-2-540, Environmental Stewardship Opera-
tions and Maintenance Policies, and EP 1130-2-540, Environmental Stewardship and Mainte-
nance Guidance and Procedures, Change 2 (31 July 2005), which outline Corps policy, guidance,
and procedures to apply principles of good environmental stewardship to the natural and cultural
resources on USACE administered and/or managed lands and waters.
2.12.2. Cultural resources management issues related to water management vary depending
on the management objectives and the operational capabilities of the project. Water managers
should be aware of the potential adverse effects to cultural resources by continually evaluating
the effects of project regulation.
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CHAPTER 3
Water Control Plans
3.1. General.
3.1.1. A water control plan is based on operating criteria pertinent to the daily water man-
agement of Corps water resources projects. The water control plan is documented within the wa-
ter control manual and provides operating guidelines to deliver congressionally authorized pro-
ject purposes and benefits. This chapter outlines various steps and technical considerations that
should be used to develop water control plans for projects and systems.
3.1.2. Water control plans for all Corps projects must be prepared according to established
general principles and guidelines consistent with Federal policy. The variety of projects, their re-
spective congressionally authorized project purposes, and conditions related to water management
throughout the nation make it impossible to develop a single water control plan that applies to all
projects. Each watershed, river basin, and region has unique requirements. Furthermore, a wide
range of infrastructure (dams, canals, culverts, spillways, locks, pump stations, hydroelectric tur-
bines) may exist at the projects. For example, the criteria required for a series of single purpose
locks and dams designed for improving navigation are different from the criteria required for large
multipurpose reservoir systems involving several projects and complicated interactions among the
various authorized purposes. Some Corps projects may have specific legislation requiring prepara-
tion of documents other than a water control plan or a water control manual.
3.1.3. The Corps is responsible for conducting operations consistent with the water control
plan and for providing oversight of non-Corps entities using a Corps water control plan. In addi-
tion, several water resources projects have been constructed through international agreements
with Canada and Mexico in which the Corps participates in implementing a water control plan
developed and approved by boards or commissions. These international bodies may choose to
use this EM as guidance in developing their water control plans.
3.1.4. The principal means by which to provide the most beneficial use of limited water re-
sources and to achieve national water management goals is to operate water resources projects
and systems according to an approved water control plan.
3.1.5. Any physical operating constraints should be clearly outlined in the water control plan
to ensure that water management features are operated in a safe manner and within design limita-
tions during all phases of project life, including the construction phase.
3.2. Principles and Objectives.
3.2.1. General.
3.2.1.1. The Corps is required to develop water control plans and may provide those plans to a
non-Federal sponsor responsible for a project’s O&M. The principal guidelines used to schedule
project water management activities are discussed in this chapter. A water control plan:
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a. Addresses the water management needs and methods required to meet congressionally
authorized project purposes through water management operating criteria (e.g., regulation sched-
ule or guide curve, minimum flow, optimum water level range, desirable discharge, drought con-
tingency plan).
9. Considers all water management objectives (functional, environmental, social, and aes-
thetic) and various techniques, organizations, systems, and facilities involved in the water
management of a Corps water resources project.
10. Addresses reasonably foreseeable conditions and may include procedures to respond to
hydrometeorological events in a timely manner or to avoid anticipated detrimental im-
pacts.
11. Outlines the process to deviate from normal operation.
3.2.1.2. The development of the water control plan should originate during the earliest studies
conducted as part of the planning process and should continue through the various phases of investi-
gation, justification, authorization, design, construction, and O&M of a water resources project. De-
velopment of a water control plan should proceed with full knowledge of planning and design stud-
ies, and with the realization that changed conditions may require adjustments from the previously de-
veloped operating criteria, whether those criteria are associated with early studies or previously im-
plemented water management activities. Chapter 2 contains fundamental information in the develop-
ment of water management information (e.g., constraints, operating criteria) to meet the congression-
ally authorized project purposes.
3.2.1.3. Proposed water management operating criteria should be contained in the appropriate
final National Environmental Protection Act (NEPA) document (e.g., Letter of Environmental Com-
pliance, Environmental Assessment, Environmental Impact Statement).
3.2.2. Progression of the Water Control Plan through a Project Life. As project facilities are
constructed and become operational, a series of water control plans may be required (listed here
in chronological order): interim (during construction); preliminary (before full-scale operation);
and approved (full-scale operation); water control plans may also be required as a dam safety in-
terim risk reduction measure. A description of such plans is presented in Chapter 9. After com-
pletion of project construction, further refinements or enhancements of the water control plan
may be made to account for changed conditions resulting from new requirements, additional
data, or changed social or economic goals.
3.2.3. Interdisciplinary Involvement. Major system water management involving many au-
thorized purposes often includes multiple disciplines (e.g., hydraulic engineers, hydrologists, me-
teorologists, biologists, archaeologists, chemical engineers, structural engineers, geotechnical en-
gineers) to support water control plan development. The water control plan for such major sys-
tems may include specialized elements such as desirable conditions for species or habitat of con-
cern, surveillance and monitoring plans, water supply demands, flood inundation mapping, and
required navigation depths.
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3.2.4. Annual Water Management Plans. A water control plan may be supplemented by an
annual water management plan for the current operating year for multipurpose regulation. An-
nual water management plans outline how an office intends to implement the approved water
control plan for the coming year. Annual water management plans define guide curves for water
supply functions, such as hydroelectric power generation, irrigation, navigation, water quality,
etc. based on the water management conditions for the current year. The annual water manage-
ment plan may be used to develop a regulation outlook for more than 1 year in advance. The
methods of systems analysis used in developing the annual plan may be similar to those used in
planning and design studies.
3.2.5. Integrating Congressionally Authorized Project Purposes.
3.2.5.1. A water control plan contains operating criteria to meet congressionally authorized pro-
ject purposes with flexibility to allow for adaptation to actual conditions. This requires an under-
standing of the extent of the authorized project purposes as defined in the planning studies and subse-
quent authorizing legislation, an identification and definition of constraints, a familiarity with design
information, and the gathering of pertinent information. See Chapter 6 for information on tech-
niques. The preparation of a water control plan also includes information from Federal, state, local,
tribal, and other stakeholders, as appropriate, that may be affected by or may affect Corps water man-
agement activities.
3.2.5.2. Information presented in the previous paragraph allows for the identification of prob-
lems, opportunities, and capabilities for a project and existing non-project infrastructure necessary to
develop a water control plan. For projects that have a non-Federal sponsor or are non-Corps projects,
the process should include collaboration with the associated entities. The water control plan typically
outlines the quantity, timing, and duration of water releases or storage associated with a project.
3.2.5.3. For a project with multiple authorized purposes, the water control plan may balance
tradeoffs across multiple needs, since managing for one project purpose can affect the delivery of
benefits for other purposes. For example, risk management for threatened or endangered species or
public health and safety may be managed with a flexible operating plan that recommends allowable
quantity, timing, and duration of water releases or storage for a project.
3.2.5.4. Once alternatives are identified, an iterative approach may be undertaken to predict and
analyze the results and associated benefits and impacts. Chapter 6 includes related material. The im-
pacts of preliminary operating criteria may require a request for input from Federal, state, local, and
tribal organizations, other stakeholders, and the general public and a consideration of any responses.
Responses may reflect existing constraints that become interrelated and typically evolve under spe-
cific circumstances such as physical, legal, political, social, and major conflicts between authorized
project purposes.
3.2.6. Integrating Public Laws. In addition to the original congressionally authorized project
purposes, Corps water resources projects are often subject to public laws enacted after the origi-
nal authorization. Integrating post-project public laws into a water control plan typically in-
volves a process similar to that discussed above for congressionally authorized project purposes.
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3.2.7. Integrating Incidental Benefits. Benefits to one or more congressionally authorized
project purposes may be provided by defining water storage and releases in the water control
plan. Incidental benefits may be taken into account when developing water control plans.
3.2.8. Input from Other Water Management Interests.
3.2.8.1. Development of water control plans involves input from external agencies, entities, or
stakeholders that may be affected by water management activities. These interests may include non-
governmental entities as well as Federal, state, local, and tribal organizations.
3.2.8.2. Hydroelectric power generation is an example of a congressionally authorized project
purpose that requires coordination for the water control plan. A water control plan for a coordinated
power system considers all elements of the system, including estimates of loads and resources for
each of the operating utilities, project and power transmission operating characteristics, methods for
scheduling, dispatching, and marketing power, and a myriad of details that affect water management
activities. The coordinated water management activities, data inputs, and technical evaluations to
achieve hydroelectric power generation objectives may be met by establishing coordinating bodies or
groups that are voluntarily agreed upon by the parties involved. The coordinating groups may pro-
vide for the exchange of data and the establishment of work groups to develop project power operat-
ing plans. The water control plan for Corps projects that include hydroelectric power generation in-
clude descriptions of this type of data exchange with other operating utilities or power marketing
agencies, as appropriate.
3.2.8.3. Other congressionally authorized project purposes may need data input and coordination
between the Corps and stakeholders. Releases to maintain or improve water levels to facilitate navi-
gation, for example, should be coordinated with appropriate navigation-related interests (e.g., ship-
ping, recreation). Water supply deliveries to meet demands (e.g., agricultural, municipal, industrial,
ecological, water quality, species of concern) require coordination and input from the stakeholders to
define the specific water delivery requirements or desired conditions.
3.2.8.4. During water control plan development, stakeholders may also request that a water con-
trol plan contain water management criteria related to congressionally authorized project purposes
not specifically documented in prior Corps studies. To determine whether to incorporate a request
into the water control plan, the Corps water manager should evaluate the request while working with
appropriate Corps disciplines. The major determining factors regarding whether the stakeholder re-
quest is included in the water control plan are potential impacts and benefits to all project purposes.
3.2.9. Physical Limitations of Projects. The water control plan should reflect any of the pro-
ject’s physical limitations. For example, if an access road to the site gets inundated at a certain
pool level or by a known amount of rainfall, then that condition should be identified and a con-
tingency plan for access to the site should be detailed. Potential issues should be identified for
higher pool levels or releases such as inundation of operating equipment, flooding of the power-
house, or issues with the stilling basin.
3.2.10. Use of Hydrometeorological Data.
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3.2.10.1. The water control plan (e.g., regulation schedule or guide curve, minimum flow, opti-
mum water level range, desirable discharge, drought contingency plans) is usually developed using
historical hydrometeorological data such as water levels, streamflow, and rainfall. Many of the con-
cepts for analyzing data that are contained in Chapter 6 may be used to address items in this chapter.
3.2.10.2. Often, only the most critical high-flow or low-flow hydrometeorological data repre-
senting operating criteria for single or multiple purpose projects (e.g., flood risk management and/or
water supply) is sufficient for water control plan development. In other cases, all available hydrome-
teorological data should be used to develop a water control plan, especially for a design with a short
period of record. Revisions to water control plans should consider data not previously available.
Modification of guide curves may need adjustment if the additional data include records of extreme
floods or droughts. A complete system re-analysis may even be needed.
3.3. Flood Risk Management Regulation.
3.3.1. Principles and Objectives.
3.3.1.1. Flood risk management operating criteria are developed in accordance with authorizing
legislation to reduce flood damages to the extent possible using available facilities. The best method
to attain this objective depends principally on the location and types of damages to be prevented, lo-
cation and amount of storage capacity, flood characteristics, flood frequencies, and extent of uncon-
trolled drainage area.
3.3.1.2. To develop a water control plan to provide flood risk management, a study should be
made of water management operating criteria alternatives applied to past record floods and selected
hypothetical floods. The historical flood record is the principal source of data to derive and test oper-
ating events even if it is too basic or short for a comprehensive investigation.
3.3.1.3. Non-damaging channel capacities must be available to achieve flood risk management
objectives. A water manager may release stored floodwater that produces downstream stages con-
sistent with the water control plan, provided the releases do not exceed peak inflow into the project or
system. Ideally, releases would be made to not exceed channel capacities, but during certain events
releases may exceed channel capacity in accordance with the water control plan to ensure the pro-
ject’s structural integrity. Every effort should be made to prevent encroachments in the channel
downstream of dams to achieve optimum flood risk management. If encroachment occurs it may re-
sult in public pressure to operate outside the water control plan, which has the potential to impact
other authorized purposes and potentially the structural integrity of the dam.
3.3.1.4. Water managers and project operators should collaborate to prevent channel capacity
encroachments downstream of dams. However, it should be recognized that the Corps has limited
capability to determine the level of development in areas downstream of project. That is normally
under the purview of local or county government to review and/or approve the development in
“riverfront” areas. That being said, since the Corps is responsible for managing its projects as de-
signed and authorized, the Corps should provide appropriate feedback to local officials if proposed
developments may be impacted by the Corps operating their project as designed and authorized.
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3.3.1.5. Water managers should work closely with project operators to be aware of upstream and
downstream conditions that might impact water management procedures. For example, during pub-
lic involvement opportunities, stakeholders should be reminded of potential maximum water control
plan release rates. Another example is if a downstream area would be flooded with maximum water
control plan release rates, the water manager or project operator must contact the owner of the site
and, if necessary, follow through with correspondence stating that the Corps will not reduce the exist-
ing maximum release rate to prevent flooding of the site. In such cases, correspondence should also
be forwarded to appropriate Federal, state, local, and tribal organizations.
3.3.2. Classification of Flood Regulation Methods.
3.3.2.1. General.
3.3.2.1.1. Although various bases exist to classify flood regulation methods, a simple analysis
is insufficient in the more complicated situations. This section presents a general plan to classify
flood regulation into two basic methods, and a third method, which combines concepts of the first
two methods and which is commonly used to provide the most effective flood regulation.
3.3.2.1.2. Each of the proposed methods for defining the flood regulation plan has strengths
and weaknesses. The determination of the plan for a particular system should be based on the
study results from the planning and design phases of project development, together with more
detailed project regulation studies conducted in the operational phase. Alternative methods of
flood regulation may be conveniently evaluated using models to achieve the optimum regulation.
Furthermore, the experience gained in the application of these models may be applied in real-
time conditions with the assurance of achieving an appropriate overall regulation. Section 3.3.8
discusses evacuation of accumulated flood storage.
3.3.2.2. Method A. Method A regulation involves maximizing storage of runoff and limiting re-
leases to lower downstream stages and damages as much as practicable during each flood event.
This method maximizes downstream flood risk reduction benefits for small and medium-sized
floods, but increases the risk of having an appreciable portion of the flood storage capacity filled
when a large, subsequent flood occurs. Obtaining maximum benefits in minor to moderate floods
using this method is highly dependent on the ability to forecast inflow conditions at the control struc-
tures and incremental flows at the damage centers. CWMS hydrologic and reservoir models for real-
time streamflow and pool elevation forecasting can optimize this method of regulation by maximiz-
ing flood risk management and analyzing potential regulation of future events. Actual operations
must be based on observed watershed conditions to the extent practicable (i.e., water-on-the-ground)
per ER 1110-2-240 unless otherwise provided for in an approved water control plan. Method A’s
effective time-span is limited to the ability to reliably forecast weather-related parameters (rainfall,
air temperature, etc.). Method A also makes it possible to take advantage of seasonal damage levels
by storing more water when downstream stage targets are lower and allowing higher releases when
downstream targets are higher. In reaches principally used for agricultural production, non-damag-
ing stages are generally higher during the non-growing season than during the growing season.
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3.3.2.3. Method B.
3.3.2.3.1. Method B regulation involves making reservoir releases strictly according to the
release schedule of the inflow design flood (see ER 1110-8-2 [FR], Inflow Design Floods for
Dams and Reservoirs). The release rates are based on schedules established to use all the storage
capacity during hypothetical regulation of an inflow design flood. The schedules are then fol-
lowed at all times on the assumption that the result will be the best overall flood regulation. Pro-
jects that have a limited amount of flood storage with a primary flood risk management objective
may regulate based on continual releases up to specified amounts to provide reservoir flood stor-
age for a specified inflow design flood. Considering the ongoing flood conditions and reservoir
levels, Method B regulation consists of releasing water at an established rate and storing all ex-
cess inflow as long as flooding continues at specified target locations.
3.3.2.3.2. While Method B regulation provides considerable assurance of successfully regu-
lating major floods, regulation may result in higher releases for lesser floods, potentially reduc-
ing benefits. This is particularly true for damage centers where managed releases could be timed
to avoid an undesired combination with flows from uncontrolled areas. Uncertainties with the
use of Method B may result from being too optimistic about assumed project releases or from
considering that each major flood is a single event, which may significantly affect the release
patterns for a subsequent flood. Another effect of this method could be a possible increase in the
duration of downstream flooding from holding release rates higher for a longer period of time.
One example of Method B regulation would be a dam designed with an ungated service spillway
and a flood pool sized to store the inflow design flood. In this type of operation, the release rate
through the ungated service spillway is a function of the reservoir elevation and induced storage
results from restricted capacity of the outlet or weir crest height.
3.3.2.4. Method C. Method C regulation is a combination of Method A and Method B. This
method takes advantage of Method A by storing flood inflows and making releases to meet flow targets
downstream during small floods, and during larger floods establishes a guide curve to store the inflow
design flood as in Method B. A local flood storage zone could be established to store water, thereby
enabling reduced releases to meet downstream flow targets during small flood events as in Method A.
A decision to provide exclusive flood storage may also be desirable to give increased assurance of
flood risk management for an important leveed area or a town generally endangered only by unusual
floods or to provide storage for an inflow design flood using Method B. Thus, after the lower portion
of the flood pool is filled by regulating with Method A, a fixed schedule of releases would follow to
ensure regulation of major floods at the expense of less regulation of moderate floods using Method B.
See Section 4.5 for directions to develop induced surcharge envelope curves.
3.3.3. Flood Regulation Schedule for a Single Reservoir.
3.3.3.1. The regulation schedule is a simple matter for the case of a single dam built for flood risk
management of the local area immediately downstream from the dam (small uncontrolled intermediate
area). The release schedule consists of storing runoff and regulating releases up to the value of the
channel capacity. To obtain benefits at remote locations only (where there is appreciable uncontrolled
intermediate area between the dam and location), regulation under Method A consists of maintaining
the damage center stage at or below bankfull capacity or of providing a minimal release from the dam
for damage areas experiencing above-bankfull conditions. For such regulation, releases of available
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storage at the dam would be based on observed or forecast runoff conditions for the uncontrolled drain-
age area. The success of such regulation depends on the ability to make a timely, adequate downstream
flow forecast based on water already on the ground unless otherwise approved in an approved water
control plan. Releases would be based on observed and/or forecasted conditions at the project site and
downstream locations. A regulation schedule using Method B would provide for the release of water at
specified rates to control the inflow design flood runoff without exceeding flood storage capacity.
Method C would incorporate these two approaches into a single water control plan.
3.3.3.2. To provide flood risk management benefits primarily at downstream local and remote
locations, additional restrictions on releases would require more reservoir storage capacity to offset
reduction of releases. Therefore, the method of regulation and preparation of schedules becomes
more complicated than that for local or remote benefits alone. The adequacy of the forecasts is of
primary importance, and streamflow simulation models for forecasting river and reservoir conditions
are beneficial in real-time regulation for making the most efficient use of reservoir storage for flood
risk management.
3.3.4. Flood Regulation Schedules for Multireservoir Systems.
3.3.4.1. General regulation schedules for an integrated system of projects are usually developed
first for the tributary projects operating as separate units. The adjustment of the individual regulation
schedules for coordinated regulation of the various tributary and main river projects are generally
based on system analyses of the basin development, design floods, and historical floods of record.
The critical flood regulation plan may be determined by the occurrence of a succession of moderate
floods rather than one severe flood, or an unusual flood event that is distributed in time or space dif-
ferently from normal flood occurrences. Also, flood regulation criteria should be established consid-
ering the magnitude of expected seasonal runoff volume for cases in which seasonal runoff volume
forecasts are made several months in advance (e.g., snowmelt runoff).
3.3.4.2. Method A is most commonly used for multireservoir systems. If channel capacities be-
low the individual dams are limited and both local and remote benefits are to be achieved, sufficient
storage may not be available for complete management during a critical basin-wide flood. Regula-
tion based on a maximum use of available storage probably would provide the most benefits for the
system. However, to verify that maximum use of available storage would provide the most benefits
and to provide the necessary information for successful regulation of such systems, extensive data
should be collected and periodically updated to determine seasonal channel capacities and damage
areas. Stream profiles for various combinations of releases from different projects should be estab-
lished and the areas flooded at successive profile elevations should be determined. These stream pro-
files along with damage data can then be used to create stage-damage curves for various reaches.
Control points may be established to evacuate flood storage in a reasonable length of time and to re-
duce damage in the basin. The stage-damage curves may be evaluated with simulation models.
Through testing various methods of regulation, a plan of flood regulation may be formulated that
provides the highest level of flood risk management to stakeholders conforming to the structure’s
physical features. Water management offices should move toward using CWMS software to opti-
mize multireservoir system operation, including HEC-RAS to create stream profiles and profiles of
flooded areas, HEC-FIA for stage damage curve development, and the Control and Visualization In-
terface (CAVI) for model evaluation.
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3.3.4.3. The regulation schedules depend on forecasting both controlled and uncontrolled river
stages at all of the control points. If forecasted stages are expected to be above flood level due to
runoff in uncontrolled areas, reservoir releases may be adjusted to compensate for the uncontrolled
runoff and maintain downstream stages at or below target levels. This is especially true when con-
sidering a large uncontrolled area with a difficult to estimate or unknown runoff flow rate. The travel
time for releases should be taken into account when considering incremental runoff and downstream
stage targets. To achieve system regulation, the reservoir release schedules may be simulated using
historical data with different outflow scenarios. The results of the simulations should be used to pre-
pare rule curves or guide curves that define relative amounts of storage between projects and general
guides for reservoir filling or evacuation. In real-time regulation, the same principles are applied, but
the analysis of data is based on current forecasts of streamflow and reservoir levels rather than on his-
torical data. At each of the projects, revised forecasts result in adjustments to reservoir releases to
make the best use of the residual flood storage. Also, various extremes of weather-related factors
may be tested and evaluated with model simulation to ensure that sufficient storage space is available
for management of unusual rainfall or snowmelt events.
3.3.4.4. In summary, the guide curves provide general guides for reservoir filling and evacuation
to meet the flood risk management objective of maximum beneficial use of available storage. In ac-
tual operation, the analysis afforded by real-time model simulation of current and forecasted hydro-
meteorological conditions should be included to make operating decisions that achieve the optimum
balanced regulation.
3.3.4.5. Regulation based on Method B may be feasible if relatively large channel capacities ex-
ist below dams, and the remote flood risk management benefits are obtained at a few centralized lo-
cations. Regulation schedules should be based on making fixed or variable releases that depend on
existing or forecasted stages at downstream control points, and by managing the design floods at the
individual projects.
3.3.4.6. Normally, the most dependable flood risk management benefits are accrued at major or
complex river basin developments using Method A or Method C because they store inflows for the
more frequent events and provide higher levels of flood risk management.
3.3.5. Flood Regulation for Projects with Uncontrolled Outlet Works. Some projects have
been constructed with uncontrolled outlets or weirs and the resulting release of water depends on
conditions of inflow and storage. With no gates or other provisions for water management
through controlling the release of water, the induced storage results from restricted capacity of
the outlet or weir crest height. These facilities allow for a predictable and consistent approach to
water management, but they lack operational flexibility. Detailed regulation schedules, rule
curves, or guide curves for this type of project are typically unnecessary, but pertinent water
management details and information should be understood. The water manager should include
the project’s effect on upstream and downstream areas and the relationship to any other projects
in the system.
3.3.6. Seasonal Variation in Flood Storage Requirements. Water resources systems are usu-
ally multipurpose. Although many Corps projects have been authorized to meet flood risk man-
agement or navigation objectives, the other water management functions described in Chapter 2
may also be included as authorized purposes to achieve the full use of available water resources.
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While flood risk management may represent the primary function for particular projects, the ca-
pabilities of projects to manage floods may be maximized with other functional uses by season-
ally allocating project flood storage space. The seasonal variation of flood risk management re-
quirements should be determined by flood routing studies using floods of various magnitudes,
distributed seasonally over the period of historic record. Synthetically derived floods may also
be analyzed if the historical period of record is insufficient to provide an adequate sample of
flood distributions. The seasonal guide curves that define the flood storage space requirement
should be determined from these studies for each project or system of projects. These guide
curves are drawn as enveloping lines of storage space required for the management of historical
floods as a function of the time of year. They are usually drawn as straight lines on a monthly or
seasonal basis. The guide curves represent the maximum desirable reservoir storage levels for
other multipurpose uses on a seasonal basis. For rain-fed rivers, the seasonal flood storage reser-
vation guide curves generally apply to all years. However, for those rivers that may have a sig-
nificant contribution of runoff from snowmelt, a family of guide curves representing the flood
storage reservation requirements may be derived based on anticipated seasonal runoff volume.
Also, flood storage may be designated in different categories. For example, consider that the up-
per portion of the flood pool (termed primary or exclusive flood pool) is maintained at a fixed
level, but the lower portion (termed secondary or annual flood pool) is conditionally maintained.
The secondary flood storage may fluctuate, depending on the time of year and other desired mul-
tipurpose uses under certain pre-planned operating rules for regulation.
3.3.7. Management of Individual Floods. The water control plans for flood risk manage-
ment, as described above, provide the general concepts and guidelines for flood regulation.
These plans are developed mostly from analysis of historical flood events. They are designed to
achieve a generalized, optimally balanced plan of regulation for all floods, considering both mi-
nor and major floods of record as well as design floods. No two flood events are the same, and
the history provided in the flood records cannot possibly represent all future events. The use of
real-time hydrologic modeling provides the water manager a means to analyze the system regula-
tion and to adjust operation hourly or daily to provide the desired flood regulation.
3.3.8. Reservoir Evacuation.
3.3.8.1. General Principles.
3.3.8.1.1. Post flood evacuation of water stored in exclusive flood pools for flood regulation
must be accomplished as soon as possible following the flood event. The three general criteria
for post flood evacuation are: (a) releases made to regulate streamflows at downstream control
points are at or below bankfull or non-damaging channel capacities, noting that non-damaging
stages may vary seasonally in agricultural areas, (b) releases made to maintain downstream flows
are at levels that do not exceed the peak flows or stages that occurred during the course of the
preceding flood event where such peaks exceeded bankfull capacity, or (c) releases made to
evacuate storage are at or above bankfull for emergency or other reasons.
3.3.8.1.2. The release of flood storage is made to provide storage to manage subsequent
flood events. To avoid the risk of a series of floods having a combined volume exceeding reser-
voir storage capacity, the stored water should be evacuated as quickly as possible, consistent
with downstream runoff conditions and weather forecasts. To evacuate flood storage, evacuation
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plan (b) provides the fastest evacuation of stored water. Release of stored water that results in
above bankfull stages prolongs the period of downstream flooding, but may reduce peak stages if
subsequent events occur. Evacuation plan (a), on the other hand, may result in much delayed
evacuation of stored water that would increase the risk of flooding from subsequent storms.
Evacuation plan (c) could be used to address an emergency dam safety concern, a need to evacu-
ate flood storage before the next runoff season, or a need to evacuate flood storage before the
winter ice period. In actual practice, a compromise between evacuation plans (a) and (b) is usu-
ally adopted, and the post flood evacuation results in river stages somewhat higher than bankfull,
but lower than peak stages experienced during the flood due to the contribution from uncon-
trolled areas. The decisions made on adopting post flood evacuation criteria should be based on
flood routing studies of individual floods, damages that occur from prolonged above bankfull
stages, and risks of future flood events. The water control plan should specify how flood storage
will be evacuated and address concerns related to physical reservoir conditions such as sedimen-
tation or geotechnical concerns including erosion or slope stability.
3.3.8.2. Quantitative Precipitation Forecast (QPF) Consideration.
3.3.8.2.1. Regulation decisions are typically made based on the principle of water-on-the-
ground, which includes observed precipitation that has fallen in the form of rain or snow. As
water managers become familiar with stakeholder needs and project hydrology, and as forecast-
ing tools become more accurate, the most effective regulation for a project may include use of
forecasted precipitation. Exceptions to the water-on-the-ground policy are permitted when docu-
mented as part of an approved water control plan and typically occur during flood storage evacu-
ation to give the water manager the flexibility needed to most effectively regulate the project.
These exceptions must be supported in the water control plan by an evaluation of the potential
risks, uncertainties, and the risk tradeoffs. A decision process must be included and documented
to evaluate and make risk tradeoff decisions in a real-time operating environment. Coordination
with stakeholders is important when creating a water control plan that incorporates QPF.
3.3.8.2.2. Several examples follow, of regulation could benefit by considering QPF. Pro-
jects that are located in areas affected by tropical storm or hurricanes may need to outline regula-
tion that includes QPF. Another example is making higher than normal non-damaging releases
based on a QPF to evacuate flood storage and reduce the risk of uncontrolled spill from a project
as a result of runoff from future rain. During a forecasted break in rainfall, a higher than normal
release could be made to evacuate water at a faster rate when there is room in the downstream
channel, or in advance of planting season. Releases could also be reduced based on QPF to leave
more room for local runoff in a downstream channel that is near target or damage levels.
3.3.8.2.3. It is very important that regulation considering QPF be outlined in the water con-
trol plan with supporting information and risk evaluation.
3.3.8.3. Ramping Down Releases. Another consideration is to plan the reduction of the releases
so that they will be reduced to conservation rates by the time the flood storage space has been evacu-
ated. The rate of fall for releases should be less than the maximum rate of fall observed before the
project’s existence. When the opportunity exists to reduce the possibility of wasting water for other
project purposes unnecessarily, release criteria should be developed to transition between flood man-
agement operation and water conservation operation for other project purposes.
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3.3.8.4. Emergency Drawdown. Emergency drawdown for dam safety or other similar reasons
may be requested and should be coordinated with relevant Corps organizations and stakeholders.
This could occur when the reservoir is in the flood pool or below the flood pool.
3.4. Navigation Regulation.
3.4.1. Principles and Objectives.
3.4.1.1. Operating criteria for navigation projects are to provide required water flows and to
maintain authorized project navigation depths. Navigation needs should be integrated with other pro-
ject authorized purposes, such as flood risk management and hydroelectric power generation. Fac-
tors to be considered in the water control plan include type of navigation improvement, environmen-
tal considerations, design options to accommodate ice or debris passage, normal operation to pass
flood flows, and removal of sediment.
3.4.1.2. Navigation constraints may affect the short-term regulation of projects. In some rivers,
supply of water for lockage is a significant concern, particularly during extended periods of low flow
or droughts. In critical low-water periods, water use for lockage may be curtailed to conserve water
and maintain navigation, possibly at a reduced level of service. The need to preserve water quality in
a navigation canal may be considered a water requirement for navigation.
3.4.1.3. Additional information to include in a water control plan for navigation are a communi-
cation system among projects, water management offices, towing industry, and Coast Guard, as well
as a regulation plan for a river system.
3.4.2. Navigation Waterway Types. Types of navigation projects include canals, locks,
dams, and reservoirs. In addition, other types of navigation improvements include maintained
channels and estuaries, bank protection, pile dikes, and other forms of channel stabilization.
Making reservoir releases to increase river levels and thereby improve channel depths is another
type of navigation improvement project. A water control plan should reflect the type of naviga-
tion project and may include several of the methods mentioned above. Whether a project in-
volves open river navigation or includes spillway structures (controlled or uncontrolled) to pro-
vide navigation flows or depths, the water control plan should detail how water will be stored
and managed to meet the authorized navigation purpose. The issues to be considered are dis-
cussed in Section 2.3.
3.4.3. Navigation Regulation Schedules.
3.4.3.1. Shallow Draft. Regulation schedules for shallow draft navigation projects vary greatly
among river basins and development type. Normal and special spillway operations to be included in a
water control plan are described in EM 1110-2-1605, Hydraulic Design of Navigation Dams. Items to
be included for normal operation are maintenance of navigation pools, low flow periods, flood flow pe-
riods, and ice and debris passage. Items to consider for special operation are loss of scour protection,
operator error, equipment malfunction, spillway maintenance, and emergency operations.
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3.4.3.2. Deep Draft. Deep draft navigation is generally different from inland navigation in that it
is geographically connected to coastal waters, and/or the Great Lakes. The design of deep draft sys-
tems take into account average high and low water levels as they change with the tides, as well as the
size and draft of ships that will be navigating on that system, see EM 1110-2-1613, Hydraulic Design
of Deep Draft Navigation Projects. Structures are generally not included in design for the purpose of
“managing the water,” and a water control plan or regulation schedule is not typically required.
However, most deep draft projects should include a comprehensive plan for project O&M after con-
struction, to include the following elements: changes and costs after construction, a surveillance plan
to detail type and frequency of hydrographic surveys, data collection, periodic inspection schedules,
and project performance assessments.
3.5. Development of Water Management Operating Criteria.
3.5.1. Tools for Developing and Implementing Operational Criteria.
3.5.1.1. In addition to being included as text in a water control plan, water management operat-
ing criteria may be represented by a diagram, schematic, table, flowchart, or other compilation of
regulating criteria, guidelines, guide curves, rule curves, and specifications that govern the storage
and release functions of a water resources project. It is important to note that these products are
based on the water control plan rather than defining the water control plan. The diagrams indicate
concise specifications such as water level and limiting rate of project releases during the calendar
year, which act separately or in combination with other projects in a system. The diagrams are used
in the decision-making process to determine water management activities to meet congressionally
authorized project purposes. The diagrams are sometimes called guide curves, rule curves, or regula-
tion schedules. Figure 3-1 shows an example of a water management guide curve.
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60,000 to 40,000 cfs
Figure 3-1. Example of Water Management Guide Curve.
3.5.1.1. Guide curves are an important element of the water control plan, since the diagrams pro-
vide the technical guidance and specific rules of regulation that are mandated from studies, public in-
put, and the review and approval process in the planning and design phases as well as in the O&M
phase. However, the diagrams are only a part of the overall water control plan, which provides for
adjusting project water management activities on other factors that may develop in actual operation
as the result of unique hydrometeorological or ecological conditions, changing water management
needs, and other factors that may influence current project water management.
3.5.1.2. Guide curves must be documented to ensure that project water management is accom-
plished according to the water control plan as developed from the project and systems analysis stud-
ies. Daily water management activities are carried out according to specific operational rules that de-
fine the requirements at the project, and at downstream locations to meet congressionally authorized
project purposes. Physical operating limits should be established that define the limiting releases and
water levels at the project; and in some cases, at downstream locations, together with rates of change
of discharge and water levels. Special limitations should also be applied to define limits of operation
of water management facilities (e.g., gated culvert, spillway, outlet works, power generation equip-
ment, pump station, navigation lock, fish passage facilities) that may affect the scheduling of water
releases. Detailed charts and diagrams should be prepared to define flood risk management operat-
ing criteria related to hydrometeorological conditions, storage, and system water management. Simi-
lar types of charts and guides should be prepared for management of diversion and bypass structures,
hurricane or tidal barriers, and interior drainage facilities for levee projects. For hydroelectric power
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generation projects, detailed instructions should be provided to define the methods for scheduling
power, controlling power facilities, dispatching power in an integrated power system, maintaining
the operation of the power facilities within design limitations, and monitoring system operation.
3.5.2. Integration of Basic Seasonal Flood Risk Management Guide Curves with Other Ob-
jectives.
3.5.2.1. An increasing number of multipurpose projects have been constructed in connection with
basin-wide development of natural resources. Therefore, development of the water management guide
curves must be compatible with all water management objectives to the greatest extent possible. For
some projects, storage for low water regulation, navigation, irrigation, hydroelectric power generation,
water supply, or recreation is provided by allocating storage capacity between particular levels for spe-
cific purposes in addition to that required for flood risk management. Note that the regulation sched-
ules for these various uses may be independent of each other. In many reservoir systems, the multipur-
pose functions are compatible for joint use of the reservoir storage space, and the allocated storage
space and project capabilities for all joint use functions are determined from reservoir systems analysis
studies. The seasonal storage allocation for flood risk management, as discussed in Section 3.3.6, pro-
vides for flood regulation in a manner similar to single purpose flood risk management projects, and the
seasonal guide curves that define storage capacities for all functions are depicted by charts plotted with
ordinates representing storage amounts and abscissas representing time of year.
3.5.2.2. Reservoirs are designed and built to meet authorized purposes, but sometimes storage is
insufficient to fully provide all desirable functions year-round. In this case, priority may be given to
certain purposes based on hydrologic conditions and operational requirements, consistent with au-
thorizing legislation. Figure 3-2 shows an example of a seasonal guide curve.
3.5.3. Development of Systems Analysis Studies for All Multipurpose Uses.
3.5.3.1. General. The basic concepts of reservoir systems analysis that are used in the planning
and design phases apply to the development of guide curves. The emphasis of the studies in the
planning and design phases should be to determine the project capabilities, such as firm or secondary
power potential, peaking capability, unit sizes, irrigation capabilities, water supply potential, low
flow augmentation, and service to other authorized purposes based on the historical record stream-
flows and proposed regulation criteria. The emphasis in the operational phase should be to develop
the general framework of guide curves that account for changed conditions and refinements of plan-
ning and design studies. Also, the water control plan may call for specific guide curves based on the
known conditions of project regulation in the current year. System analysis should be used for multi-
project or multipurpose systems.
3.5.3.2. Hydroelectric Power. Regulation schedules for hydroelectric power operation cover a
wide range of requirements. The general methods for evaluating power capabilities and determining
power regulation are described in EM 1110-2-1701, Hydropower, and the application of these meth-
ods determines the principles of regulation for a specific project. Power guide curves are developed
from the following criteria:
a. The monthly reservoir operating schedule and operating limits for each project as re-
quired for system power regulation.
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12. The plant and power system capability as related to the sale of electrical energy.
13. The regulation of each project in the system to meet its proportional share of the electri-
cal power system load, in conjunction with all other water management requirements.
Figure 3-3 shows an example of a guide curve for regulation to meet the hydroelectric power
generation authorized purpose.
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Figure 3-3. Wolf Creek Dam Guide Curve.
3.5.3.3. Navigation. Navigation regulation schedules are developed generally with the basic
concepts of reservoir systems analysis studies as described above. Methods for developing naviga-
tion requirements, which are described in EM 1110-2-1605, may include hydraulic studies to estab-
lish the following criteria:
a. Stage-discharge relationship over entire area affected by the project.
14. Channel discharge rating curves.
15. Water surface profiles.
16. Establishment of navigation pool elevations.
Additional needs vary with type of project. Applications of specific methods are described in
EM 1110-2-1611, Layout and Design of Shallow-Draft Waterways, and in EM 1110-2-1613,
Hydraulic Design of Deep-Draft Navigation Projects. Navigation regulation during extreme low
water conditions should be included in a drought contingency plan, as outlined in ER 1110-2-
1941, Drought Contingency Plans.
3.5.3.4. Winter Navigation. A water control plan that includes winter navigation should discuss
management of ice accumulations to reduce adverse impacts. Methods to evaluate winter navigation
are described in EM 1110-8-1(FR), Winter Navigation on Inland Waterways, and include the follow-
ing:
a. Ice and related hydrometeorological data collection and monitoring.
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17. Ice forecasting.
18. Decision matrix to determine ice conditions that are too severe to maintain project opera-
tion for navigation.
3.5.3.5. Water Quality.
3.5.3.5.1. Water quality is an authorized purpose for many projects by specific congressional
action. Water quality considerations include both the quality of the water stored by a Corps fa-
cility and the quality of water downstream of an impoundment. Corps policy for water quality
management at Corps civil works projects is outlined in ER 1110-2-8154, Water Quality and En-
vironmental Management for Corps Civil Works Projects. Critical water quality components
may include:
a. Temperature.
19. Dissolved oxygen.
20. Nitrogen supersaturation.
21. Sediment starvation.
22. Organic and inorganic contamination.
3.5.3.5.2. The water control plan could present water quality issues that may occur due to
construction of a facility and appropriately balance these issues with the other authorized benefi-
cial purposes. Potential operations that address these concerns may include an augmentation re-
lease from the multipurpose storage that specifies the water withdrawal elevation, or physical
changes to the outlet structure.
3.5.3.5.3. Unforeseen water quality issues may develop after construction is completed and
the water control plan has been implemented. These conditions include threats to fish from inad-
equate dissolved oxygen levels or to humans from blue-green algae blooms within impound-
ments. While such issues need to be addressed immediately to alleviate the conditions, changes
to the water control plan should be considered to reduce or prevent similar future conditions.
3.5.3.6. Irrigation, Fish and Wildlife, M&I, and Other Functional Use Considerations. Similar to
integrating water management operating criteria (diagrams) with hydroelectric power generation, the
water supply needs for irrigation, fish and wildlife, M&I, and other functional uses may be integrated
with basic flood risk management operating criteria. Since water supply and flood risk management
functions need to balance the use of reservoir storage space, guide curves define the upper and lower
water level limits for these water supply functions and for flood risk management. These limits are
usually defined as seasonally variable water levels, which govern in actual operation except as neces-
sary to meet the specific functional goals set forth in the planning and design phases. The definition
of these water levels is to balance the relative use of reservoir storage with conflicting multipurpose
functions to meet the project functional commitments. The functional objectives of water manage-
ment to provide for water supply and associated accounting methods to analyze water control plans
have been described above. The methods to achieve these objectives should be incorporated in the
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water systems analysis operational studies as discussed in this section. Also, the refinements in water
management should be incorporated into the seasonal operating criteria. The operating criteria are
usually generalized for application to all years and should account for future variable hydrologic con-
ditions. Some basins develop annual operating criteria.
3.5.3.7. Environmental, Social, and Aesthetic Considerations. Environmental, social, and aes-
thetic values have become a focus of water management for many Corps water resources projects.
Some management guidelines related to these values are detailed in Federal legislation, while others
result from regional, state, local, or tribal input that may represent the desires of particular interest
groups or the general public in preserving or enhancing these values. A wide range of desires may be
considered in connection with environmental, social, and aesthetic values, some of which may be
easily accommodated in the general concepts of water management for the congressionally author-
ized project purposes. Other desires may be infeasible or impractical from an economic point of
view, considering the functional uses for which the project was authorized and constructed. The
evaluation of these issues and the integration into operating criteria should be made with full
knowledge of the history of project development, legislative actions, project justification, and the
planning of project utilization. Various alternatives to meet environmental, social, and aesthetic
goals should be analyzed in connection with water management studies to determine the effects on
each of the water management functions, and recommendations for change should be made based on
the judgment of the results of the studies. The water management operating criteria, which include
environmental, social, or aesthetic values, may be in the form of generalized relationships and rules
that apply to all future years. Others may be specifically developed for a particular year or season
and may change annually. The detailed operating criteria may include:
a. Seasonal storage guide curves in conjunction with other functional water uses.
23. Minimum project releases that may vary seasonally or as a function of storage, and that
are usable for downstream release and surplus to other needs.
24. Rates of change of discharge or water surface elevation, either at the project or at a down-
stream control point.
25. Special short-term releases for a particular environmental, social, or aesthetic need.
3.5.3.8. Cultural Resources. While most large water management projects are authorized and
designed for multiple purposes and must be operated within the constraints of these purposes, there
may be enough flexibility to permit some manipulation of water levels and reservoir releases with
consideration for effects to cultural resources. Water managers should be aware of the potential ad-
verse effects to cultural resources by continually evaluating the effects of project regulation. This in-
cludes being aware of pool level fluctuations, quantity of project releases, and the frequency and du-
ration of droughts. These factors, or a combination thereof, affect cultural resources, primarily as a
result of erosion caused by water level fluctuation. Short-term operation deviations may be made to
allow protection of significant cultural resources.
3.5.4. Solutions of Systems Analysis to Determine Optimal and Balanced Regulation. The
use of reservoir systems analysis techniques, discussed in Section 3.5.3, provides the basic
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means to develop and test the detailed water management operating criteria and diagrams. Stud-
ies may be used to simulate the water management of projects using forecasts of project inflows.
For cases that lack an inflow forecast, the observed conditions of runoff may be used for testing,
and should be so stated. Various assumptions for operating criteria for each of the elements dis-
cussed in Section 3.5.3 may be individually tested in conjunction with all other elements, and the
optimum and balanced regulation criteria and schedules may be derived from repetitive solutions
of the simulation.
3.6. Drought Contingency Plans
3.6.1. ER 1110-2-1941, Drought Contingency Plans, states that as part of overall water man-
agement, drought contingency plans must be developed within existing authorities at all Corps
projects with controlled reservoir storage. The drought contingency plan will include the spe-
cific conditions needed to enact the plan, such as state or county declaration of drought, or spe-
cific flow conditions. The drought contingency plan must be included or referenced within the
water control manual for each project, and in addition, basin-wide drought contingency plans
should be incorporated into water control master manuals.
3.6.2. After a drought contingency plan has been developed based on existing constraints,
forecasts of basin development and water supply needs may present different long-term con-
straints to a project, requiring modified operating criteria to lower impacts from future droughts
and to meet authorized project purposes. To complete such a modified drought contingency
plan, a reconnaissance study may be conducted to evaluate alternative actions that involve re-
moving or modifying current operating constraints. Operating criteria modifications may be
made to project operation guide curves, minimum flow requirements, and storage allocations.
3.7. Monitoring and Revising Water Control Plans. Operating criteria for water control plans
must be revised, as necessary, to ensure that congressionally authorized project purposes are met.
Chapter 9, “Preparation of Water Management Documents,” outlines a series of water control
plan types (preliminary, interim, and final) that address a lengthy project completion period and
coincidental changing water management conditions. However, water management activities for
a completed project (defined as all project components in the O&M phase) may begin several
years after the design phase and perhaps decades after the time that the original planning studies
were conducted. In such circumstances, a review of the current water control plan should be
conducted, considering new data or changes in project conditions, to verify that plan implemen-
tation will meet project purposes. Water managers should be vigilant to perform reviews and
necessary revisions to the operating criteria for water control plans. Chapter 9 also discusses
steps involved with updating these plans.
3.7.1. Constraints on Water Management Operating Criteria. A constraint on water manage-
ment operating criteria is a condition that arises subsequent to project design that prevents, or is
allowed to prevent, the achievement of a water management objective. Constraints may result
from physical, social, or economic impacts on residential, agricultural, industrial, or environmen-
tally sensitive areas that are affected by a project’s water management capabilities. The water
control plan should attempt to address known constraints.
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3.7.1.1. Impacts Due to Incomplete Project Development. Incomplete project development may
result in, but is not limited to, the following impacts:
a. The design downstream channel capacity is not achieved, possibly due to delay in clear-
ing and snagging, realignment, enlargement, dredging, or levee construction.
26. Inadequate, vague, or complete lack of easement acquisition that prevents full use of stor-
age or flowage downstream of water management structures.
3.7.1.2. Issues to Consider During Development and Revision of Water Control Plans. Many
issues should be considered during development and revision of water control plans. Some potential
issues are:
a. Encroachments in the floodplain downstream and in areas upstream of water manage-
ment structures.
27. Effects of new development in low lying lands on channel capacity.
28. Erosion associated with pool levels or releases.
29. Frequency of filling and runoff volume may increase at impoundments as compared to
pre-project conditions, requiring higher release rates from reservoirs and additional
pumping capacity at local (interior drainage) projects.
30. An occurrence of an extreme low flow event, more severe than any in the hydrologic rec-
ord used for design, may impact conservation purposes by restricting releases for water
quality, water supply, hydroelectric power generation, etc.
3.7.2. Additional or New Hydrometeorological Data. After a project has been planned or
designed and additional hydrologic data from existing or new data stations become available,
system regulation schedules should be periodically reviewed. The hydrometeorological data
may be in the form of streamflow, rainfall, snow accumulation, or other elements collected rou-
tinely to help define the hydrologic character of a drainage basin. The additional records not
only extend the period of record of the basic data used in the initial planning studies, but also en-
hance the determination of regulation criteria and basin watershed characteristics that are used in
modeling procedures. The new data may also include records of extreme floods or droughts that
require modification of the operating criteria. In some cases, the additional basic data may war-
rant an updated system hydrologic analysis to refine the derived project streamflows. In any
case, all available hydrologic data should be considered during revision of the water control plan.
3.7.3. New Water Management Objectives.
3.7.3.1. Water management goals now include environmental and social aspects of project regu-
lation in addition to the basic public safety and economic functions for which water resources pro-
jects were originally authorized and constructed. The water management goals conform to relevant
public laws that were enacted after the authorization of most existing water resources projects. The
public laws require inclusion of certain aspects of environmental, fish and wildlife, and recreational
uses in the management projects, or improvement of the environment of the rivers downstream
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through project regulation. The specific uses are determined from river basin investigations and are
incorporated into the water control plan.
3.7.3.2. Re-evaluations of the water management criteria to meet authorized project purposes
should be conducted, as necessary. Significant changes in policy procedures or other conditions may
occur between the planning or design studies and the preparation of a detailed water control plan.
Such changes should prompt implementation of a study program in connection with the development
of water management operating criteria to refine the regulation through the use of additional basic
data, authorized purpose requirements, and systems analysis techniques that became available subse-
quent to the planning and design studies.
3.7.4. Periodic Review for Flood Risk Management. A periodic review of flood risk man-
agement parameters is often a result of changed seasonal downstream channel capacities, down-
stream development adjacent to the river channel, or changed economic values for flood dam-
ages prevented. In many cases, encroachments in the flood plain may trigger a re-evaluation of
target control elevations for flood regulation or controlled river levels during the post flood evac-
uation period if it can be demonstrated that modifying the water control plan does not transfer
risk to a point where the project would not function as designed. The studies may be used to re-
fine guide curves in conjunction with the additional flood data described in Section 3.7.2. Sys-
tem flood risk management studies for multipurpose river basin developments should be made
using hydrologic and reservoir regulation models. Enacting the findings of a study may require
an update to the water control plan, NEPA documentation, a public meeting, and potentially fur-
ther congressional authorization.
3.7.5. Revising or Modifying Water Quality Operating Criteria.
3.7.5.1. Water quality conditions associated with initial impoundment and a short period after-
ward should be monitored using appropriate techniques. During the first year or so after the first fill-
ing, reservoirs are likely to have poorer water quality than the normal quality in subsequent years.
For example, in stratified reservoirs, inundated vegetation will generate high concentrations of hydro-
gen sulfide, which will flush out of the project by the second or third year of operation. A revision or
modification of water quality operating criteria and plans should be made, as necessary, to address
unanticipated water quality conditions.
3.7.5.2. Changes in water quality and the need to revise operating criteria in response should be
anticipated. Land use changes, changes in water user needs, changes in management objectives, and
extreme or unusual weather events may induce abrupt or long-term changes in water quality. Oper-
ating experience may suggest a need for alternative criteria or major modifications.
3.7.5.3. Monitoring and surveillance activities, which provide data for operating guidance, usu-
ally include watershed surveillance, inflow and discharge monitoring, and the plotting of water qual-
ity profiles. These practices identify long-term trends as well as abrupt changes. In some instances,
special studies of project conditions are used to develop guidance for modifying operating criteria.
Such studies may be relatively brief and simple in scope or may require modeling, reservoir systems
analysis, or physical modeling.
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3.7.5.4. Data obtained from monitoring and surveillance should also be a source of information
for revisions of water control plans and manuals. Water quality summaries should be included in
project descriptions and used to identify changes in conditions. Operating experience should be doc-
umented to describe the success and failure in meeting water quality objectives. Results of studies
used to modify operating criteria must be documented.
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CHAPTER 4
Operational Characteristics of Water Management Facilities
4.1. General Considerations. Any physical operating constraints should be clearly outlined to
ensure that water management features are operated in a safe manner and within design limita-
tions during all phases of project life, including the construction phase. Particular care should be
exercised during initial acceptance testing of the project’s regulating features.
4.1.1. Background Information. The water manager should understand the operational char-
acteristics of water management facilities to achieve water management objectives. This need
covers a broad spectrum of knowledge regarding the types of design, hydraulic characteristics,
and methods of operation of these facilities.
4.1.2. Types of Facilities. This chapter summarizes the types and design of project water pas-
sage facilities used to meet water management objectives and identifies the requirements, operation
methods, capabilities, and limitations of each of these facility types. The water management facili-
ties most commonly operated at projects are spillways and outlet works consisting of sluices, con-
duits, or tunnels. These facilities are usually gated. Several other types of water management fa-
cilities have specialized functions related to the regulation of streamflow, water level, and water
quality at the project or at downstream locations. These facilities include hydroelectric power gen-
eration units, navigation locks, fish passage facilities, sluiceways for passing trash or ice, interior
drainage facilities, hurricane and tidal barriers, bypass structures, siphons, and selective withdrawal
facilities for outlets or power turbines. The specific design limitations and methods of operation
must be noted in the project regulation criteria and in scheduling water releases.
4.1.3. Design Criteria. Guidance to design hydraulic features at Corps projects is presented
in ER 1110-2-1150, Engineering and Design for Civil Works Projects. During project develop-
ment, specific design of hydraulic structures is documented in the feature design memorandums.
These design documents include information pertaining to the functional design criteria, design
capacities, operating restrictions, control equipment, and methods of operation. During design,
these criteria should be developed through coordination between the design, construction, opera-
tion and maintenance, and water management functions. After a project becomes operational,
experience gained under actual operating conditions may provide additional information regard-
ing facility capacities and operating limits.
4.1.4. Physical Condition of Facility. The water manager needs ready access to documents
related to the physical condition of the water management facility. Generally, the stored files
should include: as-built drawings, periodic inspection reports (PIs), periodic assessment reports
(PAs), post-flood after-action reports (AARs), emergency action plans (EAPs), and any other
documents that could aid the water manager in addressing critical decisions.
4.1.5. Spillways vs. Outlet Works. The following paragraphs define and discuss flow pas-
sage facilities at dams, spillways and outlet works used in Corps general design practice.
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4.1.5.1. Spillways.
4.1.5.1.1. Spillways are typically classified as service spillways or auxiliary spillways and
can be gated or ungated structures. A service spillway is designed to provide continuous or fre-
quently regulated or unregulated releases from a reservoir, without significant damage to either
the dam or its appurtenant structures. An auxiliary spillway is any secondary spillway that is de-
signed to be operated infrequently, possibly in anticipation of some degree of structural damage
or erosion to the spillway that would occur during operations. It may release floodwater that
cannot be passed by other water passage facilities at a dam to prevent overtopping of the dam.
4.1.5.1.2. Gated spillways are often designed for flood risk management to provide more
discharge capacity when the gates are opened. They allow a lower spillway crest elevation that
could not be achieved with an uncontrolled spillway. A gated spillway may be used to make
controlled releases other than for flood risk management purposes. For example, gated spillway
releases may be needed in addition to hydroelectric power releases to meet downstream water
quality requirements.
4.1.5.2. Outlet Works. Outlet works are sluices, tunnels, or conduits used to pass flows from a
reservoir to meet project functions or to manage reservoir levels.
4.2. Spillways. Operating problems considered in design of spillways and appurtenant facilities
can be significant to the water manager. Routine periodic inspections, periodic assessments, and
annual inspections are the appropriate time to address spillway operational constraints, including,
but not limited to:
a. Cavitation.
31. Erosion.
32. Uplift.
33. Hydraulic jacking.
34. Vibration of gates.
35. Gate operation related to manual, remote, or automatic operating mechanisms, incremen-
tal openings, operation under partial gate openings, and selective spillway gate operation
to achieve desired flow patterns for hydraulic considerations or to improve fish passage.
36. Gate operation related to the functional use of storage, particularly to manage floods and
flood surcharge storage.
37. Debris passage or management.
38. Ice formation in the reservoir, ice flows, and the effect of ice or subfreezing temperatures
on gate operation.
39. Passage of upstream and downstream migrant fish.
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EM 1110-2-1603, Hydraulic Design of Spillways, describes the technical design aspects for the
hydraulic features of spillways, spillway chutes, energy dissipators, and spillway gates. The fol-
lowing sections describe types of spillways normally encountered at dams and reservoirs.
4.2.1. Energy Dissipation.
4.2.1.1. Energy dissipation is the most important technical hydraulic problem related to the de-
sign of spillways and outlet works. The energy to be dissipated is extremely high for spillways con-
structed at major dams, particularly for those with high head. High spillway velocities can cause
considerable erosion in the spillway and along the walls. Energy dissipators are designed to mini-
mize damage resulting from high velocity flows that occur either in the stilling basin or in the areas
immediately downstream from the dam. Four typical causes of damage to energy dissipators are:
a. Cavitation resulting from high velocities and negative pressures downstream from baffle
blocks, lateral steps, or other projections in the stilling basin.
40. Abrasion due to gravel, boulders, or other hard materials in the stilling basin or roller
bucket, which erodes the surfaces and also may increase the damage by cavitation.
41. Pulsating pressures, which may cause failure or deformation of sidewalls or splinter walls
constructed in or adjacent to stilling basins.
42. Erosion and scour of the area immediately downstream from the energy dissipator, which
may undermine the structure.
4.2.1.2. Three basic types of energy dissipators have been used: (a) a stilling basin (the most
common type) that dissipates energy by creating a hydraulic jump; (b) the roller bucket, which has
been used at some projects where substantial tailwater is available, and which dissipates the energy
immediately downstream from the bucket in the area of turbulent flows created by the rolling action;
and (c) the flip bucket (or ski jump spillway), which directs the jet of water a considerable distance
downstream from the dam to ensure that riverbed erosion does not occur near the downstream toe of
the dam or terminal spillway structure. Flip buckets are generally used at projects where the down-
stream channel is founded in sound rock, at locations where water depths that receive impinging flow
are relatively great, or at locations where erosion in the stream bed will not endanger the dam or ap-
purtenant structures.
4.2.1.3. The performance of the energy-dissipating facilities may be critical to the water man-
ager. If significant damage occurs to the stilling basin, the basin may be inoperative or only partially
operative until repairs are complete. Repairs must be conducted to maintain the safety of the struc-
ture, and extreme flows must be managed during the repair period. Also, the repair schedule should
consider the normal flows that may be impacted by the repair, and any resulting adjustments in the
operating schedules. The use of other facilities that may cause damage to the energy dissipators
should be limited. In addition, consideration should be given to lower the adverse effects of flow in
the stilling basin on fish migration, total dissolved gas supersaturation, navigation, and public safety.
4.2.2. Spillway Gates. Spillway crest gates are used primarily to manage the spillway dis-
charge according to specified operating criteria to achieve flood risk management objectives, but
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may be used to manage other water uses. Since gated spillways may allow for releases that
greatly exceed the reservoir inflow, special care must be used in making gate releases to ensure
that the outflows are maintained within operation standards. The following paragraphs describe
the three main types of commonly used spillway gates. Engineer Technical Letter (ETL) 1110-
2-584, Design of Hydraulic Steel Structures, provides more detailed information.
4.2.2.1. Tainter (Radial) Gates. Many major projects use Tainter gates with a design head of 30
to 60 ft and a width of 30 to 50 ft. Tainter gates are not designed to overtop and are usually designed
to maintain 2 ft of freeboard at maximum operating pool with the gates closed. For some Corps pro-
jects, the top of the flood pool is the top of the Tainter gates, and no freeboard is included in the de-
sign with the gates closed. The gate seal on the spillway crest is usually located downstream from
the crest axis to ensure that the water jet issuing from under the gate has a downward direction, re-
sulting in positive pressures immediately downstream from the gate. Tainter gate side arms, which
transfer the load to the trunnions, eliminate the need for gate slots. However, some Tainter gates
have been identified as needing trunnion arm strengthening so they can be operated as designed.
Spillway gates have been known to vibrate for various reasons, such as bottom hip and spill design.
After construction, spillway gates cannot always be tested due to lack of water on the spillway gates,
but operators should be aware of the potential for vibration.
4.2.2.2. Vertical Lift Gates. Vertical lift gates are most commonly used on low head dams. The
split-leaf option for vertical lift gates allows the top portion to be hoisted independently of the low por-
tion. The hydrostatic load of a vertical lift gate is transferred to the structure through bearing plates in
the gate slots rather than through a trunnion, as is the case for a Tainter gate. The type of side bearing
characterizes the gate as a wheel gate, tractor gate, or Stoney gate. These gates should not be over-
topped without verification from the dam safety officer that the design can withstand overtopping.
4.2.2.3. Drum Gates. Drum gates, although seldom used at Corps projects, have been com-
monly used at USBR dams (e.g., Grand Coulee Dam). A drum gate is designed to float on water in a
chamber located in the spillway crest. The water being released flows over the top of the drum onto
the ogee section of the spillway. The drum is raised by hydrostatic pressure and has an operating
range from the lower limit, in which the top of the drum is at the spillway crest level (fully open), to
the upper limit, in which the top of the drum is at full pool level (fully closed).
4.2.3. Spillway Capacity and Discharge Ratings. Spillways are sized according to criteria
and methods for accommodating floods contained in ER 1110-8-2 (FR), Inflow Design Floods
for Dams and Reservoirs. EM 1110-2-1603, Hydraulic Design of Spillways, provides details
concerning the methods for determining the ratings for spillways.
4.2.4. Operation of Spillway Gates. Spillway gate operation is based on prescribed discharges
in reservoir regulation schedules. In some cases (e.g., run-of-the-river power-navigation projects),
the spillway gates are operated to maintain a particular water level. Some gate control mechanisms
have a safety override feature that prevents a gate opening movement more than a prescribed incre-
ment without an intentional restarting of the gate operating mechanism. Spillway gate control
equipment is usually located near the gate, but at some projects the gates may be operated remotely
from a project control room on site or at another location. At a few projects, spillway gates may be
operated by automatic control, based on reservoir levels or hydroelectric power generation load as
outlined in ER 1110-2-1156, Safety of Dams – Policy and Procedures.
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4.3. Outlet Works.
4.3.1. Functional Requirements. The following paragraphs, extracted in part from EM 1110-
2-1602, Hydraulic Design of Reservoir Outlet Works, briefly summarize functional requirements
and related design considerations for outlet works used to regulate streamflows at dams and res-
ervoirs. This summary provides a general background of the principal elements and engineering
considerations in the design and use of outlet works to manage water systems.
4.3.1.1. Flood Risk Management. Flood outlets are designed for relatively large capacities in
which fine regulation of flow is less important than other requirements. Although controlled by
gates, the conduits may be ungated, in which case the reservoir is normally low or empty. Gates, wa-
ter passages, and energy dissipators should be designed with special care for projects in which large
discharges are released under high heads.
4.3.1.2. Conservation. Reservoirs that store water for subsequent release to support downstream
navigation, irrigation, fish migration, water supply, and water quality usually discharge at lower ca-
pacity than flood risk management reservoirs, but at these locations, the need for accurate flow regu-
lation is more important. For water quality, multiple intakes and control mechanisms may be in-
stalled to ensure reliability, to enable the water to be drawn from any selected reservoir level to ob-
tain water of a desired temperature, or to draw from a stratum relatively free from silt or algae or
other undesirable contents. Ease of maintenance and repair without interruption of service is of pri-
mary importance.
4.3.1.3. Power. Outlet facilities required for operation of hydroelectric power generation are dis-
cussed in EM 1110-2-1701, Hydropower. Power tunnels or penstocks may be used for flood risk
management and other water passage requirements.
4.3.1.4. Diversion. Flood risk management outlets may be used for total or partial diversion of
the natural stream during construction of the dam.
4.3.1.5. Drawdown. Requirements for low-level discharge facilities for drawdown of impound-
ments are discussed in ER 1110-2-1156, Safety of Dams – Policy and Procedures.
4.3.2. Sluices for Concrete Dams. Sluices constructed in concrete dams may be rectangular,
circular, or oblong. Those designed primarily for flood risk management may be sized to pro-
vide a relatively large number of individual sluices, each being in the general range of 4 to 6 ft
wide and 6 to 10 ft high. The flow through each sluice is controlled by individual gates or
valves, providing a finer degree of control than could be derived from a smaller number of
sluices of larger cross-sectional area. Sluice intakes may have trashracks for debris protection.
4.3.3. Outlet Facilities for Dams. Outlet facilities for dams consist of conduits and tunnels.
The intake structure may be a gated tower; multilevel, uncontrolled two-way riser; or a combina-
tion of these. The control structure may be located either in the intake tower or in a central con-
trol shaft. A combined intake and gate structure is most commonly used. Gate passage and con-
trol gate designs for sluices also apply to conduits through dams. Special problems involved in
the operation of outlet works through dams include:
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a. Head loss, boundary pressures, and vortices in the intake structure approach.
43. Debris and important fish species entrainment.
44. Hydraulic loads for vertical lift gates.
45. Gate “catapulting,” resulting from water pressure building up on the downstream side of
the intake gate during filling of the area between the service and emergency gates.
46. Vibration and resonance of cable supported gates.
47. Transition and exit flow conditions of the conduit or outlet tunnel.
4.3.4. Gate Passageways. The gate section, which is that portion of the sluice or conduit in
which the gates operate, is designed to eliminate or minimize the effects of cavitation. Particu-
larly during operation of partially open high head gates, passageways may be subject to severe
cavitation and vibration, and may have a high air demand. Air vents are provided to reduce cavi-
tation for control valves that do not discharge into the atmosphere. Two gates in tandem are nor-
mally provided for each sluice to ensure flow regulation in case one gate becomes inoperative.
Emergency gates must be provided for each service gate passageway to allow for closure of the
gate passageway in the event that a service gate becomes inoperative in any position. Bulkheads,
which allow inspection and maintenance of the upstream gate frame and seal, are provided for
each gate passage. Gate passages of circular cross section are designed for circular gates or
valves, such as knife and ring-follower gates and butterfly, fixed cone, and needle valves. Rec-
tangular gate passages are used for slide, Tainter, and tractor or wheel-type gates.
4.3.5. Control Works. Control works for sluices or conduits are classified as gates and con-
trol valves. Vertical lift gates may be slide, fixed wheel, tractor gates, or gate-within-a-gate,
which are operated by hydraulic cylinders, cables, or rigid stem connections to the hoist mecha-
nism. Hydraulically operated gates are preferred for high heads and for long periods of opera-
tion. Tainter gates are also used as service gates operating at high heads. Control valves, includ-
ing knife gate, needle-type, fixed-cone, and various commercial valves, have been used for flow
control to discharge water freely into the air or into an enlarged, well-vented conduit. Com-
monly used valves include butterfly, needle-type (hollow jet), fixed-cone, and commercially
available valves for small conduits.
4.3.6. Operation of the Control Works. The operation of control valves or service gates may
be based on manual, automatic, or remote control. In a few cases, the outlet works are under au-
tomatic control using water level sensors. Remote control operations should not be used if a sys-
tem failure could result in loss of life. Remote control operations are subject to additional safety
requirements, including visual verification, as addressed in ER 1110-2-1156, Safety of Dams –
Policy and Procedures. Vertical lift gates are usually manually operated by use of lifting mecha-
nisms, which may be “dogged” at fixed increments of elevation to approximate a particular gate
setting. Tainter or slide gates driven by hydraulic or electrical hoists may be controlled either at
the site of the gate machinery or, in some cases, remotely from the project control room. The
gate control mechanisms may have an override feature that limits the opening increment, requir-
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ing successive iterations to increase the opening size. Special problems may arise with the oper-
ation of the outlet works, such as ice and trash accumulation, excessive vibration, erosion, and
cavitation. Such problems must be resolved to meet the water management objectives and also
to maintain the integrity of the project facilities.
4.3.7. Discharges. Discharge is normally determined from theoretically derived discharge
ratings as described in EM 1110-2-1602, Hydraulic Design of Reservoir Outlet Works; however,
metering devices to monitor flow through conduits may be provided under unusual circum-
stances, especially when flow accuracy is important for regulation.
4.3.8. Low-Flow Facilities. Projects may be required to make comparatively small releases
for a variety of reasons, such as water supply or downstream aquatic benefit. The operation of
large gates to create small openings (less than 0.5 ft) is not recommended due to the increased po-
tential for cavitation downstream from the gate slot. Projects that require low-flow releases may
provide for releases by using low-flow bypass culverts, center pier culverts, multilevel wet well fa-
cilities, or a low-flow gate incorporated into the service gate, sometimes referred to as a “gate-
within-a-gate.” For projects in which a single tunnel is used and no other water release facility is
available, a bypass is desirable to maintain low flows in the river during repair periods.
4.3.9. Selective Withdrawal Systems.
4.3.9.1. Selective withdrawal systems may be provided to draw water from specified elevations
in the reservoir. These systems fall into three general types:
a. Inclined intake on a sloping embankment.
48. Freestanding intake tower, usually incorporated into the flood risk management outlet fa-
cilities of embankment dams.
49. Face-of-dam intake, constructed as an integral part of the vertical upstream face of a con-
crete dam.
Types b and c predominate at Corps projects due to the types of dams and time of construction,
however any of the types may be incorporated during rehabilitation of outlet structures.
4.3.9.2. Each type of selective withdrawal system described above includes the following struc-
tures:
a. Elevation specific inlets and collection wells for mixing.
50. Control gate passages to specify release.
51. Exit passages to discharge downstream.
4.3.9.3. Inlet ports for selective withdrawal are designed to be operated fully open or closed, and
the total flow is regulated by a downstream control gate or power unit. The inlet ports are operated
manually with gate hoists or other operating equipment. Some successful, single-well systems allow
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for blending of water withdrawn from more than one level. An inlet port that is not totally sub-
merged can be operated as an inlet weir, and the combined operation of the weir and downstream
control can be balanced to provide the desired flow characteristics. Collection wells are provided to
direct the flow of water from the intake system to the outflow passages. In dual wet well systems,
blending of flows for water quality should be from separate wet wells. Each wet well should have
individual flow control, and inlets at only one elevation should be open in each wet well. Submerged
weirs upstream of outlet works can be used to prevent withdrawal of bottom waters from reservoirs
by conduits and penstocks. Conversely, facilities may be used to withdraw bottom waters as rapidly
as possible after a flood, e.g., for turbidity management. In general, all water quality control devices
for selective withdrawal are individually designed to meet the particular project requirements, and the
regulation of these facilities is based on the experience gained during the operational phase.
4.3.10. Energy Dissipation. Energy dissipation for all types of dam outlet works is an im-
portant feature of the project’s hydraulic design. A hydraulic jump type stilling basin is most fre-
quently used for energy dissipation from conduits or sluices. The stilling basin may also incorpo-
rate the energy dissipation requirements for spillway discharges. Stilling basins are generally de-
signed to provide optimum energy dissipation of managed flows equal to the capacity of the outlet
works. The design of the stilling basin requires a detailed hydraulic analysis, which usually in-
cludes hydraulic model studies. Energy dissipation using stilling basins or other methods is an im-
portant consideration in the overall management of water releases from projects, and the effective-
ness of the system may be of particular significance to water and fishery resources managers.
4.3.11. Summary. The water manager should have general knowledge of the hydraulic de-
sign of the outlet works to evaluate special operating problems that may arise. Specific
knowledge of the detailed design for projects is also required to understand design limitations,
unusual operating problems, discharge characteristics, and other factors that may influence the
use of these facilities on a daily basis. Note that this summary of outlet work design is only a
general description of outlet facilities and design requirements. EM 1110-2-1602 provides a
more complete description of the methods of design for outlet works and the individual feature
design memorandums for a description of the design of outlet works for specific projects.
4.4. Flood Risk Management Operation.
4.4.1. Project Outflows. Chapter 3 presents the basic methods for developing water control
plans. Flood risk management releases are usually made through either the spillways or outlet
works; however, the total release may be met by combining releases from spillways, outlet works,
and hydroelectric power generation units, if available. The regulating outlets are sized to provide
the post-flood evacuation of reservoir flood storage. During a flood regulation period, project out-
flows are frequently adjusted to achieve downstream flood risk management objectives. In gen-
eral, the outlet works are designed to manage releases during the evacuation of flood storage, while
the spillway is used when the reservoir approaches full pool level and during induced flood sur-
charge operations. Downstream constraints may limit operation as originally designed.
4.4.2. Managing and Monitoring Outlet and Spillway Gate Regulation. The water manager
issues flood regulation schedules and operating instructions to the project operators. These in-
structions may include guidance on total discharge, gate settings, flow rates of change, and the
gates and structures to be used. The regulation should clearly state whether the outlet works
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should be opened or closed in conjunction with spillways to release flood flows. Outlet works
should not be used if they are not designed to operate at those extreme heads that are experienced
with extreme events. The water manager determines the reservoir regulation plan and ensures
that the project operational data reports reflect those decisions detailing discharge amounts, gate
settings, and reservoir levels. For some projects, automatic sensors at gate openings provide
continuous reservoir regulation data. Chapter 5 discusses WMESs. The water manager must be
informed of any problems related to the operation of the outlet works and the spillway. Any ad-
justments to reservoir regulation that may result from restrictions in the use of the outlet or spill-
way facilities should be coordinated between the project operator and the water manager.
4.4.3. Combined Use of Outlet Works and Spillways.
4.4.3.1. One technical hydraulic problem related to the flood risk management regulation of res-
ervoirs is the combined use of outlet works and spillways to pass the desired outflows during flood
periods. Many projects base the spillway design discharge capacity on the combined use of the full
capacity of the spillway and outlet works. In some cases, this capacity also includes a portion of the
capacity of hydroelectric power units that can be expected to be operable at the time of the flood.
Combined use of outlet works and spillways depends on evaluations of the hydraulic and structural
designs at the particular project. These evaluations include:
a. The flow characteristics of the spillway and outlet works with regard to symmetry of
flow in the spillway or outlet channel.
1. The allowable head on the outlet works.
2. Cavitation in the outlet works or spillway.
3. Back pressure on the outlet tunnel resulting from high tailwater.
4. Tailwater conditions that affect the performance of the stilling basin.
5. Gate operation with partial gate openings for both outlet and spillway gates.
6. The effect of the discharges on the flow patterns in the stilling basin.
7. Erosion or damage in lined or unlined channels that transport the water to the river below
the dam.
8. The interrelationships among flow conditions affecting other facilities, such as fish pas-
sage and survival, navigation channels, and revetments.
4.4.3.2. Projects should be operated to limit damage to the project structures. Some projects are
designed to use spillways only rarely. For example, using an unlined spillway outlet channel could
cause erosion in the spillway and the downstream river channel. In such cases, every effort should be
made to use the full capacity of the outlet works and hydroelectric power plant, if applicable, to limit
the magnitude and duration of flows over the spillway. Each project has unique design characteris-
tics, and operational decisions should minimize damage to the project structures based on design
data, past project performance, performance of similar projects, and anticipated flood regulation.
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This information should be incorporated into the project water control manuals, and periodically up-
dated to reflect the experience gained from operation.
4.4.4. Free-Flow Operation of Projects with Little or No Flood Risk Management Mission.
Some projects are constructed with dams and gate-controlled spillways to regulate the water sur-
face elevations and outflows of large natural lakes or run-of-the-river impoundments. Such pro-
jects may also have on-site hydroelectric power generation installations, navigation locks, or
other water management facilities. Usually, the operating range of the reservoir levels is limited
to relatively modest amounts; that is, the difference in elevation between minimum and normal
full pool levels rarely exceeds 15 to 25 ft. The primary purpose of these projects is to supply wa-
ter for seasonal uses, such as hydroelectric power production, irrigation, navigation, or water
supply. During a flood, such projects are managed to use the storage that is approximately equal
to the uncontrolled natural storage in the lake or river reach. Seasonal storage regulation for
these projects consists of filling to normal full pool level during the high-flow season, holding
the water in storage until needed for on-site or downstream flow regulation, and using the stored
water to augment streamflows during the low-water period. Projects of this type use spillways
designed to provide approximately the equivalent capacity of the natural outlet. The spillway
discharge may be augmented by outflows through power units.
4.5. Induced Flood Surcharge Storage.
4.5.1. General Principles.
4.5.1.1. Flood surcharge storage in projects with authorized flood storage is the volume of water
stored above the top of flood pool. For those projects without flood storage, such as a run-of-river
lock and dam projects, the flood surcharge storage is the volume above the top of the multipurpose
(navigation or hydroelectric power) pool. This volume is not water stored, but is left empty for use
when needed.
4.5.1.2. Reservoirs managed with gated spillways present special operating problems during
flood regulation. Particularly for large floods, the use of spillway gates (sometimes in combination
with the outlet works) must be carefully scheduled to reduce downstream flood flows while optimiz-
ing reservoir storage capacity. Spillway releases should be increased gradually, because sudden,
large flow increases may pose a hazard to public safety. They could also carry more debris, cause
more damage, and complicate downstream emergency responses, e.g., by shortening evacuation
times. To protect the project facilities, the facilities should be operated to maintain the integrity of
the outlet works and spillway and to keep the dam from overtopping. The operation of spillway
gates during floods should be regulated to compensate for current watershed hydrologic characteris-
tics differing from those used for design. Design hydrologic characteristics may be out of date due to
upstream valley storage loss, changed river channel hydraulic properties, synchronization of tributary
inflows, and changes in basin runoff characteristics. Rain falling directly on the reservoir surface
should not be neglected. In summary, three major concerns that the water manager must balance
while optimizing storage during a flood surcharge operation are:
1. Protecting the project’s integrity – do not overtop gates or embankment core.
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2. Limiting downstream damages – peak release should be no more (and preferably less) than
the instantaneous peak inflow during the event, i.e., less than the peak flow would have
been before the project was built so that damages are not induced by the project.
3. Maintaining the rate of outflow increase within acceptable limits.
4.5.1.3. Reservoir simulation models may be used for study purposes (developing operating cri-
teria) or operational use (calculating the effect of reservoirs on current river system regulation). Ad-
ditionally, simulation models are useful for comparing natural and regulated flow conditions for the
system, both for real-time reporting and economic studies.
4.5.1.4. Figure 4-1 illustrates the various levels and conditions involved in spillway gate opera-
tion for induced flood surcharge storage. The dotted lines in Figure 4-1 show the gate in a closed
position and the solid lines show the gate in an open position. As the gate is opened, additional water
is stored in the reservoir as flood surcharge storage and water is released under the gate.
Figure 4-1. Spillway Section Showing Surcharge.
4.5.2. Flood Surcharge Storage for Uncontrolled Ungated Spillways. The degree of control
afforded by an uncontrolled spillway is determined by outlet capacity and reservoir storage.
Storage routing may be calculated by a number of methods using basic storage and flow relation-
ships for a particular reservoir. Uncontrolled reservoir spillways store water above the spillway
crest, and the reservoir pool elevation rises and falls according to the inflow, outflow, and stor-
age relationships. Since flow regulation is determined by the inflow, storage, and spillway de-
sign and characteristics, the water manager has little capability to affect the releases from this
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type of project. It is important that communities and landowners downstream from the project
are aware of this so that they fully understand the limited regulation capabilities during high in-
flow, and possible high outflow, flood events.
4.5.3. Development of Induced Surcharge Envelope Curves.
4.5.3.1. The induced surcharge envelope curve defines the maximum permissible reservoir ele-
vation for a given reservoir release. The maximum induced flood surcharge storage elevation de-
pends on the design characteristics of the dam and spillway; design flood elevations; limitations im-
posed by flowage rights in the reservoir; economic, critical infrastructure; and life safety issues, par-
ticular to the basin. The envelope curve is developed using the following steps:
1. Compute a set of spillway-rating curves as shown in Figure 4-2.
2. Define top of gate limit.
3. Identify the greatest non-damaging flood risk management release.
4. Select fully-open-gate pool elevation.
5. Draw the induced surcharge envelope curve.
Figure 4-2. Gated Spillway Discharge Characteristics.
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EM 1110-2-3600
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4.5.3.2. The steps in the development of the envelope curve are more fully described below.
1. Compute a set of spillway rating curves (see Figure 4-2). Generally, the discharges are
computed in 1-ft pool elevation increments and 1-ft gate openings (with all gates open
same amount) including the fully open gate configuration.
2. Define top of gate limit. Top of spillway gate elevations corresponding to various gate
openings are superimposed on the rating curves (see Curve G, dashed line, Figure 4-2). In-
duced flood surcharge storage cannot exceed the elevations indicated by this curve without
overflowing spillway gates in the partially open position. In practice, the pool should be
limited to a lower elevation to provide some freeboard, particularly after gate openings of a
few feet are attained. Ideally, the gate limit curve provides a risk margin of 1 or 2 ft above
top of flood pool with gates in the closed position. EM 1110-2-1420, Hydrologic Engi-
neering Requirements for Reservoirs, addresses freeboard requirements.
3. Identify the greatest non-damaging flood risk management release. Usually, the non-
damaging release equals the downstream channel capacity or the flow associated with
flood stage at a downstream regulating station.
4. Select the fully-open-gate pool elevation. Selection of the fully open elevation must con-
sider economics, critical infrastructure needs, and life loss risks. The economic portion
of the decision must balance upstream and downstream flood damage risks. Often, the
upstream property damage risks are identified by setting the project real estate taking line
(see EM 1110-2-1420). The downstream property damage risks are identified by over-
laying economic data (e.g., Hazus mapping) on downstream inundation maps. Critical
infrastructure and life loss concerns are often connected, with releases or pool elevations
impacting evacuation routes, capacity of downstream dams, dam safety concerns, areas of
high population density, and national security sites. The water manager should exercise
proper engineering judgment to ascertain whether the spillway gates should be com-
pletely opened. Consideration should include current and forecasted inflow and corre-
sponding reservoir elevations as well as recommendations from the district and division
dam safety officers.
5. Draw the induced surcharge envelope curve from a point corresponding to the non-dam-
aging flood risk management release at the top of the flood pool elevation to the dis-
charge capacity of the spillway at the elevation at which all gates must be fully opened,
as illustrated by Curve E, solid line, Figure 4-2.
4.5.3.3. A straight-line connection ensures the minimum rate of increase in spillway discharge
under critical flood conditions and may be the proper form in some cases. However, curvature as il-
lustrated by Curve E, Figure 4-2, permits lower release rates in the lower flood surcharge ranges, the
most common event scenario. The minimum permissible slope of the line is governed by the rate of
increase in spillway discharge considered acceptable during extraordinary floods. Determination of
the minimum permissible slope of the curve should reflect downstream impacts and project capabili-
ties. Although consideration should be given to the timeliness of the closure of downstream evacua-
tion routes during the highest discharge of the flood surcharge release, a more important requirement
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is to confirm that the gates can be opened at a sufficient rate to route the design event using the pro-
posed induced surcharge envelope curve.
4.5.4. Development of Spillway Gate Regulation Schedules.
4.5.4.1. Projects with gated spillways may require a spillway gate regulation schedule, which is a
family of curves that relate inflow, outflow, and project storage. The schedule is used to identify the
minimum release required to evacuate the forecasted inflow volume that exceeds available storage
(including available flood surcharge storage) and could occur on the rising or falling limb of the in-
flow hydrograph. The general methodology to develop a spillway gate regulation schedule is to cal-
culate the required storage to pass a given inflow at a given outflow; the required storage is used to
identify the correlated pool elevation. This procedure is used to determine the minimum volume of
inflow expected at a particular time during a flood. The forecasted inflow volumes should be mod-
eled and based on observed precipitation. The procedure is also used to compute a family of curves
(termed the spillway gate regulation schedule) that relate the inflow and residual reservoir storage
volume (including induced flood surcharge storage) to determine the outflow required to avoid mak-
ing regulated downstream flows greater than under a pre-project condition while at the same time
providing for an orderly increase in outflows during extreme floods such that project overtopping is
prevented. The computations are presented in the Institute for Water Resources, Humphreys Engi-
neer Center (IWR-HEC) publication Volume 7, Flood Control by Reservoirs. The spillway gate reg-
ulation schedule is developed using the following steps:
1. Define recession constant (T
s
).
2. Calculate the inflow storage (S
A
).
3. Identify the elevation (
) on the surcharge envelope curve.
4. Determine the total reservoir storage (S
E
).
5. Calculate critical storage (S
c
).
6. Determine the tentative maximum allowable pool elevation (
).
7. Test each tentative maximum starting reservoir elevation (
).
4.5.4.2. Each of the listed steps is discussed below.
1. Define recession constant (T
s
). The first step in the procedure is to analyze recession
characteristics of inflow hydrographs to obtain a recession constant to predict a minimum
inflow volume that can be expected, with the only known information being the reservoir
elevation and the rate of rise of the reservoir elevation.
For conservative results, the assumed recession curve should be somewhat steeper than
the average observed recession; it can normally be patterned after the inflow design flood
recession. A variety of decay functions can be used to fit the recession curve; however,
in most cases, an exponential function is adequate, where the flow (Q) after a time period
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EM 1110-2-3600
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(t) is predicted for the initial flow (Q
i
), and where the recession constant is defined by T
s
,
as shown in:
=
(4-1)
Graphically, the recession constant can be obtained by plotting the recession curve as a
straight line on semi-log paper, with the flow on a logarithmic scale and time on an arith-
metic scale. The recession constant, T
s
, is defined as the time required for the discharge
to decrease from any value, say Q
A
, to a value Q
B
, where Q
B
equals Q
A
/e, and 2.7.
Mathematically, the recession constant is the time required for a given inflow to recede
by about 63%.
2. Calculate the inflow storage (S
A
). The volume of water that will need to be stored given
an inflow peak and outflow is the total future event volume (area under the recession
curve) minus the outflow volume (release rate multiplied by the time required for inflow
to recede to match outflow). Consider Figure 4-3, which schematically illustrates terms
to be used in solving for the volumes to be stored, S
A
. In Figure 4-3, Q
1
represents the
inflow, Q
2
represents the constant outflow, and c represents the conversion constant (in
most cases, = 1.983 to convert cfs-day into ac-ft). The recession constant, T
s
, may be
defined as the additional volume stored (V
s
) and released (V
r
) during the duration for the
inflow to recede until matching the release:
V + V
(S / c) + Q t S + cQ t
s r
A 2 A 2
T = = =
(4-2)
S
∆Q
Q − Q c(Q − Q )
1 2 1 2
Figure 4-3. Schematic Hydrograph.
The time (t) for the inflow to recede until equal to the release may be solved by:
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EM 1110-2-3600
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t = T − T = −T log (Q / Q ) = T log (Q / Q )
(4-3)
2 1 S e 2 1 S e 1 2
Substituting (4-3) into (4-2) and rearranging:
S
A
= cT
S
[
Q
1
− Q
2
− Q
2
log
e
(Q
1
/ Q
2
)
]
(4-4)
S = cT
[
Q − Q (1+ log (Q / Q ))
]
(4-5)
A S 1 2 e 1 2
For each of various inflow rates and for each of various outflow rates, compute the vol-
ume of water that must be stored, S
A
, using Equation 4-5.
3. Identify the elevation (
) on the surcharge envelope curve (see Section 4.5.3) that cor-
relates to each inflow (Q
i
). For example, in Figure 4-4, the elevation on the induced sur-
charge envelope curve corresponding with an inflow equaling release of 40,000 cfs is
1571.1 ft.
4. Determine the total reservoir storage (S
E
) corresponding to each surcharge envelope
curve elevation (
) using the project elevation-storage relationships.
5. Calculate critical storage (S
c
) given each inflow volume to be stored (S
A
). The critical
storage is the maximum allowable storage that can be used in the reservoir during the in-
flow event such that the reservoir elevation does not exceed the surcharge envelope
curve. The critical storage (S
c
) is the total reservoir storage (S
E
) less the volume to be
stored (S
A
).
S
= S
S
(4-6)
6. Determine the tentative maximum allowable pool elevation (
) given each critical stor-
age value (S
c
) using the project elevation-storage relationships.
7. Test each tentative maximum starting reservoir elevation (
) against spillway limits to
determine the maximum starting reservoir elevation (
). The maximum starting eleva-
tion represents the maximum pool elevation for which an operator could begin a flood
surcharge operation for a given peak inflow and release condition and meet the induced
flood surcharge objectives listed in Section 4.5.1. The regulation schedule seeks to an-
swer the question: Is the spillway capable of passing the set outflow given the calculated
maximum starting pool elevation? The lower limit is the outlet works crest elevation, at
which the maximum pool level (
) equals the spillway crest. The upper limit is defined
by the maximum discharge curve (spillway free-flow capacity); if the tentative maximum
starting reservoir elevation (
) does not provide enough head to pass the given inflow,
then the critical elevation (
) is the elevation capable of passing the inflow. Otherwise,
if the tentative starting elevation is between the spillway limits, then the tentative eleva-
tion is the maximum starting elevation (
).
4.5.4.3. The family of curves based on inflow is shown as Regulation Schedule A in Figure 4-4.
Families of curves, such as those shown in Figure 4-4, are appropriate to use in a central office, but
the relationships for an emergency operation schedule for dam tenders can be applied more directly if
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EM 1110-2-3600
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the rate of rise of reservoir level is substituted for the inflow. This is readily accomplished by obtain-
ing the difference between the volume of inflow and outflow for a selected time interval and express-
ing the volume as a rate of rise for any particular reservoir elevation. A typical family of curves
based on rate of rise is shown as Regulation Schedule B in Figure 4-5.
Figure 4-4. Spillway Gate Regulation, Schedule A.
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EM 1110-2-3600
10 Oct 17
Figure 4-5. Spillway Gage Regulation, Schedule B.
4.5.4.4. The steps to convert an inflow regulation schedule to a rate of rise gate regulation sched-
ule are:
1. Select the appropriate time interval (T).
2. Find each difference between the inflow and outflow.
3. Calculate each storage change.
4. Determine the critical storage (S
c
).
5. Calculate each storage (
) for one time interval in the past.
6. Identify each elevation (El) for one time interval (T) in the past.
7. Finally, determine the rate of rise.
4.5.4.5. Each of the listed steps is more fully discussed below.
1. Select the appropriate time interval (T) to measure the change in pool elevation. The
time interval to determine rate of rise should be based on the reservoir and drainage basin
characteristics, with 1 to 3 hours being typical, given that adjustment in gate openings at
1- or 2-hour intervals is adequate for most projects.
2. Find each difference between the inflow and outflow; ∆ =
.
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EM 1110-2-3600
10 Oct 17
3. Calculate each storage change; = /T.
4. Determine the critical storage (S
c
), given each critical elevation (
) using the project
elevation-storage relationships.
5. Calculate each storage (
) one time interval (T) in the past;
=
.
6. Identify each elevation (El) for one time interval (T) in the past using the project eleva-
tion-storage relationships.
7. Finally, determine the rate of rise, which is the difference of the critical elevation and the
previous elevation divided by the time interval; = (
El)/T.
4.5.5. Testing Spillway Regulation Schedule. Spillway gate regulation and induced sur-
charge envelope curves should be tested by simulating regulation of historic or hypothetical
floods. Several computer programs are available to model regulation conveniently, most notably
HEC-ResSim software (which is also capable of calculating spillway regulation schedules given
the elevation-storage curve and surcharge envelop curve), developed by the Hydrologic Engi-
neering Center. Testing should include a variety of storm patterns and magnitudes considered
reasonable for the project.
4.5.6. Methods of Operation. Operating options available during rising and falling reservoir
levels should be described in project water control manuals and water control plans.
4.5.6.1. Rising Reservoir Levels.
4.5.6.1.1. If forecasts based on observed precipitation indicate that runoff from a storm will
appreciably exceed the remaining reservoir storage capacity, the opening of spillway gates may
begin before the time required using the spillway gate regulating schedule. This could occur on
the rising or falling limb of the inflow hydrograph See Section 7.3.2 for further discussion on op-
erating based on water-on-the-ground.
4.5.6.1.2. Opening of spillway gates should be scheduled to limit the rate of increase in out-
flow to acceptable values to the extent possible. For outflows required by the spillway gate regu-
lation schedule, induced flood surcharge is used to partially manage outflow rates. The elevation
attained and the volume of induced flood surcharge storage used varies with the volume and rate
of reservoir inflow during individual floods and the exact schedule of gate operation.
4.5.6.2. Falling Reservoir Levels.
4.5.6.2.1. Releases should be based on the most appropriate of the available options once
flood surcharge storage has peaked. The flood surcharge storage should be evacuated as rapidly
as possible, while considering conditions downstream from the project as well as project safety.
The type of project (e.g., concrete arch, rolled earth embankment) should be considered when as-
certaining how long high pool levels should be maintained. Also, Corps water resource projects
vary greatly in design, storage, and release capability as well as dam safety action classification
(DSAC). Each of those components must be considered on a case-by-case basis when determin-
ing the drawdown strategy from flood surcharge storage. On completion of drawdown to the top
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EM 1110-2-3600
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of flood pool level, the regulation schedule for releasing stored waters should be followed. Some
of the more common procedures for drawdown of induced flood surcharge storage for falling
reservoir levels and decreasing inflow are:
1. Drawdown gradually to top of flood pool level within a specified time (e.g., hours or
days).
2. Maintain maximum spillway gate opening.
3. Release a flow equal to a fixed percentage (over 100%) of the mean inflow for the pre-
ceding 3 hours without exceeding the event’s instantaneous peak inflow.
4. Make the release in excess of the current inflow by some specified increment of dis-
charge without exceeding the event’s instantaneous peak inflow.
5. Make the release conform with a hydrograph similar to the natural inflow hydrograph.
6. Maintain a non-damaging or channel capacity discharge.
7. Make releases that do not induce additional damages at downstream control points.
4.5.6.2.2. If all spillway gates are opened fully during the storage operation, discharge is un-
controlled until the outflow decreases to the value at which the uncontrolled condition began.
Regulated operation should then conform to one of the preceding release schedules for falling
reservoir levels.
4.5.7. Effect on Spillway Gate Design. The most efficient induced storage operation would
normally require that the spillway gates be designed for operation with partial openings and with
individual operating mechanisms. Unless the gates are designed for overtopping, the height of
gates should be 1 or 2 ft greater than required for the induced flood surcharge operation, since all
gates cannot feasibly be operated simultaneously to obtain the desired discharge on some struc-
tures. The design should also consider that gates should not be operated such that only the lip of
the gate is in the flow.
4.6. Outlet Works Releases.
4.6.1. General Considerations. The design requirements for outlet works to support water
supply are different from the requirements for flood risk management. Generally, the water re-
leases for irrigation, navigation, M&I water supply, fish passage or habitat enhancement, and
other water uses are fairly uniform over a period of days or weeks as compared with the rapidly
changing requirements for flood risk management. The use of outlet works for water supply may
involve special operating issues, which should be considered by the water manager. The regula-
tion should clearly state whether the outlet works should be open or closed in conjunction with
spillways to release flood flows.
4.6.2. Special Considerations. Outlet works designed primarily for flood risk management
may have some restrictions during low-flow regulation due to cavitation. Also, operation of
flood gates may not provide the degree of gate control to achieve the low-flow requirements.
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EM 1110-2-3600
10 Oct 17
Some types of gate operating mechanisms have a tendency to creep over time, and the gate set-
ting must be recalibrated periodically to maintain the desired uniform outflow from the project.
As the reservoir rises or falls gates may need to be adjusted to account for the changing head to
maintain a desired release. The water manager must also be aware of hydraulic problems associ-
ated with long-term operation of outlet works, such as the adverse effects of spray that may re-
sult from the use of a ski jump energy dissipator, turbulence or undesirable flow patterns in the
downstream tailwater area, problems related to ice formation and cold weather operation, and the
general continuity of operation of outlet work facilities generally unattended except as needed to
make adjustments in outflows.
4.7. Diversion and Bypass Structures.
4.7.1. Project Purposes and Types. Diversion structures and systems vary widely in size,
complexity of operation, and degree of control. In many cases, excess flood water is transported
from a main stream by a management structure and auxiliary channel to reduce flood flow and
stages at potential damage centers on the main stem. Water supply diversions for M&I and irri-
gation purposes are the most common and include closed conduit bypass facilities and open
channels. Other reasons for diverting flow may be to accommodate recreation, to improve con-
ditions for fish and wildlife, to suppress saltwater intrusion in estuaries, or to lower the ground
water table. Diversions to existing channels for other purposes may provide incidental naviga-
tion benefits. Water is diverted into some reservoirs at night, following a hydropower generation
cycle (pumpback) and is reused for the same purpose in the next generation cycle. A diversion
may generate power by passing flow through turbines in route to an auxiliary channel used for
other purposes. Some diversion systems have seasonal objectives for high-flow conditions, for
low-flow conditions, and for both high- and low-flow conditions. Other diversions operate con-
tinuously: some manage the flow both into and out of a given area.
4.7.2. Regulation Procedures and Schedules. Diversion projects that have uncontrolled
structures do not require water management decisions. However, knowledge of the periods that
these structures operate may be needed to notify the general public, evacuate auxiliary channels,
and take other appropriate action(s). The most complete hydrometeorological data available, in-
cluding stage and discharge forecasts, should be used for regulation. Detailed analyses are often
made for controlled structures for water management, whether for flood risk management, water
supply, or other project purpose. Withdrawal from a stream or impoundment may be a highly
sensitive issue; therefore signed agreements with appropriate interests are advisable to address
both normal and rare climatic events. Long-range regulation schedules are made to define the
duration of an event and to define stage and discharge hydrographs upstream and downstream of
the management structures. Various factors that should be taken into account in developing reg-
ulation schedules include:
1. Duration of inundation.
2. Stream and channel capacities (stage or flow reduction targets).
3. Navigation channel (width and depth).
4. Relationship to dredging.
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EM 1110-2-3600
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5. Levee grades.
6. River stage and reservoir levels.
7. Water quality in reservoirs, streams, and estuaries.
8. Seasonal considerations.
In general, physical operating characteristics of the management structure, such as energy dissi-
pation and velocities, are critical.
4.8. Hurricane or Tidal Barriers. Hurricane barriers are operated to protect coastal communities
from tidal flooding associated with severe storms. The design and operation of these projects
must include the effects of interior runoff, pumping station requirements, and availability of
ponding. The length of time that navigation gates will be operated is needed, as well as gate
head differentials that allow gate opening. The manager should also be aware of the discharge
capabilities of emergency sluices in case a navigation gate becomes inoperable in the closed po-
sition or must be closed for maintenance for a long period. A description of the protected area,
including expected damages associated with various levels of flooding, should be prepared.
4.9. Interior Flood Risk Management Facilities.
4.9.1. General. Interior floodwater is normally passed through line-of-protection gravity out-
lets whenever interior water levels are higher than exterior water levels (gravity conditions). The
floodwater may be stored, diverted, or pumped past the line-of-protection if exterior stages are
higher than interior stages (blocked gravity conditions). Gravity outlets, pumping stations, interior
detention storage basins, diversions, and conduits are the primary measures used to reduce flood
damages in interior areas. Other measures, such as reservoirs, channels, flood proofing, relocation,
regulatory policies, flood warning, and emergency preparedness, may also be integral elements of
the interior flood reduction system. EM 1110-2-1413, Hydrologic Analysis of Interior Areas, pro-
vides general guidance for the analysis of interior flood risk management facilities.
4.9.2. Operating Criteria. Generally the Corps plans, designs, and documents detailed oper-
ating criteria for newly completed interior flood risk management facilities for use by the local
personnel responsible for operation and maintenance. These criteria should include instructions
to obtain and report appropriate hydrologic data, including current and forecasted values of river
stages, interior runoff from area rainfall, and ponding levels. The criteria should be supported by
a description of the proper use of the data to effectively operate the water management facilities.
Provisions to obtain supplementary data should be included, as needed. General flood emer-
gency preparedness plans should be carefully described, including all arrangements to ensure
timely closure of gravity drains, to implement emergency closures, and to operate pumping
plants. Periodic schedules to inspect, test, and maintain the facilities should be defined.
4.9.3. Legal Requirements. The capability of an interior flood risk reduction system to func-
tion over the project life must be ensured. This requires legally binding commitments from the
project’s local sponsors to properly operate and maintain the system. Real estate requirements
and specifications for operating and maintaining detention storage areas, pumping facilities, and
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EM 1110-2-3600
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conveyance networks are integral to all agreements for implementation of an interior system of
flood measures.
4.10. Hydroelectric Power Generation Facilities.
4.10.1. General. The functional use of hydroelectric power facilities encompasses a broad
spectrum of technical knowledge. At Corps hydroelectric power generation projects, the turbine-
generator units, control facilities, power transformers, switchyards, and operational techniques
include complex equipment that is under Corps operational control. However, a higher level of
electrical power system operation and integration exists, which involves not only the physical
hydroelectric power facilities, but also regional electrical power system operation. A clear un-
derstanding at the higher level is needed to support decisions affecting the operation of the total
regional electric power resource and the relationship between power operation and the manage-
ment of multipurpose river developments.
EM 1110-2-1701, Hydropower Engineer Manual, provides guidance on the technical aspects of
hydroelectric power generation studies from pre-authorization through the General Design Mem-
orandum (GDM) stage. Specific topics addressed include the need for power, determination of
streamflows and other project characteristics, estimation of energy potential, sizing of power
plants, cost estimating, and power benefit analysis. Other EMs address design details for hydro-
power facilities, such as powerhouses, turbines, and generators. While EM 1110-2-1701 primar-
ily concerns hydropower, background information is also provided on power systems operation
and the general features of hydroelectric development.
4.10.2. Major Hydroelectric Facilities. Hydroelectric power projects are classified by type of
operation as run-of-the-river, pondage, storage, pumped storage, and reregulation. All hydroelec-
tric power plants include the following major hydraulic components: dam and reservoir, intake,
conduit or penstock, surge tank (when necessary), turbine-generator unit, draft tube, and tailrace.
The types and designs of each of the components are determined by the specific design require-
ments for individual projects and vary widely, depending on the project’s type of operation and
physical characteristics. The heart of a hydroelectric power plant is the powerhouse, which shel-
ters the turbines, generators, control and auxiliary equipment, electrical buswork, circuit breakers,
disconnects, and, in some cases, erection bays and service areas. Generator step-up (GSU) trans-
formers are usually placed on or adjacent to the powerhouse, and switchyards are located nearby.
4.10.3. Plant and Unit Control Systems.
4.10.3.1. Control equipment is necessary to facilitate the automatic or manual operation of the
power units and other necessary power plant equipment. Larger multi-unit attended plants often
have a central control room and automatic control, which require large computer-based supervisory
control and data acquisition (SCADA) control systems. These SCADA systems need to be in com-
pliance and have or be working towards receiving a current Authority to Operate (ATO). In general,
individual power units, multiunit power plants, and large interconnected power systems are operated
by a variety of manual and automated control systems. At Corps projects, the hydroelectric power
facilities and control systems are generally operated under the supervision of the operations division,
which has direct responsibility for the operation and maintenance of the individual projects. The op-
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eration of these facilities for daily regulation and functional management to meet all water manage-
ment objectives, including hydroelectric power generation, is performed according to instructions
and schedules provided by the reservoir management center, water management center, or other wa-
ter regulation unit that has responsibility to schedule plant operation.
4.10.3.2. The water manager responsible for projects operated under AGC must be familiar with
the interrelationships between system controllers and the planned use of equipment to schedule plant
operation for normal and emergency conditions. Although the planned and scheduled use of power
plants is coordinated through the water managers, the ultimate plant operation is determined by the
AGC equipment. The plant operation should be continuously monitored to ensure that the water
management objectives are being met, and that any necessary corrective action(s) are taken.
4.11. Use of Water Management Facilities for Fishery Enhancement.
4.11.1. General Information.
4.11.1.1. Fish passage features and water management operations have been used predominately
to preserve anadromous fish runs, such as for salmonids. However, the importance of avoiding ad-
verse impacts to other fish, such as lamprey, paddlefish, and sturgeon, has been increasing and the
design and operation of water management projects have been changing to better support other spe-
cies of interest.
4.11.1.2. Specially designed facilities and operations for fish passage and enhancement of fish
life have been incorporated into many water management projects. Physical features for these facili-
ties may include adult fish passage (fish ladders, attraction water, counting stations, bypass channels,
fish collection and transport facilities, etc.), juvenile fish passage (bypass and transport facilities),
“fish-friendly” turbines, spillway surface passage, fish hatcheries, water quality improvements (water
temperature and multilevel flow control outlets, modified spillways to reduce nitrogen supersatura-
tion, etc.), and improvements to fish spawning areas. In addition to physical facilities, special water
management operations may be desired, such as regulating project water releases to meet fishery
specifications (streamflow, water level, spill level, and temperature) and making special test opera-
tions to support biological research.
4.11.1.3. Special release operations for the downstream migrant fish passage season are typically
developed for the full range of seasonal river flows to provide the most efficient egress of the fish
along a path that avoids high predation risk zones.
4.11.2. Operations to Aid Dissolved Gas Supersaturation.
4.11.2.1. Dissolved gas supersaturation may occur in rivers below dams. As water plunges
down a dam spillway, the churning and deep plunging action can cause gas (mostly nitrogen) to be
pressurized in the stilling basin and become dissolved in the river. Long exposure to gas supersatura-
tion may injure juvenile and adult fish by causing gas bubble disease. Supersaturation has been suc-
cessfully reduced by modifying the structural shape of spillways, by adjusting the water regulation in
the system where possible to reduce spillway releases, and by adjusting the distribution of spillway
releases. Although gas supersaturation caused by dam spillage can be reduced, a method to eliminate
damaging levels of supersaturation for all streamflow conditions does not exist.
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4.11.2.2. As feasible, the plan for system-wide operation should be to lessen the spillway re-
leases at downstream locations to minimize gas supersaturation. The timing of the spillway release
reductions may be scheduled to better coincide with the fish runs. These objectives may be incorpo-
rated into the AOP and into daily schedules.
4.11.2.3. Depending on the project type, the most direct way to reduce gas supersaturation
through water management is to adjust spillway releases between projects under real-time operation.
This can be accomplished by shifting power loads to maximize spillway releases at those projects in
which the spillway releases produce the least amount of gas supersaturation. Also, spillway releases
may be reduced by arrangements to increase power loads on the hydroelectric power system and by
reducing loads on thermal plants or other outside resources. Models are available to simulate the lev-
els of gas supersaturation and may be used to analyze and forecast the levels resulting from the
scheduled system releases. These programs use current system data, which are essential to initialize
and evaluate the effects of current release conditions.
4.11.3. Operations to Aid Passage of Downstream Migrants.
4.11.3.1. A number of alternative project operations are being tested at large dams to assist fish pas-
sage and to determine the most satisfactory and economical methods. For example, voluntary project re-
leases (not needed for flood risk management) are being used to enhance the passage of downstream mi-
grants. Furthermore, due to the longer travel times of downstream juvenile fish migration that result from
the impact of reservoirs in the river system, increasing streamflows by releasing water stored in upstream
reservoirs may be desirable at times to increase velocity in the stream. During warmer water periods, pro-
vision of cooler water from upstream reservoirs is desirable to reduce downstream water temperatures
and reduce fish stress and increase survival rates. These three factors are considered in the daily manage-
ment of the water facilities in conjunction with all other project purposes.
4.11.3.2. Multilevel intakes, usually considered to provide general water quality control, may
have been justified primarily to meet the fishery specifications for management of water tempera-
tures or other water quality parameters that affect fish life. Scheduling the use of multilevel intakes is
usually based on the fishery needs, and the water manager should understand the fishery manage-
ment programs and the desired conditions affected river reaches.
4.11.3.3. Although operating plans may recognize and account for fishery concerns under actual
operation, the values of many variables that affect the daily fishery needs cannot be accurately esti-
mated more than a few days in advance. This is particularly true of the need for induced releases and
increased discharge through the reservoirs during critical times in the spring. Mathematical model-
ing systems to simulate and evaluate hydraulic and fishery conditions are being used as an aid in
scheduling water regulation during critical times of downstream fish migration.
4.11.4. Fishery Regulation and Coordination. Detailed knowledge and management respon-
sibility of the fishery resource may be shared by the state and Federal fish and wildlife agencies,
tribes, and international organizations. The fish and wildlife agencies represent the interests of
sport and commercial fishing. The tribes have treaties that may involve fishing rights. Interna-
tional organizations represent fishery interests of other countries that share in the responsibility
for fishery management through treaties and compacts. To support fishery concerns, input from
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all of these organizations should be included in the water control plans and in the daily manage-
ment of the water and fishery resources.
4.11.5. Fish Hatcheries. Fish hatcheries are used to mitigate fish losses caused by the con-
struction of dams, to maintain and increase overexploited fish stocks, and to enhance fish pro-
duction in areas deficient in production. Water intakes for the hatcheries, which may be from the
reservoir or from the downstream channels, may require water management activities. Water
quality characteristics, including temperature, pH, dissolved oxygen, and nitrogen, should be
maintained within specified tolerances.
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CHAPTER 5
Water Management Enterprise Systems
5.1. Overview.
5.1.1. Water Management Decision Support System.
5.1.1.1. ER 1110-2-249, Management of Water Control Data Systems, provides guidance for the
management of Water Management Enterprise Systems (WMESs) including descriptions of the
equipment and software used for acquisition, transmission, and processing of real-time data used to
regulate Corps water projects. A WMES includes all Corps hardware and software being used for
acquisition, transmission, processing, display, and dissemination of hydrologic, meteorologic, water
quality, and project data to support the Corps water management mission, along with the software
using the data. Chapter 6 of this manual further discusses the software portion of a WMES.
5.1.1.2. A WMES is the automated system supporting water managers in making real-time oper-
ational decisions to determine and set water release schedules for Corps water resources projects.
The WMES performs the continuous acquisition; storage; computational analysis; and watershed
modeling, visualization, and dissemination of the hydrometeorological information necessary to op-
erate Corps projects and provide project benefits. Through proper administration, the WMES pro-
vides an effective means of data management that supports daily water management activities. In
addition to being used to assist in daily decision making, the data collected or generated are fre-
quently used internally and externally for various purposes (e.g., navigation studies, floodplain stud-
ies, construction activities). These data are also provided to various tribes, Federal, state, and local
agencies, private entities, and the general public.
5.1.1.3. Water management forecasts, operational decisions, and guidance are coordinated with
many Federal, state, and local government agencies. Various computer and server-based applica-
tions are used and are a component of the WMES. One of the fundamental purposes of the WMES
is to provide a mechanism to efficiently streamline two-way communication between the water man-
agement office and a variety of internal and external stakeholders.
5.1.1.4. The primary system components of the WMES are standardized so they provide for
common use, inter-office compatibility, and continual nationwide support and development. Hydro-
meteorological data are acquired, stored in a database, validated, transformed, and used to model wa-
tersheds in real-time. The resulting processed, transformed, and modeled data are then used by the
Corps water management decision makers to regulate their projects to meet the congressionally au-
thorized project purposes. The standardized WMES tool set allows each district/region to report out
on both the standard project parameters common to all similar projects as well as any unique project
parameters unique to a project. All collected and processed data are used for the purpose of support-
ing mission and appropriately reporting out on the project’s status to Corps staff and leadership, asso-
ciated decision makers, and the public.
5.1.1.5. The size and complexity of each WMES will be dependent on the specific water man-
agement mission requirements of the district.
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5.1.1.6. Primary system components include:
1. Data Acquisition. The real-time acquisition and decoding of hydrometeorological infor-
mation.
2. Data Storage, Validation, and Transformation. Storing information in Corps database,
screening information for accuracy, and computing dependent values (e.g., stage to flow,
elevation to storage).
3. Watershed Modeling. Numerical simulations of watershed hydrology, reservoir opera-
tions, and river hydraulics.
4. Visualization and Data Dissemination. Presentation of river and reservoir conditions, op-
erational forecasts, model results, and other information for water managers, associated
decision makers, and the public.
5. COOP. Documented and tested plan to ensure the capability to accomplish the water
management mission under all conditions.
5.1.2. Corps Water Management System (CWMS).
5.1.2.1. As described in Section 6.2.2, CWMS is a national Corps automated information system
(AIS) that was designed and developed to be a critical and significant core component of a WMES;
Corps water management offices are required to use CWMS. CWMS software suite provides the
Corps Water Management Community with a common interface to a set of data management tools
and watershed models with which to perform the water management mission. The Corps Hydrologic
Engineering Center (HEC) is the CWMS system developer and is responsible for CWMS develop-
ment and implementation oversight. Development and implementation of nationwide systems such
as CWMS provides tremendous long-term benefits to the water management community, allowing
for economy of cost (i.e., by developing one basic system for many) and easing the ability of water
managers to provide assistance to a neighboring office during a significant hydrometeorological
event, e.g., a flooding event. Independent efforts to supplement CWMS should consider the overall
nationwide viewpoint and purposes of an AIS. Figure 5-1 shows an example of the integration of a
CWMS AIS into a WMES.
5.1.2.2. A full CWMS suite of models is the goal for every regulated basin in the Corps. Other
software is currently used and a transition is expected to take a decade or more, depending on funding.
5.1.3. Modeling. The WMES provides the foundation for development of CWMS watershed
models. A nationwide CWMS-based modeling effort has been initiated in response to several
significant flooding events that have involved multiple major subordinate commands (MSCs).
The main objective for collaboration of modeling efforts between multiple Corps civil works
programs is to increase the effectiveness of meeting the overall water management mission. See
Chapter 6 for detailed information related to water management modeling methods and imple-
mentation.
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Figure 5-1. Typical Example of CWMS AIS Integration into a WMES.
5.2. Water Management Enterprise System Hardware.
5.2.1. Hardware requirements have been established via the WMES initiative. This initiative is
reviewed and revised on an ongoing basis and its purpose is to establish standard systems that can be
deployed and maintained by the Corps enterprise information technology (IT) service provider.
5.2.2. The risk of hardware failure is always present, but can be mitigated to some degree.
Redundant hardware availability can increase system reliability.
5.2.3. Some examples of redundancy at the hardware level that are part of the WMES include:
1. Multiple Servers. A failover server that can run in place of the production server pro-
vides an excellent level of protection against the breakdown of the production server.
2. Dual Power Supplies in the Server. Server downtime can be reduced by ensuring that the
power supplies are hot swappable.
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3. Disk Arrays. Disk arrays are storage systems that link multiple physical hard drives into
one large drive for advanced data control and security. The array drives are hot swappa-
ble to minimize data downtime. The array may be accessed by the server either through
direct bus (small computer system interface [SCSI]) connection, or via the network (net-
work attached storage [NAS]). The use of a disk array ensures hardware and software
availability.
4. Uninterruptible Power Supplies (UPSs) and Emergency Backup Generator/Power. UPSs
are essentially battery packs that keep the server and associated hardware powered up for
a limited time during a power failure. This provides time for an effective shutdown of
the hardware. The UPS may also provide power between the point of the power failure
and resumption of power via an emergency generator. Emergency generator power is
ideal during times of prolonged power failure, but represents a significant maintenance
cost.
5. Remote Server/Disk Array Location. Servers located in areas prone to natural disasters
(hurricane, earthquake, tornados, etc.) are at high risk of being offline for extended peri-
ods of time. Data centers in remote locations (staffed by water managers or accessed via
the network during emergencies) can mitigate the risk associated with prolonged events.
5.3. Water Management Data.
5.3.1. Data Acquisition.
5.3.1.1. Types of Data.
5.3.1.1.1. Hydrometeorological conditions at projects and remote field sites are automati-
cally sampled by specialized sensors to provide real-time information to water managers. The
most commonly sampled parameter is water level (reservoir level or river stage). Various types
of sensors may be used to collect water-level information, including bubblers, pressure transduc-
ers, encoders attached to floats, and radar. Another frequently sampled parameter is rainfall us-
ing tipping buckets or impact sensors. For precipitation measurements other than rain (e.g.,
snow, sleet), weighing buckets may be appropriate. Other hydrometeorological conditions, such
as air temperature, wind speed and direction, solar radiation, and relative humidity, may be sam-
pled. Water quality parameters, such as water temperature, dissolved oxygen (DO), pH, and tur-
bidity may be sampled. Some project data, such as gate positions, can also be sensed automati-
cally. Each sensor is controlled by a programmable device known as an electronic data logger
(EDL). The water managers determine the frequency of data sensor sampling and program the
EDL to query the attached sensors at the prescribed sample frequency.
5.3.1.1.2. Mountain snowpack accumulation may be represented by direct measurement of
snow accumulation at snow courses or automated U.S. Department of Agriculture (USDA) Na-
tional Resources Conservation Service (NRCS) Snow Telemetry (SNOTEL) sites, or by indirect
measurements of seasonal precipitation at selected climatological stations.
5.3.1.1.3. There are generally two sources of plains snowpack information: ground surveys
and modeled snowpack assessments that combine ground measurements, airborne assessments
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and satellite estimates. Ground surveys of snowpack performed by the Corps, the National
Weather Service, state agencies, the Community Collaborative Rain, Hail, and Snow (CoCo-
RaHS) Network, and other enlisted volunteers measure the snow depth, snow water equivalent,
snow density, and other characteristics of snow at random or predetermined locations. Surveyed
assessments of snowpack over large areas possess inherent uncertainties because of snow move-
ment due to wind, snow accumulation, and melting cycles, and changing land surface conditions
at measurement locations that cause inconsistencies in the long-term measurement record. Mod-
eled snowpack assessments can compensate for some of these uncertainties by combining multi-
ple sources of information into a product modeled over large areas. A primary modeled snow
product is available through the National Weather Service National Operational and Remote Hy-
drologic Sensing Center (NOHRSC). NOHRSC’s snow product is a modeling and data assimila-
tion system that integrates snow data from satellite, airborne platforms, and ground stations with
model estimates of snow cover. Another source of snowpack information is the National Aero-
nautics and Space Administration (NASA) National Snow and Ice Data Center, which develops a
satellite-based daily snow covered area assessment.
5.3.1.2. Methods of Receiving Data.
5.3.1.2.1. Data Collection Platforms. The majority of EDLs used by Corps water managers
are fitted with Geostationary Orbiting Environmental Satellite (GOES) transmitters. An EDL
combined with a GOES radio transmitter is commonly termed a Data Collection Platform (DCP).
The transmission of DCPs to GOES satellites is regulated by the National Environmental Satel-
lite Data and Information Service (NESDIS), which issues a DCP owner a GOES transmission
channel, transmission time, and transmission interval for each DCP. A field-installed DCP sends
its data to either the GOES-East or GOES-West satellite. The telemetered sensor data are then
bounced off of the satellite back to a ground receive station. A Direct Readout Ground Station
(DRGS) is a ground receive station that can directly monitor the specific transmission channels
from either the GOES-East or GOES-West satellites. Several Corps water management offices
use a DRGS, but the majority of Corps water management offices use ground receive systems
that monitor a retransmitted complete channel GOES data stream that is uplinked to secondary
set of satellites and receives data within a few seconds of a DRGS. All ground receive stations
can be software-linked over the network to provide a reliable GOES data acquisition system. All
environmental data transmitted to a GOES satellite is public and can be collected using a ground
receive system regardless of the originating agency. The digital Low Rate Information Trans-
mission (LRIT) is an international standard for data transmission, including GOES data, that was
developed in response to a recommendation on digital meteorological satellite broadcasts. Fig-
ure 5-2 shows a schematic example of a typical data transmission.
5.3.1.2.2. Line of Sight Radios. Line of Sight (LOS) radios are another method to transmit
field-collected data to a WMES. LOS systems typically consist of gaging stations, base stations,
and repeaters. Equipment at a typical LOS radio gaging station consists of an EDL, a battery, a
radio transceiver, and an antenna aimed at a repeater or at the base station. The station transmits
data at specified times and frequencies. The station also can receive instructions from the con-
troller located at the base station, which can be useful for remote configuration and ad hoc poll-
ing of data. Power may be supplied by commercially available power lines, solar cells, or on-site
generators. Repeaters that re-broadcast transmissions are used to forward transmissions between
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the base station and DCPs that are either out-of-range and/or behind a mountain range obstruct-
ing a direct LOS transmission between the base station and one or more DCPs. Repeaters are
usually located on prominent high points to meet LOS requirements. Repeaters are powered the
same as gaging stations. Base stations consist of a transceiver, controller, and antenna array.
Base stations are typically located in project offices and water management offices.
Figure 5-2. Typical Example of Data Transmission.
5.3.1.2.3. Networked Data Loggers. EDLs can be connected to computer networks and use
those networks for two-way communication. This allows for near real-time, frequent transmis-
sion of sensor data to the office and provides the means for water management personnel to re-
motely troubleshoot and reprogram the data logger.
5.3.1.2.4. Receiving Data from Internet Sources. Some data needed for making water man-
agement decisions are only available from internet sources. This may require water management
offices to develop custom procedures to securely receive internet data from data acquisition part-
ners. Two examples are the need to acquire data from a hydroelectric power company that posts
current water usage as well as forecasted water needs for several days, and the need to acquire
SNOTEL information from the NRCS.
5.3.1.2.5. Project Data. Some data continue to be collected manually by staff at the project
as part of their routine daily tasks or part of their routine during operational periods. Examples
of the data collected this way include current gate settings; and reservoir, downstream channel,
lock, gate and local weather conditions. Methods used to transmit this data to the WMES in-
clude voice communication between the project staff and the district water management staff,
email or a software interface allowing the project staff to enter the data on a local workstation
that then transmits the data directly to the district’s WMES.
5.3.1.2.6. National Weather Service Data. The National Weather Service (NWS) is one of
the key partner agencies with which the Corps exchanges hydrometeorological data. Key data
that the Corps receives from the NWS include precipitation and snow forecasts (both point fore-
casts as well as gridded coverage forecasts) and river forecasts that are used by Corps Water
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Managers to model future watershed conditions and likely reservoir release scenarios. The
Corps then sends the NWS its reservoir operational scenarios, which are in turn used by the
NWS to formulate their next round of river forecasts. The NWS encodes and transmits its data
in standard/agreed-on formats, e.g., the Standard Hydrologic Exchange Format (SHEF). The
CWMS software suite provides utility tools that can decode data received from the NWS and
store it in the CWMS database, making the data available for further processing, watershed mod-
eling, or simply for direct access/viewing. Three main sources for NWS data are:
1. A direct network connection between the NWS and the Corps.
2. A dedicated NWS satellite feed (commonly termed NOAAPORT).
3. NWS public web pages (internet source).
5.3.1.2.7. Telephonic Data. Some water management offices connect cellular or local area
network (LAN) telephone lines to remote EDLs to enable the water managers and project staff to
directly receive real-time site-related conditions. These data are not automatically input into the
WMES; however, the data can be very valuable in the decision making process during rapidly
changing conditions at a remote site.
5.3.1.2.8. Other Data Systems. Several private companies provide satellite communications
capabilities using private satellite constellations. These for-profit companies provide another
method to send and receive EDL data and offer two-way communication with the EDLs
equipped with a specific type of transmitter. Water managers may be required to use data sys-
tems owned or operated by non-Federal sponsors responsible for O&M of Corps projects and
will need to work access issues with the individual sponsors.
5.3.1.3. Data Acquisition Partners.
5.3.1.3.1. The U.S. Geological Survey (USGS) is another key partner in deploying and
maintaining DCPs. Depending on the water management office, the Corps may independently
support a DCP network. In other cases, the Corps partners with the USGS to fully or partially
fund the USGS DCP network through the USGS Cooperative Streamgaging Program.
5.3.1.3.2. In addition to the USGS, the NWS, USBR, TVA, NRCS, private hydroelectric
power companies, and other Federal, state, and local water resources agencies make data availa-
ble to the Corps.
5.3.2. Data Processing.
5.3.2.1. Data processing begins with the arrival of data to one of the data receive components of
the WMES such as a Commercial-off-the-Shelf (COTS) satellite data receive appliance or a system
running a network data exchange service. The initial goal is to have the system that is processing the
data either decode the data and store it directly into the Corps CWMS database, or to minimally decode
the data into a CWMS supported format (e.g., SHEF or one of several Gridded data formats) so that the
CWMS data ingest utilities can store the data into the Corps CWMS database. Some of the data re-
ceived are text data or graphic images that simply need to be stored in the appropriate WMES that then
makes the data/files available for review and analysis by a water manager.
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5.3.2.2. For data destined for the Corps CWMS database, once the raw or initial data are stored
in the Corps CWMS database, further processing of the data is usually triggered that validates the
data (e.g., performs range checks and quality checks) and that then transforms the data (e.g., trans-
forms a river stage to a flow value or computes a reservoir inflow based on the reservoirs current re-
lease and pool level change) into values that are of use by watershed models and/or meaningful in
evaluating the hydrometeorological condition of a watershed by a water manager.
5.3.2.3. Format conversions is a common preprocess that may occur. Though the Corps will re-
quest that data be sent in a standard format (e.g., SHEF), many cooperating agencies and power com-
panies may not be able to convert their data into a standard text and/or standard binary format. The
office’s water management team will then need to script a local conversion process to handle the
non-standard data sets.
5.3.2.4. A Corps CWMS database is the goal for every water management office, but it is not yet
the operational database in some places. A complete transition to the CWMS database for opera-
tional use is expected over the next decade depending on funding.
5.3.2.5. Gridded Data.
5.3.2.5.1. Gridded data may be used to visualize approaching storms and to follow a storm
track moving throughout a watersheds and river systems. Gridded data may also be used to
quantify climatological events and to provide a runoff forecast, based on the effects of tempera-
ture on an accumulated snowpack.
5.3.2.5.2. Although gridded data can come from a variety of sources, these data are typically
generated and obtained from the NWS Next-Generation Radar (NEXRAD) system. The system,
which is composed of approximately 160 radar installations, provides up-to-the-minute scans of
the national weather system. The NWS uses the system to provide a variety of products such as
temperature and precipitation grids, wind shear data, and severe weather alerts.
5.3.2.6. Data Transformation. Transformations of data are an essential process in the WMES.
At a basic level, water management data are collected in the field and transmitted as river stages, res-
ervoir levels, and gate opening increments. That data are then verified and transformed; the river
stage is transformed to river flow, the reservoir level is transformed to reservoir storage, and the gate
opening amount to a flow. More complex data transformations are calculated for differing datums,
dimensions, scales, and coordinate systems in both time and physical domains.
5.3.2.7. Data Quality Control.
5.3.2.7.1. Data acquired and transformed should be visually reviewed and corrected, if nec-
essary, before being integrated into real-time models. Various quality assurance/quality control
(QA/QC) applications are available within CWMS or have been developed specifically to meet
office requirements.
5.3.2.7.2. Validations can be part of an automated process that quantitatively evaluates the
quality of data. This data quality is signified by modifying a quality flag associated with each
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data/timestamp pair within a time series of data. The validation process identifies missing data,
questionable data, and erroneous data through range-checking and rate of change checking.
5.3.2.7.3. Data correction processes may be automated or manual. Automatic data correction
processes include the interpolation, extrapolation, or smoothing of missing and incorrect values.
Values that have been automatically corrected should be flagged as such. Manual data review and
manipulation interfaces are available to allow the water management data technicians or managers
to quickly review and correct values that are either clearly out of bounds or missing. Manually up-
dated/corrected values are also flagged as having been manually modified. For an external data
source, a process could be established to communicate corrections back to the data provider.
5.3.3. Data Storage and Retrieval.
5.3.3.1. The database and associated management software comprise the database management
system (DBMS), which is essential for the storage, manipulation, retrieval, security and, if necessary,
recovery of water management data. The CWMS database provides these features and meets appli-
cable Army and Corps standards for data storage and retrieval.
5.3.3.2. The DBMS must be capable of storing a variety of data types:
1. Data/timestamp time series data, both regular and irregular interval.
2. Paired data (e.g., rating curves or gate curves).
3. Relational/metadata, which includes pertinent project data, reservoir rule curves and zones,
rating curves, control point regulating criteria (seasonal), water quality profiles. Metadata is
sometimes referred to as “data about data” and allows for the user to further describe the data
collected.
4. Gridded data, which consists of a multidimensional rectangular array of grid points con-
taining values. Gridded data are used in modeling applications such as rainfall/runoff com-
putation.
5. Geo-spatial data, i.e., raster data (basin topography) and vector data (point data, outlines
of basins, rivers, reservoirs, roads, and political boundaries).
5.3.3.3. The DBMS must be capable of storing, retrieving, and revising high volumes of data.
Revising data in a database includes adding new records, deleting existing records, and changing in-
formation within a record.
5.3.3.4. The DBMS must support concurrent updates. These are updates that occur when multi-
ple users make updates to the database simultaneously.
5.3.3.5. Data must never be permanently lost. The DBMS must have the capability to back up
data and, in the event of a catastrophe, restore the database to a pre-damaged state.
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5.3.3.6. The DBMS must be capable of preventing unauthorized access. Authorization for data
access must be based on a user or group (e.g., office, region) and incorporate allowable permissions
for those individuals or groups (view restrictions, edit values, etc.).
5.3.3.7. The DBMS should be installed on server-level hardware, preferably on a dedicated
server for maximum resource availability and custom software flexibility.
5.3.3.8. The database must be available at all times.
5.3.4. Data Dissemination.
5.3.4.1. Methods.
5.3.4.1.1. The data collected and processed by the WMES are ultimately used for reporting
the status of CWMS and the subsequent dissemination or publishing of this information to oth-
ers. This reporting may be for Corps decision makers and operating staff, external stakeholders,
and the general public.
5.3.4.1.2. Data may be for internal or external use. Internal use is data that are intended for
use and review by the Corps only. Reports that are intended for internal use only will be marked
as Unclassified – For Official Use Only, in accordance with existing regulations.
5.3.4.1.3. There are two types of external users, namely the general public and other Federal,
state, and local agencies or organizations that are involved in water resources management activ-
ities or other related public services or earth science missions.
5.3.4.1.4. Examples of external data users are the USGS, NOAA, USBR, Bureau of Land
Management (BLM), U.S. Forest Service (USFS), National Park Service (NPS), USDA, NRCS,
state agencies, county agencies, regional river authorities, irrigation districts, levee boards, water
suppliers, flood warning systems, and law enforcement agencies.
5.3.4.1.5. The Water Management mission is a real-time mission that makes it difficult to
fully perform quality control checks on all data that need to be released either to staff and leader-
ship within the Corps itself or to customers outside of the Corps. Data that are released and/or
used to report on the current status of projects do go through several automated validation
checks, as well as human checks as the data are used internally and/or during the running and
evaluation of watershed model runs. Even so, some erroneous data will slip through. Therefore,
all reports (either textual or graphical) need to be marked as containing “Provisional Data” sub-
ject to further review and change.
5.3.4.1.6. Historic data distribution was typically done by paper reports. Printed reports are
still commonly used in all Corps offices, although the reports are now usually created using
desktop printing technologies that produce electronic reports that can be posted on a web site and
are only printed if a paper copy is needed. Public meetings, especially before, during, and after
major events such as flooding, still require a paper copy for distribution and are still a highly ef-
fective way to inform the public and affected agencies.
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5.3.4.1.7. In today’s world, just about everyone has access to a network connected device.
Data on the status of Corps water management projects is published on both publicly accessible
and internal only accessible Web services. In addition to general Web services, the Corps will
establish direct data links (e.g., sftp [secure file transfer protocol] feed/socket) to specific servers
of stakeholders. This type of connection is used when either or both agencies expect to be rou-
tinely exchanging high value data needed by both the Corps and the stakeholder agency (e.g., ex-
change hourly or daily data sets between the NWS).
5.3.4.1.8. Even historical data are now available for download off of Corps websites. Occa-
sionally large data sets are requested and a special one-off compact disk (CD), digital video disk
(DVD), or possibly even an external hard drive must be prepared and shipped off in the mail.
Given the ever increasing bandwidth and evolving data compression technologies, those one-off
data exchanges are expected to disappear too.
5.3.4.2. Types of Reports.
5.3.4.2.1. Many different types of reports are generated and disseminated by all Corps water
management offices. The data disseminated in water management offices throughout the Corps
are very similar. Though the type of information contained in these reports is very similar, the
format of these reports varies regionally, because the reports have been developed over the past
several decades to meet the needs of the stakeholder, cooperating agencies, partners, and the gen-
eral public within the local area of responsibility.
5.3.4.2.2. Some examples of typical reports are inflow reports and plots, hydroelectric
power, reservoir elevation forecasts and plots, gate rating tables and plots, tile gage readings,
gate settings, facility closure reports, project weather reports, daily reservoir and system sum-
maries, release reports, related links pages, and many more. Many of these reports contain pre-
liminary data or analysis and are intended for official use only by Corps decision makers in eval-
uating water management regulation options.
5.3.4.2.3. The level of access to the various reports is determined by each district related to the
individual missions and circumstances. Efforts to provide more standard reports and data delivery
methods are being pursued by Corps water management offices to improve the experience and ease
of use by end users, whether internal, external stakeholder, cooperator, or the general public.
5.4. Continuity of Operations Plan and WMES.
5.4.1. Every water management office should have a viable, current, and complete COOP
that includes provisions to recover or remotely access a WMES. The main objective of a WMES
COOP is to provide guidance to water managers and affected local and enterprise information
management (IM) support personnel on how to restore WMES access and functionality to an ac-
ceptable degree for emergencies, disasters, and mobilization. This may require a remote site. In
addition, the WMES COOP is needed to maintain a state of readiness to provide the necessary
information to meet the water management mission should the primary method be unavailable
(e.g., server failure, internet outage). Note that COOP planning does need to address a total
WMES failure, i.e., a worst case scenario where a functioning WMES is simply unavailable for a
prolonged period of time. Fallback to paper copies of the projects’ water control manuals and
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training of project staff and water control managers on paper and pencil operations should be in-
cluded in the planning.
5.4.2. Ideally, each WMES will be designed such that each component previously discussed in
this chapter will include high availability (HA) capability. HA will ensure that each component of
the WMES has at least two levels of functionality. Whether a local WMES does or does not im-
plement HA design concepts, each office should maintain a documented and annually tested
COOP plan that addresses how the office will deal with the failure of their primary WMES.
5.4.3. The HA capability becomes more viable for certain aspects of a WMES as enterprise
initiatives are implemented into each local WMES. Each water management office is expected to
continue to customize portions of the WMES to meet specific mission requirements. However,
with the implementation of nationwide applications, aspects of data acquisition, data processing,
data dissemination, and modeling could be simultaneously maintained at multiple locations (e.g.,
local off-site, national processing center, division, other district, cloud) to maintain HA capability.
Care should be taken to ensure that the development of the multiple-location structure meets the
water management objective. To meet this critical objective, the non-local COOP structure may
require that certain WMES components, such as data acquisition, be divided between multiple lo-
cations. Determination of non-local COOP sites should consider that an emergency or disaster re-
quiring COOP capability (e.g., flooding, internet outage) may also affect nearby WMES locations.
The system should also be sufficiently robust for emergency, simultaneous use by multiple water
management offices due to large regional and or geographically concurrent floods.
5.4.4. Maintaining a viable, current, and complete WMES COOP may be challenging, expen-
sive, and time-consuming. District and division leadership beyond water management, not just an
individual in a water management office, is responsible for ensuring that the local water manage-
ment mission can be met should the primary means not be available. Since security and access ca-
pability, and application upgrades are ever-changing, each office should test various portions of the
WMES COOP several times each year to ensure that full COOP functionality is maintained. Non-
working portions of the WMES COOP should be addressed as soon as possible.
5.5. WMES Master Plan.
5.5.1. ER 1110-2-249 outlines the requirements for WMES master plans. WMES master
plans include all the essential information related to the requirements, justification, scope, and
recommend procedures for implementing water control data systems. Master plans may include
an outline of performance requirements to adequately maintain a fully functioning WMES at the
district, division, and national levels. Since water management mission requirements can vary
considerably by district and division, this outline will need appropriate detail. In addition,
changing missions may require that this outline be reviewed and revised annually.
5.5.2. Performance requirements to provide all aspects of a fully functional WMES may in-
clude:
1. Local servers and processing power to acquire and process data and operate real-time
models.
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2. Local Area Network/Wide Area Network (LAN/WAN) connectivity, speed and reliability.
3. Database with the size, speed, and ability to backup and retrieve lost data.
4. Scalability to increase/decrease system components as mission requirements change.
5. Reliability and performance of associated equipment/services (e.g., switches, processing
centers).
6. Support from the U.S. Army Corps of Engineers–Information Technology (ACE-IT) for
hardware, software and connectivity.
7. Replacement of non-working, non-compliant hardware and software.
5.5.3. A master plan should describe alternative approaches taken and associated successes or
failures and recommendations for future upgrades to the system, both at a local and enterprise
level, to meet requirements unmet by existing facilities or to provide a more cost effective system.
5.5.4. Justification and recommendation of a system should consider timeliness, reliability,
economics, and other important factors.
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CHAPTER 6
Water Management Techniques
6.1. General Considerations.
6.1.1. Importance of Technical Evaluations.
6.1.1.1. Real-time regulation of a major water resource system depends ultimately on the experi-
ence and judgment of the water manager. Complex interactions among the many meteorologic and
hydrologic processes, combined with the effects of project management, encompass a wide range of
continuously changing conditions that must be evaluated and understood. Judgments made by the
water manager must be founded on the best available scientific and engineering evaluations, and
must consider time constraints and available data.
6.1.1.2. There are many analytical tools now available that may be used to quantify those ele-
ments that would otherwise be subjectively determined to forecast and mitigate flood risk throughout
the nation. Optimal operation of flood risk management reservoirs and accurate prediction of flood-
ing may prevent damages on the order of many millions to billions of dollars each year. Hydrologic
and hydraulic modeling programs may enhance such operations by providing information to support
decisions made by water managers and other Corps staff. These computer models must incorporate
rigorously defined analytical procedures and methods based on hydrologic and hydraulic theory.
6.1.1.3. Accordingly, the overall objective is to perform technical evaluations using these recog-
nized and approved models, rather than subjectively determined estimates. These models are used to
analyze water resource systems to meet water management objectives. These computer models may
also constitute the technical foundation for making water management decisions for project regula-
tion, and provide the basis for the planning of water management activities.
6.1.2. Hydrologic Analysis.
6.1.2.1. A primary technical challenge in real-time water management is hydrologic analysis.
Water is the prime resource to be managed in water systems, and this demands an understanding of
the natural processes by which water is distributed and accounted in a river system. The science of
hydrology is defined as the body of knowledge related to the behavior of water in the atmosphere, on
the surface of the ground, and underground. Although hydrology is considered to be a science, a
blending of scientific theory and empirical knowledge occurs in the application of hydrology to the
analysis of river systems.
6.1.2.2. For many years, the Corps has used widely accepted hydrologic analysis procedures in
flood hydrology. Refer to EM 1110-2-1420, Hydrologic Engineering Requirements for Reservoirs,
for a discussion of factors to be considered in determining the magnitude of design floods. ER 1110-
8-2(FR), Inflow Design Floods for Dams and Reservoirs, defines design flood requirements to evalu-
ate dam and spillway adequacy. Application of these principles was also extended to rivers affected
by snowmelt runoff and is described in EM 1110-2-1406, Runoff from Snowmelt. Another good
source of technical information on snowmelt is the Engineer Research and Development Center,
Cold Regions Research and Engineering Laboratory (ERDC-CRREL). Initially, these methods were
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used for project planning and design studies, but more recently have become the basic method of
analysis for project planning and real-time project regulation. Detailed methods of analysis have
been refined through continued development of computer models that incorporate recognized proce-
dures for analyzing runoff. Computer models such as Hydrologic Engineering Center – Hydrologic
Modeling System (HEC-HMS) are tools that blend theory and empirical knowledge to provide hy-
drologic analysis for project planning and real-time regulation. Additionally, some offices rely on
the NWS to provide the hydrologic analysis component of real-time forecasting. Other computer
models, such as Hydrologic Engineering Center – Reservoir System Simulation (HEC-ResSim), al-
low the water manager to evaluate proposed operations based on hydrologic input. The Hydrologic
Engineering Center – River Analysis System (HEC-RAS) may be used to compute the extent of
flooding for various alternatives.
6.1.2.3. Long-range analyses of river and project conditions may be based on historical or de-
rived streamflows (using a hydrologic model such as HEC-HMS) that are used in connection with
the development of water control plans. Simulations of project regulation incorporating streamflows
may be accomplished using computer models such as HEC-ResSim or RiverWare, which incorpo-
rate system analysis techniques to predict river and reservoir conditions for an extended period of
time, based on current reservoir conditions and historical or derived streamflow. Thus, this type of
continuous simulation, in which the end conditions of the previous time step serve as the starting
conditions for the next time step, can be used to test the system capability to meet the project’s au-
thorized purposes over an extended period. Project regulation simulations may also consider each
year of historical record to be an individual event or independent event. These may be very useful in
obtaining a probability distribution of project regulation conditions during an ensuing year or a por-
tion thereof, to assess the probabilities of meeting water demands based on historical records of
streamflows, current reservoir levels, and water or power demands.
6.1.2.4. In summary, the overall objective in analyzing real-time water management systems is
to use all the current water management data available using computer models to derive streamflows
(if necessary), to regulate projects in the most effective manner possible, and to evaluate the effects
of those operations. This analysis may provide information to schedule the regulation of individual
projects and to forecast system regulation needs. Project regulation schedules, including the operat-
ing criteria, guidelines, rule curves, and specifications that govern the reservoir operation, must be
generalized since the schedules are based on historical data and known or simulated operation.
When plans are applied in real-time, however, operational decisions need to follow the guidelines of
the water control plan, or possibly be adjusted to meet unique conditions. The use of computer mod-
els can facilitate this effort.
6.2. Analytical Methods in Modeling for Water Management.
6.2.1. Modeling Concepts. Models that express the hydrologic functions affecting stream-
flow must be based on sound hydrologic and hydraulic theory, but must also be practical repre-
sentations of hydrologic processes that consider the availability and quality of the data. These
models must also be intricately linked to real-time and forecasted data within a system to provide
the optimum means of decision making. These computer models are tools that may provide real-
time and forecasted water conditions data to the water manager to support improved water man-
agement decisions, detailed schedules, and better planning. In summary, computer modeling
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should be used by the water manager to test various alternatives and conditions affecting regula-
tion related to water control plans. The Hydrology, Hydraulics and Coastal Community of Prac-
tice (HH&C CoP) maintains a list of approved software that can be used for these purposes. An
enterprise standard for software evaluation also exists.
6.2.2. Types of Models.
6.2.2.1. The Corps Water Management System, or CWMS, is the Corps recognized AIS for ac-
complishing the water management mission. CWMS consists of a database (software and hardware)
and a suite of computer models (hydrologic, reservoir, hydraulic, and flood impact analysis).
CWMS may be used to collect, validate, and store real-time hydrometeorological data from many
sources and formats for real-time reporting and water management decision support. CWMS also
may provide support for operational decisions by forecast modeling using a combination of hydro-
logic models that incorporate recognized analytical and empirical methods. The types of computer
models and systems that may be applied to real-time project regulation using CWMS are generalized
into the following groups:
1. HEC-HMS — Hydrologic models to simulate the hydrologic cycle to estimate stream-
flow, to forecast flow resulting from rainfall or snowmelt, and to calculate base flow and
interflow estimated from known hydrologic conditions (e.g., observed, real-time) and
forecasts of future meteorological events.
2. HEC-ResSim — Reservoir system analysis models to simulate the response of single or
multipurpose projects, based on observed or derived streamflows, and to determine future
project capabilities from known river and reservoir conditions.
3. Reservoir water temperature and water quality models to simulate the conditions of water
quality in a reservoir and at downstream locations for assessing future conditions of water
quality and scheduling the operation of multilevel outlet works or other facilities related
to water quality project management.
4. HEC-RAS — Hydraulic models to compute river stages and water surface profiles for
steady and unsteady flow regimes for proposed project regulation and to compute an in-
undation boundary and depth map of water in the flood plain.
5. Flood inundation models such as RAS mapper to map impacted areas and contribute to
economic and life safety impacts (HEC Flood Impact Analysis [HEC-FIA]) determina-
tion of different flow alternatives.
6. Water supply and forecast models to forecast seasonal runoff, based on statistically de-
rived procedures using predictor hydrometeorological variables such as precipitation,
snowmelt, streamflow, and recognized and approved climate indexes.
7. Special auxiliary programs to determine release schedules, summarize data, display data,
and analyze particular functional needs that affect water regulation. Note that these ap-
plications or tools can be considered to be post-processing in nature. For instance, the
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applications may distill model output from a reservoir operations model necessary for
water managers to provide instructions to operators.
6.2.2.2. The user-configurable sequence of modeling software allows engineers to evaluate oper-
ational decisions for reservoirs and other management structures, to and view and compare hydraulic
and economic impacts for various “what if?” scenarios. These same models may allow an engineer
to perform technical analyses of alternative water control plans in the development of a new water
control plan, to develop interim risk reduction measures, and to analyze a deviation request.
6.2.2.3. A full CWMS suite of models is the goal for every regulated basin in the Corps. Other
software is currently used and a transition is expected to take a decade or more depending on funding.
6.3. Meteorological Forecasts Used in Water Management.
6.3.1. General.
6.3.1.1. River system response is ultimately the result of hydrometeorological factors that affect
runoff. The time, form (e.g., rain, snow, sleet), and areal distribution of precipitation, together with
meteorological factors that affect energy inputs that cause evapotranspiration and snowmelt, are con-
trolled by meteorological processes in an ever-changing atmosphere. The analyses described in the
preceding sections are concerned not only with the current conditions of hydrometeorological factors
affecting runoff, but also with forecasts of these conditions. For this reason, meteorological analyses
are an important consideration in making forecasts of project regulation, and the water manager
should have basic knowledge of weather-related phenomena, both physical and statistical. A higher
level of meteorologist expertise may be retained if needed due to the complexity of a district or divi-
sion’s water management operations or the geographical location. Note that the NWS currently pro-
vides observed precipitation based on gaged or radar-based precipitation (gridded), QPFs, and other
future precipitation scenarios that can be used to provide forecasts of uncontrolled flows into and
downstream of reservoirs. It is important to note that water management decisions at Corps projects
must be based on water-on-the-ground (as further discussed in Section 7.3.2) unless otherwise pro-
vided for in an approved water control plan.
6.3.1.2. All streamflow forecasts must make some specific assumption regarding additional mete-
orological input during the forecast period. These expectations may be based on subjective evaluations
made from cursory examinations of current weather data, or by detailed analyses and forecasts that
quantify the expected precipitation, air temperature, wind, humidity, solar radiation, and other factors
that affect the hydrologic balance during the forecast period. Basic weather forecasts (precipitation and
temperature) are prepared nationally by the NWS. As stated in ER 1110-2-240, Water Control Man-
agement, NWS is the authorized Federal agency with responsibility for issuing weather forecasts and
flood warnings to the public. Local or regional analysis, including the development of streamflow pro-
jections from meteorological forecasts, may be done by the local offices of the Corps or through coop-
erative arrangements with the NWS forecast offices. The Corps produces streamflow forecasts solely
to enable appropriate project operation, and that are not meant for release to the general public. The
NWS produces the official Federal streamflow forecast for public release.
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6.3.1.3. Analyses may be performed to provide a family of forecasts, sometimes referred to as an
ensemble forecast, to provide a means of estimating the uncertainty in forecasted meteorological con-
ditions such as rainfall, air temperature, and snowmelt. Application of ensemble probabilities pro-
vides insight into the time range of reasonably accurate weather forecasts. Ensemble datasets are
most commonly created using multiple iterations of numerical weather or climate prediction models,
or through an application of historical datasets modified to current conditions. Ensembles based on
numerical weather and climate models are based on a statistical aggregation of output from numer-
ous model runs to quantify the uncertainty in the results. In situations with high forecast confidence,
the majority of models will have similar forecasts of temperature, precipitation, and other parameters.
Ensemble data sets created using historical meteorological data apply each individual water year on
record to current basin conditions to determine a range of possible streamflow scenarios. Either
method may be used to determine not only most likely projections of future runoff and project condi-
tions, but also extremes that may occur under unusual circumstances.
6.3.2. Short-Term Weather Forecasts.
6.3.2.1. Quantitative Precipitation Forecast. One of the more important types of weather fore-
casts for project regulation is the QPF. Refer to Section 3.3.8.2 regarding use of QPF in a water con-
trol plan and to Section 7.3.2 regarding the use of QPF in real-time operations. Note that QPF can
come in the form of a basin-averaged forecast or gridded basin forecast. In some cases, gridded fore-
casts may provide better forecasts, depending on the areal extent and direction of storm movement
within the basin. New products are being developed on a frequent basis and can be used in computer
models once the data have been acquired, transformed, and validated. As noted, weather forecasts
are the purview of the NWS, in conjunction with national support centers and local Weather Forecast
Offices (WFOs).
6.3.2.2. Air Temperature Forecasts. Air temperature and associated forecasts also have a signifi-
cant impact on hydrologic response. Note the NWS can also produce temperature forecasts for a ba-
sin average or on a gridded basis. These temperature forecasts are used to differentiate between liq-
uid and frozen precipitation, the contribution of snowmelt in runoff accounting, or for the impact to
flow attenuation due to ice formation. Air temperature forecasts are usually specified as maximum
daily or minimum daily. Consecutive days of air temperatures below freezing, may reduce flow
from a watershed. During low water conditions, the significant reduction in flow due to upstream ice
formation at locks and dams and on the smaller tributaries (known as “ice bite”) can have a signifi-
cant impact to navigation in winter months. In addition to surface air temperatures, upper air condi-
tions at particular atmospheric levels provide a vertical temperature profile that enables the forecaster
to identify freezing levels or warm/cold layers, which are particularly important for determining the
type of precipitation falling across a basin.
6.3.2.3. Forecasts of Snowmelt Runoff Parameters.
6.3.2.3.1. Hydrologic forecasts for those rivers that are fed at least in part by snowmelt run-
off need weather forecasts of appropriate snowmelt parameters for the runoff portion of the sea-
son. Water supply forecasts (regression-based) can provide estimates of total volume runoff in
the basin; however, evaluations of snowmelt runoff are needed to determine how the runoff will
occur. These are very complex from a theoretical point of view, and considerable research effort
has been made to determine the relationships between meteorological parameters and snowmelt
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runoff. (See EM 1110-2-1406, Runoff from Snowmelt, and EM 1110-2-1417, Flood-Runoff
Analysis.) Note these parameters include snow water equivalent (SWE), precipitation, stream-
flow, and in some cases the El Niño Southern Oscillation (ENSO) Index.
6.3.2.3.2. Weather forecasts for snowmelt runoff forecasting are generally confined to fore-
casts of air temperature and, in some cases, forecasts of short-term precipitation. Forecasted air
temperature is used as indexes for snowmelt. The air temperature forecasts may be either maxi-
mum temperature, mean temperature, or a combination of maximum and minimum temperatures.
Other parameters such as dew point, relative humidity, wind, or solar radiation may also be
needed. These include initial conditions, boundary conditions, and the current state of the pa-
rameters. Note that short-term precipitation forecasts can be extremely useful during years
where the runoff is delayed due to cooler than normal temperatures in conjunction with an in-
creasing snow pack or a full reservoir.
6.3.2.4. Forecasts for Tropical Storms.
6.3.2.4.1. EM 1110-2-1412, Storm Surge Analysis and Design Water Level Determination,
provides guidance for storm surge analysis and design water level determinations in coastal ar-
eas. The factors affecting operations for a hurricane are the forward speed moving toward a pro-
ject and the track of the storm center approaching the coastline.
6.3.2.4.2. For each hurricane season (June 1 – November 30 for the Atlantic and 15 May– 30
November for the Eastern Pacific), the NWS Climate Prediction Center (CPC) provides a proba-
bilistic outlook of storm activity, relative to activity of previous years. Ongoing storm activity
results in the National Hurricane Center (NHC) providing forecasts containing valuable infor-
mation such as tidal surge, rainfall, wind speed, storm speed, probable track, and cone of error
for approaching storms (e.g., tropical depression, tropical storm, hurricane). These characteris-
tics associated with the approaching storm affect the available time for implementation of water
management activities. The water management decision making process must consider these
storm characteristics, post-storm hydrometeorological condition forecasts, and project accessibil-
ity and functionality.
6.3.2.4.3. All tropical storms in the northern hemisphere rotate in a counterclockwise direc-
tion due to the Coriolis effect, therefore, locations subject to the northeast quadrant of the ap-
proaching storm typically have the greatest potential to receive the highest winds and largest
storm surge. High winds, flooding, and the occasional tornado associated with hurricanes can
cause damage to the equipment needed to operate gates. Backup equipment has now been in-
stalled at many of these coastal locations, but timing is critical. Gate position should be deter-
mined, if possible, before the storm while also considering that access to or functioning of the
gate may be interrupted due to storm effects. All of these components are additive. Such condi-
tions may cause abnormally high tides and waves that are often intensified at the head of coves
and bays. Thus, in operating a hurricane project, it must be assumed that mobilization of person-
nel and closure of gates will be necessary. Some predicted storm paths will change and produce
no appreciable tidal surge. The gate closure timing would be a combination of blocking surge
while releasing the water upstream if rainfall is on land before the surge reaches a point where
gates need to be closed. The difficult decision as to the time to close gates should be made with
the best knowledge, modeling, and experience available.
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6.3.2.5. Forecasts for Extratropical Storms. Extratropical storms also produce abnormal tides
above damage stages; for these storms, operation of a barrier is dependent on the wind speed and di-
rection as well as the predicted tide and estimated surge. Based on past studies and operating experi-
ence, the highest abnormal tides during an extratropical storm nearly coincide with the time for a pre-
dicted astronomic high tide (within 1 to 2 hours). Therefore, the time of operational requirements
can be more readily predicted than for a hurricane. However, slow moving extratropical storms often
produce abnormally high levels for several consecutive tide cycles, which may require more than one
operation of a barrier.
6.3.2.6. Severe Weather Forecasting. Beyond the activities involved in management of wa-
ter management systems, the Corps relies on real-time weather forecasts to ensure safe operating
conditions at construction projects and other District operational projects and facilities. In addi-
tion to real-time weather data, forecasts of anticipated severe weather such as damaging winds,
hail, and tornados can be used in support of any resulting Corps emergency response mission.
For severe weather information, the Corps and appropriate functional offices partner with the re-
spective local NWS WFO.
6.3.3. Long-Term Weather Forecasts.
6.3.3.1. Long-term (monthly, seasonal, or annual) weather forecasts can be useful for planning
purposes and for developing reservoir runoff forecasts several months in advance. These weather fore-
casts from the CPC are updated and released on a monthly basis for the United States and are based on
a combination of global climate model guidance and long-term climate trends. The information from
the climate forecasts can incorporate heavy or light snowpack or rainfall potential into runoff forecasts
and can influence the timing of snowmelt runoff between early spring and mid-summer.
6.3.3.2. Some of the commonly discussed large scale weather patterns are limited in their ability
to be incorporated into long-range forecasts, such as the Arctic Oscillation (AO), Pacific Decadal Os-
cillation (PDO), and Atlantic Multidecadal Oscillation (AMO). The onset and duration of the AO
can occur at relatively short durations of less than a month; thus, its overall seasonal impact can often
be muted and difficult to forecast with any significant lead time. Conversely, while a PDO event can
persist for several decades, its effects on a particular season are often diluted by the impacts of the
much shorter lived ENSO events. Nevertheless, a “cool” PDO period could enhance a “cool” ENSO
cycle, and “warm” episodes would behave similarly.
6.3.3.3. The ENSO cycle, however, has been demonstrated to having distinct impacts on various
regions of the continental United States based on both the phase (warm versus cold) and intensity.
These correlations are greatest from late fall into early spring with the general correlation during an
El Nino event being cooler and wetter along the southern tier states and warmer and drier from the
Pacific Northwest into the Northern Rockies. The opposite impacts are often observed within these
regions during a La Nina episode.
6.3.3.4. However, it should be noted that not every event within the ENSO cycle has the same
characteristics or intensity so the water manager should be cautioned not to reduce the level of flood
risk management based solely on long-range weather forecasts or climatic indexes. These forecasts
can inform the water manager of the possibility of those conditions; however, an unjustified use of
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such forecasts may, in the long run, result in inaccurate regulation of project facilities, and under ex-
treme conditions, impact the projects’ authorized functional use.
6.4. Simplified Analytical Procedures for Analyzing River Response.
6.4.1. Manual Aids for Use in Emergency. Manual analytical procedures may be required to
ensure continuity of project regulation during a COOP situation. Simplified analytical tech-
niques must be available for use by field or project offices in the event that communication is
lost between the management center and the projects. If appropriate, generalized manually ap-
plied aids should be developed that can be used in an emergency. These would be simplified in-
dex procedures or graphical relationships that can be used to estimate runoff conditions from
whatever data may be available. These aids may also be guides for project regulation, including
in emergency situations that require increased discharge to avoid dam overtopping or an unnec-
essary fill-and-spill scenario, as determined from known project inflows or other water manage-
ment data. These aids or guides may be developed from analyses of historical data and may also
be derived through computer simulations of hydrologic conditions and project response.
6.4.2. Creating a Graphical Runoff Relationship. A particularly convenient and useful
method for deriving multivariable graphical aids for estimating runoff is based on the use of cali-
brated hydrologic simulation models. As part of a hydrologic study, the forecasting diagrams are
derived by simulating the runoff processes for a range of conditions, including variable amounts
of rainfall and variable initial conditions of the basic soil moisture and base flow infiltration in-
dexes. This information can be generalized into linear or curvilinear relationships as multiple-
function co-axial diagrams. As outlined in Linsley, Kohler and Paulhus (1982) Hydrology for
Engineers (3
rd
ed.), forecasting diagrams of this general type have been developed for use in op-
erational forecasting based on observed conditions of rainfall and runoff that have been corre-
lated with computed runoff index values, as, for example, the Antecedent Precipitation Index
(API) method. The use of a computer simulation model in developing these relationships is ben-
eficial because the various ranges of values for each of the runoff indexes and rainfall amounts
may be tested as individual parameters. A series of simulation runs covering all ranges, includ-
ing use of historical data, provide an array of data that can conveniently be put into a graphical
relationship. A procedure that is based on runoff characteristics derived from multiyear calibra-
tion studies for streamflow simulation models provides good evaluations of runoff potentials is
described in: Smith, P. (2012). Cut to the chase: Online video editing and the Wadsworth con-
stant (3rd ed.). Washington, DC: E & K Publishing.
6.5. Long-Range Predictions of Streamflow.
6.5.1. General. Section 6.3.3 examined long-range weather forecasts and their potential im-
pact on water management. There is a need to consider long-range predictions of streamflow
that cover periods up to several months in advance of the date of forecast. Long-range weather
forecasts do not provide sufficient accuracy for application to real-time project regulation, but
are used in planning future regulation scenarios. The interrelationship of hydrometeorological
factors affecting runoff imposes similar restrictions in long-range streamflow forecasts, but some
hydrologic factors have carry-over effects, which provide the ability to develop useful and relia-
ble long-range streamflow forecasts. The following paragraphs describe situations for which
long-range streamflow forecasts may be significant.
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6.5.1.1. Rainfall Runoff. For rain-fed rivers, these effects are limited to long-range changes in
ground water conditions that may be determined at a particular time and projected into the future as a
basis for long-range streamflow forecasts. The accuracy of such forecasts limits the use to assessing
general trends in low-flow conditions of runoff that may have significant effects on project regulation
for hydroelectric power generation or water supply functions. These long-range streamflow forecasts
for rain-fed rivers would have little or no significance to flood regulation.
6.5.1.2. Low-Elevation Mountain and Plains Snow Runoff. Spring runoff from snowmelt is an
important component of spring streamflow and runoff forecasts. Snowmelt runoff forecasting methods
have used simple empirical relationships between spring runoff and snowpack indices including snow
depth and snow water equivalent, monitored winter precipitation and land-surface conditions such as
soil moisture conditions and soil frost. Deterministic hydrologic models combine snowpack infor-
mation, forecasted precipitation and forecasted temperature to model spring snowmelt runoff. To un-
derstand the uncertainties associated with deterministic model results, ensembles of forecast input data
based on either an ensemble of historic input data or modeled meteorological input data may be simu-
lated in hydrologic models to provide a range of forecasted runoff due to snowmelt.
6.5.1.3. High-Elevation Mountain Snow Runoff. The runoff from predominately high-elevation
mountain snow-fed rivers may be forecasted several months in advance on the basis of known condi-
tions of the accumulation of the snowpack over the watershed. In general, the snowpack accumu-
lates progressively through the winter season and then melts in the late spring or early summer. The
knowledge of the water equivalent of the snowpack based on regression analysis or a more physi-
cally based hydrologic model provides as much as 4 to 6 months advance notice of the expected run-
off volume. The water supply forecasts based on this knowledge are extremely useful in managing
project regulation for all purposes, including water supply, irrigation, navigation, flood risk manage-
ment, hydroelectric power generation, fish passage, recreation, and other environmental functions.
Long-range forecasts of snowmelt runoff provide an estimate of the volume of runoff to be expected
in the runoff period, but do not forecast the time-distribution of runoff. Factors affecting daily snow-
melt are related to weather parameters that cannot be forecasted on a long-range basis. See the dis-
cussion in Section 6.3.2.3 on the use of forecasts of snowmelt runoff parameters in a physically based
hydrologic model to determine the time-distribution of runoff and even as a check to a regression
based procedure.
6.5.1.4. Statistical Procedures for Forecasting Seasonal Mountain Snowmelt Runoff Volume.
6.5.1.4.1. Determining snowmelt runoff volume based on regression analysis of snowpack is
extremely efficacious. There is a long history of development and application of procedures for
forecasting seasonal snowmelt runoff volume. This development has occurred mostly for the
rivers of the mountainous west, in connection with regulation of multipurpose projects, and for
management and forecasting of uncontrolled rivers as related to irrigation developments and
flood risk management needs. Some of the principles involved in these methods have also been
applied to rivers in the Northeast, Midwest, and Alaska. Nearly all of the procedures are based
on the use of relatively simple month-to-month indexes of snow accumulation and precipitation.
Some forecast procedures may take into account climatic indexes, such as the ENSO Index, par-
ticularly to inform early-season forecasts before a snowpack is established. Refinements in pro-
cedures are made through use of indexes of other factors involved in the water balances of the
areas, including soil moisture increase, evapotranspiration, and changes in ground water storage.
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The forecasting relationships are generally derived by mathematical statistical correlations of
runoff with single or multivariable indexes. This type of analysis generally uses the multiple lin-
ear regression technique, applied to historical data of runoff and index parameters. While varia-
bles such as climatic indexes may reduce error in the streamflow forecast, consideration should
be that climatic indexes shift the probability of, but do not negate or guarantee the occurrence of,
a given weather pattern. Although nearly all procedures are based on statistical analysis of sim-
plified indexes of runoff, some attempt has been made at a more rigorous water balance approach
to seasonal runoff forecasting.
6.5.1.4.2. EM 1110-2-1406, Runoff from Snowmelt, presents a summary of methods used in
developing procedures for forecasting seasonal snowmelt runoff volume. The manual describes
the index and water balance approaches and discusses at length the various indexes that may be
used. In summary, the main emphasis of procedural development is to use rationally based in-
dexes of snow accumulation that represent the water balance of the area involved. EM 1110-2-
1420 also presents methodology for developing regression-based equations used for forecasting
seasonal snowmelt runoff volume. Additionally, other agencies such as the U.S. Department of
Agriculture-Natural Resources Conservation Service (USDA-NRCS) have also developed meth-
odologies and tools for regression based analysis.
6.5.2. Use of Models for Long-Range Streamflow Forecasts.
6.5.2.1. A logical extension of the use of deterministic hydrologic models is the application to
long-range streamflow forecasting as an alternative to the use of statistically derived forecasting pro-
cedures. The principal objective in formulating statistical procedures for forecasting seasonal snow-
melt runoff volume is to select indexes that are most highly correlated with runoff and are also repre-
sentative of the physical hydrologic processes defined by the water balance of the area involved. Alt-
hough the lumped hydrological parameters used in deterministic simulation models are also consid-
ered to be indexes of the hydrologic processes, the parameters represent an average basin or zonal
value, or in some cases, gridded values of these processes as best estimated from a large array of
available data. The parameters are more physically based and represent the best of analytical and
empirical methods. The model simulation is considered to represent the water balance of the area in-
volved. The models are rigorously applied in daily or smaller time increments to best represent the
physical processes of snow accumulation, snowmelt runoff, and all other hydrologic processes in-
volved in the water balance of the area.
6.5.2.2. Deterministic hydrologic models can not only incorporate all of the data used in statisti-
cal procedures, but can also use additional data that pertain to evaluations of snow accumulation and
other hydrologic processes, and thereby better represent the true determination of those factors that
affect future runoff. Therefore, deterministic models account for the processes in daily or smaller
time increments and provide a much more rigorous analysis of runoff events than can be done by
monthly based statistical methods. Furthermore, the fact that the application of this type of model
allows for maintaining daily continuity of all hydrologic parameters in a forecast mode permits a
continuous appraisal of runoff conditions for operational forecasting in a way that is completely in-
feasible with statistical models developed from monthly data. This is particularly important for ap-
praising changed conditions of runoff potential at any time within the monthly forecast evaluation
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period commonly used with statistical procedures. These procedures also allow for rational determi-
nation of the effects of an array of assumed weather conditions subsequent to the date of the forecast;
examples are median, mean, percentile of exceedance, or extremes.
6.5.2.3. While deterministic models can give a range of results by altering the assumed weather
conditions, it can be desirable to obtain a more complete range of possible long-range streamflow
forecasts. Probabilistic forecasts provide the user with flow estimates by varying the model inputs to
account for uncertainty and error. Ensemble forecasts can be created by using a set of historical
weather conditions as inputs into a hydrologic model considering current basin conditions. Ensemble
forecasts can also be produced by varying inputs based on uncertainty of historical weather pattern
observations. In both cases, the intent is to provide a long-range forecast that more realistically con-
veys the uncertainty and range of possibilities in the forecast and to give a sense of potential impacts
on project operations.
6.6. Long-Range Analysis of Project Regulation.
6.6.1. General.
6.6.1.1. Long-range analysis of project regulation may be necessary on a current real-time basis
to assess the planned regulation beginning with currently known project conditions and with
knowledge of current regulating criteria, which may include revisions to the generalized criteria con-
tained in the water control plans. Projections of this type are used primarily in connection with ana-
lyzing water management plans for hydroelectric power generation, water supply, flood risk manage-
ment, or environmental considerations. Examples of revisions to water management criteria would
be changed hydroelectric power needs caused by revised load estimates or unplanned plant outages,
special needs for preserving fish runs, or other functional or environmental needs that arise on a cur-
rent basis that were not anticipated in the water management studies.
6.6.1.2. As discussed in Chapter 3, development of the water control plan involves a lengthy
process of studying project regulation from the planning and design stages to preparation of the regu-
lation schedules and documentation in the water control plan. Furthermore, an AOP may be devel-
oped that applies the regulation principles contained in the water control plan to the current year’s
regulation. The regulation would be based on assumed hydrologic and project conditions, which
may depart significantly from actual conditions. Accordingly, there is a need to re-evaluate the cur-
rent regulation as conditions change from those contained in the water management studies, to reflect
the effects of the current operating experience on future regulation.
6.6.2. Analytical Techniques. The methods used for this type of analysis are essentially the
same as those used in developing the water control plans, but some modification in the methods
of application of those techniques may be made. Thus, the concept of reservoir system analysis,
which is fundamental to planning system regulation, is routinely applied to current regulation of
a system of multipurpose projects. Chapter 3 discusses the analyses used to develop water con-
trol plans and simulation models that can be used.
6.6.3. Basic Data and Types of Analyses. Long-range analyses normally cover the current
year’s operation, but when planned use of reservoir storage occurs over a multiyear critical pe-
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riod, the projections may be extended over a 2- to 3-year period. The hydrologic data used as in-
put for current system analysis studies could be similar to the topics in Section 6.5, or it could be
the same historical mean monthly streamflow data used in water management studies with a mi-
nor modification of streamflow data made to reflect a transition from the currently observed
streamflow conditions to the historical data. The historical streamflows can be analyzed to rep-
resent the effect of the most critical streamflow sequence on system regulation, a statistically de-
rived sequence of streamflows representing median or mean conditions, or an analysis of the en-
tire historical record as a continuous process to determine the long-range effects of future system
regulation based on the most recent data. Also, it may be desired to test the current year regula-
tion by analyzing system regulation for each yearly historical streamflow data as an independent
event, commencing with the current project conditions, and to thereby obtain a statistical distri-
bution of future probabilities of all of the elements of system regulation for the remainder of the
operating year.
6.6.4. Using Results of Long-Range Analysis.
6.6.4.1. The long-range analyses of system regulation as discussed above have the greatest sig-
nificance in assessing low-flow water supply and hydroelectric power capabilities. Specifically, the
analyses provide the technical evaluations necessary for optimizing power production, for determin-
ing the strategy for marketing surplus power, for assessing probabilities of meeting firm power com-
mitments, and for determining the probable effects of power operation on non-power functions. The
same principles of analysis may also be applied to assess future conditions of regulation as related to
other project functions, such as navigation, irrigation, water supply, recreation, fish and wildlife re-
lated activities, and other environmental uses. Thus, by maintaining continuity and surveillance of
system regulation, long-range analyses provide the water manager with the ability to anticipate future
conditions that may be averse to meeting the overall water management goals and to take appropriate
corrective action in time to be effective.
6.6.4.2. In summary, real-time long-range projections based on monthly (or smaller) reservoir
system analysis techniques are used primarily as an aid in regulating large multipurpose reservoir
systems. The importance of such analysis depends on the particular hydrologic and project condi-
tions that are being experienced. Any modification of the planned regulation to meet such circum-
stances does indeed depend on these types of long-range projections, and reanalysis on a monthly or
weekly basis may be required.
6.7. Water Quality Forecasting.
6.7.1. General. Up to this point, this chapter has dealt with water management techniques
that are geared basically to managing the quantity or potential quantity of water in a river-reser-
voir system. ER 1110-2-8154, Water Quality and Environmental Management for Corps Civil
Works Projects, is the policy regulation for water quality and environmental management. Many
environmental impacts are attributed to Corps water management projects, and some are quite
significant. Even though water quality may not be an original authorized project purpose, the
Corps tries to protect and enhance the quality of water and land resources at its projects as a mat-
ter of policy. Therefore, the water management team must recognize and address the environ-
mental potential of each project or system of projects. This awareness comes from a team ap-
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proach that blends and balances a wide range of disciplines, which should include hydraulic en-
gineers, water chemists, biologists, and individuals from additional specialized disciplines as the
particular system warrants. Incorporating these team members into the projects’ real-time opera-
tion offers the best opportunity to generate environmental benefits from water resource projects.
Many situations and opportunities arise in real-time water management that can only be recog-
nized by specialized team members. Several important aspects of water quality management of
Corps projects are forecasting future quality, evaluating existing quality, and predicting the effect
of various management options with respect to project purposes on the projects and the areas in-
fluenced by the projects. Several analysis and forecasting techniques are available.
6.7.2. Analytical Techniques. Analytical techniques vary widely, but follow the same gen-
eral types of analysis that are involved in weather, flow, and volume forecasting. These analyses
may involve computer simulation of historical records to evaluate various management options
for planning purposes, or be models of real-time, existing conditions that allow tests of a variety
of management choices on present and future water quality conditions. Recognized water qual-
ity models in the Corps include CE-QUAL-W2 and the water quality component of HEC-RAS.
6.7.3. Forecasts.
6.7.3.1. General. Many aspects of water quality may need to be forecasted. Some of the more
typical parameters are temperature, dissolved oxygen, turbidity, nutrients, sediment, pH, dissolved
solids, algae, fish migration, metals, and contaminants. Long-range cycles of some parameters, such
as temperature, may be needed to evaluate the impact of various operating scenarios on the project
waters and on the downstream zone of influence. In other cases, short-term factors, such as the pas-
sage of an “acid slug” in a stream influenced by mine drainage, may need to be forecasted, and a
real-time response may need to be developed. At some reservoirs, management decisions made to-
day may have an impact that could last for years or possibly decades. Water managers should under-
stand that long after the physical and chemical effects of a management decision have occurred, the
biological consequences may linger for weeks, months, or years, depending on the project and asso-
ciated conditions.
6.7.3.2. Long-Range Forecasts. Long-range forecasting of water quality should include projec-
tion of conditions as far in the future as is practical and useful to project management decision mak-
ing. Reasonable forecast computer models for many physical and chemical parameters can be used
to estimate weeks and months ahead. Long-range forecasting can also be much less sophisticated,
using a graphical evaluation and projection of conditions. EM 1110-2-1201, Reservoir Water Qual-
ity Analysis, is a good reference for analytical techniques. Long-range forecasting is usually im-
portant to large projects with longer retention times.
6.7.3.3. Short-Term Forecasts. Short-term forecasts are those that evaluate or forecast for only a
few days or, at most, a week or two. These forecasts are used to evaluate real-time conditions and
project management alternatives and may be especially useful for managing small projects. Short-
term water quality forecasts should always be made to evaluate the consequences of possible project
management alternatives before making a decision. These decisions may be as simple as changing a
port in a selective withdrawal tower or decreasing a release to stabilize a pool level. Each decision in
one form or another is based on a forecast. Decisions should not be based solely on a flow forecast,
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but also include a water quality forecast to determine any better alternatives and the possibility to
manage the project environment more positively.
6.8. Special Hydrologic Analyses.
6.8.1. General. Many other special analysis types concern specific hydrologic problems, in-
cluding:
1. Determination of streamflows and water level in a major river that incorporates diversion
structures in the management of water levels (e.g., the Lower Mississippi River), where
the determination of unsteady flow two-dimensional flow conditions within the confines
of the river is the dominant hydrologic problem.
2. Behavior of rivers and reservoirs under conditions of ice and sedimentation, and the effects
on projects, project operation, channel capacities, and flooding along the rivers.
3. Effects of winds, storms and tides on water levels in rivers, reservoirs, and estuaries, to-
gether with the effect on determination of project inflows.
4. Determination of reservoir evaporation and its effect on regulation.
5. Determination of special water quality operations.
6. Dam break scenarios, DSAC project develop interim risk reduction measures (IRRMs).
7. Risk and uncertainty and consequence analysis of proposed deviations or IRRM.
8. Determination of effect of bank storage on reservoir capacity.
9. Changing effects of forest removal and urban development on runoff.
10. Determination of backwater effects and three variable relationships.
The above list indicates only the more general types of hydrologic problems that are encountered
during water management activities, and each river system has unique problems that may involve
many other facets of hydrologic analysis. The particular analytical methods for solving these
problems are usually developed by the operating office in which the problems occur, and the use
is usually limited to the particular application areas. The following sections summarize briefly
some of the specific problems and methods that have been developed for solving these problems.
6.8.2. Unsteady Flow Determinations in Major Rivers. Many common methods are used to
simulate the response of unsteady flows in river systems. Streamflow routing procedures range
from simple, empirical methods for translating and computing the attenuation of the unsteady
flow fluctuations, to highly complex and completely rigorous computerized solutions of the un-
steady-state flow equations. Each has particular types of applications, depending on the type of
river system; the general ranges of flow variations normally experienced; the effects of variable
backwater conditions caused by tides, project operation, or “looped” ratings of channel flow; the
overall accuracy of the computed fluctuations in relation to the needs for a particular application;
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the time and effort that can be expended in the solution for timely use; and the availability of
basic data needed for application. In some cases, a 2-dimensional model may be necessary to ac-
curately represent braided streams or flooding scenarios.
6.8.3. Effects of Sedimentation in Rivers and Reservoirs. Sedimentation has long been an
important aspect of planning and designing projects. In the operational phase of water resource
development, potential problems may develop as the result of sediment deposits in both reser-
voirs and natural stream channels. The problems may involve the loss of active storage space in
reservoirs, changes in channel characteristics and sedimentation balance for rivers downstream
from projects, effects of sediment deposits in small tributaries entering reservoirs, changes in
maintenance dredging resulting from water management, and the lack of knowledge of sediment
density currents in reservoirs. These effects relate to water management activities in relation to
changing conditions for downstream control, to the management of water levels, and to the con-
trol of the regulation of multilevel intake structures or other outlet facilities.
6.8.4. Effects of Ice in Rivers and Reservoirs.
6.8.4.1. The occurrence of ice has major significance to management of water resource projects
in the northern tier of states and Alaska. River ice forms in the fall or early winter and may gradually
increase in thickness until the spring thaw. River ice may constitute a major threat for flooding as the
result of ice jams that build up at critical locations, especially at the time of the spring thaw or at
other times when streamflows increase and the ice jams severely restrict the flow of water in the river
channels. The prediction of the occurrence of ice jam flooding involving the release of water from
upstream reservoirs may be important. Ice jams are also likely to occur where tributaries enter reser-
voirs. This is mainly the result of reduced channel velocities in the river immediately upstream from
the reservoir. This type of occurrence may require special regulation of the water surface in reser-
voirs to help mitigate adverse effects in the upstream tributaries. The occurrence of ice in river chan-
nels also affects the flow rating relationships used for determining streamflows from reports of water
levels, and special efforts must be made to properly apply rating curves under these conditions. For-
mation of ice in reservoirs is common in cold climates, and ice cover may persist for as much as
6 months, with thicknesses up to 3 ft. The occurrence of ice on large reservoirs may be of concern in
the vicinity of the dam or control works related to navigation. Ice flows caused by wind may build
up in reservoirs in the vicinity of the dam and could impair the operation of outlets, spillways, navi-
gation locks, or other facilities. In cold weather, spillway gates are susceptible to freezing, which
may restrict normal operation unless specific measures such as seal heaters are incorporated into the
design. The occurrence of frazzle ice in penstocks may also restrict the operation of hydroelectric
power facilities at certain times.
6.8.4.2. ERDC-CRREL has made extensive investigations of the formation and movement of ice
in river channels, reservoirs, navigation locks, and other water management facilities. The results of
the investigations are contained in research documents and reports, which are available from the
headquarters office located in Hanover, NH.
6.8.5. Effects on Discharge. The occurrence of upstream and downstream aquatic habitat,
vegetation, and debris can have an effect on discharge capacity. For example, debris clogging
intake trash racks can affect penstock efficiency. Additionally, debris downstream can cause a
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backwater effect, thus requiring reduction in discharge. These are just some of a few of the
things that can affect discharge and thus should be considered if these are an issue.
6.8.6. Reservoir Evaporation. The hydrologic methods used in river system analysis for
managing water systems usually entail the logical accounting of the water balance from both nat-
ural and man-caused effects. Reservoir evaporation may result in significant water losses to the
river system. These losses are in addition to those that occur by natural evapotranspiration from
the drainage area contributing to runoff. The streamflow data used for operational studies are
usually adjusted to account for water loss by reservoir evaporation. Many procedures are being
used for making such adjustments. The degree of refinement in developing these procedures de-
pends on: (a) the relative importance of reservoir evaporation in the overall water balance of the
region and the effect on the management of the system; (b) the types of basic data available to
make estimates to be applied to current and historical data; and (c) practical considerations con-
cerning the accuracy of the estimates to be attained, as compared with the effort required to ob-
tain and apply the basic data in a computational method.
6.8.7. Determination of Effect of Bank Storage on Reservoir Capacity. Reservoir area-stor-
age-capacity curves used in operational hydrology are normally determined by the use of topo-
graphic maps of the reservoir area or special field surveys. The reservoir level pool area is deter-
mined incrementally for each of a range of elevations that will represent the variations of area
and storage within the operating range of the reservoir. These determinations, however, do not
normally take into account any possible effects of storage of water within the aquifers underlying
the reservoirs. Evidence may exist of significant bank storage in some reservoirs, based on the
geology of the area and water balance computations. In most cases, however, bank storage is not
believed to be of sufficient magnitude relative to the computed inflow and outflow to warrant
water management consideration.
6.8.8. Effect of Wind Setup on Water Levels in Reservoirs, Lakes, and Tidal Estuaries.
6.8.8.1. Water levels observed and reported for reservoirs, lakes, and tidal estuaries may reflect
the effects of wind or storm tides, superimposed on the hydraulic effects of flow and tides that occur
without wind effects. Particularly in lakes and large reservoirs, the normally assumed “flat pool” or
“static pool” as used for computation of daily or period inflows from observed outflows and change
in storage may be invalid. Inflows computed in this manner may show apparent fluctuations that are
not real and reflect the effects of daily variations in wind on the lake or reservoir. Corrections must
be made to properly account for the effects of wind in this type of computation. A practical expedi-
ent for doing this is to maintain a continuous graphical plotting of inflows computed from change in
storage computations for the reservoir, along with a plotting of key index inflow gaging stations, the
streamflows of which contribute to the reservoir inflow. The total computed inflow is “smoothed”
by eye, as judged by the inflow gaging station plots, to best represent the actual variations of project
inflows. When the operation of spillway gates or other outlet facilities are determined, the project
releases should be based on best estimates of inflow as adjusted for the effects of wind discussed
above, or on inflows computed directly from fixed relationships between total project inflow and ob-
served inflows at key upstream gaging stations.
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6.8.8.2. Prediction of the effect of storm tides and hurricanes on water levels in estuaries is of
great importance to water management activities in coastal regions. A third factor is the effect of tsu-
nami ocean waves generated by earthquakes that may occur in coastal areas or in the ocean hundreds
or even thousands of miles away. Flood risk management works that are constructed for coastal riv-
ers and estuaries are designed for the effects of storm tides, hurricanes, or tsunami waves as applica-
ble. When these projects become operational, the occurrence of storms that would affect the areas
should be monitored, and, if necessary, special precautions should be taken to ensure the proper pro-
ject operation or to institute flood fights. The methods of monitoring and predicting floods under
these conditions should be developed on the basis of requirements for each particular area or project.
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CHAPTER 7
Real-Time Water Management
7.1. Basic Considerations. Corps offices have the responsibility to manage projects under Corps
jurisdiction. Water management at Corps water resources projects is conducted in real-time, over
the short-term, and in a way that addresses anticipated long-range effects. The water manager uses
iterative, adaptive, real-time management of water resources projects to achieve congressionally
authorized project purposes. Water managers must make informed real-time decisions based on
observed conditions and on an understanding of location-specific cause and effect relationships.
Water managers should revisit these decisions regularly to incorporate the latest information avail-
able. Experience with these decision processes helps develop abilities that are applicable to both
short-term and long-term water management. Daily real-time water management prepares the wa-
ter manager to make sound decisions during non-routine conditions such as floods.
7.1.1. Integration of Generalized Operating Criteria, System Analysis, and Water Manage-
ment Activity Scheduling.
7.1.1.1. Chapter 3 discussed the methods used in developing regulation schedules and operating
criteria for project or system water management as documented in the water control manual. These
criteria represent the commitment to an assured water management plan based on congressionally
authorized project purposes, environmental policy, project infrastructure considerations, operational
constraints, state and local stakeholder agreements, and overall public health and safety. Considera-
tion should be given to historic factors that could lead to reduced detrimental impacts or that could
provide additional benefits to project purposes. The operating criteria are documented through such
items as: seasonal guide curves, optimum water level range, downstream control points, drought con-
tingency plans, and deviations from normal regulation.
7.1.1.2. Special situations or unanticipated conditions may arise during water management activ-
ities. These conditions may require that a certain degree of flexibility be maintained in the water
control plan to adapt operating criteria. Any decision to deviate from the approved water control
plan must follow the process outlined in ER 1110-2-240, Water Control Management.
7.1.1.3. Unusual occurrences, such as the spill of pollutants into waterways, may require imme-
diate action that departs from normal project operation, and the water control plan should allow for
emergency response flexibility, to the extent possible. For example, toxic spills into projects with
water supply require immediate response from water managers, including prediction of dilution rates
and time of travel. Such an event may require extensive, complicated coordination and quick devel-
opment of alternative operating strategies. Similarly, unanticipated changes in requirements may oc-
cur that involve the safety or use of navigation facilities and waterways, such as vessel groundings or
sinkings, shoaling of waterways or docking facilities, or special water needed for managing terminal
or vessel repair facilities; the rescue of persons in the waterway; or other circumstances that require
immediate action for the safety and well-being of the general public. In addition to the problems re-
lated to projects’ normal functional use, a water management office is often requested to perform a
variety of miscellaneous water management activities for special purposes, such as maintaining water
levels on a short-term basis for construction activities near or in a water body or in the upstream or
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downstream waterway, maintaining flows for recreation activities, or regulating reservoir levels for
improvement of wildlife habitat.
7.1.1.4. All of the above conditions require that decisions by the water manager adapt the ap-
proved operating criteria to real-time water management. The water manager should rely on infor-
mation provided by the WMES and obtained from any necessary additional sources to make deci-
sions for daily, short-term, and long-term water management activity scheduling. The majority of
the daily decisions based on the approved water control plan or an approved deviation do not have
far-reaching effects on project regulation and are part of routine water management activities. How-
ever, some proposed operating criteria may constitute a departure from approved operations and
should follow the deviation process outlined in ER 1110-2-240.
7.2. Appraisal of Current Project Water Management. Monitoring system response and schedul-
ing future project activities should be coordinated. The objective of monitoring project response
is to verify that the regulation is proceeding according to the operational objectives, within the
water control plan or approved deviation from normal operation. Ongoing water management
activities, hydrometeorological occurrences, evolving ecological conditions, concerns for safety,
or other conditions require routine assessment of operating criteria by the water manager. As-
sessment of operating criteria may also occur as a result of stakeholder input that includes spe-
cific concerns related to the effect of ongoing or planned Corps water management activities.
7.3. Performing System Analyses for Water Management Activity Scheduling.
7.3.1. Analytical Considerations for Scheduling of Projects.
7.3.1.1. Changing conditions and corresponding water management actions result in situations in
which the water manager continually applies a comprehensive, iterative approach to water manage-
ment that considers possible cause and effect relationships. This may include:
1. Assessing current conditions and forecasts (e.g., hydrometeorological, ecological).
2. Determining effectiveness of implemented water management activities in reference to
water management operating criteria.
3. Evaluating the need and risk of implementing additional/alternative water management
activities.
4. Determining whether deviation from normal operation is beneficial.
5. Developing a condition-based schedule for future water management activities.
6. Beginning implementation of scheduled water management activities.
7.3.1.2. This approach should be repeated, as needed, based on evolving conditions, as more de-
finitive forecasts becoming available.
7.3.1.3. The water manager may also consider input from others that affects water management
activities (immediate needs for hydroelectric power generation, navigation, water supply, or other
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multipurpose functional needs). The water manager must also review current hydrometeorological
conditions and the latest forecasts of weather elements that will affect project regulation.
7.3.1.4. For simple projects, experience and judgment or general estimates for operating deci-
sions may be sufficient to properly evaluate and schedule project activities with knowledge of the
changing conditions. However, the regulation of complex or major water management systems and
the many variables that must be considered in a detailed manner precludes the use of simplified pro-
cedures or general estimates for scheduling. Computer-based analyses may be used to perform com-
prehensive, timely analyses of the water management systems. Computer modeling may sometimes
account for the effects of each of the major hydrologic and project regulation elements on various al-
ternative project schedules or hydrologic conditions. Ultimately, the development of operating crite-
ria to achieve congressionally authorized project purposes should consider a water management ap-
proach to achieve shared benefits across multiple project purposes or to prioritize project purposes.
7.3.2. Operations Based on Water-on-the-Ground.
7.3.2.1. In general, regulation decisions are made based on the overarching principle of water-
on-the-ground, which includes observed precipitation that has fallen in the basin in the form of rain-
fall or snow. However, exceptions to this philosophy are permitted when included as part of an ap-
proved water control plan as described in Section 3.3.8.2, or in a deviation to an approved plan under
certain circumstances. Both of these exceptions require careful consideration of forecasting method-
ologies that incorporate future precipitation and/or runoff, and identification of the associated risks
and benefits.
7.3.2.2. The principal objective is to ensure that releases from reservoirs are restricted insofar as
practical, to quantities that, in conjunction with uncontrolled runoff downstream of the dam, will not
cause water levels to exceed the controlling maximum non-damaging stages that are currently in ef-
fect or that exceed peak inflows. Other factors to consider when determining whether to include fu-
ture precipitation/runoff in regulation decisions may include the potential for future runoff, whether
on the rising limb of an inflow hydrograph or evacuating flood water from an earlier event, down-
stream channel capacity, dam and levee safety, and impacts to other authorized purposes.
7.3.2.3. Refer to ER 1110-2-240, Water Control Management, for policy related to evacuating
stored water based on the principle of water-on-the-ground. In addition to this principle, the water
manager relies on reservoir and streamgage information provided by the WMES and data from addi-
tional sources to make real-time, short-term, and long-term release decisions. These additional data
include the use of QPFs, streamgage forecasts, and runoff forecasts based on snowmelt. This is
where the monitoring of system response (real-time conditions) and scheduling of future water man-
agement activities must be closely coordinated, applying a comprehensive and iterative approach
within the context of sound engineering experience and professional judgment.
7.3.3. Components of a Comprehensive Analysis. Analysis of water management-related
conditions and operating criteria may be conducted with computer applications based on histori-
cal, real-time, and forecasted hydrometeorological data. The scheduling of water management
activities requires analysis of comprehensive water management-related information and data
sets, including:
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1. Non-variable data, which describe physical features such as drainage areas, watershed run-
off characteristics for each component watershed, channel routing characteristics, reservoir
storage and flow characteristics, and other physical parameters that define the system.
2. Current conditions of all watershed indexes; ecologically driven indicators related to
items such as fish spawning, estuary conditions, and species of concern; incremental flow
routing values for upstream and downstream watersheds and channels; current project
water levels and outflows; and downstream water levels.
3. Time-variable data expressed as a time series for representing hydrometeorological inputs
and forecasts such as precipitation, air temperature, snowmelt, and evapotranspiration
functions, streamflow data, project regulation data, or other time-variable elements that
affect runoff, project regulation, and system requirements.
4. Infrastructure constraints such as maximum allowable gate opening, gate opening sequence,
maximum allowable head differential, and minimum allowable elevation for pumping.
7.3.4. Input from Others.
7.3.4.1. Water managers often have some flexibility in the operations to meet required objectives.
For example, an operation to meet a required flood risk management drawdown may be achieved in
various ways, and those options could, in turn, have various effects on the river system. To determine
the operations that will be used to satisfy the water control plan, the management of nearly all water re-
sources projects can benefit from multiagency or multipurpose input. Even though some Corps water
resources projects may have been constructed initially as single purpose projects, potential environmen-
tal, economic, social, and safety aspects related to Corps projects have resulted in the establishment of a
variety of entities with an interest in the Corps water management decision making process. These
stakeholders may include non-governmental entities as well as Federal, state, local, and tribal agencies.
While the Corps is ultimately responsible for determining water management decisions at Corps pro-
jects, stakeholders may be uniquely qualified to provide input on current hydrologic, ecological, and
fish and wildlife conditions that optimize regulation within the water control plan.
7.3.4.2. In addition, historic, current, and forecasted hydrometeorological conditions and data
useful in the Corps decision making process are often provided by other entities. These include:
1. Streamflow, water quality, and water level data from the USGS or other agency.
2. Current weather data, weather forecasts, and hydrometeorological data from NWS.
3. Snow water equivalent data and related hydrometeorological data and basin data (e.g.,
soil moisture, frost depth, runoff potential) from NOAA and NRCS.
4. Hydrometeorological and water use project data from state and local agencies.
5. Hydrometeorological data from foreign agencies.
7.3.4.3. Chapter 8 discusses the methods for coordinating interagency water management activi-
ties in greater detail.
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7.3.5. Collaboration with Non-Federal Sponsor. For Corps water resources projects at which
a non-Federal sponsor conducts daily water management activities, appropriate collaboration
with district or division water management staff is necessary. As stated in Section 208.11, Title
33 of the CFR, the Corps is responsible for prescribing water management operating criteria and
providing oversight to ensure that congressionally authorized project purposes are met. This
may include assessment of water management operating criteria and current water management
activities, processing of requests for deviation from normal operation, development of water con-
trol manuals, and revision of water control manuals and plans.
7.3.6. Results Evaluation. As stated earlier, the main purpose of system analysis is to pro-
vide the water manager with information related to the potential effects of proposed water man-
agement activities for use in making decisions. The most complete knowledge of recent hydro-
meteorological trends, as well as current conditions and future forecasts, should be used to pro-
duce desired effects over a specified time frame. After operational decisions are made, the re-
sulting effects must be monitored and compared to desired conditions. Often multiple analyses
are necessary to allow depiction of a range of potential future conditions that can be compared
and considered in making water management decisions.
7.4. Water Management Decisions and Project Scheduling. Water management includes making
decisions that consider all the congressionally authorized project purposes for a Corps project.
The process to determine the storage or quantity, timing, and duration of the potential releases
from a Corps project includes consideration of water management information. This information
may include project design information, project operation manuals and procedures, hydrometeor-
ological information, river and reservoir levels, and forecasts and ecological and fish and wildlife
information that are specific to the project as well as upstream and downstream from the project,
as appropriate.
7.4.1. Need for Judgment in Project Scheduling.
7.4.1.1. Even with the engineering analysis described in the preceding section, the final decisions
in formulating project schedules may require the judgment and experience of the water manager.
The water control plans provide the general guidance for project regulation, and when applying that
judgment, the operating decisions must still fall within the boundaries established by the water con-
trol plan unless a deviation is approved. Actual conditions (e.g., limitations to the project operations,
upstream and downstream activities) must always be considered in the implementation and schedul-
ing of water management activities.
7.4.1.2. On a broader scale, judgment may be required to adjust the operational plan for condi-
tions that indicate a particular need, for example, a mid-month adjustment in operating guide curves,
which are specifically defined as month-end values, and current analysis and projections indicate a
probable change in conditions by month’s end. The simulation of streamflows and project conditions
may be used to estimate future conditions. These evaluations may form the basis for mid-month ad-
justments of guide curve operation. By monitoring changes in runoff potentials, the overall effi-
ciency of multipurpose project regulation may be significantly improved. Modifications of the guide
curve operation must be based on rational evaluation of runoff conditions that warrant such depar-
tures. At the time such modifications are made, the water control manager must detect conditions
that would require a return to normal guide curve operation.
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7.4.2. Water Management Coordination Agreements.
7.4.2.1. Coordination of water management activities with appropriate agencies and stakeholders
must be conducted by the water manager to avoid unintended detrimental effects, maximize benefits,
and provide alerts. In some cases, coordination is outlined in:
1. Interagency water control management agreements with power marketing authorities, fish
and wildlife agencies, etc.
2. Hydroelectric power generation utility coordinated power operating plans and contractual
agreements.
3. Water control plans for non-Corps projects that involve flood risk management or naviga-
tion requirements.
4. Water control plans for water regulation projects developed under international treaties.
5. Water compacts with state, regional, or local agencies or councils.
7.4.2.2. Other types of input from agencies or entities outside of the Corps are not based on for-
mal operating procedures, but through voluntary informal arrangements. The many types of inputs
covered by these operating arrangements and agreements may have widely varying significance as
considered in making decisions. Typically, this informal coordination process informs water man-
agement decisions that fit within the approved water control plan. However, at times, the water man-
ager may determine that the input received would lead to water management activities inconsistent
with the water control plan, which would require a deviation request and approval by the division en-
gineer or delegated party per ER 1110-2-240. Examination of the impacts on other authorized pur-
poses must be undertaken before proceeding with a deviation request, and may result in the water
manager denying the request from outside agencies or entities.
7.4.3. Water Management Activity Schedules and Operating Instructions.
7.4.3.1. The monitoring, coordinating, scheduling, and evaluation of project regulation is per-
formed on an ongoing basis, and the schedules usually represent an operating commitment for a de-
fined period of time. However, all schedules are subject to change based on evolving conditions or
new information. The schedules and operating instructions may take various forms, including one or
more of the following provisions:
1. Mean total project discharge in cubic feet per second for weekly, daily, hourly, or other
specified release periods.
2. Gate opening sequence and amount; gate closing or opening prompted by water level at
downstream location.
3. Target water level (e.g., canal, lake, impoundment, reservoir) as an end of daily or period
value.
4. Target pulse release in duration of pulse and daily release quantity.
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5. Mean reservoir storage change in acre-feet per day or day-second-feet (the volume of wa-
ter represented by a flow of 1 cubic foot per second for 24 hours; equal to 86,400 cubic
feet).
6. Specific operating constraints for the ensuing day, as, for example, maximum and mini-
mum reservoir levels, maximum and minimum project discharges, rates of change of
tailwater levels, etc.
7. Power plant generation as scheduled daily or hourly amounts.
8. Special operating instructions not covered by the specified normal limits of project opera-
tion.
9. Special operating instructions for multilevel intake structures.
7.4.3.2. All water management activities should be accomplished with consideration of all known
operating constraints whether specified in water control manuals or in other documents. The con-
straints apply to conditions at the project and at upstream and downstream locations, and may vary sea-
sonally or apply to specific needs that depend on the conditions of tributary flow, recreational activities,
water supply or irrigation intakes, or other downstream water use functions. The water manager is re-
sponsible for determining that the water management activities are consistent with all operating con-
straints and that the schedules and operating instructions are properly implemented.
7.4.3.3. In times of flood or other types of emergencies, the project schedules must be revised as
necessary to meet the flood risk management or other emergency objectives. This may require 24-
hour staffing during emergencies, at which times considerable effort is needed to keep abreast of
conditions and to adjust the project schedules to reflect changed conditions. These issues are dis-
cussed further in Section 7.6.
7.4.3.4. In periods of extreme low water, drought contingency plans provide details for the
proper assessment of project scheduling needs by balancing congressionally authorized purposes and
project goals with regard to available water in the system and applicable water law. In general, pro-
ject releases are reduced to preserve stored water while meeting critical downstream needs such as
municipal water supply, industrial water supply, water quality or environmental flows, agricultural
water supply, and navigation. A critical aspect of drought operations is coordination with state and
local agencies or tribal representatives that may have primary jurisdiction over water use in times of
shortage. Special local water supply requirements may be needed during drought situations that are
not part of normal water management activities. These requirements and any special coordination
requirements should be documented in a drought contingency plan. The drought contingency plan is
discussed in Section 3.6.
7.5. Disseminating Water Management Activity Schedules.
7.5.1. Within the Corps of Engineers. Water management activity schedules and operating
instructions for real-time, short-term, or long-term implementation must be communicated in a
timely and accurate manner from the water management office to project operators. Internal
communication with other Corps offices (e.g., operations, geotechnical engineering, RCO) may
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be necessary to provide information on the effects of future water management activities such as
projected water levels and release targets that have the potential to affect those offices’ activities.
As necessary, oral communication with appropriate staff should accompany written documenta-
tion or communication transmitted through fax, electronic mail, internal or public website, or
other electronic means. For water management activities that have potential upstream or down-
stream effects beyond the jurisdiction of the water management office, information associated
with the activity should be disseminated to the affected group (other districts or divisions).
7.5.2. To Non-Corps Projects. Water management activity schedules may be transmitted to
the project owner of a non-Corps project according to approved operating agreements. However,
some operating agreements require the project owner to prepare all schedules and the Corps wa-
ter management office to monitor the operation to ensure that coordinated project operating crite-
ria is followed. Section 7 of the Flood Control Act of 1944 and 33 CFR Section 208.11 require
the Corps to prescribe regulations for the use of storage allocated for flood control or navigation
at reservoir projects constructed wholly or in part with Federal funds (other than TVA projects,
except in case of danger from floods on the lower Ohio and Mississippi Rivers).
7.5.3. To NWS Offices. The NWS is the responsible Federal agency to provide weather, hy-
drologic, river stage, climate forecasts, and warnings for the protection of life and property. Wa-
ter management activity schedules may contain information of importance to NWS in forecasting
water levels. Often, the information to be transmitted to the NWS is customized to more effec-
tively support NWS forecast needs. The water manager should fully understand the regional re-
sponsibility of the NWS office with regard to the areas both upstream and downstream of
planned or implemented water management activities. The water management activity schedule
and other information may be transmitted to the appropriate NWS office orally or by fax, email,
or other electronic means.
7.5.4. To Stakeholders. The Corps should share water management activity schedules as
necessary, with other stakeholder agencies or entities that are not project owners or operators.
These stakeholders include non-governmental organizations, private utilities, power marketing
authorities, streamflow forecasters, fish and wildlife or environmental protection agencies, public
safety agencies, navigation partners, and recreational businesses. The schedules are provided, as
required, to communicate the water management activity details such as targeted outflow, antici-
pated water level, and implementation time and duration. These schedules may be distributed by
press release, public website, email, or automated process.
7.5.5. To the General Public. Normally, the water management activity schedules are consid-
ered to be internal working directives that are distributed externally to Federal and state agencies,
local entities, or stakeholders that may be particularly affected by water management activities.
The general public may benefit from water management information distributed by press release,
public website, email, or other electronic means. The public affairs office can assist with posting
information to social media locations as desired. Fishing, boating, irrigation, construction, flow
measurement, water sampling, and academic research are activities that can benefit from publica-
tion of water management schedules. Dissemination of information to the public should follow
policy set forth in ER 25-1-110, Information Management Enterprise Data Management Policy
Corporate Information.
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7.6. Water Management Activities during Emergency Events.
7.6.1. Importance of Water Management Activities.
7.6.1.1. Water management decisions and the scheduling of water management activities typi-
cally occur on a daily cycle consistent with division and district staff administrative work hours. To
be prepared for unexpected events, project operators or stakeholders should have contact information
for water managers. The intensity of the water management office workload, as well as communica-
tion with internal and external parties, may increase significantly during times of flooding and ap-
proaching severe weather (e.g., tropical storm, hurricane, cold front), requiring the water manage-
ment office and affected projects to be staffed 24 hours per day, including weekends and holidays.
Water managers must closely monitor rapidly changing hydrometeorological conditions and be pre-
pared to re-evaluate tidal surge, storm track, wave runup, precipitation and temperature forecasts, and
runoff conditions, as necessary, since the conditions may affect project schedules along with up-
stream and downstream conditions.
7.6.1.2. In rare circumstances, floods may result from dam breaks, earthquakes, landslides, or
volcanic eruptions, which may cause serious and unexpected life threatening flood disasters. While
this type of occurrence cannot be forecasted, such disasters require immediate action. During normal
floods resulting from rain or snowmelt runoff, frequent direct communication should occur between
the water managers and project operators to ascertain the most recent project conditions that affect
project regulation. The water management office must issue flood reports to higher authority and
keep other office elements fully informed of operational conditions that may affect other Corps activ-
ities (e.g., flood fighting, disaster emergency operations, coordination with Federal, state, and local
authorities, public relations).
7.6.1.3. The entire effort of Corps installations within a region may be diverted to the activities as-
sociated with extremely critical flooding. The district and division office elements often involved in
such emergencies include engineering, operations, construction, planning, procurement, personnel,
public affairs, as well as other supporting elements. Activities related to such extreme events must be
directed and coordinated by top level management, and because of the potential for rapidly changing
circumstances during emergencies, management must be prepared to respond intensively. Water man-
agement provides support to the RCO group during floods and emergencies in the form of written and
oral communication. Special situation reports may be required and are discussed in Section 9.5.2.
7.6.2. Collaboration with National Weather Service. The NWS is the Federal agency respon-
sible to provide weather, hydrologic, river stage, climate forecasts, and warnings for the protection
of life and property. During emergencies such as tropical storms, hurricanes, and high water
events, a critical need exists for the timely and accurate information exchange between Corps wa-
ter managers and NWS personnel. NWS rainfall forecasts may influence water management activ-
ities, which in turn may influence NWS flood forecasts. The typical exchange of information
through email and other electronic means during non-flood conditions should be expanded to in-
clude oral communication or co-location of staff with the appropriate NWS office to ensure that
critical details are understood by both water managers and NWS personnel.
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7.6.3. Coordination of Corps Activities.
7.6.3.1. Corps office activities during floods require coordination and centralized direction. One of
the important aspects of coordination is the provision of authoritative and timely flooding information.
Responsible Corps office elements must be fully informed of current conditions. The USACE Opera-
tions Center (UOC) located at Headquarters is responsible for national level situations awareness for all
Corps Contingency Operations. The typical communication process is for districts to provide a situa-
tional report to division through ENGLink that is then passed to the UOC for use in their situational
awareness briefings. Depending on the circumstances, extensive coordination with RCO, geotechnical
engineering, project operations, levee and dam safety program managers, and other Corps offices may
be essential. For events that span more than one district or division, extensive coordination must take
place to ensure an appropriate agency response. Therefore, the water management office must be pre-
pared to provide the latest pertinent information on flood conditions, including:
1. A general summary of current weather and hydrologic conditions, the associated effects
on runoff, and areas of flooding.
2. Weather conditions forecasts, with particular emphasis on the flood potential outlook.
3. Natural and regulated streamflows forecasts at project and key downstream locations.
4. The current status of water control facilities as related to project and system wide water
management for all project purposes, with special emphasis on the effects of flood regu-
lation throughout the system.
5. The expected water levels at all key downstream locations, with special emphasis on
those areas protected by levees or other control structures.
6. The planned use of storage, interior drainage facilities, and bypass and diversion struc-
tures for the duration of the flood.
7. The planned use of non-Corps projects (including international projects) for current flood
regulation and the coordination necessary to achieve the flood risk management objec-
tive.
8. Flood regulation coordination in the management of multipurpose water control projects
with other interests such as public and private utilities, power marketing authorities, fish
and game agencies, and state or local water agencies.
9. A description of any special conditions related to weather and river conditions that might
affect water regulation and Corps activities being undertaken as the result of the flood.
10. Coordination and awareness of operational constraints that affect the projects capability
to be operated according to the approved water control manual.
7.6.3.2. If conditions warrant, district resources may follow current policy regarding release of
inundation data.
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7.6.3.3. During floods, the water management office is not only responsible for analyzing the
system, scheduling and coordinating project regulation, and maintaining continuity of data systems,
but also for displaying information in briefings. Facilities available for normal river and reservoir
briefings that ideally should provide all of the needed aids may not be sufficient for a larger district-
wide event. During a larger scale flood, an emergency operation center may be set up to assist the
district or division commander in directing flood activities. Section 8.2 discusses the design and use
of briefing room facilities.
7.6.4. Monitoring and Reanalyzing River and Reservoir Conditions during Emergencies.
7.6.4.1. The principles and methods of real-time system analysis for normal scheduling opera-
tions are also applied during emergencies, but with special emphasis on maintaining knowledge of
current hydrometeorological conditions. Maintaining the ability to respond to potentially rapidly
changing events during emergencies requires intensive analytical efforts. Using all available tools,
the relationship between forecasted and observed conditions must be coordinated frequently and
sound judgments must be made to schedule project water management activities most effectively.
7.6.4.2. An awareness of changes in a river system and proper maintenance of the hydrometeor-
ological data system are critical to prepare water managers for floods. During floods, water manag-
ers must make decisions based on hydrologic and hydraulic data developed from calculations and
historical observations. These can include stage-discharge relationships, stage-damage relationships,
level of levee flood risk management, levee integrity, hydraulic travel times, and many other assump-
tions. In dynamic systems and during floods, these relationships may change from event to event,
and water managers should be in contact with field personnel to provide visual confirmation of river
and reservoir conditions and the level of impacts. Observations may be made by Corps employees,
local or Federal RCO personnel, or USGS or NWS field personnel. It is critical that river and reser-
voir gage levels be verified throughout a flood event to ensure that water managers are making deci-
sions based on accurate data. The hydrologic conditions during flood events could test the perfor-
mance limits of the automated gaging equipment. Additionally, temporary stream gages may need to
be installed during a flood.
7.6.5. Adjusting Reservoir Water Management Activity Schedules. Monitoring and reanalysis
of conditions during emergencies may require frequent adjustment of water management activity
schedules. The needs are determined from the knowledge and experience of the water manager.
7.6.6. Non-Federal Sponsor Water Management Activities. Corps water management over-
sight of the non-Federal sponsor application of Corps-developed operating criteria is typically
increased during flood events. During floods, the exchange of accurate, timely information be-
tween water managers is critical. The typical exchange of information through email and other
electronic means that occurs during non-flood conditions should be expanded to include oral
communication, as necessary, to ensure that critical details are understood by water managers of
all agencies. In some instances, Corps assistance may be provided to the non-Federal sponsor to
address project-related technical questions or staffing beyond normal duty hours.
7.7. Coordinating Flow and Water Level Forecasts.
7.7.1. General.
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7.7.1.1. Corps water management personnel must recognize and observe the authorized respon-
sibility of the NWS for issuing weather forecasts and flood warnings to the public as described in ER
1110-2-240, Water Control Management. Consistent and timely communication of Corps water
management activities that may prompt flood notifications or affect forecasts must be provided.
Corps water managers often need to make additional forecasts of streamflows and river levels to best
meet multipurpose project water management objectives, although unnecessary duplication of effort
among forecasting agencies should be avoided, and forecasts should be coordinated and shared to the
greatest extent possible. If the Corps and NWS develop separate forecasts that indicate significant
differences, increased coordination should occur, such that both agencies fully understand the rea-
sons for the differences.
7.7.1.2. The exchange of the most current hydrometeorological and operational data is an im-
portant part of coordination among the offices. Water management and water level forecasting agen-
cies should coordinate the hydrometeorological and operational data to support water management
decisions and forecasts. Coordination of forecasts and water management operations can be accom-
plished through oral communication, regionally coordinated electronic communication, and the dis-
tribution of flow schedules to the forecasting agency. Corps water managers must continually pro-
vide current operation plans to Federal and state agencies involved in streamflow and water level
forecasts because accurate information is critical to the forecasting ability and emergency planning
efforts of the agencies.
7.7.2. Basin-Wide Forecasting Services.
7.7.2.1. The Corps is engaged in ongoing cooperative efforts to develop and implement basin-
wide river forecasts and to estimate the impacts of those forecasts.
7.7.2.2. The Columbia River basin offers a good example of a joint operation that provides ba-
sin-wide forecasting of a river system, in conjunction with requirements for project operation and
preparation of river forecasts for the general public. Since 1963, the Northwestern Division Office of
the Corps of Engineers and the Northwest River Forecast Center of the NWS have jointly developed
reliable and timely forecasts of streamflow at key locations in the Columbia River basin. The current
method of creating the joint basin-wide forecast uses the NWS Community Hydrologic Prediction
System (CHPS), which enables NWS forecasters to create natural streamflow forecasts and Corps
water managers to remotely input and route projected reservoir releases in the same computer model.
The result is a basin-wide, regulated streamflow forecast for the entire Columbia River system, dis-
tributed by the NWS.
7.7.2.3. During emergencies, forecasting of releases, stages, and flows often supports an overall
flood fight, which may include monitoring of critical infrastructure, emergency levee construction,
evacuations, and reinforcement of levee systems. District resources may provide real-time inunda-
tion mapping or previously prepared inundation maps that complement forecasts and help locate
trouble areas during emergencies. The Corps, USGS, NWS, and Federal Emergency Management
Agency (FEMA) develop and maintain inundation maps. Ongoing and future inundation mapping
efforts should proceed collaboratively among the agencies and focus on the development of con-
sistent end products to support future emergencies.
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CHAPTER 8
Administrative and Coordination Requirements for Water Management
8.1. Administration of Water Management Activities.
8.1.1. Organization.
8.1.1.1. The overall responsibility for water management throughout the Corps is assigned to the
Engineering and Construction Division, HQUSACE (CECW-CE). CECW-CE establishes major
policy and guidance pertaining to Corps-wide water management activities and has assigned water
management as part of the HH&C CoP.
8.1.1.2. ER 1110-2-1400, Reservoir/Water Control Centers, delegates water management re-
sponsibilities and defines roles for Headquarters (HQ), divisions, and districts.
8.1.1.3. The divisions may contain water management offices in the division office, in district
offices within the divisions, or in both district and division offices. In division or district offices that
do not have separate water management offices, the water management responsibilities are usually
carried out by the hydrology/hydraulics element located within an engineering or operations division.
Each division-led water management office is responsible for division-wide oversight of district wa-
ter management activities. The organizational structure and responsibilities of water management
division offices vary across the Corps. Although the basic mission and water management objectives
of each division are similar, differences exist in the types of water management projects and respon-
sibilities in the division and district offices. Many districts operate independently, according to estab-
lished operating procedures, with varying degrees of division oversight.
8.1.1.4. In addition to the duties described in ER 1110-2-240, Water Control Management, and
ER 1110-2-1400, examples of other functions are listed in Section 8.1.2. Three division offices,
Northwestern Division (NWD)-Portland, NWD-Omaha, and Great Lakes and Ohio River Division
(LRD), have direct reservoir regulation responsibility for mainstem projects within the respective ge-
ographic regions.
8.1.2. Functions.
8.1.2.1. Water management decisions are made by the Corps each day throughout the nation
during normal and extreme hydrometeorological conditions. The number and difficulty of these de-
cisions may vastly increase during flood and drought events, and most of them are made at the dis-
trict level. Some division offices make real-time water management decisions for major projects.
Some examples of principal functions required for real-time water management are:
1. Hydrometeorological data collection and processing.
2. Hydrologic, hydraulic, and reservoir modeling.
3. Inter- and intra-agency data exchange.
4. Water management decision making.
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5. Instructions to project operators.
6. Reporting to higher authority.
7. Monitoring project effectiveness and preserving project integrity.
8.1.2.2. The real-time functions stated above are generalized and encompass many tasks, such
as: information exchange, hydrologic and hydraulic forecasting, water data system management, ap-
plication of computer models, briefings, and release scheduling.
8.1.2.3. Additional support activities, such as O&M of instrumentation and communication fa-
cilities in the office and in the field are also required. Routine activities include formulation of water
control plans and “Standing Instructions to Project Operator,” compilation or updating of water con-
trol manuals, development and adaptation of numerical models, database management, data archival,
and the establishment of discharge ratings for streams and structures. A significant amount of work
in the form of annual and post-flood reports is also required. ER 1110-2-1400, Reservoir/Water
Control Centers, provides additional guidance on water management offices’ roles and responsibili-
ties.
8.1.3. Staffing. Water management staff in divisions and districts may include civil (hydrau-
lic) engineers, meteorologists, environmental engineers, and hydrologic and civil engineering
technicians. In addition, hydrologists, agricultural engineers, biologists, chemists, physical sci-
entists, computer technicians, and mathematicians contribute significantly to water management
in several offices. Key field personnel may also include streamgaging technicians, dam tenders,
hydroelectric power plant superintendents, pumping plant operators, other water management
structure operators, and park rangers. The responsibilities of water management staff are highly
diversified, and much of the work leverages computer use from basic data collection to modeling
water resource systems for multiple water management objectives. Most district and division
water management elements use computer systems dedicated to water management activities.
Responsibility for computer systems hardware and software is shared between the district, divi-
sion, HEC, and the support organization that has immediate control over Corps hardware and
software installation (currently ACE-IT). For more information on computer systems see Chap-
ter 5 of this EM.
8.1.4. Role of Project Operator. Physical operation of water management structures for
which the Corps has management responsibility is provided by the districts’ operations divisions
of the Corps, owners of non-Corps Federal projects, other Federal agencies, or by local interests.
Project operators, which include dam tenders, power plant superintendents, lock masters, re-
source managers, and others, are furnished standing instructions for water management by the
water management office. Section 9.4 discusses the information to include in the instructions.
The hydraulic and hydrologic aspects of any operation plan in O&M manuals and similar docu-
ments are typically limited to the physical operation of structures, such as the manipulation of
gates, placement or removal of stoplogs, and operation of pumps. Except for very small water
management projects where little chance exists for mishap by incorrect operation, project opera-
tors are also furnished oral instruction and general information on a real-time basis by water
managers. Clear and direct lines of communication and authority should be established between
the water manager and the project operator. No delay in the communication between the water
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manager and the project operator should occur. Communication should be made directly with
the project operator to best achieve water management objectives in a timely manner without
confusion and error. In cases where direct lines of communication are lost, the “Standing In-
structions to Project Operator” should be used until communications are restored.
8.1.5. Training.
8.1.5.1. Corps water management staff must be familiar with current technical procedures and
computer programs. Although most colleges and universities offer training in the general disciplines
involved in water management, regular programs at these institutions do not generally provide formal
training focused on specific aspects of water management in the Corps. Many offices rely on men-
toring by senior water managers to train new employees in water management.
8.1.5.2. Training directly related to the kinds of problems and situations involved in water man-
agement is available through selected short-term courses offered by the Proponent Sponsored Engi-
neer Corps Training (PROSPECT) program of the Corps. In addition, workshops on these and other
subject areas are conducted periodically by HEC, ERDC, and other Corps offices and organizations.
Table-top exercises simulating potential operational scenarios are useful training tools as well.
8.2. Briefing Room Facilities.
8.2.1. General. Water management briefings may be held in division, district, or local area
offices. Briefing facilities range from work areas equipped with whiteboards, static displays, and
desktop computers, to specially designed briefing rooms equipped with a computer driven video
projector, teleconferencing capability, and high speed internet connectivity to facilitate web
meetings or live video teleconferences. Water management briefings are conducted daily or
weekly in some offices, and only during floods or emergencies in others.
8.2.2. Purpose. A briefing room provides a setting to exchange information on field condi-
tions and water management activities. Water management office staff should have priority use
of the briefing room. A briefing room may be developed as an adjunct to a water management
office to display data related to water management activities, to conduct briefings of current and
forecasted conditions, and to present current and planned project regulation details. The facility
should benefit not only water management office staff, but also other offices and agencies that
depend on or are affected by water management decisions. The facility may be needed to brief
the general public via the news media. During an emergency as described in Section 7.6, the
briefing room may serve as a command center to direct not only water management functions,
but also urgent related activities.
8.2.3. Design. A briefing room is planned and designed to be used for exchanging infor-
mation and informing others of current and forecasted conditions and water management activi-
ties on a regular and systematic basis. The facility should provide for the display of visual aids
to support description of water management problems, activities, and decisions. The scope and
breadth of water management office activities, including an analysis of appropriate space to ac-
commodate command personnel, office staff, and guests, should be a prime consideration in the
design of a briefing room. The design should provide for adequate privacy, lighting, wiring, and
display space. Additional features should include teleconferencing and web meeting capabilities.
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Mobility of furniture and adaptability to the incorporation of new technologies are other design
considerations. Experts should be consulted, as necessary, to achieve an effective design. All
seating should be designed to provide clear lines of sight to information displays, and audio
equipment should be considered, if necessary, to permit good sound quality throughout the brief-
ing room and voice communication with others in remote locations. The primary video display
should be the focal point in the briefing room. Space should be available to accommodate a pro-
jection screen, a large whiteboard, and maps or other printed figures.
8.2.4. Utilization.
8.2.4.1. The briefing room should accommodate water management office staff and others for
water management-related meetings and briefings. Water management staff members are responsi-
ble for conducting the meetings, but support may be provided by other groups such as a NWS River
Forecast Center (RFC) or hydraulic engineers who are specialists in hydrologic engineering, hydroe-
lectric power, water quality, or other fields of water engineering. The briefings may be attended or
remotely monitored by other Corps offices or by personnel from other agencies. These persons may
also need to contribute to the discussions.
8.2.4.2. The frequency of briefings and attendance by staff members of a water management of-
fice and others depends on the scope of the water management activities, current conditions, and
forecasted conditions.
8.2.4.3. Water management briefings are conducted under the supervision of the chief of the wa-
ter management office or designee. For example, a briefing agenda may include:
1. Summary of current meteorological conditions and weather forecasts.
2. Summary of unregulated (natural) streamflow forecasts.
3. Summary of system reservoir regulation requirements for flood risk management, hydro-
electric power generation, irrigation, navigation, fish and wildlife, recreation, or other
functional uses.
4. Description of reservoir regulation and individual schedules of project operation in down-
stream order within the system.
5. Summary of outlook of water management conditions expected in the ensuing weeks or
months.
6. Questions and discussions among participants.
The purpose of the briefings is to inform those not directly involved in the scheduling process of
conditions and the rationale of current operations. The briefings provide a means to critically re-
view current operations to ensure that the regulation is performed according to operating plans,
and to achieve general coordination of water management activities. Specific input obtained
from the briefings may guide future operations.
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8.3. Administration of Water Management Data Collection Agreements.
8.3.1. Cooperative Data Collection. The Corps performs or supports the collection of most
water data it uses. The USGS, NWS, and other agencies, through cooperative arrangements,
provide services to the Corps to install, operate, and maintain the instrumentation for essential
water data stations. The USGS/Corps Cooperative Stream Gaging Program (stage and dis-
charge) and the NWS/Corps Cooperative Reporting Network (stream stage and precipitation)
were established specifically to enable these agencies to assist the Corps. Arrangements to share
the cost at stations are also made to best meet the needs and constraints of each organization.
Arrangements may also be made with the USGS to measure streamflow or to process the data,
including both collection (measurement and transmission) and handling (processing, archiving,
and publication). Contractual arrangements for water data collection may be made by the dis-
tricts, and the draft agreements are submitted to the divisions for review and approval.
8.3.2. Water Quality Data Collection. A significant amount of water quality data is obtained
by contract for the Corps. The contracts may apply to physical, chemical, or biological parame-
ters in water and sediments and may consist of everything from field survey to interpretative re-
ports. All contract water quality data should meet the quality assurance/quality control criteria
outlined in ER 1110-2-8154, Water Quality and Environmental Management for Corps Civil
Works Projects.
8.4. Interagency Coordination and Agreements.
8.4.1. Types of Coordinating Groups. The following paragraphs discuss groups that have
been formed to establish the working relationships necessary for coordinating water management
activities.
8.4.1.1. International Boards, Entities, and Operating Committees. International boards, entities,
and operating committees operate according to treaties for development or use of international rivers
and waterways. These organizations consist of representatives of the United States and an adjacent
country sharing a water body. Such groups may operate at national, regional, or local levels within
the country. As such, the groups may be supervisory and meet infrequently to oversee water man-
agement operations to ensure compliance with treaty provisions, or they may be working organiza-
tions that meet frequently and communicate as necessary to schedule project regulation.
8.4.1.2. National Water Resource Coordinating Groups. National water resource coordinating
groups are composed of representatives of Federal agencies at the national headquarters level. These
groups coordinate the hydrologic and hydraulic data observation and acquisition programs, weather
data acquisition and forecasts, satellite- and ground-based communication systems, radio frequency
assignments for hydrologic reporting networks, etc., as needed for management of water systems.
8.4.1.3. Regional River Basin Interagency Committees, Compacts, and Commissions. Regional
river basin interagency committees, compacts, and commissions coordinate water management activ-
ities within a major river basin or regional area of the country. These organizations consist of repre-
sentatives of Federal and state government agencies concerned with project planning and construc-
tion and management of water resources within the region. The groups may be formed voluntarily,
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by legislative action, or through river basin compacts. Although the primary concern of these organi-
zations may be related to planning and construction for river basin development, an additional focus
may be to improve coordination of water management activities for an existing system. These or-
ganizations may have subcommittees that deal with the specific problems of coordinating data and
river forecasts and with the technical problems related to multiagency river regulation objectives in
general accordance with agency policies and objectives. These organizations are not generally con-
cerned with day-to-day scheduling, but with monthly or seasonal regulation.
8.4.1.4. Operating Committees for Water Use. Operating committees for water use are formed
to coordinate project operating input, as established under contractual agreements with cooperating
agencies or utilities for coordinated operation of water management facilities. These committees
consist of representatives of the water users, utilities, or government agencies (including the Corps)
who are parties to the contract. The representatives generally work at the organizational operating
level and have technical expertise in the scheduling of water or power to meet the contractual re-
quirements. These committees are informed of current operations on a weekly or monthly basis and
provide input to water managers for specific needs. This guidance is coordinated with other project
needs to modify project schedules. A supervisory committee may be included to periodically over-
see the operating committee activities and to ensure that project authorities and contractual commit-
ments are being met.
8.4.1.5. Working Groups.
8.4.1.5.1. The preceding paragraphs described four formal types of coordinating groups that
reflect overarching political, geographic, and functional factors affecting Corps projects, often at
the administrative or project management level. A fifth type of group consists primarily of
Corps field office personnel and corresponding members in other agencies that may be in fre-
quent contact with each other, by voice or text, to manage water. Such frequent contact may nor-
mally occur throughout the year, or may instead occur mostly during periods of flood, drought,
or other events requiring close coordination. The Corps members of the group may be field of-
fice engineers, forecasters, technicians, or other personnel with hands-on duties. Working
groups may be formal or informal, have irregular periods of greater or lesser activity, and may
have varying numbers of members over time.
8.4.1.5.2. Formal working relationships may be formed to coordinate and divide responsibili-
ties between Corps water management offices and other Federal agencies, states, counties, cities,
tribal groups, local drainage and flood risk management districts, operators of water management
projects owned by navigation companies, commercial or industrial organizations, etc., which are
affected by river or reservoir regulation. An annual water management meeting is an example of a
recommended formal relationship and that can include representatives from national, regional, and
local agencies, as applicable, to share information and to address current water management needs
and challenges. Another example of a formal relationship is that relationship between the TVA
and the Corps, which permits TVA operational control of multipurpose reservoirs during normal
(non-flood, non-drought) times, but which cedes operational control to the Corps during flooding
and severe water shortages. The hour-by-hour coordination between the Corps and TVA is often
accomplished by a working group that includes Corps personnel stationed in different districts or
divisions. A third example is a formal relationship with a drainage district that operates a pumping
station or other structure according to Corps protocols. A fourth example is an agreement with an
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entity, such as the U.S. Coast Guard, to provide security for Corps vessels during an authorized
flood fight. A final example of a formal relationship is an agreement with a county or municipality
to assist in the warning of persons that live downstream of a reservoir in danger of failure. Formal
relationships should be pursued as needed to prevent critical operational delays that can risk public
safety or have unintended results and diminish public confidence.
8.4.1.5.3. To some extent, an informal relationship is characterized by persons taking the ini-
tiative to contact people in other organizations. Quite often the tone or setting of communication
is also informal, through voice and text transmissions or meetings in the field. Informal working
relationships provide an additional source of information and coordination to support water man-
agement decisions and should be pursued and maintained as needed to maximize water manage-
ment effectiveness, enhance public relations, and engender public confidence. It is essential to
establish and maintain informal relationships with applicable Federal, state, and local agencies in
advance of flooding or other emergencies to support and coordinate critical water management
decisions.
8.4.2. Types of Water Management Agreements. The functions and responsibilities of the
above coordinating groups, except informal working relationships, may be formalized by Con-
gressional legislation, by written agreement, or both. The agreements are usually in the form of
MOUs signed by the agency heads at the national, regional, or local levels. These agreements,
which include such areas as hydroelectric power generation, fish and wildlife resources, and wa-
ter supply, form the basis for coordination of water management activities by water managers.
This type of arrangement may also be made for coordinating the flood risk management and nav-
igation regulation of non-Corps projects that are subject to Section 7 of Flood Control Act of
1944. Even though much freedom may be given to another agency with regard to meeting a de-
sired water management objective, the agreements explicitly state that the Corps is ultimately re-
sponsible for the overall achievement of water management objectives, whether complementary
or conflicting. Many such agreements exist concerning water management. All such agreements
should be reviewed for approval by the appropriate water management center or water manage-
ment element before completion, and the agreements normally require signature by the Division
Commander. The following sections provide three examples.
8.4.2.1. Data Exchange. Agreements are made with Federal or state agencies regarding the ex-
change of hydrologic and hydraulic data to be used in making forecasts and project regulation in gen-
eral. These arrangements may be made at the national, regional, or local level. The need for coordina-
tion is usually associated with scheduling project regulation. The requirements for coordination of data
gathering and exchange and forecasts and/or forecasting activities must be specifically addressed in
each river basin. Actions taken to coordinate these activities may range from simple exchange of data
between agencies to a coordinated data and forecasting center with joint staff participation.
8.4.2.2. Hydrologic and Hydraulic Forecasting. The NWS is responsible for the forecasting of
hydrological and meteorological events, and for disseminating this information to the public. As part
of the Corps responsibility for water management, NWS forecasts are often supplemented with
Corps internally determined project inflow and local flow forecasts. Also, the Corps may routinely
develop separate internal hydraulic and hydrologic forecasts to consult with the NWS, and to support
project construction, operation, and navigation.
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8.4.2.3. Hydroelectric Power Generation.
8.4.2.3.1. EM 1110-2-1701, Hydropower, discusses the relationship between a Corps project
and the Administrator of a regional Power Administration Office of the DOE. Such an agree-
ment is supplementary to a water control plan and manual and may be explicit regarding some
aspects of coordination and very general in regard to others. Reasons for the DOE to seek such
an agreement are to clarify the DOE role in the use of Corps projects, and to express the DOE
objective to maximize hydroelectric power generation. Reasons for the Corps to enter into such
an agreement are to clarify the overall Corps responsibility for water management and to limit
adverse impacts to other authorized project purposes to the extent permissible.
8.4.2.3.2. In the interest of multipurpose water management, the Corps requires a signed
MOU with the licensee for non-Federal hydroelectric power construction at a Corps project,
which specifies that the operational procedures and power guide curve be used and be consistent
with overall project management objectives and efficient system regulation.
8.4.3. Coordinating with Operating Entities and Other Public and Private Water Use Organi-
zations.
8.4.3.1. General Considerations.
8.4.3.1.1. The Corps seldom works alone in the field of water management. The regulation
of a major river system involves many other organizations that have an interest in the daily and
seasonal water regulation from an operational or forecasting point of view. The coordination of
activities may stem from many years of effort in working with others in the planning, design, and
construction phases of project development. In the operational phase, coordination of all phases
of project regulation with various interest groups may be needed. Water control plans, particu-
larly regulation schedules and AOPs, are usually developed in concert with other agencies as ex-
pressed in contractual arrangements, formal operating agreements, or informal accords to ensure
that various multipurpose water use functions are achieved to mutual satisfaction. These basic
efforts for coordination extend beyond the planning and design stages into current operations,
usually through interagency coordinating groups, operating committees, or working relationships
established with individual agencies. Most of these arrangements are not legally required, alt-
hough some are based on commitments made in the planning and design phases of project devel-
opment. The water management activities may require coordination on an international, na-
tional, regional, or local basis, involving countries adjacent to the borders of the United States as
well as Federal agencies, regional or state water or energy authorities, public or private utilities,
local water-oriented agencies, or public interest groups.
8.4.3.1.2. Certain water management coordination requirements directly affect project regu-
lation schedules. Examples are coordinated system regulation required under operating agree-
ments for hydroelectric power generation, water use agreements and commitments set forth in
international treaties, and flood risk management and navigation requirements established for
projects subject to Section 7 of the Flood Control Act of 1944. These firm commitments, which
must be incorporated into project regulation schedules, require coordinated efforts among the op-
erating agencies. This requires exchange of operating data and communication to achieve pro-
ject regulation that complies with the water control plan. Where several operating agencies are
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involved, the coordination may be achieved under the authority of an operating committee, the
membership of which includes representatives of each of the cooperating entities or under the au-
thority of a single operating agency, by direct communication with that agency.
8.4.3.1.3. Some elements of water management coordination involve agencies that do not
own or operate projects, but that represent water interests concerned with project regulation.
These may include Federal, state, or local entities involved in environmental protection, fish and
wildlife, navigation, irrigation, water supply, recreation, and local boards concerned with land
use in the operation of diversion and by-pass facilities. The needs for coordination with these
individual entities are usually met by periodic contacts with the water management center or
other water management office of the Corps.
8.4.3.1.4. A final element of water management coordination is related to streamflow and
river level forecasting. This function may involve a daily exchange of data and associated coor-
dination, such as providing Corps daily and forecasted reservoir outflows to the NWS to improve
the estimation of river stages affected by the reservoir releases. Clear coordination and good
working relationships are important to create a level of trust and confidence between the interact-
ing agencies, and to produce the best forecasting estimates. The particular requirements and
methods for coordinating the water management activities described above with other agencies
vary widely from region to region within the United States. The needs and desires for achieving
coordination depend on the local conditions. Although no set procedure exists to achieve such
water management coordination, annual water management meetings and other interagency co-
operative efforts should be considered to share knowledge, which can support the ultimate objec-
tive of effective water management.
8.4.3.1.5. Regional or river basin water management coordinating groups may be used to in-
stitutionalize coordination of water management activities. As noted previously, coordination
may be achieved through voluntarily formed committees or groups, or by an operating commit-
tee formed as an adjunct of formal operating agreements to implement the regulation plans in-
volving two or more agencies.
8.4.3.1.6. The water manager should be responsive to all types of river users and have an
“open door” policy to local interest groups, as well as to other operating agencies, to consider
special requests or to explain operating procedures. Infrequent interactions of this type can be
addressed informally on a case-by-case basis. Establishment of formal working relationships
should be considered in circumstances that require a continuing need for exchange of data or
consideration of special operating requirements.
8.4.3.1.7. In some respects, the needs and desires for interagency coordination are interre-
lated. The desires for coordination may reflect long-standing working relationships between the
organizations, which over a period of time build confidence in and respect between individuals
and organizations involved in attaining the water management objectives. However, no pre-
scribed method exists to foster such relationships or to determine the effort required. Inasmuch
as many of the procedures are based on voluntary actions between the agencies, the decisions on
these matters are based on the initiative and judgment of all parties with the goal to best serve the
public interests.
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8.4.3.2. Conflicts in Water Use. In formulating operating strategies for water management, con-
flicts may arise reflecting differing interests of water users. The conflicts may arise in connection
with interpretation of operating rules and agreements for carrying out the authorized project functions
by user groups (e.g., navigation, power, irrigation, or flood risk management interests), or they may
arise in areas related to the achievement of environmental or social goals in conjunction with the eco-
nomic and authorized regulation requirements. These conflicts may encompass local or regional
problems that have major impacts on various and diverse segments of society with regard to social
and economic well-being and perceptions of the importance of the contested issue(s) to the public
good. Although many of these types of problems are resolved in the planning and design phases of
project development, other problems of water utilization often arise in the operational phase. Fur-
thermore, changes in public attitudes may occur with regard to water management procedures, and
these changed attitudes should be taken into account in project regulation. The conflicts may involve
a wide range of impacts, varying from minor effects in formulating regulation schedules to accom-
modate a limited water use requirement, to major effects on regional power supplies and employ-
ment, fishery resources, flood regulation, environmental impacts, or other impacts related to water
use. These issues may be considered to the extent the currently authorized water control plan per-
mits, or to the extent that a deviation or revision to the water control plan may be pursued as de-
scribed in ER 1110-2-240.
8.4.3.3. Efforts to Resolve Conflicts through Coordination. Efforts to resolve conflicts in water
management are initiated at the working level through coordinated operation described in the preced-
ing sections. Initially, a thorough exchange of data and information is required pertaining to the cur-
rent operation, together with an explanation of the scheduling requirements between the operating
office and the individual water user groups who have an interest in the project’s functional use.
These discussions often clarify operating requirements and interpretations of project regulation
schedules and serve as a basis for a better understanding of the overall requirements for multipurpose
regulation. From these discussions, relatively minor conflicts may be resolved by negotiation to ad-
just project schedules and accommodate special requirements without significantly jeopardizing
other water use functions. Recording the resolution of such conflicts should be considered through
an MOU or similar document.
8.4.3.4. Public Meetings. Communication with the general public should follow the public in-
volvement process outlined in ER 1110-2-240, Water Control Management. The purposes of the
meetings are to inform local interest groups and the general public about issues related to the water
management and river regulation activities in the project area, to exchange views on the impacts of
alternative methods of regulation, and to seek input that could be considered in formulating operating
decisions. The content of public meetings could include the effects of the operating decisions on the
general public, with particular emphasis on public use functions such as fishing, boating, recreation,
and aesthetics, combined with the effects on the local economy, employment, safety, environment,
and general well-being of the people.
8.4.3.5. Involvement with Elected Public Officials. Elected public officials, particularly con-
gressional representatives and governors, should be informed in cases where water management de-
cisions may be of significant interest to their constituencies, and the Corps should be responsive to
public concerns. Informal contacts by the District or Division Commanders can alert these public
officials to potential problems that may have political significance.
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8.5. Water Management Reports on Prevailing Conditions.
8.5.1. General. Much of project and real-time water data are stored in a data system, as dis-
cussed in Chapter 5. The data are used to regulate projects and to prepare reports. The following
sections describe reports prepared from real-time water data to assist in water management decisions.
8.5.2. Project Operator Reports. In addition to reporting water management actions, dam ten-
ders often monitor water data, as specified in the “Standing Instructions to Project Operator” (see
Section 9.4), and furnish the data directly to the appropriate water management element in the dis-
trict or division. The requirements for monitoring and reporting are usually more intensive during
flood and drought events; reference ER 1110-2-8156, Preparation of Water Control Manuals.
8.5.3. Water Management Morning Reports. Water management morning reports are used
to evaluate watershed and project conditions and are the principal means of informing in-house
staff that have a need to know prevailing conditions. These daily reports are generated from pro-
ject and hydrometeorological data that have been entered into a database management system in
a water management office. The information in the reports may include observed water data, hy-
drologic and hydraulic forecasts, release schedules, power generation schedules, and other rele-
vant information such as inflows and current constraints.
8.5.4. Special Advisories.
8.5.4.1. Potential and actual emergencies of any nature that have a significant impact on water
management decisions associated with Corps projects should be reported immediately by telephone
or other designated form of communication to the appropriate division water management element
who will then notify CECW-CE. If the district deems the information to be critical, the report can go
directly to CECW-CE and be copied to division. Chapter 7 of ER 500-1-1, Civil Emergency Man-
agement Program, describes the circumstances in which such a project information report that is
compiled by the district RCO is required. The RCO role is to pass information between Planning
and Policy Division at HQ (CECW-P) and the district. An example of a special advisory is a project
information report related to an imminent threat of unusual flooding that is forwarded by the district
through the division to CECW-P. Examples of other special advisories are:
1. Severe weather warnings.
2. High runoff potential advisories.
3. Flash flood warnings.
4. Emergency condition alerts concerning the quantity of streamflow, water quality, and
ecology.
5. A report of an unsafe condition connected with water management that could impact
streamflow conditions or the integrity of a water management structure, considering both
Corps and non-Corps projects.
8.5.4.2. These advisories are required to keep the division commander and the Chief of Engi-
neers apprised of critical events. Reports made by telephone are followed immediately by a concise
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narrative summary (special advisory) of the event. The follow-up advisories are reported by the most
rapid means available, often by emails and briefings. ENGLink is the recommended form of com-
munication because it is a good command and control tool that helps eliminate multiple emails on the
same subject.
8.5.5. Discharge Data. During flood events, discharge measurements at critical sites should
be made and preliminary results should be promptly reported to the water management office to
support real-time water management decisions. Any adjustments of the preliminary discharge
results should be immediately provided to the water management office. Discharge measure-
ments are often made by the Corps, the USGS, and state offices.
8.5.6. Flood Damages. On request, the districts provide flood damage estimates of desig-
nated areas, potential and actual, to the division water management elements during prevailing
flood events. Complementary maps depicting areas of inundation and land use may accompany
the basic data and may be furnished as computer graphics. These reports are prepared according
to ER 500-1-1.
8.5.7. Reports for the Media, Local Entities, and the Public.
8.5.7.1. Water data at projects and at control points on streams are furnished to the news media,
local entities, and the public. Automated reports may be made available to the public and dissemi-
nated via district and division Internet web pages in bulletin or plot format. These reports may in-
clude observed water data, hydrologic and hydraulic forecasts, release schedules, and power genera-
tion schedules.
8.5.7.2. Caution should be exercised to avoid furnishing river stage forecast information to the
press or organized interest groups since dissemination of official river stage and discharge forecasts
is the authorized responsibility of the NWS. ER 1110-2-240 gives further information regarding
communicating river forecast information to the public, and working with the NWS.
8.6. Documents, Reports, and Records. Standard types of water management documents and re-
ports are prepared to guide regulation of water resources projects, to support administration at
the division and HQUSACE levels, and to provide a permanent record of project and control
point conditions.
8.6.1. Water Management Documents. ER 1110-2-8156, Preparation of Water Control
Manuals, states the basic requirement for preparation of water management documents. The
contents of these documents, which are discussed in Chapter 9, consist of:
1. Standing instructions to project operators.
2. Water control plans.
3. Water control manuals (for individual projects and for water resources systems).
8.6.2. Annual Operating Plans and Other River Basin Committee Reports. AOPs and other
river basin committee reports commonly address the achievement of water management objec-
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tives during the previous year and the operating plan for the current year for certain project pur-
poses of interagency (joint) interest. AOPs are based on long-term runoff projections. Naviga-
tion, hydroelectric power generation, flood risk management, and water supply are the primary
project purposes reflected in these reports.
8.6.3. Annual Water Management Reports. Annual water management reports are prepared
by the districts, consolidated for the division by water management elements, and submitted to
CECW-CE. The reports include project accomplishments, flood risk management activities, and
status of water management documents, with a schedule for preparation and revision. The report
is required by ER 1110-2-240.
8.6.4. Annual Report on the Cooperative Stream Gaging Program. The annual report on the
Cooperative Stream Gaging Program concerns the funding of water data collection (stage and
discharge) provided to the Corps by the USGS. ER 1110-2-1455, Cooperative Stream Gaging
Program, discusses this activity and the report in further detail.
8.6.5. Annual Billing for the Cooperative Reporting Network. The annual billing transaction
for the cooperative reporting network consists of a reverse billing procedure between CECW-CE
and the districts to fund water data collection provided to the Corps by the USGS and the NWS.
8.6.6. Annual Budget Request. Construction funding is the preferred funding source for the
required preliminary and final water management documents related to new Corps projects.
O&M funding is normally used to revise and update water management documents. Water man-
agers in the districts prepare budget requests 2 years in advance for water management activities.
The requests are prepared in the March through June timeframe according to annual budget guid-
ance provided by Programs Division, Directorate of Civil Works.
8.6.7. Summary of Runoff Potential. Seasonal reports on hydrometeorological conditions
include the outlook for floods resulting from snow accumulation and for droughts, with supple-
mental reports as the situation progresses. These reports help inform the chain of command and
support organizations on potential issues and reservoir operations.
8.6.8. Post Flood Reports. Water managers contribute significantly to the preparation of
post flood reports (see ER 500-1-1). Project regulation effects, including evaluation of stage re-
ductions at key stations and estimates of damages prevented by projects, are determined and in-
cluded in the report. These are historic documents; water managers should invest sufficient re-
sources to properly document the flood event. Funding for this documentation should be ac-
quired from Flood Control and Coastal Emergencies (FCCE) funds to the extent available and
then from O&M funds.
8.6.9. Water Data Records. Records of stage, discharge, water quality parameters, and other
information that define water management events are compiled and stored using various media,
including the use of national paper archives and on the Internet using websites hosted by the
Corps, U.S. Environmental Protection Agency (USEPA), USGS, NWS, and other entities.
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8.6.10. Federal Register.
8.6.10.1. A list of Corps and non-Corps projects authorized by Federal laws and directives is
published in Part 222.7, Title 33 of the CFR. The list is maintained by CECW-CE with input from
the division and district offices. ER 1110-2-240 details related policy.
8.6.10.2. Section 7 of the Flood Control Act of 1944 requires the Corps to prescribe regulations
for the use of storage allocated for flood risk management, or for navigation at all reservoirs con-
structed wholly or in part with Federal funds provided on the basis of such purposes. (TVA projects
are special cases.) Part 208.10 applies to small (<12,500 acre-feet) local flood risk management pro-
jects that are turned over to local interests for physical O&M after completion. The requirements in
Part 208.10 address O&M, but do not address the regulation of water management projects. When
appropriate, documents entitled “Standing Instructions to Project Operator” are prepared by water
managers and furnished to local project operators. Part 208.11 applies to all other projects subject to
Section 7 that are not included under Part 208.10. The Corps prepares water control manuals for pro-
jects listed under Part 208.11, including water control plans and standing instructions.
8.6.11. Annual Report on Project Benefits. Monetary benefits are determined annually for
project purposes that produce tangible benefits. The economics team collaborates with engineer-
ing and operations personnel to routinely compute the benefits attributable to flood risk manage-
ment, navigation, hydroelectric power generation, water supply, and recreation. The information
is then provided to HQUSACE for preparation of the Annual Report of the Chief of Engineers,
Civil Works Activities. When appropriate, benefits are also determined for water quality and
fish and wildlife enhancement, streambank and beach erosion control, and restoration of the en-
vironment (e.g., terrestrial, wetlands, and aquatic plant control). An annual flood damage report,
which includes damages prevented and damages incurred in each state, is prepared by CECW-
CE with significant input from partner agencies. The report is submitted to Congress according
to House Committee Report 98-217, Energy and Water Appropriations Act, 1984.
8.6.12. Annual Water Quality Report. A water quality report should be prepared annually
by each division and submitted to CECW-CE to ensure that adequate information on Corps water
quality management activities is available to HQUSACE, division and district water manage-
ment elements, and other interested parties. The report should summarize the water quality man-
agement program for the past fiscal year and highlight specific project information, planned ac-
tivities, and other pertinent information, issues, and proposed solutions. ER 1110-2-8154 con-
tains guidance on this report.
8.6.13. Periodic Inspections and Reports. Water managers should participate in annual and
periodic inspections, periodic assessments, operational condition assessments, and review pre-
pared reports for each project to avoid problems that might impact project regulation. The in-
spections should include gage verification and redundancy to assure stakeholders of properly
functioning streamgages. A periodic inspection is held every 5 years. A periodic assessment in-
cludes a semi-quantitative risk assessment that supplements every other period inspection (every
10 years) and a Potential Failure Mode Analysis (PFMA) and evaluation of downstream conse-
quences. The periodic assessment essentially confirms or reassigns a project’s DSAC.
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CHAPTER 9
Preparation of Water Management Documents
9.1. Basic Documents.
9.1.1. Types of Documents. The basic water management documents for projects or systems
of projects include:
1. Water control manuals.
2. Water control plans.
3. Standing instructions to project operators.
4. Initial reservoir filling plans.
9.1.2. Types of Projects.
9.1.2.1. Table 9-1 defines and categorizes all water management projects according to size and
complexity to identify the appropriate amount of documentation needed. These projects may include
culverts, floodwalls, weirs, lakes and reservoirs, locks and dams, controlled channels and floodways,
gated saltwater and hurricane barriers, backwater projects, and large pumping plants. Table 9-1 also
lists the categories of projects and the associated characteristics and structure types.
9.1.2.2. The level of documentation needed for water management projects has been scaled to
match the types of projects listed in the above table. Type I projects should seldom need any water
management documentation due to the simplicity of these projects. Any documentation should be
provided by the engineering group within a district or division for inclusion in an O&M manual or
Emergency Action Plan. To clearly distinguish water management objectives and requirements from
physical operation procedures, only Type I projects include water management documentation in
O&M manuals. Water management documentation for Types II, III, and IV projects are discussed in
the following sections.
9.2. Water Control Manuals.
9.2.1. Project Water Control Manuals.
9.2.1.1. Purposes. Water control manuals are typically prepared for only Type III and IV pro-
jects. The main purposes of the manuals are to document the water control plan and to provide a ref-
erence source on project issues, authorities, data, schedules, and all other information necessary to
regulate a project. A manual is generally prepared for a project within 1 year after the project is
placed in operation. The primary reason for preparing a separate manual or an appendix to a master
manual for a water management project is to facilitate the use of specific information such as instruc-
tions, plates, tables, diagrams, and charts; and to execute the water control plan.
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Table 9-1. Categories and Characteristics of Water Management Projects.
Project
Type Description Examples
Water Management
Documentation
Type I
• Small structures
• Operation by opening and
closing water passageways
• Engineering provides water
management requirements
• Operations division operates
and collects data
• Culverts
• Floodwalls
• Uncontrolled Weirs
• Pumping stations
• Gated structures
• Fuseplugs
• Not required
Type II
• Small structures
• Operation by opening and
closing gates or pumping
• Operation dependent on
hydrometeorological
conditions
• Operation limited to fully
opened or fully closed
positions
• Culverts
• Pumping stations
• Gated structures
• Standing Instructions
to Dam Tender
Type III
• More complex structures
• Timely reporting of project
conditions important
•
Water managers responsible to
monitor project
• Reregulating structures
• Locks and dams
• Completely
uncontrolled projects
• Water Control Plan
• Water Control Manual
when part of a system
• Standing Instructions
to Dam Tender
Type IV
• Major structures
• Require complex water
management procedures
• Usually require attendants
during unusual
hydrometeorological
conditions
• Reservoirs
• Lakes
• Major diversion
structures
• Pumping stations
• Floodways
• Water Control Plan
• Water Control Manual
• Standing Instructions
to Dam Tender
• Initial Reservoir
Filling Plan
9.2.1.2. Contents. ER 1110-2-8156, Preparation of Water Control Manuals, contains the prepa-
ration requirements for water control manuals. A manual should contain information to assist water
management regulation, and should consider all foreseeable conditions that may affect a project or
system. All chapters and exhibits in a water control manual should focus on providing a full under-
standing of the project and water control plan. The water control manual should include descriptions
of structures and water management conditions that constitute an integral part of a project such as
reregulation, pumpback, or diversion facilities. The water control plan for a separate neighboring
project within the same system should be presented in a separate manual. The scope of certain chap-
ters or topics in water control manuals for individual projects may be less extensive for those projects
within basins or systems for which water control master manuals are either available or planned for
the near future. For example, consider a water control master manual that documents operation of a
system of locks and dams with respect to forecasted flows. The water control manual for one of the
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locks may refer to the master manual for operation based on forecasted flows in lieu of presenting an
unnecessary duplication of the information contained in the master manual.
9.2.2. Water Control Master Manuals.
9.2.2.1. Purpose. Similar to project water control manuals, water control master manuals are
prepared to document the overall system water control plan to facilitate regulation. A master manual
should be prepared when the scope and complexity of a system of interrelated projects are signifi-
cant. Aspects to consider whether preparation of a master manual is necessary are whether the reser-
voir operations are based on system criteria, general hydrometeorology, network data collection,
common forecasting points, complexity and objectives of the system water control plan, and manage-
ment responsibilities shared by multiple districts, divisions, or other requirements. For example, a
system of reservoirs with a common control point could have a water control master manual.
9.2.2.2. Contents. ER 1110-2-8156 contains the preparation requirements for water control manu-
als, including master manuals. Appropriate cross-referencing between a master manual and appendixes
(individual project manuals or plans, as required) can serve to reduce the duplication of information re-
garding specific subjects. All charts, graphs, diagrams, and other items pertaining to individual projects
should be presented in the individual project manuals as appendixes to the master manual.
9.2.3. Revisions. ER 1110-2-240, Water Control Management, provides guidance on update
intervals for water control plans and water control manuals. As a minimum, Chapter 7 of the
water control manual should be updated following any change to the water control plan. Com-
plete updates should be made at regular intervals to incorporate additional hydrologic data as
well as any other new information.
9.3. Water Control Plans.
9.3.1. General. The water control plan guides water release decisions for a project. As out-
lined in ER 1110-2-8156, the water control plan is contained in Chapter 7 of the water control
manual. An interim water control plan is required for the construction phase of a project; a pre-
liminary water control plan is required once full-scale operations begin and before the approved
water control plan is authorized; and an approved water control plan is required within 1 year af-
ter operation begins. If operations are desired outside the flexibility the plan provides then a de-
viation may be requested.
9.3.2. Interim Water Control Plan during Construction. To ensure that water resource pro-
jects perform safely and effectively during construction or modification, an interim water control
plan is required for Type III and IV projects before the alteration of the watercourse or when the
construction site becomes subject to flood damage. Interim water control plans remain in force
until the project is formally accepted for full-scale normal operation under the preliminary water
control plan. The interim plan should include, but is not limited to:
1. A description of hydraulic features provided to protect the project during each phase of
construction, including compliance with ER 1110-2-8152, Planning and Design of Tem-
porary Cofferdams and Braced Excavation.
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2. A plan for water control management during each phase of construction with references to
the maps and plates and identification of all water data collection stations, measured param-
eters, and data transmission modes, and an explanation of the method used and time needed
to forecast streamflow at the construction site during a flood event.
3. Identification of any special conditions during construction that may cause operational
constraints.
4. A description of the impacts of overtopping cofferdams, diversion dikes, or embankments
at the project site, of flooding borrow areas, and of high stages and high streamflow ve-
locities not associated with overtopping.
5. Safety precautions and appropriate warning systems for potential hazards to upstream and
downstream properties or residents, and plans for minimizing the adverse effects associ-
ated with partially completed relocations or incomplete flowage rights.
6. Map(s) showing each construction phase, and plan views and cross-sections of diversion
dikes.
7. Discharge rating, stage duration, and flow frequency curves for natural and modified con-
ditions, and degree of flood risk management provided during each construction phase
(discharge, stage, and freeboard).
8. Instructions to protect operators during the physical operation of completed or partially
completed water control features of the project for interim regulation and for acceptance
testing.
9.3.3. Preliminary Water Control Plans. The preliminary water control plan should be pre-
pared to provide an initial plan of regulation before preparation of an approved water control
plan (see ER 1110-2-240, Water Control Management). A preliminary water control plan, perti-
nent data, filling schedule for storage projects, and standing instructions to project operators are
required at least 60 days before completion of construction. The preliminary water control plan
should be prepared using the outline and format detailed in Exhibit A for Type III projects or in
ER 1110-2-8156 for Type IV projects or Type III projects that are part of a water resource sys-
tem. The preliminary water control plan should explain the relationship to any neighboring wa-
ter resource projects, and the plans for storage projects should always include drawdown require-
ments. Sufficient tables and graphs should be included to support understanding of the prelimi-
nary plan.
9.3.4. Interim Risk Reduction Measure Water Control Plans. Any changes to an approved
water control plan related to IRRMs must follow the guidance outlined in ER 1110-2-1156,
Safety of Dams – Policy and Procedures.
9.3.5. Initial Reservoir Filling Plans. The initial reservoir filling plan should include the in-
terim and preliminary water control plans and should cover the broad needs of project operation
during the construction and initial filling phases.
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9.3.5.1. New Corps Reservoir Projects.
9.3.5.1.1. A design memorandum on initial filling plans must be developed during early con-
struction stages for all new reservoir projects. As a minimum, the report should address the fol-
lowing:
1. Interim water control plan.
2. Preliminary water control plan.
3. Project surveillance.
4. Cultural site surveillance.
5. Flood emergency plan.
6. Public affairs.
7. Safety plan.
8. Transportation and communications.
9.3.5.2. Existing Corps Reservoir Projects. At existing Corps projects that have exceeded the top
of the flood pool, reviews should be made to verify compliance with requirements outlined in Section
9.3.5.1. For projects with undocumented contingency plans that have a potential danger from filling or
impounded storage, a report should be developed outlining the contingency plans. The document may
be titled “Emergency Action Plan,” provided that revised initial filling requirements are determined to
have minimal potential impacts on the safety of the structure. However, such a determination does not
preclude the emergency action plan from citing appropriate references to water control plans, project
surveillance, cultural site surveillance, safety plan, transportation, communications, etc. A review
should be made of reservoirs that have been filled or nearly filled to determine any problems that oc-
curred during the initial filling stage. A filling plan should be developed for any reservoir that exhibited
a problem during initial filling that would likely recur during subsequent fillings.
9.3.5.3. Interim Risk Reduction Measure Pool Restriction Removed. An initial filling plan may
also be required after an IRRM reservoir pool restriction is removed. This plan could designate fill-
ing targets that pause at an intermediate elevation to assess the project’s structural integrity and to
evaluate instrument readings. A good communication plan among the different elements at the dis-
trict, division, and HQ levels (i.e., water management, dam safety, environmental, office of counsel,
and public affairs) is extremely important in successfully refilling a reservoir. Automated real-time
data collection benefits a filling operation by allowing conditions to be monitored continuously. One
difference between a refill and an initial fill could be the significant volume of water already in the
reservoir at the time when an IRRM restriction is lifted; there would be much lower incremental in-
creases of total hydrostatic pressure on the structure as the reservoir fills during a refill than as the
reservoir fills during an initial fill for a new project.
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9.3.6. Approved Water Control Plans.
9.3.6.1. A final approved water control plan for Type III projects or a water control manual in
final form for a Type III or IV project, as appropriate, should be prepared within 1 year after the pro-
ject is placed in operation. The water control plan should be prepared using the outline in Exhibit A
for Type III projects, or in ER 1110-2-8156 for Type IV or Type III projects that are part of a water
resource system.
9.3.6.2. The initial water control plan and subsequent updates should be developed in close coordi-
nation with other agencies, such as local county emergency managers, city representatives, recreational
interests, and applicable state departments. Development of the water control plan must also have a
public involvement process. Appendix B to this manual contains partial lists of Federal Water Re-
sources Management Laws. The developed plan must be reviewed by the appropriate division and
headquarters offices before submission to the division commander or designee for review and approval.
9.3.6.3. IRRMs that require modifications to the Water Control Plan should follow the process
outlined in ER 1110-2-1156, Safety of Dams – Policy and Procedures.
9.3.6.4. A deviation request from the approved water control plan must be submitted to the divi-
sion commander or delegated party per ER 1110-2-240 for review and approval. If deviations are
required because of permanent situations, the water control plan should be modified to reflect the
necessary change.
9.3.7. Revisions. See Section 9.2.3 for information on revising water control plans.
9.4. Standing Instructions to Project Operators for Water Management.
9.4.1. General.
9.4.1.1. Standing instructions to project operators for water management are essential to ensure
efficient and safe operation of the project at all times. The instructions apply to dam tenders, power
plant superintendents, lock masters, resource managers, etc. Any physical operating constraints
should be clearly outlined to ensure that water control features are operated in a safe manner and
within design limitations during all phases of project life, including the construction phase. Particu-
lar care should be exercised during initial acceptance testing of the project’s regulating features. The
standing instructions must be kept distinct and separate from O&M manuals and are required for all
Type II, III, and IV projects. However, the instructions should be referenced within O&M manuals
and water control manuals, as appropriate.
9.4.1.2. The instructions and project release orders guide the regulation of projects for water
management. Therefore, the hydraulic and hydrologic aspects of any operation plans in O&M manu-
als and similar documents must be limited to the physical operation of structures, such as the manipu-
lation of gates, placement or removal of stoplogs, operation of pumps, etc. Thus, the operation plans
will apply to physical operation and not to water management.
9.4.2. Format. Exhibit B provides an example of the format and summarizes the infor-
mation to be included in standing instructions to project operators.
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9.5. Related Water Control Documents.
9.5.1. Deviation Requests. Occasions may occur that require a deviation from the water
control plan. ER 1110-2-240, Water Control Management, covers the process for deviating from
an approved water control plan.
9.5.2. Situation Reports. Situation reports may be prepared and submitted to the district
management on a regular schedule or as events warrant the need to provide information regard-
ing current watershed conditions and pending water management operations. A situation report
detailing conditions and potential flood damage locations should be provided to the RCO office
once a threat of major flooding is identified.
9.5.3. After Action Reports. After action reports should normally be prepared after major
weather events that result in extreme periods of low water drought, high reservoir pool levels,
high river flows downstream of reservoirs or other water management structures, or other signifi-
cant flooding. The after action reports should document the meteorological and hydrologic con-
ditions leading up to the event and all reservoir and structural operations related to the weather
event. After action reports are normally coordinated by the RCO office.
9.5.4. Drought Contingency Plans. A drought contingency plan should provide a basic refer-
ence for water management decisions and responses to water shortage induced by a climatologi-
cal drought. The drought contingency plan may address the operation of a single isolated reser-
voir or other water management structure or a system of reservoirs or structures. As a water
management document, the plan should be limited to drought concerns related to water manage-
ment actions. Additional information on drought contingency plans is provided in ER 1110-2-
1941, Drought Contingency Plans.
9.5.5. Cultural Resources Documents. Developing guidance to address water control effects is
essential to meet legal requirements and cultural resources objectives. All Corps activities should
develop guidance related to the evaluation and protection of cultural resources at the district level,
in collaboration with district cultural resources professionals following objectives outlined in the
District Cultural Resources Management Plan. Guidance should address issues such as inadvertent
discoveries (including human remains) in compliance with the Native American Graves Protection
and Repatriation Act (NAGPRA); site protection and mitigation for ongoing impacts according to
the National Historic Preservation Act (NHPA); and required consultation with Indian Tribes (Ex-
ecutive Order [EO] 13175), State Historic Preservation Offices, other affected agencies, and the
public (36CFR800.2); and the potential of looting and theft as a result of erosion caused by water
management operations and the Archaeological Resource Protection Act (ARPA).
9.5.6. Federal Register. Changes or proposed changes in the rules or policies relating to the
regulation of Corps reservoirs may be published in the Federal Register for public notice.
9.6. Coordination of Water Management Documents.
9.6.1. Responsibility. MSC Commanders, who normally delegate this responsibility to the
division water management office, are responsible for approving water control plans and related
manuals. See ER 1110-2-240.
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9.6.2. Coordination. All water management documents should be prepared by or under the
direction of water managers within the districts or divisions. All documents must be coordinated
within the district and/or division offices and, when appropriate, with local, state, and Federal
agencies. Water managers must maintain a close contact with water management divisions
throughout the development and revisions of all water management documents. Meetings with
all entities involved may be appropriate throughout the development and updates of these docu-
ments. Preliminary documents should be reviewed by cooperators, project personnel, and any
other agencies that are affected by the project operation before the technical review.
9.6.3. Agreements. All interagency water management agreements proposed by a district must
be submitted to the division office or appropriate water management element and office of counsel
for review. Some examples are: MOUs, field working agreements, power and water supply con-
tracts, biological opinions, compacts, etc. All agreements should be reviewed on a regular basis to
ensure that current requirements are addressed and that the documents are still valid.
9.6.4. Review. On completion of a draft water management document, the review process
should begin following the requirements of EC 1165-2-217, Civil Works Project Reviews (or
successor document). Additionally, the following general policy guidance is suggested:
9.6.4.1. The National Programmatic Review Plan for Routine Operations and Maintenance
Products, reference 1.d, is applicable to all routine O&M products that only require District Quality
Control (DQC). At a minimum, all routine O&M products require DQC review. The Programmatic
Review Plan is applicable to revisions to Water Control Manuals that are administrative or informa-
tional in nature, that do not change the water control plan, and that do not require public meetings in
accordance with ER 1110-2-240.
9.6.4.2. Each update must be evaluated against EC 1165-2-217 (or successor document), to de-
termine whether an Agency Technical Review (ATR) and/or an Independent External Peer Review
(IEPR) is required. Water Control Manual Updates that include changes to the operation of the pro-
ject or revisions to Chapter 7 of the manual must have a separate individual review plan prepared and
submitted for approval, and will undergo ATR as a minimum.
9.6.4.3. Updates to Water Control Manuals would generally be categorized as “other work prod-
ucts” in EC 1165-2-217 (or successor document). Authorities for allocation of storage and regulation
of projects owned and operated by the Corps of Engineers are contained in legislative authorization
acts and referenced project documents. These public laws and project documents usually contain
provisions for development of water control plans, and appropriate revisions thereto, under the dis-
cretionary authority of the Chief of Engineers. Some modifications in project operation are permitted
under congressional enactments subsequent to original project authorization.
9.6.4.4. Water control manuals may also be required to undergo IEPR under certain circum-
stances, based on a risk-informed decision, as described in EC 1165-2-217 (or successor document).
A deliberate, risk informed recommendation whether to undertake IEPR on updates to water control
manuals which include revisions to Chapter 7 shall be made and documented in an individual pro-
ject-specific review plan. Depending on the scope and nature of the changes, some revisions to
Chapter 7 of water control manuals may trigger IEPR.
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9.6.5. Approval. After all the review requirements for water management documents and re-
lated manuals are completed, the finalized documents will be forwarded to the MSC Commander
and, if required, to headquarters for approval. The finalized document package will include all
signed agreements, review certificates, and any other related documents. On approval, documents
will be made available as outlined in ER 1110-2-1400, Reservoir/Water Control Centers.
9.7. Vertical Datum Reference. All new and revised water management documentation should
follow the vertical datum policy in ER 1110-2-8160, Policies for Referencing Project Elevation
Grades to Nationwide Vertical Datums.
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APPENDIX A
References
33 CFR 208.11, Part 208, Flood Control Regulation, Use of Storage Allocated for Flood Control
and Navigation Purposes, Published in Federal Register, 47184, 13 October 1978, as
amended at 46 FR 58075, 30 November 1981; 55 FR 21508, 24 May 1990; 79 FR 13564,
11 March 2014.
EC 1165-2-216, Policy and Procedural Guidance for Processing Requests to Alter U.S. Army
Corps of Engineers Civil Works Projects.
EM 1110-2-1201, Reservoir Water Quality Analysis.
EM 1110-2-1406, Runoff from Snowmelt.
EM 1110-2-1412, Storm Surge Analysis.
EM 1110-2-1413, Hydrologic Analysis of Interior Areas.
EM 1110-2-1417, Flood-Runoff Analysis.
EM 1110-2-1420, Hydrologic Engineering Requirements for Reservoirs.
EM 1110-2-1602, Hydraulic Design of Reservoir Outlet Works.
EM 1110-2-1603, Hydraulic Design of Spillways.
EM 1110-2-1605, Hydraulic Design of Navigation Dams.
EM 1110-2-1611, Layout and Design of Shallow-Draft Waterways.
EM 1110-2-1613, Hydraulic Design of Deep Draft Navigation Projects.
EM 1110-2-1701, Hydropower.
EM 1110-2-4000, Sedimentation Investigations of Rivers and Reservoirs.
EM 1110-8-1(FR), Winter Navigation on Inland Waterways.
EP 1130-2-540, Environmental Stewardship and Maintenance Guidance and Procedures, Change 2.
ER 10-1-53, Roles and Responsibilities, Hydroelectric Design Center.
ER 500-1-1, Civil Emergency Management Program.
ER 1105-2-100, Planning Guidance Notebook.
ER 1110-2-240, Water Control Management.
ER 1110-2-249, Management of Water Control Data Systems.
ER 1110-2-1150, Engineering and Design for Civil Works Projects.
ER 1110-2-1156, Safety of Dams – Policy and Procedures.
ER 1110-2-1400, Reservoir/Water Control Centers.
ER 1110-2-1454, Corps Responsibilities for Non-Federal Hydroelectric Power Development
under the Federal Power Act.
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ER 1110-2-1455, Cooperative Stream Gaging Program.
ER 1110-2-1941, Drought Contingency Plans.
ER 1110-2-8152, Planning and Design of Temporary Cofferdams and Braced Excavation.
ER 1110-2-8154, Water Quality and Environmental Management for Corps Civil Works Projects.
ER 1110-2-8156, Preparation of Water Control Manuals.
ER 1110-2-8160, Policies for Referencing Project Elevation Grades to Nationwide Vertical Datums.
ER 1110-8-2(FR), Inflow Design Floods for Dams and Reservoirs.
ER 1130-2-540, Environmental Stewardship Operations and Maintenance Policies
ETL 1110-2-584, Design of Hydraulic Steel Structures
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APPENDIX B
Water Management-Related Legislation
Name Key Items
Flood Control Act of 1928
(P. L. 70-391)
This Act authorized comprehensive flood control plan for the Mississippi River
and tributaries
Flood Control Act of 1936
(P.L. 74-738)
Section 1 declares flood control as proper Federal activity, and that improvements
for flood control are in the interest of the general welfare. Federal government
should improve or participate in the improvement of navigable waters or their trib-
utaries for flood control if the economic benefits exceed the costs (33 USC 701a).
Section 2 sets forth the jurisdiction of Federal activities and prescribed among
other things, that the Corps Chief of Engineers would have jurisdiction over, and
supervision of Federal investigations and improvements of rivers and other water-
ways for flood control and allied purposes (33 USC 701b).
Section 3 requires local interests to: (a) provide without cost to the United States
all lands, easements, and rights-of-way necessary for the construction of the pro-
ject, except as otherwise provided herein; (b) hold and save the United States free
from damages due to the construction works; (c) maintain and operate all the
works after completion according to regulations prescribed by the Secretary of
Army (33 USC 701c). Requirement (b) was modified by Sec. 9 of the Water Re-
sources Development Act of 1974 (Pub. Law 93-251).
Section 7 of the Flood Control Act
Section 7 of the FCA of 1944 specifies that the Secretary of the Army shall pre-
(FCA) of 1944,
scribe regulations for the use of storage allocated for flood control or navigation at
(33 USC 709)
all reservoirs constructed wholly or in part with Federal funds, including those of
the Tennessee Valley Authority (TVA) when the lower Ohio or Mississippi Rivers
are in danger of flooding. This law therefore creates a specific requirement for
Corps regulation of reservoirs that include flood control or navigation storage, and
that are operated by Federal agencies other than the Corps or by non-Federal agen-
cies. All U.S. Bureau of Reclamation projects constructed after (and some before)
1944, where flood control is one of the project purposes, are included in the provi-
sions of this Act. Projects that come under the authority of this legislation are gen-
erally referred to as “Section 7” projects.
Section 4 of the
Flood Control Act of
1944, as amended (16 USC 460d)
Section 4, as amended, grants authority to the Corps to construct, operate and
maintain recreational facilities at Corps reservoirs, and to permit local interests to
do the same. Storage was not allocated
Water Supply Act of 1958, as The Water Supply Act of 1958, as amended, grants general authority to the Corps to in-
amended (43 USC 390b) clude storage for municipal and industrial (M&I) water supply in Corps reservoirs
upon agreement by State or local interests to reimburse the Government for the costs,
including reallocation of storage that is compatible with other project purposes.
Fish and Wildlife Coordination Act
The FWCA requires coordination between Federal agencies and the U.S. Fish and
(FWCA) of 1958 (16 USC 661-664)
Wildlife Service (USFWS) in the planning of Federal water resources develop-
(amending Act of March 10, 1934
ment projects to evaluate impacts to fish and wildlife species, with a view to the
and August 14, 1946)
conservation of wildlife resources and the development and improvement of such
resources. Storage was not allocated.
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Name Key Items
Sections 401 and 404 of the Federal
Water Pollution Control Act
(FWPCA) of 1972, as amended
(33 USC 1341 and 1344)
The FWPCA establishes the basic structure for regulating discharges of pollutants
into the waters of the United States and regulating quality standards for surface
waters. Sections 401 and 404 require the Corps to obtain from States water quality
certifications when planning water resources development projects that involve the
discharge of dredged or fill material in the waters of the United States, to the effect
that the proposed projects will comply with applicable pollution standards. The
FWPCA provides certain exceptions to this requirement.
Section 306 of the Water Resources
Development Act of 1990
(33 USC 2316)
This Act provides that the Secretary of the Army shall include environmental pro-
tection as one of the primary missions in the planning and operating of Corps of
Engineers water resources projects.
Section 7 of the Endangered Species
Section 7 of the ESA states that each Federal agency shall, in consultation with
Act (ESA) of 1973, as amended
and with assistance of the Secretary of the Interior, ensure that any action author-
(16 USC 1536)
ized, funded, or carried out by such agency is not likely to jeopardize the contin-
ued existence of any endangered or threatened species, or result in the destruction
or adverse modification of critical habitat.
Executive Order 12088, Federal
This Executive Order provides that the head of each executive agency is responsi-
Compliance with Pollution Control
ble for ensuring that all necessary actions are taken for the prevention, control, and
Standards (October 13, 1978) as
abatement of environmental pollution with respect to Federal facilities and activi-
amended by Executive Order 12580
ties under control of the agency.
(January 23, 1987)
Executive Order 13693-Planning for
Federal Sustainability in the Next
Decade (March 19, 2015)
This Executive Order provides that Federal agencies shall propose targets for
agency-wide reductions in greenhouse gas emissions from agency facilities, and
promote measures to meet those targets. .
Section 6 of the Flood Control Act of
1944 (33 USC 708)
This Act authorizes the Secretary of the Army to make agreements with States,
municipalities, private entities, or individuals, for domestic and industrial uses of
surplus water at Corps reservoirs at such prices and terms as he deems reasonable.
Fish and Wildlife Conservation Act This Act encourages all Federal departments and agencies to use their statutory
of 1980 (16 .USC §§ 2901-2911)
and administrative authority, to the maximum extent practicable and consistent
with each agency’s statutory responsibilities, to conserve and promote conserva-
tion of non-game fish and wildlife and their habitats.
Federal Water Project Recreation Act
of 1965, as amended
(16 USC 460l-12 et seq.)
This Act provides for the inclusion of recreation or fish and wildlife enhancement
as project purposes in the pre-authorization planning of multiple purpose projects,
subject to cost sharing agreements with non-Federal public bodies.
Magnuson-Stevens Fishery Conser-
This Act promotes the protection of essential fish habitat in the review of projects
vation and Management Act of 1976
conducted under Federal permits, licenses, or other authorities that affect or have
as amended
the potential to affect such habitat.
(16 USC § 1801 et seq.)
Migratory Bird Treaty Act of 1918 as
The Act states that it is unlawful to pursue, hunt, take, capture or kill; attempt to
amended (16 USC §§703-712) take; possess, offer to or sell, barter, purchase, deliver or cause to be shipped, ex-
ported, imported, transported, carried, or received any migratory bird, part, nest,
egg or product, manufactured or not, included in the treaty.
National Environmental Policy Act
(NEPA) of 1969, as amended (42
USC §§ 4321-4347)
NEPA requires that all Federal agencies prepare detailed environmental impact
statements for “every recommendation or report on proposals for legislation and
other major Federal actions significantly affecting the quality of the human envi-
ronment.” This Act also stipulated the factors to be considered in environmental
impact statements, and required that Federal agencies employ an interdisciplinary
approach in related decision making and develop means to ensure that unquanti-
fied environmental values are given appropriate consideration, along with eco-
nomic and technical considerations.
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Name Key Items
North American Wetlands Conserva-
This Act encourages partnerships among public agencies and other interests to
tion Act, as amended
protect, enhance, restore, and manage an appropriate distribution and diversity of
(16 USC 4401 et seq.)
wetland ecosystems and other habitats for migratory birds and other fish and wild-
life.
Wild and Scenic Rivers Act of 1968,
as amended (16 USC 1271 et seq.)
This Act protects the environmental values of free-flowing streams from degrada-
tion by impacting activities, including water resources projects.
Executive Order 11988, Floodplain This Executive Order directs Federal agencies to evaluate the potential effects of
Management (May 24, 1977) as proposed actions on floodplains and to avoid undertaking actions that directly or
amended by Executive Order 12148
indirectly induce growth in the floodplain or adversely affect natural floodplain
(July 20, 1979) and by Executive Or-
values.
der 13690 (January 30, 2015)
Executive Order 12962, Recrea-
tional Fisheries (June 7, 1995) as
amended by Executive Order
13474 (September 26, 2008)
This Executive Order states that Federal agencies shall evaluate the effects of Fed-
erally funded, permitted, or authorized actions on aquatic systems and recreational
fisheries and document those effects relative to the purpose of this order.
National Historic Preservation Act
(NHPA) of 1966, as amended (16
USC 470 et seq.) and implementing
regulation 36 Code of Federal Regu-
lations Part 800
The NHPA d
irects Federal agencies to establish programs to identify and evaluate
historic properties located on public lands. Section 106 requires any Federal
agency having direct or indirect jurisdiction over a proposed Federal or Federally
assisted undertaking to consider the effects of that undertaking on historic proper-
ties, and to consult with the appropriate agencies on those effects.
Archaeological Resource Protection
ARPA establishes civil and criminal penalties for the willful destruction, removal,
Act (ARPA), as amended
or trafficking of archaeological resources from Federal or Tribal managed land.
(16 USC 470aa-mm)
This Act also provides a mechanism for Federal agencies to issue permits to per-
sons having a legitimate interest in conducting archaeological excavations on Fed-
eral lands.
Native American Graves Protection
NAGPRA d
irects Federal agencies to return cultural items described as human re-
and Repatriation Act (NAGPRA), as mains, associated funerary objects, sacred objects, and objects of cultural patri-
amended 25 USC 3001 et seq.) mony, to Native American Tribes and Native Hawaiian organizations having an
established lineal descent or cultural affiliation with the remains.
Section 8 of the Flood Control Act of This Act authorizes the Secretary of the Army to determine, upon recommendation
1944, as amended by Section 931 of of the Secretary of the Interior, that a Corps reservoir may be used for irrigation
WRDA 1986 (43 USC 390)
purposes, after which the Secretary of the Interior may seek authorization form
Congress for construction and use of facilities for irrigation pursuant to the recla-
mation laws. Section 931 authorizes the Secretary of the Army to temporarily al-
locate M&I water supply storage to irrigation purposes until the storage is required
for M&I water supply purposes.
Section 103(c)(3) of WRDA 1986
(33 USC 2213(c)(3)
This provision establishes a 35% non-Federal share of construction costs for
Corps
projects authorized for agricultural water supply.
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APPENDIX C
Acronyms and Abbreviations
Term Definition
AAR After-Action Report
ACE-IT U.S. Army Corps of Engineers–Information Technology
AGC Automatic Generation Control
AIS Automated Information System
AMO Atlantic Multidecadal Oscillation
AO Arctic Oscillation
AOP Annual Operating Plan
API Antecedent Precipitation Index
ARPA Archeological Resources Protection Act (of 1979)
ATR Agency Technical Review
BLM Bureau of Land Management
BMP Best Management Practice
BPA Bonneville Power Administration
CD Compact Disk
CECW Directorate of Civil Works, U.S. Army Corps of Engineers
CFR Code of the Federal Regulations
CHPS Community Hydrologic Prediction System
COOP Continuity of Operations
CoP Community of Practice
COTS Commercial off-the-Shelf
CPC Climate Prediction Center
CWA Clean Water Act
CWMS Corps Water Management System
DBMS Database Management System
DCP Data Collection Platform
DO Dissolved Oxygen
DOE U.S. Department of Energy
DOI U.S. Department of Interior
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Term Definition
DQC District Quality Control
DRGS A Direct Readout Ground Station
DSAC Dam Safety Action Classification
DVD Digital Video Disk
EAP Emergency Action Plan
EC Engineer Circular
EDL Electronic Data Logger
EM Engineer Manual
ENSO El Niño/Southern Oscillation
EO Executive Order
EP Engineer Pamphlet
ER Engineer Regulation
ERDC U.S. Army Engineer Research and Development Center
ERDC-CRREL Engineer Research and Development Center, Cold Regions Research and
Engineering Laboratory
ESA U.S. Endangered Species Act
ETL Engineer Technical Letter
FCCE Flood Control and Coastal Emergencies
FEMA Federal Emergency Management Agency
FERC Federal Energy Regulatory Commission
FIA Flood Impact Analysis
FOA Field Operating Activity
FR Federal Register
GDM General Design Memorandum
GOES Geostationary Operational Environmental Satellite
GSU Generator Step-Up
HA High Availability
HAB Harmful Algal Bloom
HDC Hydroelectric Design Center
HEC Humphreys Engineer Center
HEC-FIA HEC Flood Impact Analysis
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Term Definition
HEC-HMS Hydrologic Engineering Center – Hydrologic Modeling System
HEC-RAS Hydrologic Engineering Centers – River Analysis System
HH&C Hydrology, Hydraulics and Coastal Community of Practice
HQ Headquarters
HQUSACE Headquarters, U.S. Army Corps of Engineers
IEPR Independent External Peer Review
IM information management
IRRM Interim Risk Reduction Measure
ISO Independent System Operators
IT Information Technology
IWR Institute for Water Resources
IWR-HEC Institute for Water Resources, Humphreys Engineer Center
LAN Local Area Network
LAN/WAN Local Area Network/Wide Area Network
LOS Line of Sight
LRD Great Lakes and Ohio River Division
LRIT Low Rate Information Transmission
M&I Municipal and Industrial
MCX Mandatory Center of Expertise
MOU Memorandum of Understanding
MSC Major Subordinate Command
NAGPRA Native American Graves Protection and Repatriation Act of 1990
NAS Network Attached Storage
NASA National Aeronautics and Space Administration
NEPA National Environmental Policy Act
NESDIS [National Oceanic and Atmospheric Administration] National Environmental
Satellite, Data, and Information Service
NEXRAD Next-Generation Radar
NHC National Hurricane Center
NHPA National Historic Preservation Act of 1966
NOAA National Oceanic and Atmospheric Administration
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Term Definition
NOHRSC (National Weather Service) National Operational Hydrologic Remote
Sensing Center
NPS National Park Service
NRCS Natural Resources Conservation Service
NWD Northwestern Division
NWS National Weather Service
O&M Operations and Maintenance
PDO Pacific Decadal Oscillation
PFMA Potential Failure Mode Analysis
PI Periodic Inspection (report)
PL Public Law
PMA Power Marketing Administration
PROSPECT Proponent Sponsored Engineer Corps Training
QA/QC Quality Assurance/Quality Control
QPF Quantitative Precipitation Forecast
RCO Readiness and Contingency Operations
RFC River Forecast Center
RR&R Repair, Rehabilitation, and Replacement
RTO Regional Transmission Organization
SAR Safety Assurance Review
SCADA Supervisory Control And Data Acquisition
SCSI Small Computer System Interface
SEPA Southeastern Power Administration
SES Senior Executive Service
sftp Secure File Transfer Protocol
SHEF Standard Hydrologic Exchange Format
SNOTEL Snow Telemetry
SWE Snow Water Equivalent
SWPA Southwestern Power Administration
TMDL Total Maximum Daily Load
T VA Tennessee Valley Authority
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Term Definition
UOC USACE Operations Center
UPS Uninterruptible Power Supply
USACE U.S. Army Corps of Engineers
USBR U.S. Bureau of Reclamation
USC United States Code
USDA U.S. Department of Agriculture
USDA-NRCS U.S. Department of Agriculture-Natural Resources Conservation Service
USEPA U.S. Environmental Protection Agency
USFS U.S. Forest Service
USFWS U.S. Fish and Wildlife Service
USGS U.S. Geological Survey
WAPA Western Area Power Administration
WFO Weather Forecast Office
WMES Water Management Enterprise System
WRDA Water Resources Development Act
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EXHIBIT A
WATER CONTROL PLAN
(largest bold type)
STRUCTURE OR PROJECT NAME
(large bold type)
Stream
River Basin
Appendix _____
to the
Water Control Master Manual
For
(Parent Project Name, If Applicable)
District Office
U.S. Army Corps of Engineers
Date
l. Outline for Type III project Water Control Plan
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Minimum Requirements for
WATER CONTROL PLAN
(PROJECT NAME)
Type III Project
TITLE PAGE
PHOTOGRAPH OF ALL WATER CONTROL STRUCTURES
TABLE OF CONTENTS
PERTINENT DATA
– Information in Concise Summary Form –
1. INTRODUCTION. State the requirement for the Water Control Plan (ref ER 1110-2-240, ref
Part 208.10 of CFR, Title 33, when applicable, and state as Type III project) , project authoriza-
tion, purpose, location, description, and completion date of the principle and related projects.
2. PROJECT FEATURES. Description of all water passageways (discharge facilities, inflow
and outflow channels, etc.), related water resource projects, and all public use facilities.
3. HYDROMETEOROLOGY AND WATER QUALITY. Watershed description, climate, run-
off, table showing average monthly precipitation in inches and average monthly runoff in both
inches and cfs, water quality, design conditions, water passageway characteristics, data collec-
tion stations and maintenance of instrumentation, data collection procedure and reporting (refer
to exhibit on Standing Instructions to the Project Operator), method of preparing hydrologic fore-
casts if done in-house, and source, access procedure and overall suitability of forecasts if ob-
tained from NWS.
– Detailed Information –
4. WATER CONTROL PLAN. Overall summary of the water control plan, including objectives
and major constraints, followed by: specific objectives, the regulating procedures, and the bene-
ficial effects of regulation for each water control objective. Address the following objectives, as
appropriate: flood risk management (include regulation for design flood), navigation, water sup-
ply, water quality, fish and wildlife, hydroelectric power generation, recreation, and any other
water control objectives and incidental achievements. The discussions should include examples
of regulation and any constraints.
5. PROJECT MANAGEMENT. Project owner, role of the regulating office (water control man-
agers, and summarize requirements for the water control morning report for the subject project);
role of the Project Operator (refer to exhibit on Standing Instructions); communication between
the District office and project operator; coordination with local, state and other Federal agencies,
if required, and future changes to the project and the impact on water control.
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6. PLATES (using 11-inch binding edge, label tables not in text as plates).
a. Map and plan of project area with vicinity map insert.
b. Plan and profile of structure clearly showing all discharge facilities.
c. Data collection network map (designate auto-recording, auto-reporting and key control
point(s)).
d. Water Control Diagram (guide curve), with release schedule and explanatory notes, when
applicable.
e. Discharge rating curves with rating table insert (designate important related elevations).
f. Hydrograph examples of water control regulation (inflow and outflow), with hyetographs
(for floods of record and the design flood).
g. Frequency and duration curves for headwater or pool and control point or tailwater (dis-
charge and stage).
h. Other plates as required for the project.
7. EXHIBITS
a. Detailed Pertinent Data.
b. Other Exhibits, as appropriate.
c. Memorandum of Understanding or other Agreement.
d. Standing Instructions to the Project Operator for Water
Control (see Exhibit B).
1. This format applies only to Type III projects where the scope of water management does not
require preparation of an individual water control manual. However, the water control plan
should be appended to the water control master manual when the project is in a water resource
system. The plans and standing instructions for water control structures in the system may be
prepared and submitted for approval prior to the master manual, if desired, to expedite the most
essential documentation requirements. Include project name and project type in heading.
2. Detailed presentation of these topics in the system master manual is preferred when one is pre-
pared.
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EXHIBIT B
STANDING INSTRUCTIONS TO THE PROJECT OPERATOR
1,2
FOR WATER CONTROL
(largest bold type)
STRUCTURE OR PROJECT NAME
(large bold type)
STREAM
River Basin
Exhibit _________2
to the
Water Control Plan (or Manual)
For
(Parent Project Name)
District Office
U. S. Army Corps of Engineers
Date
1
Required for all Type II, III and IV projects (see Section 9.4.1).
2
Omit for Type II projects that are not in a water resource system.
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Information to be included in
STANDING INSTRUCTIONS TO THE PROJECT OPERATOR FOR WATER CONTROL1
(PROJECT NAME)
Type Project
PHOTOGRAPHS OF ALL WATER CONTROL STRUCTURES (TYPE II PROJECTS ONLY)
TABLE OF CONTENTS
PERTINENT DATA
1. BACKGROUND AND RESPONSIBILITIES.
a. General Information.
(1) Reference compliance with Section 9.4 of EM 1110-2-3600 and ER 1110-2-240, and
state that a copy of these Standing Instructions must be kept on hand at the project site at all
times, and that any deviation from the Standing Instructions will require approval of the District
Commander.
(2) Identify authorized project purposes and all water control objectives.
(3) Identify chain of command and the entity to which the project operation is responsible
for water control actions.
(4) State project location and brief description of water control structures.
(5) Describe constraints on physical operation of the water control structure.
(6) Include a statement as to whether O&M is by the Corps or by local interests, and a
statement as to whether it is a local flood risk management project. Reference the Code of Fed-
eral Regulations (CFR Title 33, Part 208.10) when it applies.
b. Role of the Project Operator,
(1) Normal Conditions (not dependent on day-to-day Instruction). Applies to all Type II
and some Type III projects.
Include the following statements ... “The Project Operator is responsible for water control ac-
tions during normal hydrometeorological conditions (non-flood, non-drought) without daily in-
struction. However, the water control manager should be contacted any time conditions are such
that consultation or additional instruction regarding water control procedures is needed.”
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OR. … Normal Conditions (dependent on day-to-day instruction). Applies to some Type III
and most Type IV projects. When appropriate, state that. ..“The Project Operator will be in-
structed by water control managers on a daily basis for water control actions under normal condi-
tions”.
(2) Emergency Conditions (flood or drought). Same as above, as appropriate, during
flood events and other emergency conditions.
2. DATA COLLECTION AND REPORTING.
a. Normal Conditions. Instructions for collecting water data under normal hydrometeorologi-
cal conditions, and instructions for reporting the water data to the District office.
b. Emergency Conditions. Same as the above during flood events and other emergency con-
ditions. Specify more intensive requirements when appropriate.
c. Regional Hydrometeorological Conditions. State that “The Project Operator will be in-
formed by the water control manager of regional hydrometeorological conditions that may/will
impact the structure.”
3. WATER CONTROL ACTION AND REPORTING.
a. Normal Conditions. Specific step-by-step instructions for water control action under nor-
mal hydrometeorological conditions, taking into account any constraints on water control or
physical operation, and specific step-by-step instructions for reporting the action and any unusual
conditions to the water control manager.
b. Emergency Conditions. Same as the above during flood events and other emergency con-
ditions.
c. Inquiries. State that... “All significant inquiries received by the Project Operator from cit-
izens, constituents or interest groups regarding water control procedures or actions must be re-
ferred directly to water control managers.”
d. Water Control Problems. State that... “The water control manager must be contacted im-
mediately by the most rapid means available in the event that an operational malfunction, ero-
sion, or other incident occurs that could impact project integrity in general or water control capa-
bility in particular.”
e. Communication Outage. Specific step-by-step instructions for water control action in the
event a communication outage with the water control manager occurs during either normal or
emergency conditions, considering constraints.
4. PLATES (to support the above, use 11-inch binding edge).
a. Map of the project area showing the water control structures, streams, levees, dikes, chan-
nels, water data stations and parameters measured, with a vicinity map insert depicting the drain-
age area above the project.
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b. Schematic drawing of the project facilities, including a plan and profile of water control
structures which show key water levels (headwater and tailwater), and other pertinent infor-
mation.
c. Forms for collecting water data, reporting water data, and reporting water control actions.
d. Discharge rating curves, if appropriate, with key elevations identified and a rating table in-
serted on the graph.
e. Water control diagrams and release schedules, if appropriate, for normal and emergency
conditions, and for communication outages.
f. List of points of contact in District and/or Division office.
g. Other supporting plates, if needed.
1
1
Required for all Type II, III and IV projects. Include project name and type in heading. Include
water management office symbol in upper left corner, and date in upper right corner of each
page.
E-B-4
