Mission Statements

The U.S. Department of the Interior protects America’s natural 

resources and heritage, honors our cultures and tribal communities, 

and supplies the energy to power our future. 

The mission of the Bureau of Reclamation is to manage, develop, 

and protect water and related resources in an environmentally and 

economically sound manner in the interest of the American public.
U.S. Department of the Interior

Bureau of Reclamation December 2012

Colorado River Basin 

Water Supply and Demand Study

Study Report
Acknowledgement

The Colorado River Basin Water Supply and Demand Study represents the most 

comprehensive analysis ever undertaken within the Colorado River Basin. Its successful 

completion could only have been accomplished through the dedication and hard work of 

the Bureau of Reclamation, the consuting team, the seven Colorado River Basin States, 

and the collaboration of stakeholders throughout the Basin, including federally 

recognized tribes, agricultural users, purveyors of municipal and industrial water, power 

users, and conservation and recreational groups. The Study is a model, not only for

future basin studies, but for watershed planning across the country, and it will provide the 

basis for planning for future growth and climate change in the western US and its many 

watersheds for decades to come.

Special gratitude and appreciation is extended to Christina Robinson-Swett who created

the document cover art. 
December 2012 SR-iii

Contents

Page

1.0 Introduction ................................................................................................................. SR-1

2.0 Background and Need ................................................................................................ SR-2

2.1 Ongoing Efforts to Resolve Water Supply and Demand Imbalances ............... SR-3

2.2 The Need for the Study ..................................................................................... SR-5

3.0 Basin Study Program .................................................................................................. SR-7

4.0 Study Objectives and Approach ................................................................................ SR-8

4.1 Study Organization ........................................................................................... SR-9

4.2 Study Outreach................................................................................................ SR-11

4.3 Peer Review .................................................................................................... SR-12

5.0 Projected Future Supply and Demand Scenarios .................................................. SR-12

5.1 Summary of Technical Report A – Scenario Development ............................ SR-12

5.1.1 Objective and Approach ..................................................................... SR-13

5.1.2 Summary of Results ............................................................................ SR-14

5.2 Summary of Technical Report B – Water Supply Assessment ........................ SR-16

5.2.1 Objective and Approach ..................................................................... SR-16

5.2.2 Summary of Results ............................................................................ SR-17

5.3 Summary of Technical Report C – Water Demand Assessment ..................... SR-22

5.3.1 Objective and Approach ..................................................................... SR-22

5.3.2 Summary of Results ............................................................................ SR-24

6.0 Projected Future Supply and Demand Imbalances and System Reliability 

Metrics ........................................................................................................... SR-34

6.1 Summary of Technical Report D – System Reliability Metrics ...................... SR-35

6.1.1 Objective and Approach ..................................................................... SR-35

6.1.2 Summary of Results ............................................................................ SR-35

7.0 Options and Strategies to Resolve Supply and Demand Imbalances ................... SR-36

7.1 Summary of Technical Report E – Approach to Develop and Evaluate 

Options and Strategies .................................................................................... SR-38

7.2 Summary of Technical Report F – Development of Options and Strategies .. SR-38

7.2.1 Summary of Options Received ........................................................... SR-38

7.2.2 Approach to Characterize Options ...................................................... SR-39

7.2.3 Summary of Option Characterization ................................................. SR-41

7.2.4 Development of Portfolios .................................................................. SR-49

7.2.5 Portfolio Comparison .......................................................................... SR-52

8.0 Evaluation of Options and Strategies to Resolve Supply and Demand 

Imbalances ..................................................................................................... SR-56

8.1 Summary of Technical Report G – System Reliability Analysis and 

Evaluation of Options and Strategies ............................................................. SR-56

8.1.1 System Reliability Analysis without Options and Strategies ............. SR-56
Colorado River Basin 

Water Supply and Demand Study

SR-iv December 2012

8.1.2 System Reliability Analysis with Options and Strategies................... SR-57

8.1.3 Portfolio Comparison and Option Analysis ........................................ SR-67

8.2 Summary of the Evaluation of Options and Strategies ................................... SR-73

9.0 Study Limitations ...................................................................................................... SR-74

9.1 Treatment of Lower Basin Tributaries ............................................................ SR-74

9.2 Treatment of Agricultural Land Use in Water Demand Scenarios ................. SR-75

9.3 Ability to Assess Impacts to Basin Resources ................................................ SR-75

9.4 Options Characterization Process ................................................................... SR-76

9.5 Consideration of Options ................................................................................ SR-76

10.0 Future Considerations and Next Steps ................................................................... SR-77

Water Use Efficiency and Reuse ................................................................................ SR-77

Water Banks ................................................................................................................ SR-78

Water Transfers ........................................................................................................... SR-79

Water Supply Augmentation....................................................................................... SR-79

Watershed Management.............................................................................................. SR-79

Tribal Water ................................................................................................................ SR-80

Environmental Flows .................................................................................................. SR-81

Data and Tool Development ....................................................................................... SR-81

Climate Science Research ........................................................................................... SR-82

Partnerships ................................................................................................................. SR-82

11.0 Summary of Next Steps ............................................................................................ SR-82

12.0 References .................................................................................................................. SR-82

Disclaimer ....... .................................................................................................................... SR-85

Figures

1 Historical Annual Colorado River Basin Water Supply and Use ................................. SR-4

2 Historical 10-Year Running Average Colorado River Basin Water Supply and Use .. SR-7

3 The Study Area ........................................................................................................... SR-10

4 Study Phases and Tasks .............................................................................................. SR-11

5 Conceptual Representation of the Uncertain Future of a System, Also Known as 

“The Scenario Funnel” ................................................................................................ SR-13

6 Summary Statistics for Annual Colorado River at Lees Ferry Natural Flows for 

Supply Scenarios ......................................................................................................... SR-20

7 Historical Colorado River Water Consumptive Use by Basin, Delivery to Mexico, 

Reservoir Evaporation, and Other Losses, 1971–2008 ............................................... SR-25

8 Historical Colorado River Water Consumptive Use1

by Use Category, Delivery to 

Mexico, Reservoir Evaporation, and Other Losses, 1971–2008 ................................ SR-26

9 Colorado River Water Demand .................................................................................. SR-31
Study Report

December 2012 SR-v 

10 Colorado River Water Demand by Category1,2 .......................................................... SR-32

11 Current Projected (A) Scenario Demands Adjusted for Possible Future Climate 

Change ........................................................................................................................ SR-33

12 Historical Supply and Use and Projected Future Colorado River Basin Water 

Supply and Demand .................................................................................................... SR-34

13 Study Area with Locations of Defined Metrics .......................................................... SR-37

14 Distribution of Options Received ............................................................................... SR-39

15 Summary of Options Characterization Ratings (aggregated by option groups) ......... SR-50

16 Schematic Representing Options Included in the Study Portfolios ............................ SR-51

17 Total Yields over Time for Average Costs less than $750/af, less than $1,000/af, 

and less than $1,250/af for Portfolios ......................................................................... SR-56

18 Percent of Vulnerable Traces for the Lake Mead Elevation Indicator Metric 

Across Three Time Periods for the Baseline and Static Portfolio A, by Supply and 

Demand Scenario ........................................................................................................ SR-58

19 10th, 50th, 90th Percentiles for Lake Powell End-of-December Pool Elevation for 

the Baseline and Four Dynamic Portfolios ................................................................. SR-61

20 10th, 50th, 90th Percentiles for Lee Ferry Deficit in Years in Which a Deficit 

Occurs and Percent of Traces with a Lee Ferry Deficit for the Baseline and Four 

Dynamic Portfolios ..................................................................................................... SR-61

21 10th, 50th, 90th Percentiles for Lake Mead End-of-December Pool Elevation for 

the Baseline and Four Dynamic Portfolios ................................................................. SR-62

22 Percent of Vulnerable Years for Each Water Delivery Indicator Metric Across 

Three Time Periods for the Baseline and Four Simulated Portfolios ......................... SR-63

23 Percent of Vulnerable Years for Each Electric Power Indicator Metric Across 

Three Time Periods for the Baseline and Four Simulated Portfolios ......................... SR-64

24 Percent of Vulnerable Years for Each Flood Control Indicator Metric Across 

Three Time Periods for the Baseline and Four Simulated Portfolios ......................... SR-64

25 Percent of Vulnerable Years for Each Recreational (boatable days) Indicator 

Metric Across Three Time Periods for the Baseline and Four Simulated Portfolios . SR-65

26 Percent of Vulnerable Years for Each Recreational (shoreline facilities) Indicator 

Metric Across Three Time Periods for the Baseline and Four Simulated Portfolios . SR-66

27 Percent of Vulnerable Years for Each Ecological Indicator Metric Across Three 

Time Periods for the Baseline and Four Simulated Portfolios ................................... SR-67

28 Percent of Years with Occurrence of Upper Basin Vulnerability and Lower Basin 

Vulnerability in 2041–2060 with Portfolios Implemented, by Supply Scenario ........ SR-68

29 Total Annual Cost by Supply Scenario Resulting from Implementation of the 

Dynamic Portfolios over Time.................................................................................... SR-69
Colorado River Basin 

Water Supply and Demand Study

SR-vi December 2012

30 Portfolio Cost and Percent of Upper Basin Reliability Vulnerability and Lower 

Basin Reliability Vulnerability for 2041–2060 across sequences from supply 

scenarios and sequences with lower streamflow conditions ....................................... SR-71

31 Frequency of Option Implementation (percent of traces) for Each Portfolio ............. SR-72

Tables

1 List of Driving Forces Influencing Future Colorado River System Reliability.......... SR-14

2 Critical Uncertainties Affecting Water Demand Scenarios ........................................ SR-15

3 Summary of Key Streamflow Statistics for Each Water Supply Scenario ................. SR-21

4 Definition of Demand Categories and Their Associated Parameters ......................... SR-24

5 Scenario Matrix of Typical Changes in Parameters Defined by the Water Demand 

Storylines ........................................................................................................ SR-28

6 Summary Results of Water Demand Scenario Quantification by 2060 ..................... SR-29

7 Resource Categories and Attributes of Interest .......................................................... SR-36

8 Criteria Used to Characterize Representative Options ............................................... SR-40

9 Summary of Option Cost and Potential Yields by 2035 and 2060 ............................. SR-48

10 Option Criteria Preferences for the Study Portfolios .................................................. SR-53

11 Summary of Option Inclusion Across the Study Portfolios........................................ SR-54

12 Vulnerability Signposts ............................................................................................... SR-60

Appendices

1 Plan of Study 

2 Previously Published Study Documents 

3 Summary of Past Colorado River Basin Planning Studies 

4 Study Participants

5 Public Involvement Plan 

6 Outreach Activities

7 Peer Review Summary Report
December 2012 SR-vii

Acronyms and Abbreviations

2007 Interim Record of Decision for Colorado River Interim Guidelines for

Guidelines Lower Basin Shortages and Coordinated Operations for Lake Powell and 

Lake Mead

2007 Interim Colorado River Interim Guidelines for Lower Basin Shortages

Guidelines and Coordinated Operations for Lake Powell and Lake Mead

Final EIS Final Environmental Impact Statement 

af acre- feet

afy acre-feet per year

Ag agricultural

Basin Colorado River Basin 

Basin States Colorado River Basin States 

CAP Central Arizona Project

Compact Colorado River Compact 

CRSS Colorado River Simulation System

CU&L Reports Consumptive Uses and Losses Reports 

desal desalination

DOI U.S. Department of the Interior 

GCM General Circulation Model

ICS Intentionally Created Surplus 

kaf thousand acre-feet

LB Lower Basin

M&I municipal and industrial 

maf million acre-feet

mafy million acre-feet per year

Mexico United Mexican States

mod modification

msl above mean sea level

Reclamation Bureau of Reclamation

SECURE Science and Engineering to Comprehensively Understand and 

Responsively Enhance 

SoCal Southern California 
SR-viii December 2012

SSI self-served industrial 

Study Colorado River Basin Water Supply and Demand Study 

tribes federally recognized tribes

UB Upper Basin

USGS U.S. Geological Survey 

VIC Variable Infiltration Capacity
December 2012 SR-1 

Study Report

1.0 Introduction

The Colorado River Basin Water Supply and Demand Study (Study), initiated in January 2010, 

was conducted by the Bureau of Reclamation’s (Reclamation) Upper Colorado and Lower 

Colorado regions, and agencies representing the seven Colorado River Basin States1 (Basin 

States) in collaboration with stakeholders throughout the Colorado River Basin (Basin). As 

defined in the Plan of Study, the purpose of the Study is to define current and future imbalances 

in water supply and demand in the Basin and the adjacent areas of the Basin States that receive 

Colorado River water over the next 50 years (through 2060), and to develop and analyze 

adaptation and mitigation strategies to resolve those imbalances. The Study does not result in a 

decision as to how future imbalances will or should be addressed. Rather, the Study provides a 

common technical foundation that frames the range of potential imbalances that may be faced in 

the future and the range of solutions that may be considered to resolve those imbalances. 

Due to the inherent complexities of the Study and the many diverse interests and perspectives of 

the various stakeholders, interim reports and technical updates were published to reflect 

continual technical developments and the ongoing input of stakeholders. Throughout the course 

of the Study, eight of these interim products were published. These documents are listed in 

Appendix 2 – Previously Published Documents. The final documentation for the Study is 

organized into three major parts: an Executive Summary, this Study Report (including 

appendices), and technical reports (including appendices). 

This Study Report provides a summary of each of the Study’s seven technical reports as well as 

future considerations and potential next steps that could be conducted as follow-on activities to 

the Study. This Study Report includes seven appendices: 

• Appendix 1 – Plan of Study 

• Appendix 2 – Previously Published Study Documents

• Appendix 3 – Summary of Past Colorado River Basin Planning Studies

• Appendix 4 – Study Participants

• Appendix 5 – Public Involvement Plan

• Appendix 6 – Outreach Activities

• Appendix 7 – Peer Review Summary Report

The seven technical reports summarized in this Study Report are listed below:

• Technical Report A – Scenario Development. This report describes the scenario planning 

approach used to incorporate uncertainty in future water supply and water demand. 

• Technical Report B – Water Supply Assessment. This report describes the water supply 

scenarios and presents the analysis and comparison of those scenarios.

 

1Arizona, California, Colorado, New Mexico, Nevada, Utah, and Wyoming. 
Colorado River Basin 

Water Supply and Demand Study

SR-2 December 2012

• Technical Report C – Water Demand Assessment. This report describes the water demand 

scenarios, presents the analysis and comparison of those scenarios, and presents information 

on historical consumptive use. 

• Technical Report D – System Reliability Metrics. This report describes the metrics that have 

been identified for use in the assessment of the reliability of the system to meet resource 

needs under future supply and demand scenarios. 

• Technical Report E – Approach to Develop and Evaluate Options and Strategies to 

Balance Supply and Demand. This report provides the overall analytical approach used to 

analyze opportunities to resolve projected water supply and demand imbalances. 

• Technical Report F – Development of Options and Strategies. This report describes the 

ideas (options) submitted to the Study to help resolve water supply and demand imbalances

and the development of portfolios from those options.

• Technical Report G – System Reliability Analysis and Evaluation of Options and 

Strategies. This report presents the reliability of the system to meet resource needs under 

future water supply and demand scenarios and the effectiveness of options and strategies at 

improving that reliability. 

Project participants and stakeholders are encouraged to comment on the information provided in 

this Study Report and associated technical reports. Written comments should be submitted within 

90 days following the release of this report. The comments will be summarized and posted to the 

Study website, and will be considered in future planning activities in the Basin. Comments may 

be submitted in the following ways: 

1. Via the Study website at http://www.usbr.gov/lc/region/programs/crbstudy.html 

2. Email to ColoradoRiverBasinStudy@usbr.gov 

3. U.S. mail to U.S. Bureau of Reclamation, Attention: Ms. Pam Adams, LC-2721, P.O. Box 

61470, Boulder City, NV 89006-1470 

4. Facsimile transmission to 702-293-8418 

2.0 Background and Need 

Today, almost 40 million2 people in the seven western states of Arizona, California, Nevada 

(Lower Division States) and Colorado, New Mexico, Utah and Wyoming (Upper Division 

States), collectively referenced as the Basin States, rely on the Colorado River and its tributaries 

to provide some, if not all, of their municipal water needs. That same water source irrigates 

nearly 5.5 million acres of land3 in the Basin – producing some 15 percent of the nation's crops 

and about 13 percent of its livestock, which combined generate many billions of dollars a year in 

agricultural benefits. The Colorado River is also the lifeblood for at least 22 federally recognized 

 

2 About 40 million people are estimated to be in the Study Area, which encompasses the hydrologic boundaries of the Basin in the United States 

plus the adjacent areas of the Basin States that receive Colorado River water, by 2015. See Technical Report C – Water Demand Assessment 

for additional detail.

3 It is estimated that there will be about 5.5 million irrigated acres in the Study Area by 2015. See Technical Report C – Water Demand 

Assessment for additional detail.
Study Report

December 2012 SR-3 

tribes (tribes), 7 National Wildlife Refuges, 4 National Recreation Areas, and 11 National Parks.

Hydropower facilities along the Colorado River supply more than 4,200 megawatts of vitally 

important electrical capacity to helping to meet the power needs of the West and reduce the use 

of fossil fuels. In addition, the Colorado River is vital to the United Mexican States (Mexico). 

The river supports a thriving agricultural industry in the Mexicali Valley and provides municipal 

water supplies for communities as far away as Tijuana. 

The Colorado River system is operated in accordance with the Law of the River4. Apportioned 

water in the Basin exceeds the approximate 100-year record (1906 through 2011) Basin-wide 

average long-term historical natural flow5 of about 16.4 million acre-feet (maf). However, the 

Upper Basin States have not fully developed use of their 7.5-maf apportionment, and total 

consumptive use and losses in the Basin has averaged approximately 15.36 maf over the last 

10 years. Figure 1 shows the historical annual Basin water supply (estimated using the natural 

flow record) and water use7. This figure shows that there have been multiple years when use was 

greater than the supply. Because of the Colorado River system’s ability to store approximately 

60 maf, or nearly 4 years of average natural flow of the river, all requested deliveries were met in 

the Lower Basin during those times. However, there have been periodic shortages throughout the 

Upper Basin and the adjacent areas of the Basin States that receive Colorado River water.

2.1 Ongoing Efforts to Resolve Water Supply and Demand Imbalances

Throughout the 20th century, the challenges and complexities of ensuring a sustainable water 

supply and meeting future demand have been recognized. These challenges are documented in 

several studies conducted by Reclamation and the Basin States over the past six decades (see 

Appendix 3 – Summary of Past Colorado River Basin Planning Studies). Appendix 3 provides a 

summary of studies which discussed future water supply and demand imbalances and in some 

cases proposed solutions to dealing with these imbalances. 

These studies include: 

• Colorado River Storage Project and Participating Projects; Upper Colorado River Basin 

(Reclamation, 1950). This report combined various individual Upper Basin reservoir 

proposals into a comprehensive plan to increase long-term carryover water storage. 

• Pacific Southwest Water Plan (Reclamation, 1964). This report projected a Lower Basin 

water supply and demand imbalance and proposed a comprehensive plan to improve water 

supply and distribution, including the importation of water from the northern California 

coastal area.

 

4 The treaties, compacts, decrees, statutes, regulations, contracts and other legal documents and agreements applicable to the allocation, 

appropriation, development, exportation and management of the waters of the Colorado River Basin are often collectively referred to as the 

Law of the River. There is no single, universally agreed upon definition of the Law of the River, but it is useful as a shorthand reference to 

describe this longstanding and complex body of legal agreements governing the Colorado River.

5 Natural flow represents the flow that would have occurred at the location had depletions and reservoir regulation not been present upstream of 

that location.

6 Basin-wide consumptive use and losses estimated over the period 2002-2011, including the 1944 Treaty delivery to Mexico, reservoir 

evaporation, and other losses due to native vegetation and operational inefficiencies.

7 Historical use (as shown in Figure 1) does not necessarily reflect historical water demand, particularly for periods of drought. A decrease in 

reported use during a drought period may reflect the lack of available supply at the point of use rather than a decrease in the need for water.
Colorado River Basin 

Water Supply and Demand Study

SR-4 December 2012

FIGURE 1 

Historical Annual Colorado River Basin Water Supply and Use

Year

Historical water use is the total use of water throughout the Basin for agricultural, municipal and industrial (M&I), and other 

consumptive uses including Mexico, plus losses through evaporation at mainstream reservoirs and use by native and non-native 

vegetation. Natural flow is used as an estimate of water supply in the Basin. In the current natural flow record, historical inflows 

based on U.S. Geological Survey (USGS gaged records are used as estimates of natural flow for the Paria River, Little Colorado

River, Virgin River, and Bill Williams River without adjustment for upstream water uses. However, the Gila River is not included in the 

natural flow record. Therefore, the use reported here excludes consumptive uses on these tributaries. See Technical Report C – 

Water Demand Assessment, Appendix C11 – Modeling of Lower Basin Tributaries in the Colorado River Simulation System for 

additional detail regarding the treatment of these tributaries in the Study.

• Comprehensive Framework Study, Lower Colorado Region (Pacific Southwest Inter-agency 

Committee, 1971a). This federal-state study projected a Lower Basin water supply and 

demand imbalance and concluded that a future water import program would be needed as 

part of a proposed framework program for the development and management of Lower Basin

water resources to 2020. 

• Comprehensive Framework Study, Upper Colorado Region (Pacific Southwest Inter-agency 

Committee, 1971b). This federal-state study presented a framework program for the 

development and management of the water and related land resources of the Upper Basin to 

2020, including alternative plans with emphases on differing water uses, some of which were 

dependent on water importation. 

• Westwide Study Report on Critical Water Problems Facing the Eleven Western United States

(Reclamation, 1975). This federal-state study described key factors affecting future water 

needs, formulated alternative future demand scenarios, and identified options for dealing 

with anticipated shortages. The study concluded that in spite of conservation, the Basin faces 

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19141919192419291934193919441949195419591964196919741979198419891994199920042009

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ANNUAL BASIN WATER SUPPLY

ANNUAL BASIN WATER USE
Study Report

December 2012 SR-5 

future water shortages unless its natural flows are augmented or water-dependent Basin 

development is curtailed.

These studies clearly recognized the challenges facing the Basin. The Colorado River Basin 

Project Act of 1968, which authorized the construction of the Central Arizona Project (CAP), the 

Southern Nevada Water Project, and other projects in the Lower Basin, further discussed the 

need for augmentation.8 

Historically, water planning efforts resulted in the construction of significant infrastructure. 

Notable examples include Hoover and Glen Canyon Dams, the Central Arizona and Central Utah 

projects, Colorado’s many headwaters trans-basin diversions, California’s Colorado River 

Aqueduct, the All-American Canal, and a wide range of other local and regional water 

infrastructure projects. In the latter part of the 20th century and in the early portion of the 21st

century, focus has shifted from developing available water resources to an emphasis on 

improving the efficiency of the operation of Colorado River reservoirs and increasing the level of 

predictability afforded to entities who receive Colorado River water through better planning and 

managing of available water supplies. Two notable examples from this period are the Operation 

of Glen Canyon Dam Final Environmental Impact Statement (Reclamation, 1996) and the 

Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations of 

Lake Powell and Lake Mead Final Environmental Impact Statement (2007 Interim Guidelines 

Final EIS [Reclamation, 2007]). Both of these resulted in the adoption of new reservoir operating 

policies.

Colorado River stakeholders have made significant investments in developing other water

resources and implementing programs and policies to balance current and future supplies with 

existing and future demands. Many of these efforts have resulted in solutions to past water 

management challenges and will continue to provide benefit to the system in meeting the 

challenges that lie ahead. 

2.2 The Need for the Study 

Concerns regarding the reliability of the Colorado River system to meet future needs are even 

more apparent today. The Basin States include some of the fastest-growing urban and industrial 

areas in the United States. California is ranked among the five fastest-growing states in the 

country. Arizona and Colorado are in the top 10 fastest-growing states in the country. The 

continued growth and sustainability of the communities and economies of metropolitan areas 

such as Albuquerque, Denver, Las Vegas, Los Angeles, Phoenix, Salt Lake City, and San Diego 

are tied to future water availability from the Colorado River. Water demand for other uses, 

including the environment, recreation, and tribal water rights settlements, also continues to 

increase. Potential future increases in temperatures in the Basin, continuing and accelerating a 

trend observed over most of the Basin during the past 30 to 40 years (National Research Council, 

2007), would increase evapotranspiration from vegetation, as well as water loss due to 

evaporation from reservoirs. 

 

8 Section 202 of the Colorado River Basin Project Act provides in part that “The satisfaction of the requirements of the Mexican Water Treaty, 

shall be from the waters of the Colorado River pursuant to the treaties, laws, and compacts presently relating thereto, until such time as a 

feasible plan showing the most economical means of augmenting the water supply available in the Colorado River below Lee Ferry by two and 

one-half million acre-feet shall be authorized by the Congress and is in operation as provided in this Act.”
Colorado River Basin 

Water Supply and Demand Study

SR-6 December 2012

How climate change and variability affect the Basin water supply has been the focus of many 

scientific studies. Climate experts expect the southwestern United States to be drier in the future 

and to experience droughts that are of greater severity than those seen in the past. Recent studies 

have postulated that the average yield of the Colorado River could be reduced by as much as 20 

percent due to climate change (Hoerling et al., 2009). Increasing demands, coupled with 

decreasing supplies, will certainly exacerbate imbalances throughout the Basin.

Although a shortage to the Lower Division States (i.e., insufficient water available to satisfy 

annual consumptive use of 7.5 maf) has not been experienced to date, some water agencies have 

experienced shortages in water deliveries to their customers in recent years. In California, 

drought conditions, along with increased regulatory restrictions, caused the Metropolitan Water 

District of Southern California to reduce firm water deliveries to its customers in 2009 for the 

first time in nearly 20 years. The water supply allocation plan offered local water providers the 

flexibility to choose among various conservation strategies, from tiered pricing to limits on 

outdoor water use, to help ensure that demands stayed in balance with limited supplies. In 

addition, to help meet critical water supply needs in urban areas, programs have been 

implemented to fallow land in agricultural areas and transfer the conserved water to urban areas. 

Although this has helped to meet the water needs of the urban areas, it has also reduced the food 

and fiber production from the region. 

The Upper Basin will need to develop additional water supplies in order to realize full use of its 

Colorado River Compact apportionment, but such development reduces certainty. Shortages in 

the Upper Basin are a reality today. Unlike the Lower Basin, which draws its supply from 

storage in Lake Mead, the Upper Basin is more dependent on annual streamflow to meet its 

needs. 

As of December 10, 2012, Lake Mead is at approximately 51 percent capacity, with a water 

surface elevation of approximately 1,118 feet above mean sea level (msl). If the current drought 

continued and water levels in Lake Mead fell to 1,075 feet msl, the amount of water apportioned 

for use in Arizona and Nevada would be reduced, pursuant to the Record of Decision for 

Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for 

Lake Powell and Lake Mead ([2007 Interim Guidelines] (U.S. Department of the Interior [DOI], 

2007). If water levels in Lake Mead fell below 1,025 feet msl, the CAP, which delivers Colorado 

River water to the Phoenix and Tucson metropolitan areas, would have its supply cut by nearly a 

third. Under the same circumstance, the Southern Nevada Water Authority’s supplies, of which 

90 percent come from the Colorado River and serve more than 2 million people in the Las Vegas 

area, would be curtailed by 20,000 acre-feet (af) annually, nearly 7 percent of Nevada’s basic 

annual apportionment. 

Figure 2 presents the data from figure 1 as a 10-year running average to smooth out the annual 

variability so that trends are more visible. This figure clearly illustrates the existing supply and 

demand imbalance in the Basin. This imbalance will grow in the future if the potential effects of 

climate change are realized and demands continue to increase. A combination of options, 

including conservation and reuse, development of local groundwater supplies, desalination, 

augmentation, and the transfer of water from agricultural to urban uses, will likely be needed. 

The Study has assessed these and other options for resolving the projected imbalances in both the 

Upper and Lower Basins and has laid the foundation from which future discussions can occur to 

develop recommendations to sustain the environment, people, and economy of this region. 
Study Report

December 2012 SR-7 

FIGURE 2

Historical 10-Year Running Average Colorado River Basin Water Supply and Use

Year 

Historical water use is the total use of water throughout the Basin for agricultural, M&I, and other consumptive uses including 

Mexico, plus losses due to evaporation at mainstream reservoirs and use by native and non-native vegetation. Natural flow is 

used as an estimate of water supply in the Basin. In the current natural flow record, historical inflows based on USGS gaged

records are used as estimates of natural flow for the Paria River, Little Colorado River, Virgin River, and Bill Williams River. 

Additionally, the Gila River is not included in the natural flow record. As such, the use reported here excludes consumptive uses 

on these tributaries. See Technical Report C – Water Demand Assessment, Appendix C11 – Modeling of Lower Basin 

Tributaries in the Colorado River Simulation System for additional detail regarding the treatment of these tributaries in the Study.

3.0 Basin Study Program

The Basin Study Program is part of DOI’s WaterSMART (Sustain and Manage America's 

Resources for Tomorrow) Program9, which addresses 21st-century water supply challenges such 

as population growth, increased competition for finite water supplies, and climate change. The 

establishment of the WaterSMART Program addresses the authorities within the SECURE

(Science and Engineering to Comprehensively Understand and Responsively Enhance) Water 

Act (Subtitle F of the Omnibus Public Land Management Act of 2009, Public Law 111-11),

enacted into law on March 30, 2009. The SECURE Water Act provides authority for federal 

water and science agencies to work with state and local water managers to plan for climate 

change and other threats to water supplies, and take action to secure water resources for the 

communities, economies, and the ecosystems they support. 

 

9 Additional information regarding this program can be found at http://www.usbr.gov/WaterSMART/. 

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10-YEAR RUNNING AVERAGE BASIN WATER SUPPLY

10-YEAR RUNNING AVERAGE BASIN WATER USE
Colorado River Basin 

Water Supply and Demand Study

SR-8 December 2012

In 2009, Reclamation initiated the Basin Study Program to fund comprehensive studies to define 

options for meeting future water demands in river basins in the West where imbalances in supply 

and demand exist or are projected. At that time, it was envisioned that a Basin Study would 

quantify current and future water supply and demand imbalances, assess the resulting risks to the 

basin resources, and assess options to resolve those imbalances. Since that time, the Basin Study 

Program has evolved to focus on the development and analysis of options to address water 

supply and demand imbalances. The quantification of climate impacts to supply and demand and 

the subsequent risk assessment are now conducted through an activity known as the West-wide 

Climate Risk Assessments (another activity under the WaterSMART Program) and are used to 

inform subsequent Basin studies. 

In March 2011, a report to Congress was released to respond to requirements of the SECURE 

Water Act (Reclamation, 2011a). The SECURE Report provides information on the future risks 

to water supply in the eight major Reclamation river basins, whereas the Study was a moredetailed, Basin-wide risk assessment that focused on the development and evaluation of 

opportunities to mitigate and adapt to those risks. There are minor differences in the streamflow

projections based on general circulation models presented in the SECURE Report compared to 

the projections presented in this report. These differences are attributable to methodological and 

reporting differences between the two efforts and are summarized in a later section of this report 

and in Technical Report B – Water Supply Assessment. 

4.0 Study Objectives and Approach

Representatives of the seven Basin States submitted a letter of intent in February 2009, under the 

Basin Study Program, to help fund and participate in a study of the Basin. Based on that letter of 

intent, Reclamation’s Upper Colorado and Lower Colorado regions, in collaboration with the 

Basin States, developed and submitted a proposal in June 2009 to fund the Study. The proposal 

was selected for funding in September 2009, and a financial agreement between the Basin States 

and Reclamation for the Study was signed in February 2010. Reclamation entered into contracts

with CH2M HILL (including Black & Veatch and Cardno-ENTRIX) and the RAND Corporation 

to provide technical and administrative support for the Study. 

The Plan of Study, provided in appendix 1, states that the purpose of the Study is to define 

current and future imbalances in water supply and demand in the Basin and the adjacent areas of 

the Basin States that receive Colorado River water over the next 50 years (through 2060), and to 

develop and analyze adaptation and mitigation strategies to resolve those imbalances. The Plan 

of Study lays out specific objectives to be addressed through the Study, including: 

• Characterization of the current water supply and demand imbalances in the Basin and the 

assessment of the risks to Basin resources from historical climate variability

• Characterization of future water supply and demand imbalances under varying water supply 

and demand conditions in the Basin and the assessment of the risks to Basin resources from 

potential future impacts of climate change 
Study Report

December 2012 SR-9 

• Identification of potential strategies and options to resolve Basin-wide water supply and 

demand imbalances, including: 

− Modifications to the operating guidelines or procedures of water supply systems

− Modifications to existing facilities and development of new facilities

− Modifications to existing water conservation and management programs and 

development of new programs 

− Modifications to existing water supply enhancement programs and development of new 

programs 

− Other structural and non-structural solutions 

• Identification of potential legal and regulatory constraints and analysis of potential impacts to 

water users and Basin resources for the strategies and options considered

• Prioritization of identified strategies and options and recommendations for potential future 

actions, including feasibility studies, environmental compliance activities, demonstration 

programs, and/or implementation as appropriate 

The Study Area is defined by the hydrologic boundaries of the Basin within the United States, 

plus the adjacent areas of the Basin States that receive Colorado River water, as depicted in 

figure 3. 

The Study was conducted in four major phases: Water Supply Assessment, Water Demand 

Assessment, System Reliability Analysis, and Development and Evaluation of Options and 

Strategies for balancing supply and demand. Figure 4 illustrates these phases and some of their 

inter-relationships. 

4.1 Study Organization

As envisioned by the Plan of Study, two co-Study managers (one from Reclamation and the other 

representing the Basin States) led and were responsible for the overall direction and management 

of the Study. In addition, the following teams were established to facilitate the completion of the 

Study. Members of the Steering, Project, and Study Teams, as well as members of the Study’s 

various technical sub-teams, are listed in Appendix 4 – Study Participants: 

• The Steering Team (one member from each of Reclamation’s Upper Colorado and Lower 

Colorado regions, one member from each of the seven Basin States, and one member from 

the Upper Colorado River Commission) steered and guided the efforts of the Project Team 

such that the objectives of the Study were met in an effective, efficient manner, and within 

the Study’s financial and time constraints. Based on requests from the Ten Tribes 

Partnership, tribal representatives were invited to participate in Steering Team meetings. 

• The Project Team (composed of personnel from the Basin States, water agencies in the Basin 

States, Reclamation’s Upper Colorado and Lower Colorado regions, and from the consulting 

entities) ensured that the tasks that relate to the Study were completed in a cost-effective, 

timely manner and were technically sound. 
Colorado River Basin 

Water Supply and Demand Study

SR-10 December 2012

FIGURE 3 

The Study Area 
Study Report

December 2012 SR-11

FIGURE 4 

Study Phases and Tasks

• The Study Team (composed of key personnel from the Upper Colorado and Lower Colorado 

regions and the consulting entities) completed the Study tasks. 

• Sub-teams (composed of Project Team members and representatives from other interested 

parties with expertise sought by the sub-team) were formed as needed to perform specific 

technical tasks. Sub-teams consisted of personnel from tribes, conservation organizations, 

federal agencies, and other interested stakeholder groups. 

4.2 Study Outreach 

The Study was conducted in collaboration with stakeholders throughout the Basin. Interest was

broad and included tribes, agricultural users, purveyors of M&I water, power users, and 

conservation and recreation groups. Through outreach efforts, interested parties were informed 

about the Study and asked to provide input reflecting their concerns and thoughts about the 

future reliability of the Colorado River. This broad participation and input was critical to the 

Study’s success. Interested parties were encouraged to become involved in the Study and were 

provided a variety of options to do so. These options, which were not mutually exclusive, ranged 

from attending public meetings and informational webinars to participating directly in the 

development of work products through the Study’s technical sub-teams. The tools and the 

processes employed in outreach activities are detailed in Appendix 5 – Public Involvement Plan.

In accordance with the Public Involvement Plan, outreach activities included: 

• Establishing a Study website to provide on-line information. The Study web page is 

http://www.usbr.gov/lc/region/programs/crbstudy.html. 

• Establishing an e-mail address to distribute information and receive input. The Study email 

address is ColoradoRiverBasinStudy@usbr.gov. 
Colorado River Basin 

Water Supply and Demand Study

SR-12 December 2012

• Establishing a facsimile number (702–293–8418) to allow input by fax. 

• Establishing a mailing list to ensure that all interested parties receive information, 

particularly concerning the scheduling and access to public meetings.

• Scheduling public meetings for strategic times during the Study. Six public meetings were 

conducted during the Study. 

• Holding additional meetings with interested parties during the Study period. 

More than 170 outreach events occurred during the Study, and these activities are listed in 

Appendix 6 – Outreach Activities. 

4.3 Peer Review

A peer review of the Study was conducted to ensure that assumptions, findings, and conclusions 

of the Study were clearly stated and supported; oversights, omissions, and inconsistencies were 

identified; and limitations and uncertainties were disclosed. The reviewers were provided with 

focused technical questions while also being directed to offer a broad evaluation of the overall 

product. 

Peer review comments were considered and incorporated into this and the Study’s Technical 

Reports where relevant and appropriate. Appendix 7 – Peer Review Summary Report lists the 

reviewers, summarizes the comments received and what actions were undertaken to address the 

reviewers’ comments.

In general, the peer review comments indicated that the assessments had been performed 

adequately and the analyses met the intent of the Study. Many comments dealt with the clarity of 

the discussion. To address issues of clarity, discussion was added to the reports and description 

was added to figures and tables as necessary. Study limitations (both in terms of scope and 

length) prevented the more in-depth supplemental analyses some of the peer reviewers 

suggestions. Several suggestions for additional analysis are incorporated in the next steps 

described in section 10. 

5.0 Projected Future Supply and Demand Scenarios

The amount of water available and changes in the demand for water throughout the Basin over 

the next 50 years are highly uncertain and dependent upon a number of factors. The potential 

impacts of future climate variability and climate change further contribute to these uncertainties. 

Nevertheless, projections of future supply and demand were needed to assess the future 

reliability of the Colorado River system to meet Basin resource needs and to identify options and 

strategies to mitigate future risks to those resources. These projections had to be sufficiently 

broad to capture the plausible ranges of uncertainty in future water supply and demand. 

5.1 Summary of Technical Report A – Scenario Development

A scenario planning process was used to guide the development of scenarios for providing a 

broad range of projections of future water supply and demand, resulting in four scenarios related 

to future water supply and six scenarios related to future water demand. The following section 

summarizes the approach to scenario development. applied to the Study. 
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December 2012 SR-13

5.1.1 Objective and Approach

Scenarios are not predictions or forecasts of the future. Rather, they are alternative views of how 

the future might unfold. Figure 5 illustrates this concept. At present, an understanding of the state 

of the Colorado River system exists as indicated by the single point labeled “Today” on the xaxis of the figure. A range of plausible futures, represented by the funnel, can be identified. The 

suite of scenarios used in the planning effort should be sufficiently broad to span this plausible 

range of the funnel.

FIGURE 5 

Conceptual Representation of the Uncertain Future of a System, Also Known as “The Scenario Funnel” 

Adapted from Timpe and Scheepers, 2003. 

The scenario planning process involved: 

• Identifying the key forces that would likely drive future water supply and water demand 

• Ranking the driving forces (the factors that would likely have the greatest influence on the 

future state of the system and thereby the performance of the system over time) by their 

relative importance and uncertainty 

• Using the most highly uncertain and highly important driving forces (“critical uncertainties”)

to identify various themes and “storylines” (narrative descriptions of scenarios) to describe 

how water supply and water demand may evolve in the future 

Quantification of the storylines resulted in water supply and water demand scenarios used to 

assess future system reliability and thus inform the development of options and strategies to 

resolve imbalances between water supply and demands. 

The general steps involved in the scenario planning process as applied to a water resource 

planning study were customized to meet the needs of the Study as described in Technical Report 

A – Scenario Development. The approach included input from a broad sampling of stakeholders, 

experts, and others interested in the management of the system. This input was crucial 
Colorado River Basin 

Water Supply and Demand Study

SR-14 December 2012

throughout the development of scenarios to ensure that the resulting scenarios represent the 

plausible range of futures in the view of those who best know the system.

5.1.2 Summary of Results

A list of 18 specific driving forces relevant to understanding potential future conditions was 

developed with stakeholder involvement using the general categories listed below and based on 

experience managing the Colorado River system. 

• Natural Systems

• Demographic 

• Economic 

• Technological

• Social

• Governance

Table 1 lists the driving forces and numbers that were assigned to them. The numbers were 

assigned for identification purposes only and do not imply a relative priority. 

TABLE 1

List of Driving Forces Influencing Future Colorado River System Reliability

No. Driving Force

1 Changes in streamflow variability and trends

2 Changes in climate variability and trends (e.g., temperature, precipitation)

3 Changes in watershed conditions (e.g., diseases, species transitions)

4 Changes in population and distribution

5 Changes in agricultural land use (e.g., irrigated agricultural areas, crop mixes)

6 Changes in urban land use (e.g., conversion, density, urbanization)

7 Changes in public land use (e.g., forest practices, grazing, wilderness areas)

8 Changes in agricultural water use efficiency

9 Changes in M&I water use efficiency

10 Changes in institutional and regulatory conditions (e.g., laws, regulations)

11 Changes to organization or management structures (e.g., state, federal, bi-national institutions) 

12 Changes in water needs for energy generation (e.g., solar, oil shale, thermal, nuclear)

13 Changes in flow-dependent ecosystem needs for Endangered Species Act-listed species

14 Changes in other flow-dependent ecosystem needs

15 Changes in social values affecting water use

16 Changes in cost of energy affecting water availability and use

17 Changes in water availability due to tribal water use and settlement of tribal water rights claims

18 Changes in water quality, including physical, biological, and chemical processes
Study Report

December 2012 SR-15 

Based on these driving forces, 12 critical uncertainties were identified. Two critical uncertainties 

primarily affect the future of water supply and 10 critical uncertainties affect the future of water 

demand. 

The two critical uncertainties primarily affecting the future of water supply are (1) Changes in 

Streamflow Variability and Trends and (2) Changes in Climate Variability and Trends. A set of 

four scenarios focused around these critical uncertainties was constructed to represent a broad 

range of plausible future water supply conditionsin the Basin through the next 50 years. The 

scenarios were informed by the past, present, and projections of possible futures through 

incorporation of the paleo-reconstructed streamflow record, the observed historical streamflow 

record, and projections of streamflow using climate projections from general circulation models 

(GCMs). The four water supply scenarios and associated themes are presented below. 

The scenario development approach identified 10 critical uncertainties primarily affecting the 

future of water demand. These critical uncertainties are displayed in table 2. 

TABLE 2 

Critical Uncertainties Affecting Water Demand Scenarios

Critical Uncertainty Identified in Survey

General Driving 

Force Category

Changes in Population and Distribution

Changes in Agricultural Land Use (e.g., irrigated agricultural areas, crop mixes)

Demographics and

Land Use

Changes in Agricultural Water Use Efficiency

Changes in M&I Water Use Efficiency

Changes in Water Needs for Energy Generation (e.g., solar, oil shale, thermal, nuclear)

Technology and

Economics

Changes in Institutional and Regulatory Conditions (e.g., laws, regulations)

Changes in Flow-dependent Ecosystem Needs for Endangered Species Act-listed Species

Changes in Other Flow-dependent Ecosystem Needs

Changes in Social Values Affecting Water Use

Changes in Water Availability due to Tribal Water Use and Settlement of Tribal Water 

Rights Claims

Social and

Governance

After aligning the associations of the critical uncertainties with the key factors of either water 

supply and demand, the scenario development process was completed based on the process 

previously described. These critical uncertainties were combined to generate four water supply 

scenarios and four water demand storylines. These storylines and their associated themes are 

described below. 

Each of the water supply scenarios was quantified and analyzed. That work, including the 

approach and key results, is documented in Technical Report B – Water Supply Assessment and

summarized in the next section of this report. The methodology used to quantify the demand 

scenarios, as well as an assessment of historical consumptive uses and losses, are described in 

Technical Report C – Water Demand Assessment and summarized in subsequent sections of this 

report.
Colorado River Basin 

Water Supply and Demand Study

SR-16 December 2012

5.2 Summary of Technical Report B – Water Supply Assessment

Four water supply scenarios were developed using the scenario planning approach previously 

described. This section summarizes the quantification of those scenarios and the resulting range 

of potential future streamflow in the Basin. 

5.2.1 Objective and Approach

The objective of the Water Supply Assessment was to characterize and quantify the probable 

magnitude and variability of historical and future natural flows in the Basin. Natural flow 

represents the flow that would have occurred at a location had depletions and reservoir regulation 

not been present upstream of that location. The assessment included the potential effects of 

future climate variability and climate change and provides quantified projections of future 

hydrology. 

Using the scenario planning process described above and in Technical Report A – Scenario 

Development, four water supply scenarios were identified and quantified, each representing 

plausible future water supply conditions. These water supply scenarios and their associated 

themes are presented in detail in Technical Report B – Water Supply Assessment. The following 

scenarios and associated themes were considered in the Study:

• Observed Resampled: Future hydrologic trends and variability are similar to the past 

approximately 100 years.

• Paleo Resampled: Future hydrologic trends and variability are represented by 

reconstructions of streamflow for a much longer period in the past (nearly 1,250 years) that 

show expanded variability. 

• Paleo Conditioned: Future hydrologic trends and variability are represented by a blend of 

the wet-dry states of the longer paleo-reconstructed period (nearly 1,250 years), but 

magnitudes are more similar to the observed period (about 100 years). 

• Downscaled GCM Projected: Future climate will continue to warm, with regional 

precipitation and temperature trends represented through an ensemble of future downscaled 

GCM projections. 

Before 2004, Reclamation used the historical record of natural flow in planning studies. The 

implicit assumption was observed natural flow would be representative of future streamflow 

variability and trends. In 2004, Reclamation initiated a multi-faceted research and development 

program to develop methods beyond those using the observed record for projecting possible 

future inflow sequences for Basin planning studies. Through this effort, two additional water 

supply scenarios were developed; they have been used in previous Basin planning studies that 

assume the observed and paleo-reconstructed streamflow records are representative of future 

streamflow variability and trends. These scenarios were most recently detailed in appendix N of 

the 2007 Interim Guidelines Final EIS. The three scenarios previously used are the Observed 

Resampled, Paleo Resampled, and Paleo Conditioned scenarios. 

A resampling technique known as the Indexed Sequential Method (Ouarda et al., 1997) was

applied to the observed and paleo-streamflow records to generate multiple sequences of future 

streamflow in the Observed Resampled (102 sequences) and Paleo Resampled (1,244 sequences) 
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December 2012 SR-17

scenarios. Sequences for the Paleo Conditioned scenario were generated by applying a nonparametric technique to “blend” the observed and paleo streamflow records (1,000 sequences). 

To ensure that the water supply scenarios encompassed a sufficiently broad range of future water 

supply conditions, a fourth scenario was developed that used downscaled GCM projections, 

titled the Downscaled GCM Projected scenario. 

The Downscaled GCM Projected scenario entailed a method in which climate forcings (primarily 

temperature and precipitation) from 112 climate projections used in the Intergovernmental Panel 

on Climate Change Fourth Assessment Report (Intergovernmental Panel on Climate Change, 

2007), subsequently bias corrected and statistically downscaled (Maurer et al., 2007), were input 

to the Variable Infiltration Capacity (VIC) hydrologic model (Christensen and Lettenmaier, 

2009) to simulate streamflow. The VIC model (Liang et al., 1994, 1996; Nijssen et al., 1997) is a 

spatially distributed macro-scale hydrologic model that solves the water balance at each model 

grid cell. The VIC model was populated with the historical temperature and precipitation data to 

simulate historical hydrologic parameters (Maurer et al., 2002). Technical Report B – Water 

Supply Assessment, Appendix B4 – Variable Infiltration Capacity (VIC) Hydrologic Modeling 

Methods and Simulations provides details on the VIC model and its application in the Study. A 

streamflow bias correction method was developed and applied to the “raw” VIC-simulated flows 

to account for any systematic bias in the hydrology model and/or climate data sets. The 

Downscaled GCM Projected scenario consisted of 112 sequences of future streamflow. The 112 

climate projections comprised projections assuming three independent greenhouse gas emission 

scenarios (high, medium, and low), 16 distinct GCMs, and multiple simulations due to 

differences in starting climate system state (initial oceanic and atmospheric conditions). 

These four methods were used to develop hydrologic inputs into the Colorado River Simulation 

System (CRSS)10. CRSS is Reclamation’s primary Basin-wide simulation model used for longterm planning studies and, in its current configuration, requires natural flow inputs at 29 

locations on a monthly time step over the Study’s planning horizon. 

5.2.2 Summary of Results

Historical Supply

The Study assessed historical water supply in the Basin. The assessment was composed of a 

discussion of methods followed by the results for four groups of water supply indicators: climate, 

hydrologic processes, climate teleconnections, and streamflow. Two historical streamflow data 

sets, the observed record spanning the period 1906 through 2007 and the paleo-reconstructed 

record spanning the period 762 through 2005 (Meko et al., 2007), were used to characterize 

historical streamflow patterns and variability. The following observations and conclusions were 

made:

• There has been a warming trend in both the Upper and Lower Basins since the 1970s, which 

is consistent with observed North American and global trends. 

 

10 CRSS was the primary modeling tool used in the Study. It simulates the operation of the major Colorado River system reservoirs on a monthly 

time step and provides information regarding the projected state of the system in terms of output variables. Outputs include the amount of 

water in storage, reservoir elevations, releases from the dams, hydropower generation, the amount of water flowing at various points in the 

system, the total dissolved solids content, and diversions to and return flows from the water users in the system.
Colorado River Basin 

Water Supply and Demand Study

SR-18 December 2012

• Widespread decreases in springtime snowpack were observed, with consistent results across 

the lower elevation northern latitudes of the western United States. Losses of snow water 

equivalent tended to be largest at low elevations and strongly suggested a temperature-related 

effect.

• Natural inter-annual variability in streamflow tended to be more dominant than the 

relationships to either the El Niño–Southern Oscillation or the Pacific Decadal Oscillation. 

However, in 2011 and 2012, the climate was entering a strong combined cool phase of both 

El Niño–Southern Oscillation Pacific Decadal Oscillation. The alignment of both signals in 

the cool phase suggests a propensity for continued drying trends in the coming years. 

• The recent deficit (defined as the difference between the 2-year running average flow and the 

long-term mean annual flow) that started in 2000 is more severe than any other deficit in the 

observed period, at 9 years and 28 maf. 

• The period from 762 through 2005 contained deficits that were longer in duration (16 years) 

and larger (as much as 35 maf) than those in the period from 1906 through 2005. Thus, the 

wet–dry sequences from the much longer paleo record suggest that deficits of greater severity 

than the recent deficit are possible. 

In summary, the trends over the observed period and over the recent climatological regime 

suggest declining streamflows, increases in variability, and seasonal shifts in streamflow that 

may be related to warming. The paleo reconstruction indicates a slightly lower mean inflow than 

the observed record. The paleo reconstruction also suggests that annual and inter-annual flows 

have been more variable in terms of both wet and dry sequences than the observed record period. 

Deficits of longer duration and greater magnitude can be expected based on the paleo record, 

although the paleo record shows that past deficits were not significantly more intense than the 

observed record. 

Future Projected Supply

The Observed Resampled, Paleo Resampled, and Paleo Conditioned methods did not consider 

the impacts of a changing climate beyond what has occurred historically. Therefore, the key 

findings related to projected changes in temperature, precipitation, snowpack, and runoff over 

the next 50 years that may be expected under the Downscaled GCM Projected scenario in 

particular are presented below. These findings are based on the assessment described in 

Technical Report B – Water Supply Assessment. 

• Warming is projected to increase across the Basin, with the largest changes in spring and 

summer and with larger changes in the Upper Basin than in the Lower Basin. Annual Basinwide average temperature increases are projected to be approximately 1.3 and 2.4 degrees 

Celsius over the periods 2011 through 2040 and 2041 through 2070, respectively. Increases 

are measured relative to the 30-year historical period of 1971 through 2000. 

• Precipitation patterns continue to be spatially and temporally complex, but projected seasonal 

trends toward drying are significant in certain regions. A general trend towards drying is 

present in the Basin, although increases in precipitation are projected for some higher 

elevation and hydrologically productive regions. Consistent and expansive drying conditions 

are projected for the spring throughout the Basin. For much of the Basin, drying conditions 

are also projected in the summer, although some areas of the Lower Basin are projected to 

experience slight increases in precipitation, which may be attributed to the monsoonal 
Study Report

December 2012 SR-19

influence in this region. Upper Basin precipitation is projected to increase in the fall and 

winter and the Lower Basin is projected to experience decreases.

• Snowpack is projected to decrease as more precipitation falls as rain rather than snow and 

warmer temperatures cause an earlier melt. Decreased snowpack in the fall and early winter 

is projected in areas where precipitation does not change or increases, and is caused by more 

rain and less snow due to warming. Substantial decreases in spring snowpack are projected to 

be widespread, due to earlier melt or sublimation of snowpack. 

• Runoff (both direct and baseflow) is spatially diverse, but is generally projected to decrease, 

except in the northern Rockies. As with precipitation, runoff is projected to increase 

significantly in the higher elevation Upper Basin during winter, but is projected to decrease 

during spring and summer. 

Future Colorado River flows were developed for all water supply scenarios. Figure 6 shows the 

range of annual flows for the Colorado River at Lees Ferry for each of the scenarios over the 

Study period. 

The long term (2011–2060) mean natural flow for the Colorado River at Lees Ferry over the next 

50 years ranged from 14.7 to 15.0 maf for the Observed Resampled, Paleo Resampled, and Paleo 

Conditioned scenarios. The Downscaled GCM Projected scenario resulted in mean annual flows 

of approximately 13.7 maf, an 8.7 percent reduction from the observed mean. The range of mean 

flows was greatest under the Downscaled GCM Projected scenario, with the inter-quartile range 

spanning roughly 12.6 to 14.9 maf and the minimum/maximum range covering 10 to 17 maf. 

A skew of zero implies a normal distribution, in which wetter years and magnitudes are evenly 

balanced with drier years. Most scenarios had a positive skew, suggesting a bias to the drier side 

of the distribution. This was particularly noticeable in the Downscaled GCM Projected scenario.

The minimum annual flows were fairly consistent across the scenarios, with the Paleo 

Resampled scenario exhibiting the most extreme low-flow condition. The Downscaled GCM 

Projected scenario exhibited a range of maximum annual flows not seen in any of the other 

scenarios. 

Table 3 presents a comparison of several key streamflow statistics for each scenario. The 

statistics are grouped by annual, monthly, deficit, and surplus period statistics. For the purpose of 

the Study, deficit and surplus periods occur whenever the running 2-year average flow falls 

below (deficit) or above (surplus) 15.0 maf, the observed mean. Deficit and surplus period 

statistics indicate the range of inter-annual variability of streamflow across the scenarios. 

In comparison to the Observed Resampled scenario, the other scenarios exhibited a substantial 

increase in inter-annual variability, both in sustained deficits and surpluses. The maximum length 

of sustained deficit in the Observed Resampled scenario was 8 years, whereas the maximum 

sustained surplus was 7 years. The Paleo Resampled, Paleo Conditioned, and Downscaled GCM 

Projected scenarios all produced deficit and surplus periods that were much longer. The 

frequency of deficit spells that were 5 years or longer was also higher under these scenarios, with 

the Downscaled GCM Projected scenarios exhibiting a likelihood of almost 50 percent over the 

next 50 years. However, the frequency of surplus spells that were 5 years or longer was highest 

under the Observed Resampled scenario. 
Colorado River Basin 

Water Supply and Demand Study

SR-20 December 2012

FIGURE 6 

Summary Statistics for Annual Colorado River at Lees Ferry Natural Flows for Supply Scenarios

Figure shows the median (dash), 25th–75th percentile band (box), and maximum/minimum (line).
Study Report

December 2012 SR-21

TABLE 3 

Summary of Key Streamflow Statistics for Each Water Supply Scenario

Statistic1

Scenario

Observed

Resampled

Paleo

Resampled

Paleo

Conditioned

Downscaled

GCM Projected

Annual (Water 

Year)

Average Annual Flow (maf) 15.0 14.7 14.9 13.7

Percent Change from Long-term Mean (1906–2007) 0% -2% -1% -8.7%

Median (maf) 15.0 14.7 15.0 13.6

25th Percentile (maf) 14.5 14.3 14.2 12.6

75th Percentile (maf) 15.5 15.0 15.6 14.9

Minimum Year Flow (maf) 5.6 2.3 5.6 4.2

Maximum Year Flow (maf) 25.2 24.3 25.2 44.3

Monthly Peak Month June June June June

Peak Month Mean Flow (thousand acre-feet [kaf]) 4,007 3,914 4,000 3,393

Peak Month Maximum Flow (kaf) 8,467 8,531 8,678 14,693

Month at Which Half of Annual Flow (Water Year) was Exceeded June June June June

Deficit Periods2 Maximum Deficit (maf) 28.2 38.4 98.5 246.1

Maximum Spell Length (years) 8 17 24 50

Intensity (Deficit/Length) (mafy) 3.5 2.3 4.1 7.4

Frequency of 5+ Year Spell Length (percent) 22% 30% 25% 48%

Maximum 8-year Deficit (longest in 1906–2007 observed record, maf) 28.2 29.8 50 48.6

Surplus Periods3 Maximum Surplus (maf) 22.2 36.2 88 74.7

Maximum Spell Length (years) 7 15 25 19

Intensity (Surplus/Length) (mafy) 3.2 2.4 3.5 13.2

Frequency of 5+ Year Spell Length (percent) 28% 15% 18% <1%

Maximum 7-year Surplus (longest in 1906–2007 observed record, maf) 22.2 29.2 44 39.2

1 Statistics are computed over the Study period, 2011–2060. 2 A deficit period occurs whenever the running 2-year average flow is below the observed mean from 1906–2007 of 15.0 maf. 3 A surplus period occurs whenever the running 2-year average flow is above the observed mean from 1906–2007 of 15.0 maf.
Colorado River Basin 

Water Supply and Demand Study

SR-22 December 2012

The results suggest that under sequences in the Downscaled GCM Projected scenario, sustained 

periods of dryness may occur (deficit lengths of up to 50 years). Most projections resulted in 

long-term mean annual flows that were less than the 15 maf observed mean, while other 

projections resulted in long-term mean annual flows that were greater than the 15 maf observed 

mean. The future projected climate essentially arrived at a new mean state. 

The processes in which GCM projections were used to generate projections of future streamflow 

contained a number of areas of uncertainty and reflected methodological choices made in the 

Study. For example, different methodological choices with respect to downscaling techniques, as 

well as selection of a different hydrologic model used to translate GCM output into streamflow, 

yielded different results. 

There are some minor methodological differences in the technical approach to develop 

streamflow projections informed by GCMs and the analysis of those projections between the 

results presented here and those presented in the SECURE Report. The methodological 

differences consist primarily of the application of a secondary bias correction to the results 

presented here. Reporting differences are due to the selection of baseline conditions for 

comparison and the future analysis period. Specifically, the SECURE Report computed future 

decadal changes from a 1991 through 2000 baseline condition, whereas the change statistics 

reported here were computed between the observed record and the Study period of 2011 through 

2060. Therefore, results of the Study and those in the SECURE Report are not identical. 

5.3 Summary of Technical Report C – Water Demand Assessment

Four water demand storylines were developed using the scenario planning approach previously 

described. This section summarizes the quantification of the six scenarios resulting from those 

storylines and the resulting range of potential future demand in the Basin. 

5.3.1 Objective and Approach

The Water Demand Assessment examined the quantity and location of current and future water 

demands in the Study Area. These water demands were derived from Basin resource needs, 

including M&I use, hydropower generation, recreation, and fish and wildlife habitat. In addition, 

losses in the Study Area from evaporation and other factors were assessed. Because future water 

supply and demand throughout the Basin are uncertain, scenarios were developed that are 

sufficiently broad to span that uncertainty, including the potential effects of future climate 

change. 

Future demands are a function of socioeconomic parameters such as future population, irrigated 

land area, M&I and agricultural water use efficiency, tribal water use, energy production growth 

and associated water use, and others. Through the scenario planning process applied in the 

Study, the most critical uncertainties affecting future demand were identified, and a range of 

future demand scenarios was envisioned. Narrative descriptions of these scenarios (storylines) 

were developed and provide a rational basis for consideration of a wide array of future 

conditions. These storylines and their associated themes are:

• Current Projected (A): Growth, development patterns, and institutions continue along recent 

trends 

• Slow Growth (B): Slow growth with emphasis on economic efficiency 
Study Report

December 2012 SR-23

• Rapid Growth (C1 and C2): Economic resurgence (population and energy) and current 

preferences toward human and environmental values 

• Enhanced Environment (D1 and D2): Expanded environmental awareness and stewardship 

with growing economy 

Under the storylines, two logical branches or directions were considered for the Rapid Growth 

(slower technology adoption—C1 and rapid technology adoption and increase in social values—

C2) and Enhanced Environment (current growth trend—D1 and higher growth and technology—

D2) scenarios. For example, population growth or increasing energy needs and subsequent water 

demand could be offset by associated technological innovations influencing water use. The four 

storylines, two with branches, resulted in six water demand scenarios. Complete narrative 

descriptions of the scenarios (storylines) are presented in Technical Report C – Water Demand 

Assessment, Appendix C14 – Water Demand Scenario Storylines. 

The process to develop the critical uncertainties and demand storylines, and quantify scenarios, 

engaged a wide array of stakeholders and reflects a broad range of plausible conditions 

considering differing views of the future. In order to establish a solid foundation relating to 

methods and assumptions for quantifying future demands, the Study focused initial efforts on 

quantifying the Current Projected (A) scenario. The Current Projected (A) scenario provided the 

basis for consideration of departures from these assumptions, leading to the quantification of the 

Slow Growth, Rapid Growth, and Enhanced Environment demand scenarios. Each of the 

scenarios was quantified through significant input from the Basin States, with additional input 

provided by tribes, U.S. Fish and Wildlife Service personnel, and conservation organizations. 

Demand for each scenario was quantified by estimating values for individual parameters (such as 

population, irrigated acreage, water use efficiencies) associated with storylines and specific 

scenario assumptions. 

Table 4 presents the demand categories, their definitions, and associated parameters collected or 

developed for the Study. As part of the scenario quantification process, general relationships 

were used to relate the expected changes in parameters for each scenario in comparison to the 

Current Projected (A) scenario consistent with each storyline. 

Future demands may be affected by climate change, primarily changes in ambient temperature 

and the amount and distribution of precipitation. As such, the possible effects of changing 

temperature and precipitation on evapotranspiration, which may affect agriculture and outdoor 

M&I demand, and effects on phreatophyte and reservoir evaporation losses were also assessed in 

the Study. The potential impacts to evapotranspiration rates affecting agricultural demand were 

assessed using the Penman-Moteith method to estimate potential evapotranspiration (PET) under 

varying climatic conditions. 
Colorado River Basin 

Water Supply and Demand Study

SR-24 December 2012

TABLE 4 

Definition of Demand Categories and Their Associated Parameters 

Demand Category Definition Parameters

Agriculture 

Water used to meet irrigation requirements of 

agricultural crops, maintain stock ponds, and 

sustain livestock

Irrigated acreage, irrigation efficiency

M&I Water used to meet urban and rural population 

needs, and industrial needs within urban areas

Population, population distribution, M&I 

water use efficiency, consumptive use 

factor

Energy Water used for energy services and 

development Water needs for energy generation

Minerals Water used for mineral extraction not related to 

energy services Water needs for mineral extraction

Fish, Wildlife, 

Recreation1

Water used to meet National Wildlife Refuge, 

National Recreation Area, state park, and offstream wetland habitat needs

Institutional and regulatory conditions, 

social values affecting water use, 

Endangered Species Act-listed species 

needs, and ecosystem needs

Tribal Water used to meet tribal needs and settlement 

of tribal water rights claims Tribal use, settlements, and claims

1 This demand category represents the consumptive use portion of demand. Non-consumptive demands are considered in metrics, 

see Technical Report D – System Reliability Metrics. 

5.3.2 Summary of Results

Historical Consumptive Use

Figures 7 and 8 present the range of historical Colorado River water consumptive use and loss 

compiled by basin and category. This information was compiled from Reclamation’s Colorado 

River System Consumptive Uses and Losses Reports (CU&L Reports11), Reclamation’s 

Colorado River Accounting and Water Use Reports12, and additional input from the Basin States. 

The categories of consumptive uses and losses presented consist of the following: agriculture; 

M&I; energy; minerals; fish, wildlife, and recreation; exports; reservoir evaporation; and other 

losses. 

There are data and methodological inconsistencies in the CU&L Reports with respect to the 

Lower Basin tributaries (the Little Colorado, Virgin, Bill Williams and Gila rivers). These 

inconsistencies are primarily the result of changing methodologies between the 5-year reporting 

periods. Similar inconsistencies were found in these reports with respect to the Upper Basin until 

Reclamation undertook a multi-year effort to resolve them. This effort has not occurred for the 

Lower Basin tributaries, and the quality of information has suffered. Independent of the Study, 

Reclamation will engage in efforts to resolve and correct, in collaboration with the Basin States, 

the methodological and data inconsistencies in the CU&L Reports pertaining to all of the Lower 

Basin tributaries. Refer to Technical Report C – Water Demand Assessment, Appendix C11 – 

 

11 Some states produce independent estimates of consumptive uses and losses. For consistency, the analysis of historical consumptive uses and 

losses in the Study was based on Reclamation’s CU&L Reports, available at http://www.usbr.gov/uc/library/envdocs/reports/crs/crsul.html.

12 http://www.usbr.gov/lc/region/g4000/wtracct.html.
Study Report

December 2012 SR-25

Modeling of Lower Basin Tributaries in the Colorado River Simulation System, for a description 

of these issues and commitments. 

Consumptive uses and losses in the Basin increased from 1971 to the start of the drought that 

began in 2000. The information presented in figure 7 indicates that from 1971 through 1999, 

Basin-wide consumptive uses and losses (including deliveries to Mexico pursuant to the 1944 

Treaty13) have grown from approximately 13 maf in 1971 to 16 maf in 1999, an increase of 

about 23 percent. Over the same period, Upper Basin uses have grown from approximately 

3.0 maf in 1971 to 3.3 maf in 1999, an increase of about 10 percent. Lower Basin uses have 

grown from approximately 6.6 maf in 1971 to 8.0 maf14 in 1999, an increase of about 21 percent. 

FIGURE 7 

Historical Colorado River Water Consumptive Use1 by Basin,2 Delivery to Mexico, Reservoir Evaporation, and Other Losses,3

1971–2008

1 Excluding consumptive use in Lower Basin tributaries.

2 Uses in the Lower Division States greater than 7.5 maf occur during Surplus Conditions. 3 Phreatophyte and operational inefficiency losses.

 

 

13 Utilization of Waters of the Colorado and Tijuana Rivers and of the Rio Grande, Treaty between the United States and Mexico, 1944.

14 Uses in the Lower Division States greater than 7.5 maf occur during Surplus Conditions. 1,707 1,741 1,905 1,967 1,995 1,979 1,890 1,920 2,060 2,176 2,149 2,178 2,318 2,274 2,266 2,241 2,245 2,203 2,100 1,969 1,918 1,901 2,038 2,028 2,077 2,147 2,216 2,283 2,266 2,191 

2,076 

1,846 

1,696 

1,585 

1,666 

1,690 

1,664 

1,683 

1,500 

1,500 

1,500 

1,500 

1,500 

1,500 

1,500 

1,500 

1,700 

1,700 

1,700 

1,500 

1,700 

1,700 

1,700 

1,700 

1,700 

1,700 

1,500 

1,500 

1,500 

1,500 

1,500 

1,500 

1,500 

1,500 

1,700 

1,700 

1,700 

1,700 

1,500 

1,500 

1,500 

1,500 

1,500 

1,500 

1,500 

1,500 

6,564 

6,515 

6,680 

6,835 

6,414 

6,028 

6,401 

5,809 

6,028 

6,040 

6,314 

5,642 

5,394 

5,888 

6,075 

6,273 

6,735 

7,092 

7,530 

7,657 

7,050 

6,630 

7,286 

7,360 

7,082 

8,028 

8,101 

7,621 

7,977 

8,026 

8,171 

8,430 

7,538 

7,384 

7,065 

7,411 

7,454 

7,586 

3,018 

3,093 

2,915 

3,259 

3,072 

2,970 

2,431 

3,304 

3,267 

3,203 

3,234 

3,262 

3,107 

3,025 

3,310 

3,217 

3,309 

3,737 

3,823 

3,604 

3,661 

3,815 

3,527 

4,028 

3,167 

3,616 

3,376 

3,462 

3,281 

3,722 

3,979 

3,559 

3,571 

3,325 

3,403 

3,437 

3,623 

3,788 

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

19711972197319741975197619771978197919801981198219831984198519861987198819891990199119921993199419951996199719981999200020012002200320042005200620072008

Thousand Acre-Feet per Year

Year

Upper Basin

Lower Basin

Mexico

Reservoir Evaporation

Other Losses
Colorado River Basin 

Water Supply and Demand Study

SR-26 December 2012

FIGURE 8 

Historical Colorado River Water Consumptive Use1 by Use Category,2 Delivery to Mexico, Reservoir Evaporation, and Other 

Losses,3 1971–2010

1

Excluding consumptive use in Lower Basin tributaries.

2 Reservoir evaporation losses are accounted differently in the Upper and Lower Basin. In the Upper Basin, reservoir evaporation 

losses are accounted as part of each state’s total uses. In the Lower Basin, reservoir evaporation losses are accounted 

separately from each state’s uses. Reservoir evaporation losses from Upper and Lower Basin reservoirs have been aggregated 

for this presentation.

3 Phreatophyte and operational inefficiency losses.

Agricultural and M&I uses have grown over this period, as have reservoir evaporation losses. As 

shown in figure 8, agricultural uses have grown from approximately 7.7 maf in 1971 to 8 maf in 

1999, an increase of about 4 percent. M&I uses have grown from approximately 1.4 maf in 1971 

to 2.2 maf in 1999, an increase of about 57 percent. Reservoir evaporation losses have grown 

from 1.7 maf in 1971 to 2.3 maf in 1999, an increase of 35 percent. 

In the assessment of the possible impacts to agricultural demands due to changes in precipitation 

and temperature, agricultural water demands are assumed to increase by approximately 5 percent 

for each Celsius degree increase in temperature, and by approximately 1 percent for each 5 

percent reduction in precipitation. 

Future Projected Demand

The quantification of the Current Projected (A) scenario was used as a starting point for the 

quantification of the remaining scenarios. Historical consumptive use and loss information was 

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

1971

197219731974197519761977197819791980198119821983198419851986198719881989

19901991199219931994

1995199619971998199920002001200220032004200520062007200820092010

Thousand Acre-Feet per Year

Year

Agricultural

Municipal and Industrial

Energy

Minerals

Fish and Wildlife and 

Recreation

Mexico

Reservoir Evaporation

Other Losses
Study Report

December 2012 SR-27

used in conjunction with future planning data (e.g., land use, policy, population growth, 

economic conditions) to inform the development of future projected demand. Although current 

projections are not direct mathematical projections of historical data, the Current Projected (A)

scenario in particular relies on knowledge of the historical consumptive uses and losses, as 

described above, as well as planning data and expertise to estimate future trends in water 

demands. General relationships were used to relate the expected changes in parameters for each 

scenario in comparison to the Current Projected (A) scenario consistent with each storyline. 

These are shown conceptually in table 5. 

Table 6 presents summary results for the demand scenarios considered in the Study. The table 

presents agricultural and M&I demand parameters for the Study Area, which distinguishes the 

scenarios, the resulting Study Area demand, and finally the Colorado River demand by category. 

Colorado River demand is defined as Study Area demand less the demand projected to be 

supplied by other sources. The Study and the results presented in this report focus on the 

resulting Colorado River demand. 

The Study Area demand ranges between 28.7 and 32.5 maf by 2060, with Colorado River 

demand15 ranging between 13.8 and 16.2 maf. Some of the increase in Study Area demand is 

projected to be met through increases in other supplies, primarily in Colorado and California. 

The increase in Colorado River demand from 2015 through 2060 is estimated to be between 

1.1 and 3.4 maf, with the Lower Basin making up about 60 percent of the increase. Of the total 

increase in Colorado River demand, for the growing categories, between 64 and 76 percent of the 

growth is contributed by the M&I demand category. The growth in energy, tribal, and mineral 

categories constitutes the remaining increase in demand. 

Relative to water use across sectors, Study Area comparisons reflect differing levels of and 

interplay among changing societal values, economic drivers, and various types of resource 

constraints. An exception to this comparison is with respect to tribal demands. It was determined 

during the quantification process that the factors affecting tribal demands are not particularly 

well-represented by the driving force categories established by the Study. For the most part, 

tribal demands are based on quantified rights in Current Projected (A), Slow Growth (B), and 

Enhanced Environment (D1) scenarios, but consider additional demands beyond current 

settlements in the Rapid Growth (C1 and C2) and Enhanced Environment (D2) scenarios. 

Additionally, it is important to recognize that the quantification of water supply and demand 

scenarios may compare differently at state and individual planning area levels. State level 

demands generally follow broad identifiable trends, whereas individual planning areas consider 

locally relevant information, plans, timelines, and constraints. 

 

15 Mexico’s allotment and losses such as reservoir evaporation, phreatophyte losses, and operational inefficiencies are not part of this total. 

These factors were included in the modeling supporting the system reliability analysis.
Colorado River Basin 

Water Supply and Demand Study

SR-28 December 2012

TABLE 5 

Scenario Matrix of Typical Changes in Parameters Defined by the Water Demand Storylines

(In general, these represent parameter change from 2015, with growth as a blue “up” arrow, no change as a yellow bar, or reduction as a green 

“down” arrow. The size of the arrow represents larger or smaller change for a given parameter.) 

1 Self-served industrial (SSI) demand represents the demand of industries in a given area that have water supply systems independent of municipal systems. 

Population

M&I Per 

Capita Use

Self Served

Industrial

Demand1

Agricultural

Irrigated 

Acreage

Agricultural

Per Acre 

Delivery

Energy

Water

Demand

Minerals

Demand

Fish,

Wildlife,

Recreation

Demand

Tribal

Demand

Current 

Projected 

(A)

Slow 

Growth 

(B)

Enhanced

Environment

(D2)

Rapid

Growth 

(C1)

Enhanced

Environment

(D1)

Rapid

Growth 

(C2)
Study Report

December 2012 SR-29

TABLE 6

Summary Results of Water Demand Scenario Quantification by 2060

Parameter 2015

2060 Scenario Parameters

A B C1 C2 D1 D2

Key Study Area Demand Scenario Parameters

Population (millions) 38.9–41.1 62.4 49.3 76.5 76.5 62.4 76.5

Change in per capita water usage (%), 

from 2015 – -9% -7% -9% -16% -19% -17%

Irrigated acreage (millions of acres) 5.4–5.5 5.1 5.2 4.6 4.6 5.0 5.0

Change in per-acre water delivery (%), 

from 20151 – +1% +2% +1% +3% 0% +3%

Study Area Demand (maf)

Agricultural Demand 16.4–16.7 15.2 15.7 13.7 13.8 14.9 14.9

M&I Demand 8.4–8.8 12.5 10.2 15.1 13.9 11.0 13.7

Energy Demand 0.34–0.63 0.66 0.57 1.01 0.58 0.51 0.56

Minerals Demand 0.1–0.11 0.18 0.18 0.22 0.15 0.15 0.15

Fish, Wildlife, and Recreation Demand 0.16–0.23 0.08 0.08 0.08 0.10 0.16 0.16

Tribal Demand2 1.6–1.8 2.0 2.0 2.4 2.4 2.0 2.4

Total Study Area Demand3 27.3–27.8 30.6 28.7 32.5 30.9 28.7 31.9

Colorado River Demand (maf)

Agricultural Demand 7.1–7.2 6.7 6.8 6.6 6.7 6.6 6.8

M&I Demand 3.4–3.5 5.1 4.5 6.2 5.2 4.8 5.4

Energy Demand 0.21–0.23 0.44 0.38 0.74 0.37 0.34 0.35

Minerals Demand 0.09–0.11 0.17 0.18 0.21 0.14 0.14 0.14

Fish, Wildlife, and Recreation Demand 0.15–0.21 0.06 0.07 0.06 0.08 0.15 0.15

Tribal Demand2 1.5–1.7 2.0 1.9 2.4 2.4 2.0 2.4

Total Colorado River Demand3 12.6–12.8 14.5 13.8 16.2 15.0 14.0 15.2

1 Does not include reductions associated with conservation and efficiency programs such as those in Imperial Irrigation District that 

are part of transfer and acquisition agreements.

2 Tribal demand within the state of Colorado was included in other demand categories.

3 Excludes Mexico’s allotment and losses (reservoir evaporation, phreatophytes, and operational inefficiencies). These factors were

included in the modeling supporting the system reliability analysis.

The Colorado River demand at three geographic levels is presented in figures 9 and 10. These 

figures show Study Area, Upper and Lower Basin, and individual state demand across all 

scenarios. The bars at the right in these figures show the relative contribution of each demand 

category to the total Colorado River demand at a point in time (2015, 2035, or 2060) in the 

Current Projected (A) scenario. In general, the category proportions remain relatively consistent 

across the scenarios. For the purposes of the Study, demand was not limited by the Law of the 

River apportionments. In this way, the demand for Colorado River and tributary water can be 

assessed in the context of overall Study Area demand and supplies available from other sources. 
Colorado River Basin 

Water Supply and Demand Study

SR-30 December 2012

As shown in figure 9, the change in both magnitude and percentage of Colorado River demand 

varies considerably across the states. Colorado and Arizona show the greatest magnitude of 

overall growth in Colorado River demand from 2015 through 2060 across the scenarios, ranging 

between about 0.2 and 1.2 maf of increased demand by 2060 in Arizona and 0.04 and 0.64 maf 

in Colorado. 

The broad demand range across scenarios in these states is due to substantial growth in M&I 

demand, particularly in central Arizona and the Front Range of Colorado. Increase in tribal 

demand is also a significant contributor to the increases in Arizona. Demand in Nevada and 

California is projected to increase by about 0.2 to 0.35 maf, due to population growth in Nevada 

and California (with supply currently limited by Colorado River Aqueduct capacity). Demand in 

New Mexico, Utah, and Wyoming grows by about 0.1 to 0.2 maf under most scenarios. Under 

the Rapid Growth (C1 and C2) scenarios, however, the growth is about 0.3 maf in Utah, where 

population is projected to increase by nearly 4 million and per capita water use reductions do not 

fully offset the rapid growth. 

When demand by category is examined in figure 10, the contribution of demand by category 

across the Upper and Lower Basins vary, with nearly equal agricultural and M&I demand in the 

Lower Basin and nearly two-thirds of the demand in the Upper Basin from agriculture. The 

category contribution to the total demand varies considerably across states as well, with no two 

states having comparable proportions of categories. 

Tribes hold quantified rights to a significant amount of water from the Colorado River and its 

tributaries (approximately 2.9 maf of annual diversion rights). In many cases, these rights are 

senior to other uses. Therefore, representing these rights and the associated demand is a critical 

component of assessing future water demand in the Basin. An additional component of future 

demand is an assessment of demands by tribes that have unquantified rights or claims. Where 

this information was provided by tribes, it was incorporated into the Study as appropriate. 

Throughout the Study, Reclamation met with tribes in the Upper Basin, Lower Colorado River 

mainstem, and tribes served by water provided (directly or pursuant to exchanges) through the 

CAP facilities under contracts between tribes and the United States. In addition, Reclamation 

worked with the Ten Tribes Partnership, whose members have landholdings in the Upper and 

Lower Basins through which the Colorado River and various tributaries flow, as well as the Inter 

Tribal Council of Arizona, whose members are the governments of 20 tribes with land in 

Arizona. Based on this input, tribal demand, under all scenarios for all states (with the exception 

of Colorado, where tribal demand was not separated from other demands within the state, as 

requested by the tribes) met or surpassed the quantified tribal right by 2060. Refer to Technical 

Report C – Water Demand Assessment, Appendix C9 – Tribal Water Demand Scenario 

Quantification for details of quantified rights and future projected demands by tribe.
Study Report

December 2012 SR-31

FIGURE 9 

Colorado River Water Demand1,2

1 Demands do not include Mexico’s allotment and losses such as reservoir evaporation. These factors were included in the 

modeling supporting the system reliability analysis.

2 Tribal demand in Colorado, at the request of the Southern Ute Indian and Ute Mountain Ute tribes, was not separated from other 

categories in the state.

Agricultural

Municipal and Industrial

Energy

Minerals

Fish and Wildlife and Recreation

Tribal

Category Legend (Right)

0

1

2

3

4

5

6

2015 2035 2060

KAF

Demand Legend

Current Projected (A) Slow Growth (B)

Rapid Growth (C1) Rapid Growth (C2)

Enhanced Environment (D1) Enhanced Environment (D2)

0.0

2.0

4.0

6.0

8.0

10.0

12.0

2015 2035 2060

MAF

Lower Basin

Tribal

Tribal

Tribal

Municipal and Industrial

Municipal and Industrial

Municipal and Industrial

Agricultural

Agricultural

Agricultural

201520352060

0.0

2.0

4.0

6.0

8.0

10.0

12.0

2015 2035 2060

MAF

Upper Basin

0.0

1.0

2.0

3.0

4.0

2015 2035 2060

MAF

Utah

0.0

1.0

2.0

3.0

4.0

2015 2035 2060

MAF

Nevada

0.0

1.0

2.0

3.0

4.0

5.0

6.0

2015 2035 2060

MAF

California

0.0

1.0

2.0

3.0

4.0

2015 2035 2060

MAF

New Mexico

0.0

1.0

2.0

3.0

4.0

2015 2035 2060

MAF

Colorado

0.0

1.0

2.0

3.0

4.0

2015 2035 2060

MAF

Wyoming

0.0

1.0

2.0

3.0

4.0

5.0

2015 2035 2060

MAF

Arizona

12.0

12.5

13.0

13.5

14.0

14.5

15.0

15.5

16.0

16.5

2015 2035 2060

Million Acre-Feet (MAF)

Colorado River Demand 

UPPER BASIN

LOWER BASIN
Colorado River Basin 

Water Supply and Demand Study

SR-32 December 2012

FIGURE 10

Colorado River Water Demand by Category1,2

 1 Demands do not include Mexico’s allotment and losses such as reservoir evaporation. These factors were included in the 

modeling supporting the system reliability analysis.

2 Tribal demand in Colorado, at the request of the Southern Ute Indian and Ute Mountain Ute tribes, was not separated from other 

categories in the state. 

0

2

4

6

8

10

12

MAF

Upper Basin

2015 2035 2060 0

2

4

6

8

10

12

MAF

Lower Basin

2015 2035 2060

0.0

1.0

2.0

3.0

4.0

MAF

Utah

2015 2035 2060

0.0

1.0

2.0

3.0

4.0

MAF

Nevada

2015 2035 2060

0.0

1.0

2.0

3.0

4.0

5.0

6.0

MAF

California

2015 2035 2060

0.0

1.0

2.0

3.0

4.0

5.0

MAF

Arizona

2015 2035 2060

0.0

1.0

2.0

3.0

4.0

MAF

New Mexico

2015 2035 2060

0.0

1.0

2.0

3.0

4.0

MAF

Colorado

2015 2035 2060

0.0

1.0

2.0

3.0

4.0

MAF

Wyoming

2015 2035 2060

Agricultural Municipal and Industrial

Energy Minerals

Fish and Wildlife and Recreation Tribal

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

Million Acre-Feet (MAF)

Colorado River Demand

2015 2035 2060

Tribal

Tribal

Tribal

Municipal and Industrial

Municipal and Industrial

Municipal and Industrial

Agricultural

Agricultural

Agricultural

201520352060

Six columns per time 

period represent six 

scenarios. From left to 

right: A, B, C1, C2, D1, D2

UPPER BASIN

LOWER BASIN
Study Report

December 2012 SR-33

Projected Effect of a Changing Climate on Future Demands

Future demands may be affected by a changing climate, primarily due to changes in ambient 

temperature and the amount and distribution of precipitation. The Study addressed possible 

effects of changing temperature and precipitation on evapotranspiration, which affects 

agriculture and outdoor M&I demand, and phreatophyte and reservoir evaporation losses. 

Possible changes in demand related to climate change not evaluated in the Study are changes in 

water demand for energy production, changes to environmental flow requirements associated 

with increasing ambient temperature, and changes in crop type.

As part of the hydrologic modeling for the Study, and to be consistent between the calculations 

used to generate water supply scenarios, a physically based method, Penman-Monteith, as 

implemented in the VIC model, was proposed to adjust agricultural, outdoor M&I demands, 

phreatophyte losses, and reservoir evaporation rates due to climate change. Details on the 

methods used to construct the climate index factors for adjusting demands and losses under 

climate change are provided in Technical Report C – Water Demand Assessment, Appendix C15 

– Climate Change Effects on Water Demand and Losses. The mean change in evapotranspirative 

demand is on the order of 4 percent by 2060, compared to demands without changes in climate. 

A total demand increase of more than 500 kaf per year by 2060 is estimated considering potential 

effects of climate change. These changes will evolve over time with a warming climate, and 

could be higher or lower depending on the climate projection, but the magnitude of the climate 

impact to demands is expected to be substantial. 

FIGURE 11

Current Projected (A) Scenario Demands Adjusted for Possible Future Climate Change
Colorado River Basin 

Water Supply and Demand Study

SR-34 December 2012

Figure 11 presents the factors as applied to the Current Projected (A) scenario demands 

excluding Mexico’s allotment, reservoir evaporation,16 and other losses.17 The thick black line 

represents projected demand under current climate; the thick red line represents the average 

annual demand as adjusted for the climate change scenarios and the other lines represent 

individual projections of future climate. 

6.0 Projected Future Supply and Demand Imbalances and 

System Reliability Metrics 

Using the projections of future water supply and demand identified through the scenario 

development and quantification process, the range of the projected total future supply and 

demand in the Basin is shown conceptually in figure 12. Although a range of future imbalances 

is plausible, when comparing the median of water supply projections to the median of the water 

demand projections, the long-term imbalance in future supply and demand is projected to be 

about 3.2 maf by 2060. 

FIGURE 12

Historical Supply and Use1 and Projected Future Colorado River Basin Water Supply and Demand1

1 Water use and demand include Mexico’s allotment and losses such as those due to reservoir evaporation, native vegetation, and 

operational inefficiencies.

 

16 Climate change effects on reservoir evaporation are adjusted dynamically through CRSS simulations.

17 Phreatophytes are included in the “other losses” category. Losses due to phreatophytes are adjusted for climate change using similar methods 

as those proposed for agricultural irrigation.
Study Report

December 2012 SR-35

It is important to recognize two points concerning this result. First, the 3.2 maf imbalance is 

based on the median imbalance for a particular year and can either be more or less from year to

year under any one of the projections. Second, single-year imbalances of this magnitude have 

occurred several times in the past. Although there have been shortages in supply in Upper Basin 

tributaries, Colorado River deliveries of basic apportionments in the Lower Basin have been 

made with 100 percent reliability, primarily as a result of the ability to capture water in system

reservoirs during high-flow years and to deliver that water during low-flow years. The system 

reliability analysis entailed simulating the operation of the system, including the effects to

reservoir storage, and provides detailed information regarding the specific timing and magnitude 

of potential imbalances and how the Basin resources may be affected. System reliability metrics, 

summarized in the following section, are measures that indicate these impacts. 

6.1 Summary of Technical Report D – System Reliability Metrics

System reliability metrics are measures that indicate the ability of the Colorado River system to 

meet Basin resource needs under multiple future conditions. These metrics were used to measure 

the potential impacts to Basin resources from future supply and demand imbalances and to 

measure the effectiveness of options and strategies to address those imbalances. 

6.1.1 Objective and Approach

A seven-step process was adopted to develop the metrics used in the system reliability analysis. 

This process is detailed in Technical Report D – System Reliability Metrics, particularly 

figure D-1. The process for developing system reliability metrics began with the identification of 

resource categories. Based on the Plan of Study (see appendix 1) and working closely with 

stakeholders through the Metrics Sub-Team, six resource categories were identified. Following 

the identification of the resource categories, several attributes of interest associated with each 

resource category were identified. 

6.1.2 Summary of Results 

Table 7 presents the six resource categories and corresponding attributes of interest. To further 

define system reliability metrics associated with attributes of interest, locations in the Basin were 

selected where metrics could offer information about the performance of the system. Metrics 

were evaluated in either a quantitative or qualitative fashion. A metric was evaluated 

quantitatively if: (a) direct evaluation was possible using output from CRSS or results from postprocessing of CRSS output data, or (b) an indirect indicator of the attribute of interest at the 

specified location could be developed, based on output from CRSS or post-processing of CRSS 

output data. 

The ability to assess impacts to Basin resources was limited by the spatial and temporal detail of 

CRSS. In these cases, system reliability metrics were either assessed in a qualitative manner or, 

where time and resources permitted, additional analysis was conducted to result in a quantitative 

assessment. The map in figure 13 displays the Study Area and denotes the locations of the 

metrics that were defined. The locations of the water deliveries metrics were not included 

because there were more than 200 locations throughout the Study Area, though the primary 

locations used in the system reliability analysis were deliveries to the Upper and Lower Basins. 
Colorado River Basin 

Water Supply and Demand Study

SR-36 December 2012

TABLE 7

Resource Categories and Attributes of Interest

Resource Category Attribute of Interest

Water Deliveries ● Consumptive Uses and Shortages

● Water Levels Related to Intake Facilities

● Socioeconomic Impacts Related to Shortages

Electrical Power Resources ● Electrical Power Generated

● Economic Value of Electrical Power Generated

● Available Generation Capacity

● Impact on Power Rates

Water Quality ● Salinity

● Sediment Transport

● Temperature

● Other Water Quality Attributes

● Socioeconomic Impacts Related to Salinity

Flood Control ● Flood Control Releases and Reservoir Spills

● Critical River Stages with Flooding Risk

Recreational Resources ● Shoreline Public Use Facilities

● River and Whitewater Boating

● Other Recreational Attributes

● Socioeconomic Impacts Related to Recreation

Ecological Resources ● Threatened and Endangered Species

● Aquatic and Riparian Habitats

● Wildlife Refuges and Fish Hatcheries

7.0 Options and Strategies to Resolve Supply and Demand 

Imbalances 

In November 2011, the Study began its fourth and final phase: Development of Options and 

Strategies to balance supply and demand. From November 2011 through February 2012, input 

was solicited from Study participants, interested stakeholders, and the general public on options 

and strategies for helping to resolve future water supply and demand imbalances in the Basin. 

Over this period over 150 options were submitted to the Study. 

This section describes the options that were received, the evaluation of those options, and the 

development of portfolios or packages of options that reflect different strategies for resolving 

future imbalances. 
Study Report

December 2012 SR-37

FIGURE 13

Study Area with Locations of Defined Metrics
Colorado River Basin 

Water Supply and Demand Study

SR-38 December 2012

7.1 Summary of Technical Report E – Approach to Develop and Evaluate 

Options and Strategies 

The approach toward developing and evaluating options and strategies to balance future supply 

and demand is described in Technical Report E – Approach to Develop and Evaluate Options 

and Strategies. The overall approach follows the assessment of plausible future water supply and 

demand scenarios described in Technical Reports A, B, and C, and the identification of system 

reliability metrics described in Technical Report D. The following steps were undertaken in this 

approach: 

• Evaluation of system reliability without options and strategies

• Characterization of system vulnerabilities

• Identification and characterization of options 

• Development of portfolios of options 

• Evaluation of system reliability with options and strategies

This approach consisted of a structured process for evaluating system reliability across the range 

of resources metrics, identifying options that could improve the reliability, development of 

combinations of options based on particular response strategies (portfolios), and evaluation of 

the improved system reliability with the application of these portfolios. The steps involving the 

evaluation of system reliability and vulnerability analysis are further outlined in Technical 

Report G – System Reliability Analysis and Evaluation of Options and Strategies. The steps 

involving the identification and characterization of options and the development of portfolios are 

described in Technical Report F – Development of Options and Strategies.

7.2 Summary of Technical Report F – Development of Options and Strategies

The general approach for the development of options and strategies involved the following steps: 

(1) soliciting input on options for consideration in order to examine a broad range of potential 

options, (2) organizing options into common types, (3) developing representative options from 

the pool of submitted options, (4) characterizing options using a set of 17 criteria that reflected a 

broad set of attributes of interest, and (5) developing portfolios that represent potential strategies 

to address future supply and demand imbalances. Details of the process and results for each of 

the steps are described in Technical Report F – Development of Options and Strategies and 

summarized below. 

7.2.1 Summary of Options Received

Options received were organized into four types: (1) those increasing Basin water supply, (2) 

those reducing Basin water demand, (3) those modifying operations, and (4) those focusing on 

Basin governance and implementation. 

A total of 55 options were submitted related to increasing supply, 42 options related to reducing 

demand, 22 options related to modifying operations, and 41 options related to governance and 

implementation. The percentage of options in each type is shown in the chart in figure 14. 
Study Report

December 2012 SR-39

FIGURE 14

Distribution of Options Received 

Within each of the four option types, categories of options, such as importation, desalination, and 

M&I conservation, etc. were developed. Each submitted option was assigned to one category 

based on its primary function. From these option categories, about 40 unique representative 

options were described to capture the range of options submitted to and considered in the Study. 

Subsequent sections summarize the option categories and describe representative options that 

were received and considered in the Study. 

7.2.2 Approach to Characterize Options

The Plan of Study identified specific objectives related to the development and evaluation of 

options. As the Study progressed, a definitive process for the characterization of options was 

developed. This process included the quantitative characterization of options through the 

assignment of ratings to a number of evaluation criteria. The process also included the qualitative 

characterization of options that did not directly increase supply or reduce demand. The 

qualitative characterization consisted of the identification of opportunities and constraints, 

including potential legal and regulatory issues. 

Option characterization was performed to describe each of the submitted options, provide a 

relative comparison of the option attributes, and support the eventual development of option and 

portfolio evaluations. Characterization of proposed options was based primarily on information 

provided by the option submitter; however, existing literature and/or relevant studies also were 

reviewed to support the characterization process. 

Characterization of the options was based on 17 evaluation criteria that are consistent with the 

criteria outlined in the Plan of Study, as summarized in table 8. These criteria are described more 

fully in Technical Report F – Development of Options and Strategies. 

34%

26%

14%

26%

Increase Supply

Reduce Demand

Modify Operations

Governance and 

Implementation
Colorado River Basin 

Water Supply and Demand Study

SR-40 December 2012

TABLE 8 

Criteria Used to Characterize Representative Options

Criteria Summary Description of Criteria

Quantity of Yield The estimated long-term quantity of water generated by the option—either an increase in 

supply or a reduction in demand

Timing Estimated first year that the option could begin operation 

Technical Feasibility Technical feasibility of the option based on the extent of the underlying technology or 

practices

Cost The annualized capital, operating, and replacement cost per af of option yield

Permitting Level of anticipated permitting requirements and precedence of success for similar 

projects

Legal Consistency with current legal frameworks and laws, or precedent with success in legal 

challenges

Policy Considerations Extent of potential changes to existing federal, state, or local policies that concern water, 

water use, or land management

Implementation Risk Risk of achieving implementation and operation of option based on factors such as 

funding mechanisms, competing demands for critical resources, challenging operations, 

or challenging mitigation requirements

Long-term Viability Anticipated reliability of the option to meet the proposed objectives over the long term

Operational Flexibility Flexibility of option to be idled from year to year with limited financial or other impacts

Energy Needs Energy required to permit full operation of the option, including treatment, conveyance, 

and distribution

Energy Source Anticipated energy source to be used to allow option to be operational

Hydropower Anticipated increases or decreases in hydroelectric energy generation associated with 

implementation of the option

Water Quality Anticipated improvements or degradation in water quality associated with implementation 

of the option

Recreation Potential impacts to recreational activities including in-river and shoreline activities

Other Environmental 

Factors

Other environmental considerations, such as impacts to air quality, or aquatic, wetland, 

riparian, or terrestrial habitats

Socioeconomics Potential impacts to socioeconomic conditions in regions within or outside the Basin as a 

result of implementing the option

In general, each option was provided with a five-point rating (“A” through “E”) for each of the 

criteria. “A” generally represented the most favorable rating and “E” represented the least 

favorable. 

The cost criterion includes capital and annual costs expressed in terms of unit costs in present 

value dollars per acre-foot. All costs presented were developed based on annualized capital costs 

added to annual operation and maintenance (O&M) costs divided by the annual yield of the 

option. 
Study Report

December 2012 SR-41

7.2.3 Summary of Option Characterization

Importation

River and other out-of-Basin freshwater imports have been proposed to increase the overall 

water supply of the Basin. Fifteen options related to river or other freshwater imports were 

received. The submitted options were reviewed and organized into three groups according to the 

location at which the imported water would provide water to the Colorado River or would 

provide exchange water for regions reliant upon Colorado River supplies. 

One group consists of options for importing water from the Missouri River or Mississippi River 

to areas adjacent to the Basin that could use this water to meet projected shortfalls and/or reduce 

the amount of water these areas divert from the Basin. Water would be conveyed to the Front 

Range of Colorado and specific areas of New Mexico and integrated into existing water supply 

systems. Although these options are termed “imports,” water would not actually be imported into 

the Basin. Rather, water would be delivered to these adjacent areas to reduce the amount of water 

that could be exported from the upper Colorado and San Juan rivers.

The second group of options includes diverting water from the upper headwaters of rivers 

adjacent to the Green River to the headwaters of the Green River. Potential sources of supply are 

diversions from the Bear River, upper Snake River, or Yellowstone River. 

The third group consists of options that focus on importing high-quality water from other regions 

using ocean routes to Southern California coastal areas. Potential sources of water include the 

Columbia River18, rivers in Alaska, or icebergs. Delivery mechanisms include sub-ocean 

pipelines for Columbia River supplies, tanker ships for Alaskan river supplies, or tug boats for 

icebergs. All of the options in this group require extensive transport or conveyance of water from 

the source regions to Southern California and require relatively complex facilities and operations 

to integrate the supply within the current water supply system in Southern California. 

Desalination 

Ocean and brackish water desalination has been proposed to increase the overall water supply of 

the Basin. Fifteen options related to desalination were received. The submitted options were 

reviewed and organized into three groups according to the source of water to be desalinated. 

The first group consists of constructing new or expanding existing (or currently proposed) ocean 

desalination plants in strategic locations along the southern California coast or near the 

international boundary with Mexico. This concept also includes constructing new ocean 

desalination plants along the Gulf of California, Mexico. For both the Pacific Ocean and Gulf of 

California desalination plants, water users downstream would use desalted water in lieu of 

Colorado River water. Thus there would be less water diverted and/or released from Lake 

Havasu, the benefits of which would be seen up the river system to Lake Mead and possibly 

beyond to Lake Powell. 

The second group of options includes constructing new diversions upstream of the Salton Sea on 

the New and Alamo rivers that would capture agricultural drainage water and deliver it to a 

regional brackish water desalination facility. The desalinated water would be delivered back to 

 

18 Among the more than 150 options submitted to Reclamation as responsive to the Plan of Study, additional importation of water supplies from 

various sources, including importation of water from the Snake and Columbia River systems, were submitted to the Study. Such options were 

appropriately reflected in the Study but did not undergo additional analysis as part of a regional or river basin plan or any plan for a specific 

Federal water resource project. This Study is not a regional or river basin plan or proposal or plan for any Federal water resource project.
Colorado River Basin 

Water Supply and Demand Study

SR-42 December 2012

the All American Canal and exchanged for an in-kind amount of reduction in diversions from the 

Colorado River at Imperial Dam.

The third group consists of options for desalination of brackish water in Southern California and 

Arizona consistent with past similar projects, and also refurbishing the Yuma Desalting Plant to 

allow full-scale production. 

Reuse

Reuse of existing water supplies was proposed as a method of increasing overall water supply in 

the Basin. Eleven options were submitted related to wastewater reuse. The submitted options 

were reviewed and organized into three groups. Representative options were developed for each 

option group to represent the distinct nature of the options within each group. 

The first group of options related to various methods of reuse of municipal wastewater in major 

urban areas. Municipal wastewater reuse considers new and expanded programs for non-potable 

purposes such as irrigation and also for potential potable purposes through indirect or direct 

methods. 

The second group consisted of the reuse of industrial wastewater that is not traditionally 

discharged through municipal wastewater systems. 

The third group consisted of reuse of grey water at individual homes or communities for nonpotable purposes. Grey water is typically defined as untreated wastewater that has not been 

contaminated by any toilet discharge, has not been affected by unhealthy bodily wastes, and does 

not present a threat from contamination by unhealthful processing, manufacturing, or operating 

wastes (California Building Standards Commission, 2010). 

Local Supply

Developing new local supply was proposed to increase the overall water supply of the Basin. 

Four options related to local supply were received. The submitted options were reviewed and 

organized into two groups according to the source of local supply. 

In the process of developing natural gas resources, poor-quality groundwater is typically 

“produced” from natural gas wells. The coal bed methane industry has generally disposed of 

produced water at the least possible cost rather than treat and use this potential resource. In most 

cases, coal bed methane-produced waters are disposed by injection into Class II underground 

injection wells. This group of options considers treating the relatively high-salinity water and 

using it to augment supply in the Basin.

Rainwater harvesting is the capture, diversion, and storage of rainwater for landscape irrigation 

and other uses. This option group considers how individual household rainwater harvesting can 

increase local supply throughout the Basin, with particular emphasis on those areas that do not 

return flows to other users downstream. Rainwater harvesting is not legally permitted in 

Colorado, and this state-specific issue was recognized within the Study.

Watershed Management

Changes to watershed management were proposed to increase the overall water supply of the 

Basin. Ten options related to watershed management were received. The submitted options were 

reviewed and organized into five groups according to the specific type of watershed management 

recommendations. 
Study Report

December 2012 SR-43

Control of invasive tamarisk has been proposed for riparian areas to reduce the overall 

consumptive use and increase streamflow in the Colorado River. Removal of tamarisk is 

proposed on riparian benches where water that would have otherwise contributed to streamflow 

is being consumptively used by tamarisk. 

A large percentage of the runoff from the Basin is derived from forests, particularly in Colorado. 

Previous studies and information have demonstrated that areas in which forest cover is reduced 

by clear-cutting or fires have shown dramatically increased amounts of runoff. The forest 

management group of options would entail the replacement of mature forests that have been 

cleared by harvesting, fires, or insect infestations with stands of replacement growth more likely 

to be favorable for generating runoff. 

Brush control involves reducing brush and therefore reducing consumptive use by vegetation 

communities. The brush control group of options recommends various techniques available for

brush removal, including chemical spraying, chaining, roller chopping, root plowing, grubbing, 

and controlled fires. 

Dust control options propose to control land-based dust sources that contribute to dust 

accumulation on snow, which changes the albedo, or reflectivity, of the snow resulting in earlier 

snowmelt (Painter et al., 2007, 2010, and 2012; Skiles et al., 2012) and more evaporative 

moisture losses. By implementing measures to reduce the accumulation of dust on snow, lower

evaporative losses are anticipated. 

Weather modification was proposed for increasing precipitation in Basin. Cloud seeding is the 

most prominent method considered for weather modification. In particular, the seeding of clouds 

with silver iodide to serve as condensation nuclei can increase snowfall over mountainous 

regions. Winter cloud seeding operations have been in operation throughout the West since the 

late 1940s. In recent years, ongoing cloud seeding operations have been documented in at least 

five of the seven Basin States. 

Municipal and Industrial Water Conservation

Development of additional M&I water conservation was proposed to further reduce the overall 

M&I water demand in areas currently relying upon water supply from the Colorado River. 

Twenty-nine M&I conservation options were submitted for consideration in the Study, with 

several of the submitted options suggesting specific conservation measures. 

Because levels of current and future conservation vary throughout the Study Area, different 

levels of potential savings are possible for a given conservation measure. These savings range 

from essentially no savings where measures have been fully enacted to significant savings where 

measures have not been enacted or where adoption rates are relatively low. Disaggregating the 

savings potential by conservation measure and individual location was beyond the scope of the 

Study. Instead, M&I conservation measures were considered for the entire Study Area with the 

acknowledgement that, despite state and regional differences in current levels of conservation 

and potential for future conservation, some additional conservation is achievable on a Study 

Area-wide basis. 

In order to examine the potential for additional M&I conservation and to explore the range of 

costs and other factors, three levels of conservation were considered based on assumed levels of 

reductions and adoption rates for residential indoor, commercial-institutional-industrial, 

landscape, and water loss. Conservation considered in the demand scenarios ranged from about 
Colorado River Basin 

Water Supply and Demand Study

SR-44 December 2012

300 kaf per year to more than 1.1 million acre-feet per year (mafy) in 2060, depending on the 

assumptions within each scenario regarding the degree of per capita water demand reductions19. 

Additional conservation beyond that included in the demand scenarios was considered in three 

additional conservation levels (Level 1, 2, and 3) that generate up to a range of 0.7 to 1.3 maf of 

additional water savings in 2060, depending on the demand scenario. The potential savings of the 

options would be small in the early years of implementation and grow over time. 

Agricultural Water Conservation

Options were submitted proposing agricultural water conservation to reduce the overall water 

demand in areas currently relying upon water supply from the Colorado River. These options 

ranged in type from specific conservation mechanisms or best management practices

(e.g., improved irrigation efficiencies, modernization, conveyance system efficiencies, changes 

in types of crops under irrigation) to general implementation approaches to achieve further water 

conservation (e.g., water pricing or water transfers). 

The concepts received were first organized into six Basin-wide agricultural water conservation 

mechanisms that reflect different types of activities that could generate water savings in the 

agricultural sector. These agricultural water conservation measures consist of advanced irrigation 

scheduling, deficit irrigation, on-farm irrigation system improvements, controlled environment 

agriculture, conveyance system efficiency improvements, and fallowing of irrigated lands. 

Because the method of implementation is important for realization of water savings, two 

implementation approaches that could be used to encourage or incentivize adoption of these 

water conservation mechanisms were considered: 

(1) Basin-wide agricultural conservation through a federal or state incentivized program to 

encourage agricultural water use efficiency and, 

(2) Basin-wide agricultural conservation with water transfers on a willing transferor-willing 

transferee basis that promotes water conservation and/or short-term or permanent fallowing of 

irrigated lands to transfer conserved water for a similar or different use.

For purposes of the Study, each of the various conservation measures was examined as a Basinwide potential, but in reality the measures will have important regional limitations and in some 

cases may be mutually exclusive. The various measures should not be considered as additive. 

Because the conservation measures could produce different amounts of savings depending on the 

location in the Basin, implementation approach, and combination of measures, the total 

quantities were estimated as an aggregate for each implementation approach. Up to 1 mafy of 

potential savings by 2060 was considered for each approach (conservation and conservation with 

transfers) although the approaches are not considered additive. The 1 mafy of potential savings 

recognizes an amount of additional water conservation above and beyond the significant existing 

and future water conservation programs that are already included in the Study’s demand 

scenarios. 

Energy Water Use Efficiency

Options to improve the water use efficiency of the energy sector have been proposed to reduce 

the water demand of the Basin. Four options related to energy water use efficiency were 

 

19 The level of M&I conservation included in the water demand scenarios was estimated by first re-computing the M&I demands under each 

scenario assuming the 2015 gallons per capita per day value from that scenario. The difference in the M&I demand in 2060 with gallons per 

capita per day held at 2015 levels from the M&I demand in 2060 under the actual demand scenario is the amount of M&I conservation 

achieved under that demand scenario. 
Study Report

December 2012 SR-45

received. The submitted options were reviewed and organized into two groups according to the 

different concepts proposed for reducing water demand. 

The first group of options includes removing the evaporative cooling systems at the 15 largest 

power plants in the Basin and installing air-cooling systems. The second group of options 

addresses the need for a reliable water source for oil and gas development, and suggests options 

for ensuring sufficient supplies through a number of improved efficiency measures. 

System Operations 

Options dealing with modified system operations have been proposed to increase the overall 

water supply, decrease demand, reduce evaporation losses, and improve efficiency within the 

Basin. The submitted options were reviewed and organized into three option groups according to 

the overarching concept driving the new or modified operation. 

The first group includes physical and chemical methods to reduce evaporation from the major 

canals and reservoirs. Physical covers would incorporate solar photovoltaic panels to 

simultaneously reduce evaporation and generate electricity, and concepts involving chemical 

covers include the introduction of a chemical to the water surface of large reservoirs to reduce 

the evaporation rates of the reservoirs. 

The second group proposed new water storage to increase the amount of system storage available 

for either hydropower optimization or capture of water released but not diverted. It also included 

improved groundwater management. 

The third group of options consists of recommendations for changing current reservoir 

operations in the Basin to improve water management. These options consist of reoperation to 

reduce reservoir evaporation, maximize hydropower generation, or improve environmental 

conditions. 

Water Transfers, Exchanges, and Banking 

Water transfers, exchanges, and banking have been proposed to increase the efficient use of 

existing supplies in the Basin. This group consists of options that are reflected in the following 

representative options: water transfers and exchanges, guided water markets, Upper Basin water 

banking, Lower Basin water banking, and groundwater banking. 

Because of their complexity and the inability to develop representative options indicative of all 

water banking or transfer-type options, these options have not been assigned ratings for the 

17 criteria. Water transfers and banking options generally require working in conjunction with 

conservation options (agricultural or M&I) in order to generate the water to be transferred or 

banked. 

The guided water markets option would attempt a strategic, guided approach to transactions that 

could be used proactively to meet demand reduction goals to reduce the risk for Lee Ferry 

deficit. Another option proposes that a similar concept to the Intentionally Created Surplus (ICS) 

program in the Lower Basin be applied in the Upper Basin. This option creates an Upper Basin 

water bank in either Lake Powell or in an off-stream groundwater bank to increase protection 

against a Lee Ferry deficit in extremely dry conditions. 

The 2007 Interim Guidelines (DOI, 2007) implemented an ICS mechanism to provide for the 

creation, accounting, and delivery of conserved system and non-system water, thereby promoting 

water conservation in the Lower Basin. The ICS mechanism allows for conserved water in the 

Lower Basin to be stored in Lake Mead for subsequent delivery in future years. Several options 
Colorado River Basin 

Water Supply and Demand Study

SR-46 December 2012

suggested continuing this program beyond the expiration of the 2007 Interim Guidelines in 2026 

and expanding or modifying it to include participants beyond entitlement holders to Colorado 

River mainstem water in the Lower Basin, including Mexico20. 

Finally, some options focused on using groundwater recharge and recovery as an underground 

water bank. An entity could divert water to groundwater storage when there is a surplus or 

reduced need for surface supplies. When there is a critical or increased need for additional 

supply, the entity could then withdraw an equivalent amount of water that it previously banked 

subject to withdrawal limits. This concept is already used in several areas of the Lower Basin. 

Water Management and Allocation

Options were submitted that suggested modifications to Basin water management processes and 

changes in the distribution of water supply available in the Basin under the Law of the River. 

There are four representative options in this group: changes to apportionment of water supply, 

processes for expanded stakeholder involvement, population control, and conservation and trust 

funds. These options suggested modified methods for governing or managing water supply and 

demand in the Basin. Although these have been included in the Study for completeness and 

continued dialogue, mechanisms currently exist for flexible operations without destabilizing the 

Law of the River or triggering lengthy legal battles that would inevitably occur with any attempt 

to re-allocate the river. 

Tribal Water

Tribes hold quantified rights to a significant amount of water from the Colorado River and its 

tributaries (approximately 2.9 maf of annual diversion rights). In many cases, these rights are 

senior to other users. Options pertaining to water development and use were submitted by tribes 

for consideration in the Study and include concepts such as voluntary tribal water transfers, tribal 

water storage and ICS, convening of an inter-governmental forum, resolution of tribal claims, 

affordability of tribal water and removing barriers to tribal participation in federal programs, 

recognition limits to reduce demand, stabilization of soil, and development of non-tributary 

groundwater. Recalmation will work with tribes in future efforts regarding tribal water issues 

reflected in this report.

Data and Information 

Options were submitted that suggested improvements to the data and information used by 

Reclamation for analysis and modeling. These options involved improved water use accounting 

in the Upper Basin and additional improvements to CRSS. Reclamation is committed to working 

with the Basin States, interested stakeholders, and the USGS to improve water use accounting 

and to refine CRSS and other supporting models where it is feasible and useful in order to 

provide the most realistic representation of how the system is currently operated or may be 

operated in the future. 

Summary of Characterization Ratings 

For each of the quantified options developed for the Study, characterization ratings were 

assigned based on the 17 evaluation criteria. The characterization provided a relative comparison 

of the option attributes and supported the analysis of options and development of portfolios. 

 

20 On November 20, 2012, Minute 319 was signed, which created a mechanism for Mexico to store water in Lake Mead, called Intentionally 

Created Mexico Allotment. This is a temporary agreement, however, and the long-term implementation of such a mechanism is subject to 

future Minutes. 
Study Report

December 2012 SR-47

Three of the evaluation criteria were developed with both numeric values as well as letter rating: 

cost, quantity of yield, and timing. 

Table 9 summarizes the potential yield for each of the main option groups in 2035 and 2060. A 

total of 7.6 mafy of potential yield was identified for options that increase supply. The options 

with greatest yield of this type are related to watershed management methods, desalination of 

ocean and brackish water, importation, and reuse. A total of 2.2 mafy of potential savings was 

identified through options that reduce demand. The principal options that comprise this type are 

agricultural water conservation, M&I water conservation, and energy water use efficiency.

Potential savings totaling 1.2 maf y were identified under the options that modify system 

operations and primarily reflect reducing reservoir or canal evaporation through physical or 

chemical covers, or through preferential reservoir storage. When considering all options and all 

categories by 2060, a total of over 11 mafy in potential yield was identified. The potential yield 

is approximately 5.7 maf y by 2035; however, not all options are equally feasible or reliable in 

the long term. Many options such as imports to southern California or some watershed 

management options are uncertain from both a technical feasibility and reliability standpoint. By 

excluding options that were rated low for these factors (“D” and “E”), the total potential yield 

was reduced to approximately 3.7 mafy by 2035 and to approximately 7 mafy by 2060. 

The cost, yield, and timing of the representative options are shown in figure 15 (sorted based on 

cost). Some of the least-cost options are related to weather modification and chemical covers, but 

these have considerable uncertainty related to their long-term viability and implementation risk. 

Agricultural water conservation, M&I water conservation, watershed management methods, 

smaller import options, and brackish water desalination projects represent the next-leastexpensive set of options. Larger desalination, reuse, and importation projects are estimated to 

have higher costs, but still be substantially less than distributed rainwater harvesting and grey 

water reuse options, and canal and reservoir covers. 

In addition to cost, yield, and timing, each option was provided with a five-point rating (“A” 

through “E”) for the remaining 14 criteria. A rating of “A” generally represents the most 

favorable rating and “E” the least favorable. Figure 15 summarizes the resulting ratings for each 

of the option categories and groups. In some cases, multiple ratings are shown in this figure due 

to the assessment of large-scale options into smaller increments to capture the varying degree of 

difficulty of implementing larger options or degree of potential impacts. In general, options that 

improved the water use efficiency (conservation and reuse) were rated higher than other options 

for most of the criteria. Options such as importation, desalination, and reuse were rated favorably 

for technical feasibility and long-term viability risks, but less favorably for environmental 

criteria because of their greater energy needs and potential impacts to source or discharge areas. 

Most watershed management options, although potentially yielding significant new supply, were 

rated poorly for technical feasibility and long-term viability because of the unproven reliability 

of application of many of these techniques on the scale envisioned for the Basin. 
Colorado River Basin 

Water Supply and Demand Study

SR-48 December 2012

TABLE 9

Summary of Option Cost and Potential Yields by 2035 and 2060

Option 

Category Option Group

Estimated 

Cost

($/afy)

Years 

Before 

Available

Potential 

Yield by 

2035 (afy)

Potential 

Yield by 

2060 (afy)

Desalination Gulf of California 2,100 20–30 200,000 1,200,000

Pacific Ocean in California 1,850–2,100 20–25 200,000 600,000

Pacific Ocean in Mexico 1,500 15 56,000 56,000

Salton Sea Drainwater 1,000 15–25 200,000 500,000

Groundwater in Southern 

California

750 10 20,000 20,000

Groundwater in the Area near 

Yuma, Arizona

600 10 100,000 100,000

Subtotal 776,000 2,476,000

Reuse Municipal Wastewater 1,500–1,800 10–35 200,000 932,000

Grey Water 4,200 10 178,000 178,000

Industrial Wastewater 2,000 10 40,000 40,000

Subtotal 418,000 1,150,000

Local Supply Treatment of Coal Bed MethaneProduced Water2,000 10 100,000 100,000

Rainwater Harvesting 3,150 5 75,000 75,000

Subtotal 175,000 175,000

Watershed 

Management

Brush Control 7,500 15 50,000 50,000

Dust Control 220–520 15–25 280,000 400,000

Forest Management 500 20–30 200,000 300,000

Tamarisk Control 400 15 30,000 30,000

Weather Modification 30–60 5–45 700,000 1,700,000

Subtotal 1,260,000 2,480,000

Importation Imports to the Colorado Front 

Range from the Missouri or 

Mississippi Rivers

1,700–2,300 30 0 600,000

Imports to the Green River from 

the Bear, Snake1

, or 

Yellowstone Rivers

700–1,900 15 158,000 158,000

Imports to Southern California 

via Icebergs, Waterbags, 

Tankers, or from the Columbia 

River1

2,700–3,400 15 600,000 600,000

Subtotal 758,000 1,358,000

M&I Water 

Conservation

M&I Water Conservation 500–900 5–40 600,000 1,000,000

Subtotal 600,000 1,000,000
Study Report

December 2012 SR-49

TABLE 9

Summary of Option Cost and Potential Yields by 2035 and 2060

Option 

Category Option Group

Estimated 

Cost

($/afy)

Years 

Before 

Available

Potential 

Yield by 

2035 (afy)

Potential 

Yield by 

2060 (afy)

Agricultural 

Water 

Conservation

Agricultural Water Conservation 150–750 10–15 1,000,000 1,000,000

Agricultural Water Conservation 

with Transfers 

250–750 5–15 1,000,000 1,000,000

Subtotal 1,000,0002 1,000,0002

Energy Water 

Use Efficiency

Power Plant Conversion to Air 

Cooling

2,000 10 160,000 160,000

Subtotal 160,000 160,000

System 

Operations

Evaporation Control via Canal 

Covers

15,000 10 18,000 18,000

Evaporation Control via 

Reservoir Covers

15,000 18 200,000 200,000

Evaporation Control via 

Chemical Covers on Canals and 

Reservoirs

100 15–25 200,000 850,000

Modified Reservoir Operations Unknown 15 0 – 300,000 0 - 300,000

Construction of New Storage 2,250 15 20,000 20,000

Subtotal 588,0003 1,238,0003

Total of All Options 5,735,0004 11,037,0004

1

Among the more than 150 options submitted to Reclamation as responsive to the Plan of Study, additional importation of water 

supplies from various sources, including importation of water from the Snake and Columbia River systems, were submitted to the 

Study. Such options were appropriately reflected in the Study but did not undergo additional analysis as part of a regional or river 

basin plan or any plan for a specific Federal water resource project. This Study is not a regional or river basin plan or proposal or 

plan for any Federal water resource project

2 The two agricultural water conservation representative options derive potential yield from similar measures and are thus not 

additive

3 Subtotal assumes 150,000 afy for the Modified Reservoir Operations representative option. 

4 Total does not account for several options that may be mutually exclusive due to regional integration limitations or are dependent 

on the same supply.

7.2.4 Development of Portfolios 

Based on the results of the characterization and development of representative options, various 

representative options were combined into portfolios representing different potential adaptation 

strategies. The Study developed four exploratory portfolios to reflect different strategies for 

selecting and combining options to address imbalances between water supply and water demand. 

Each portfolio consists of a unique selection of options to address vulnerabilities (e.g., declining 

Lake Mead pool elevation) that may exist under future combinations of supply and demand. 
Colorado River Basin 

Water Supply and Demand Study

SR-50 December 2012

FIGURE 15 

Summary of Options Characterization Ratings (aggregated by option groups)

Agricultural (Ag), Upper Basin (UB), Lower Basin (LB), Municipal and Industrial (M&I), Modification (Mod), Desalination (Desal), Southern California (SoCal)

Technical Environmental Social Other
Study Report

December 2012 SR-51

Using the ratings associated with the criteria, preferences were expressed that resulted in two 

portfolios, Portfolio B and Portfolio C. Two other portfolios were then added, Portfolio A which 

represents a highly inclusive strategy (includes all options in either Portfolio B or Portfolio C) 

and Portfolio D, which represents a highly selective strategy (includes only options in both 

Portfolio B and Portfolio C). Portfolio B includes options with high technical feasibility and 

long-term reliability, but excludes options with the highest permitting, legal, policy, or long-term 

viability risks. Portfolio B also excludes any options that cost more than $2,500 per af. Portfolio 

C focuses on options that are also highly feasible, but excludes options that could have greater 

environmental impacts. This portfolio excludes options that cost more than $4,200 per af. The 

schematic in figure 16 shows the relationships of the options included in the Study portfolios. 

FIGURE 16 

Schematic Representing Options Included in the Study Portfolios

Portfolio A 

Portfolio A includes options with high technical feasibility, excludes options with highest 

permitting, legal, policy, and long-term viability risks. This portfolio includes options that are 

included in both Portfolio B and Portfolio C. This portfolio also includes the Upper Basin water 

bank concept that is described in Portfolio C. Portfolio A includes the largest number of options 

and option types of the four portfolios. This portfolio is the least restrictive in terms of options. 

Portfolio B 

Portfolio B is based on a strategy that seeks long-term water supply reliability through 

implementation of options with high technical feasibility and long-term reliability. The strategy 

can be defined as one that seeks options with proven technology and that, once in place, will 

produce reliable long-term yield. The strategy represents a low-risk strategy in the long-term, 
Colorado River Basin 

Water Supply and Demand Study

SR-52 December 2012

but may consider greater risk with respect to permitting and implementation. However, this 

portfolio excludes options with the highest permitting, legal, and policy risks. The portfolio 

includes a blend of options that increase supply and those that decrease demand. Water 

conservation and a variety of desalination options are included in the near-term (first 25 years) 

and imports and expansion of reuse programs dominate the longer-term options. 

Portfolio C 

Portfolio C focuses on options that are technically feasible but also have low environmental 

impacts—low energy needs, lower carbon energy sources, low permitting risk, and low impacts 

to other environmental factors. This portfolio also avoids options that are potentially unfavorable 

to recreational interests. In addition, this portfolio excludes options with the highest permitting, 

legal, and policy risks. The portfolio includes significant conservation in the near term and relies 

on reuse and watershed management rather than desalination and imports to augment supplies in 

the longer-term. In addition to options that either reduce demand or increase supply, the portfolio 

also includes a mechanism to transfer water conserved in Upper Basin through M&I, agricultural 

water conservation, and energy water use efficiency, to a conceptual Upper Basin water bank. 

Water is stored in the water bank until needed to be released in order to avoid Lee Ferry deficit21

conditions. 

Portfolio D 

Portfolio D includes only those options included in both Portfolio B and Portfolio C. Significant 

options not included in this portfolio are several desalination options and imports from the 

Missouri River. In addition to containing less potential yield than other portfolios, Portfolio D

also includes the fewest number of options. 

In developing each of the unique portfolios, a set of preferences regarding the characteristics of 

options, as defined by the criteria ratings, was defined. These preferences defined the particular 

strategy of the portfolio. The Options and Strategies Sub-Team assisted in the development of 

the four portfolios by identifying general strategies, option criteria preference sets, and reviewing 

draft portfolios. Adjustments to portfolios were made to either include or exclude specific 

options or to specify that an option is to be implemented as soon as available based on input from 

the Options and Strategies Sub-Team members. The option criteria preferences included in each 

portfolio are shown in table 10. 

7.2.5 Portfolio Comparison

The four portfolios represent different exploratory approaches for addressing the projected 

imbalances between water supply and demand. These portfolios were developed in conjunction 

with the Options and Strategies Sub-Team, but should not be considered as individual suggestive 

pathways. Rather, they were developed to explore the range of options, different preferences for 

option characteristics, and different levels of option inclusion. Table 11 provides a high-level 

comparison of the options that were either included in all portfolios, included in some but not all 

portfolios, and those options that were not included in any portfolio. As the table shows, high 

levels (above 400 kaf) of Gulf of California and Pacific Ocean desalination options, the most 

complex import options, reservoir and canal covers, and many of the watershed management 

 

21 Article III(d) of the Colorado River Compact stipulates that the Upper Division States will not cause the flow of the river at the Lee Ferry 

Compact Point to be depleted below an aggregate of 75 maf for any period of 10 consecutive years. For the purpose of the Study, a Lee Ferry 

deficit is defined as the difference between 75 maf and the 10-year total flow arriving at Lee Ferry.
Study Report

December 2012 SR-53

options were not selected for inclusion in any of the portfolios. Only 12 options are included in 

some but not all portfolios. These included ocean desalination options, imports from the 

Missouri River, expensive options related to local distributed supply or reuse development such 

as rainwater harvesting and grey water reuse, and watershed management options such as 

tamarisk control and dust management. 

TABLE 10

Option Criteria Preferences for the Study Portfolios

Criteria 

Category Option Criteria

Portfolio 

Portfolio A Portfolio B Portfolio C Portfolio D

Technical Technical 

Feasibility

Excludes 

D & E

Excludes 

D & E

Excludes 

D & E

Excludes 

D & E

Implementation 

Risk

All All All All 

Long-term 

Viability

Excludes E Excludes 

D & E

Excludes E Excludes 

D & E

Operational 

Flexibility

All All All All 

Environmental Permitting Excludes E Excludes E Excludes 

D & E

Excludes 

D & E

Energy Needs All All Excludes 

D & E

Excludes 

D & E

Energy Source All All Excludes E Excludes E 

Other 

Environmental 

Impacts

All All Excludes 

D & E

Excludes 

D & E

Social Recreation All All Excludes 

D & E 

Excludes 

D & E

Legal Excludes E Excludes E Excludes E Excludes E 

Policy Excludes E Excludes E Excludes E Excludes E 

Socioeconomics All All All All 

Other Hydropower All All All All 

Water Quality All All All All 

Cost < $4,200/af < $2,500/af < $4,200/af < $2,500/af

A rating of “A” generally represents the most favorable rating and “E” the least favorable. For example, a rating of “E” 

for technical feasibility indicates those options with the lowest scoring in terms of feasibility. A rating of “E” for 

permitting indicates those options with extremely challenging permitting requirements.
Colorado River Basin 

Water Supply and Demand Study

SR-54 December 2012

TABLE 11

Summary of Option Inclusion Across the Study Portfolios

Option 

Category Option Group

Portfolios 

Portfolio A Portfolio B Portfolio C Portfolio D

Importation Imports to the Colorado 

Front Range from the 

Missouri or Mississippi

Rivers

X X 

Imports to the Green River

from the Bear, Snake, or 

Yellowstone Rivers

Imports to Southern 

California via Icebergs, 

Waterbags, Tankers, or 

from the Columbia River

Desalination Gulf of California Up to 400 kaf Up to 400 kaf

Pacific Ocean in California Up to 400 kaf Up to 400 kaf

Pacific Ocean in Mexico X X 

Salton Sea Drainwater X X X X 

Groundwater in Southern 

California

X X X X 

Groundwater in the Area 

near Yuma, Arizona

X X X X 

Reuse Municipal Wastewater X X X X 

Grey Water X X 

Industrial Wastewater X X X X 

Local Supply Treatment of Coal Bed 

Methane-Produced Water

X X 

Rainwater Harvesting X X 

Watershed 

Management

Brush Control

Dust Control X X 

Forest Management

Tamarisk Control X X 

Weather Modification Up to 300 kaf Up to 300 kaf Up to 300 kaf Up to 300 kaf

M&I Water 

Conservation

M&I Conservation X X X X 

Agricultural 

Water 

Conservation

Agricultural Water 

Conservation

Agricultural Water 

Conservation with Transfers 

X X X X 
Study Report

December 2012 SR-55

TABLE 11

Summary of Option Inclusion Across the Study Portfolios

Option 

Category Option Group

Portfolios 

Portfolio A Portfolio B Portfolio C Portfolio D

Energy Water 

Use Efficiency

Power Plant Conversion to 

Air Cooling

X X X X 

System 

Operations

Evaporation Control via 

Canal Covers

Evaporation Control via 

Reservoir Covers

Evaporation Control via 

Chemical Covers on Canals 

and Reservoirs

Modified Reservoir 

Operations

Construction of New

Storage

Water Banking Upper Basin Water Bank X X 

The differences in the selection or inclusion of options in the portfolios also influenced the total 

potential yield and implementation cost. Figure 17 shows the potential yield of the four 

portfolios over time for three different limits on the portfolio average cost. On the right, the 

portfolios are essentially unconstrained by cost (average costs less than $1,250 per af). Not 

surprisingly, Portfolio A has the highest potential yield (~6.3 maf) and Portfolio D has the lowest 

potential yield (~4.0 maf). Portfolio B and Portfolio C yields are similar through 2042. At that 

point, Portfolio B yield increases significantly more than Portfolio C. For lower average costs, 

the differences between the four portfolios are less significant (figure 17, left and middle ), 

particularly between Portfolio B and Portfolio C. 

The four portfolios considered in the Study represent different potential strategies for 

dynamically addressing system vulnerabilities that may develop in the future. Because there are 

many more strategies than could be evaluated in the Study, the portfolios should be considered 

exploratory. The primary focus of the portfolio development and subsequent evaluation in the 

Study was to establish the range of responses, types of options that may be considered for 

implementation, their effectiveness at addressing vulnerabilities, and the range of cost and other 

attributes resulting from different portfolio implementations. 
Colorado River Basin 

Water Supply and Demand Study

SR-56 December 2012

FIGURE 17 

Total Yields over Time for Average Costs less than $750/af (left), less than $1,000/af (middle), and less than $1,250/af (right) for 

Portfolios 

8.0 Evaluation of Options and Strategies to Resolve Supply 

and Demand Imbalances

Potential future Basin supply and demand imbalances suggest that some course of action will be 

required to improve the reliability of the system to meet the stresses on the Basin resources.

From solicitation of public input, over 150 options to help improve or maintain Basin resource 

reliability were received, many aimed at closing the supply and demand imbalance. The purpose 

of Technical Report G – System Reliability Analysis and Evaluation of Options and Strategies

was to assess the effectiveness of those options at improving the reliability of the system to meet 

Basin resource needs. 

8.1 Summary of Technical Report G – System Reliability Analysis and 

Evaluation of Options and Strategies

8.1.1 System Reliability Analysis without Options and Strategies

The system reliability analysis without future actions or “Baseline” conditions, were modeled 

using CRSS, Reclamation’s long-term planning model, implemented in the RiverWareTM

generalized river-reservoir modeling software. All combinations of the supply and demand 

scenarios were including the Baseline analysis. Additionally, two operational assumptions 

regarding Lake Powell and Lake Mead operations past the effective period of the 2007 Interim 
Study Report

December 2012 SR-57

Guidelines in 2026 were considered. Since each supply scenario has over 100 individual 

sequences, the Baseline system reliability is comprised of over 20,000 simulations or “traces”. 

The Baseline simulations showed reduced streamflow at key locations and declining reservoir 

water elevations (pool elevation), as well as increasing risk of shortfalls in water availability to 

meet consumptive use demands. These conditions are further exacerbated when only considering 

the Downscaled GCM Projected water supply scenario. Although some of these findings 

translate directly to resource performance, many do not. 

From the system reliability metrics (metrics) described in Technical Report D – System 

Reliability Metrics, a set of indicator metrics were developed to inform the assessment of 

vulnerability. Defining vulnerability required the definition of thesholds beyond which the 

resource was deemed vulnerable. This offered perspective on resource performance and also a 

quantifiable measure of outcomes. Consistent with the reductions in system reliability, resourcespecific vulnerabilities were also found to increase as the supply and demand imbalance grows. 

Specific resource vulnerabilities resulting without options in place are discussed in the 

subsequent section, alongside the resulting vulnerability with options in place. The Baseline and 

each portfolio were evaluated for each combination of water supply and water demand scenarios 

and for operational assumptions. 

8.1.2 System Reliability Analysis with Options and Strategies

Static Portfolios

In addition to identifying a range of future demands, Technical Report C – Water Demand 

Assessment identified demands for Colorado River water beyond basic state apportionments in 

the Lower Division States. In the Baseline simulations, deliveries were limited to basic 

apportionments; as a result, these additional demands were only met during Surplus Conditions. 

Before attempting to address the added strain of demands growing beyond the Lower Division 

States’ basic apportionments, the effectiveness of options to remedy system performance within 

apportionment was explored. Due to the rather sizable supply and demand imbalances that are 

projected to occur, all representative options included in Portfolio A, described previously, were 

implemented as soon as available per their respective characterizations; such a strategy is 

referred to as Static Portfolio A. This ensures the full extent of the collective option capacity is 

considered in addressing vulnerabilities and imbalances. From this exercise, vulnerabilities were 

significantly reduced. In the case of some indicator metrics, the fraction of years vulnerable went 

from over 50 percent to as low as 5 percent. While this reduction was an encouraging indication 

of effectiveness, it is clear that in order to eliminate vulnerabilities entirely, additional 

investment would be required. 

As established earlier, significant demands above basic apportionment exist and must be 

considered as part of a comprehensive study of the Basin and its resources. Several options 

generate potential yield that could be directed toward either these additional demands or toward 

broader Basin resources. Assumptions were developed that attempt to balance option benefits 

between these needs. In the implementation of Static Portfolio A, yield is directed to target 

demands above basic apportionments until system vulnerabilities increase measurably, upon 

which the benefit is directed away from meeting the demands and used to benefit Basin

resources. This demonstrates the potential to strike a balanced approach with regard to yield 

benefit. Sensitivity results with different levels of balance between these needs show comparable 

improvements in resource vulnerability. 
Colorado River Basin 

Water Supply and Demand Study

SR-58 December 2012

Using the Static Portfolio A, results for the Lake Mead pool elevation vulnerability, the impact of 

supply and demand scenarios on resource performance was explored by comparing against the 

Baseline results. Figure 18 shows two sets of model results – with and without options, 

delineated by time period, supply, demand, and assumption regarding Lakes Powell and Mead 

operations past 202622. 

FIGURE 18 

Percent of Vulnerable Traces for the Lake Mead Elevation Indicator Metric Across Three Time Periods for the Baseline and 

Static Portfolio A, by Supply and Demand Scenario 

Graph reflects a subset of all scenarios evaluated for the portfolio analysis – Supply Scenarios: Observed Resampled, Paleo 

Conditioned, and Downscaled GCM Projected; Demand Scenarios: Current Projected (A), Rapid Growth (C1), Enhanced 

Environment (D1); Lakes Powell and Mead Post-2026 Operations: 2007 Interim Guidelines Extended, Revert to 2007 Interim 

Guidelines Final EIS No Action Alternative. Horizontal lines represent the minimum and maximum results across all demand 

scenarios.

 

22 For modeling purposes, future system conditions were modeled under two assumptions with respect to the operation of Lakes Powell and 

Mead beyond 2026. In one assumption, “Extend 2007 Interim Guidelines,” it was assumed that the 2007 Interim Guidelines would remain in 

place from 2027 through 2060. In the other assumption, “Revert to Final EIS No Action Alternative,” it was assumed that operations would 

revert back to those in the 2007 Interim Guidelines Final EIS No Action Alternative.
Study Report

December 2012 SR-59

In the early time period (2012-2026), vulnerabilities are driven solely by supply scenarios; 

demand trajectories are still quite similar, and reservoir operations are governed by the 2007 

Interim Guidelines. Even the difference between with and without options is somewhat small, 

mostly due to the lack of early options to address Lake Mead falling below 1,000 feet msl. The 

middle time period (2027-2040) shows some separation along the demand and operation policy 

dimensions, particularly for the Observed Resampled supply. However, for the more taxing 

hydrology scenarios, the differences in the percentage of vulnerable traces across demand 

scenarios become more muted. The effect of the portfolio has a similar dampening effect on the 

differences in the percentage of vulnerable traces across demand scenarios. In the final time 

period (2041-2060), differences due to demand and assumptions regarding Lakes Powell and 

Mead operations are at their largest, especially in the Baseline. The “Revert to No Action 

Alternative” assumption shows lower risk of vulnerability in Lake Mead elevation by creating 

sizable shortages in the Lower Basin. With the implementation of all options by the end of the 

final period, all but the Downscaled GCM hydrology vulnerabilities are reduced, again largely 

trumping the other parameters. Therefore, demand and operational policy can impact 

vulnerability outcomes but tend to be overshadowed by hydrology differences or portfolio 

implementation. 

Dynamic Portfolios

To assess the appropriate timing of simulated option implementation, a dynamic method for 

implementing representative options was developed. In this method, options triggered only when 

needed, based on signposts that precede conditions associated with vulnerable events. These 

signposts are listed in table 12 and the use of them allowed for implementation of options in the 

model simulation only when needed. The lead time listed in table 12 was the longest period 

between the triggering of a signpost and occurrence of a vulnerability that still retained sufficient 

predictive skill. Additionally, only options that addressed the anticipated vulnerability were

implemented given a particular signpost. However, signposts did not signal when feasibilitylevel studies, permitting, construction, or other key implementation decisions would be required. 

This would require a consistent and concerted effort to conduct project activities well in advance 

of triggers included in the model. 

System Response Variables

Dynamic implementation of options in the model simulations of the four portfolios resulted in 

substantial system and resource improvements over Baseline results in addition to reducing overinvestment. Relative to the static portfolio described above, the dynamic implementation of 

options reduces the annual portfolio cost by over 25 percent in 2060. This result speaks to the 

significant benefit to a dynamic and adaptive approach over one that is static. 

In figure 19 and in all subsequent figures displaying portfolio results, in order to facilitate a 

comparison between the portfolios and Baseline conditions, the results were computed based on 

all supply and demand conditions and in addition for both assumptions regarding Lakes Powell 

and Mead operations after 2026. 

Figure 19 shows all portfolios reversing the declining median Lake Powell pool elevations from 

the Baseline. Further, the 10th percentile pool elevation improved by 80 to 120 feet. It is 

noteworthy that even with such an improvement, levels can be still significantly low, indicating 

that some scenarios still pose a challenge to the system, even with options in place. 
Colorado River Basin 

Water Supply and Demand Study

SR-60 December 2012

TABLE 12 

Vulnerability Signposts

Indicator Metric/ 

Vulnerability

Lead 

Time

Conditions

Lake 

Powell

Elevation 

(feet msl) 

Lake 

Mead

Elevation 

(feet msl) 

Lees 

Ferry 

5-year 

Mean 

Flow

Upper Basin 

Shortage

Lower Basin 

Demand Above 

Apportionment

Lee Ferry Deficit1 5 Years 3,490 Not 

applicable

12.39 maf Not 

applicable

Not applicable

Lower Basin 

Shortage (>1 maf 

over 2 years) 

3 Years Not 

applicable

1,060’ 13.51 maf Not 

applicable

Not applicable

Lower Basin 

Shortage (>1.5 

maf over 5 years) 

3 Years Not 

applicable

1,075’ 13.51 maf Not 

applicable

Not applicable

Mead Pool 

Elevation 

(< 1,000’)

3 Years Not 

applicable

1,040’ 13.35 maf Not 

applicable

Not applicable

Upper Basin 

Shortage 

(>25%) 

0 Years Not 

applicable

Not 

applicable

Not 

applicable

25% Not applicable

Lower Basin 

Demand Above 

Apportionment

Varies Not 

applicable

Not 

applicable

Not 

applicable

Not 

applicable

Demand above basic 

apportionment is 

within 100 kaf of 

permissible level

1

 A Lee Ferry deficit is assumed to occur in any year when the 10-year running total flow at Lees Ferry is less than 

75 maf. The deficit is computed as the difference between 75 maf and the 10-year running flow in a particular 

year.

Following results for Lake Powell are the probability and magnitudes of Lee Ferry deficits in 

figure 20. A Lee Ferry deficit is assumed to occur in any year when the 10-year running total 

flow at Lees Ferry is less than 75 maf. Again, all portfolios showed improvements over the 

increasing probability of Lee Ferry deficit seen in the Baseline. In some cases, the probability 

even appeared to have stabilized at less than 2 percent. Although the risk of a Lee Ferry deficit 

was notably lowered, the median magnitude was affected less. In fact, at the 90th percentile, 

there appeared to be some slight increases in deficit magnitudes. This is likely an artifact of 

reducing the number of deficit events, particularly those of smaller magnitudes, thus shifting 

some of the more-extreme condition to the 90th percentile. Importantly, the portfolios that 

stabilize the probability of a Lee Ferry deficit contain an option for an Upper Basin water bank. 

This bank is used to provide additional water to reduce the risk of Lee Ferry deficit. 
Study Report

December 2012 SR-61

FIGURE 19

10th, 50th, 90th Percentiles for Lake Powell End-of-December Pool Elevation for the Baseline and Four Portfolios

FIGURE 20 

10th, 50th, 90th Percentiles for Lee Ferry Deficit in Years in Which a Deficit Occurs (top) and Percent of Traces (bottom) with a 

Lee Ferry Deficit for the Baseline and Four Portfolios
Colorado River Basin 

Water Supply and Demand Study

SR-62 December 2012

Lake Mead pool elevations also improved relative to the Baseline, albeit not as immediately and 

to a lesser magnitude, as shown in figure 21. The delayed recovery of the median pool elevation 

was due to a combination of option availability for implementation and the additional demands 

above basic apportionment that were not addressed in the Baseline run. These demands all 

originate in the Lower Basin, and therefore add extra demand strain on Lake Mead, calling for 

greater releases. In 2060, relative to the Baseline, median pool elevations rose 60 to 90 feet 

depending on the specific portfolio. Not surprisingly, Portfolio A, which had the largest 

maximum potential yield, saw the largest increase, whereas the Portfolio D, with smallest 

maximum potential yield, showed the smallest gains. 

FIGURE 21 

10th, 50th, 90th Percentiles for Lake Mead End-of-December Pool Elevation for the Baseline and Four Portfolios

Water Deliveries Indicator Metric Performance

Consistent with the improved system conditions, resource indicator metrics showed reductions in 

vulnerabilities. Figure 22 shows water delivery indicator metrics and percent of years vulnerable 

by three time periods. Additionally, in Technical Report G – System Reliability Analysis and 

Evaluation of Options and Strategies, results are shown for the percent of years vulnerable and 

indicating the percent of traces or simulated futures vulnerable. This helps in understanding the 

persistence of vulnerable events both within and across traces. For example, a low percent of 

years vulnerable but high percent of traces vulnerable, indicates that, albeit infrequently, the 

indicator metric tends to be vulnerable at least once in most traces. Conversely, a high percent of 

years but lower percent of traces vulnerable suggests considerable persistence of additional 

vulnerabilities once one has occurred for a particular trace. 
Study Report

December 2012 SR-63

FIGURE 22 

Percent of Vulnerable Years for Each Water Delivery Indicator Metric Across Three Time Periods for the Baseline and Four 

Portfolios 

For all metrics shown, vulnerabilities in the first period tended to change little from the Baseline 

results. This was a result of the combination of often low vulnerability risk in the early period 

and few options available to address vulnerabilities when they occur. The middle time period 

was the first to significantly diverge from the Baseline for most indicator metrics. However, in 

some cases, it was also the most vulnerable window, owing to the fact that options may have 

only been available for a short time, and as a result, little benefit accrued to reduce vulnerability. 

Demands above basic apportionments were not included in the Baseline modeling and thus the 

results showed a marked improvement under simulations with portfolios. Also, one might expect 

Portfolio A to show the greatest reduction in vulnerabilities simply by having the greatest yield 

available to address imbalances; however, this was not always the case. Because this portfolio 

includes the Upper Basin banking option, water generated by conservation was not immediately 

available to address vulnerabilities, but was instead “banked” to help hedge against future Lee 

Ferry deficits. This is the same reason that Portfolio A was particularly effective at reducing the 

probability of Lee Ferry deficits.
Colorado River Basin 

Water Supply and Demand Study

SR-64 December 2012

Electrical Power Resources Indicator Metric Performance

As shown in figure 23, electric power resources exhibited performance improvements similar to 

those in the water delivery indicator metrics. As more options are implemented, increased flow 

helps to raise pool elevations and greater downstream demand requires larger releases. This 

combination is a two-fold benefit to hydropower. 

FIGURE 23 

Percent of Vulnerable Years for Each Electric Power Indicator Metric Across Three Time Periods for the Baseline and Four 

Portfolios 

Gigawatt hour (GWh) 

Flood Control Indicator Metric Performance

As shown in figure 24, under the Baseline conditions, flood control vulnerabilities were few and 

actually decreased over time due to the increase in available storage associated with increasing 

demand. Under the various portfolios, the occurrence of vulnerabilites remained low, but did 

increase slightly. This result stems from the implementation of options that increase pool 

elevations, which in turn, reduces capacity to absorb extreme flow events. 

FIGURE 24 

Percent of Vulnerable Years for Each Flood Control Indicator Metric Across Three Time Periods for the Baseline and Four 

Portfolios 

Cubic feet per second (cfs) 
Study Report

December 2012 SR-65

Recreational Resources Indicator Metric Performance

Figures 25 and 26 show recreational resource indicator metric vulnerabilities. Specifically, the 

metrics in figure 25 are river boating vulnerabilities, and those in figure 26 pertain to reservoir 

recreation. River boating indicator metrics are based on the shift in long-term average 

availability of flows deemed acceptable (total days) and optimal (optimal days) from simulations 

reflective of current conditions with variable hydrology (control run). In general, the optimal 

flow metrics were consistently more vulnerable than the total flow metrics. This is because the 

window for optimal flows is more stringent and therefore more sensitive to changes in 

streamflow. All portfolios demonstrate improvements for the boating indicator metrics. Portfolio 

A showed the most improvement. The improvement in Portfolio A and in Portfolio C is due to 

the Upper Basin banking option, found in both, which routes conserved water from across the 

major tributaries to a conceptual storage facility near Lake Powell. By routing the conserved 

water, resources that depend on in-stream flows tend to benefit, including river boating 

recreation. 

FIGURE 25 

Percent of Vulnerable Years for Each Recreational (boating flow) Indicator Metric Across Three Time Periods for the Baseline 

and Four Portfolios 

 “Control run” reflects conditions that might be expected under current demand and Observed Resampled water supply conditions, 

and was used as a reference for evaluating change in vulnerability associated with future changes.
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FIGURE 26 

Percent of Vulnerable Years for Each Recreational (shoreline facilities) Indicator Metric Across Three Time Periods for the 

Baseline and Four Portfolios 

For reservoir recreation, Flaming Gorge performed notably well, even under the Baseline 

simulations. This is attributable to a combination of more-optimistic streamflow projections in 

the Upper Green River due to projected climate change and slower growth relative to other 

regions. Reductions to vulnerabilities at other locations in the Upper Basin were largely from 

conservation and weather modification options that serve to either increase reservoir inflow or 

reduce the required release.

Ecological Resources Indicator Metric Performance

Ecological resource vulnerabilities were calculated based on reference flow conditions that were

derived to reflect instream and riparian habitat conditions. In most cases, the indicator metrics 

were derived from biological opinion recommendations and coordinated through the Metrics 

Sub-Team. Ecological resource indicator metrics are shown in figure 27. Based on the 

discussion of river boating vulnerabilities, it would be logical to expect that the portfolios with 

the Upper Basin banking option and associated routing of flows would benefit ecological 

resources more than other portfolios. In the case of the Yampa and San Juan river metrics, the 

outcome was consistenct with this expectation. However, for the Green and Colorado rivers, the 

improvements were largely commensurate with other portfolios because of the particular flow 

recommendations at those sites. The Green and Colorado river flow prescriptions are specific 

with regard to timing and volume. As such, increases in flow resulting from routing water to the 

bank may not help resolve vulnerabilities if the flow pattern is not consistent with the flow 
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December 2012 SR-67

recommendations. Coordinated routing of flows would be required to achieve the maximum 

benefit to those more-detailed flow requirements. 

FIGURE 27 

Percent of Vulnerable Years for Each Ecological Indicator Metric Across Three Time Periods for the Baseline and Four Portfolios 

8.1.3 Portfolio Comparison and Option Analysis

Although the portfolio analysis successfully demonstrated that system reliability can be 

improved, it is not without significant cost and performance tradeoffs. Figure 28 illustrates the 

performance across portfolios by supply scenario in terms of addressing two key water delivery 

vulnerabilities—Lee Ferry deficit and Lake Mead pool elevation below 1,000 feet msl. For this 

discussion these are refered to as the Upper Basin vulnerability and Lower Basin vulnerability. 

Portfolio B favors options believed to have higher certainty of available water supply once 

implemented. As shown in figure 28 (on the right), this portfolio performs as well or better than 

all the other portfolios for addressing the Lower Basin vulnerability across all supply scenarios.

The portfolio performs less well than Portfolios C and A for the Upper Basin vulnerability 

(figure 28, left), particularly in the Downscaled GCM Projected supply scenario (bottom row). 

Portfolio C, while focused on options that favor lower energy needs and less environmental 

impacts, is more dependent on shifting social values towards additional conservation and reuse. 

Choosing to implement options characterized as having low energy needs (as a surrogate for 

potential environmental impacts) might come at the expense of having a less certain long-term 
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water supply. Despite this tradeoff, this portfolio performs well for addressing the Upper Basin

vulnerability (figure 28, left) and is particularly effective under the Downscaled GCM Projected 

supply scenario (figure 3, bottom row). Portfolio C is less effective, however, at addressing the 

Lower Basin vulnerabilities (figure 28, right). Note that the effectiveness of Portfolio C and

Portfolio A at reducing Upper Basin shortage vulnerability is largely due to the inclusion of a 

Upper Basin water bank concept in these portfolios. 

FIGURE 28

Percent of Years with Occurrence of Upper Basin (left) and Lower Basin (right) Vulnerability in 2041–2060 with Portfolios 

Implemented, by Supply Scenario

As discussed earlier, portfolios differ based on the representative options available to address 

supply and demand imbalances. As such, it is important to explore the portfolios beyond their 

ability to reduce vulnerabilities and improve system conditions. From analysis of the 

characterization criteria, the portfolios considered in the Study differ most notably on cost, 

energy needs, and long-term viability factors. Figure 29 shows the distribution of annual 

portfolio costs through time and for each water supply scenario. The box plots in the figure 

represent the inter-quartile range and the 10th and 90th percentiles. For all portfolios, costs 

increase substantially between the onset and end of the Study period. By 2060, the annual costs 

range from approximately $2 to $5 billion under the Observed Resampled, Paleo Conditioned, 

and Paleo Resampled supply scenarios, and increase to potentially $7 billion under the 

Downscaled GCM Projected scenario. Portfolio A is the most costly due to the inclusion of the 

greatest number of options, and Portfolio D is the least costly due to the inclusion of the least 

number of options. Although Portfolio B are costly, it brings a certainty of available supply and 

is risk averse in terms of the future security of providing water to users. By choosing to only 

consider options that were characterized as having moderate to high long-term viability, lower 

unit cost alternatives were excluded, which also had the effect of lowering total potential yield. 
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Portfolio C is similar in cost range to Portfolio B, except under the GCM Projected scenario, 

where it is less expensive largely due to the exclusion of some options that are only triggered 

under more-challenging water supply conditions within Portfolios A and B. Within Portfolio C, 

the emphasis on options characterized as having low energy needs might come at the expense of 

yield certainty. The purpose of exploring these differences is not to identify a “best” portfolio or 

strategy, but to acknowledge that there are various ways to address the supply and demand 

imbalance and that each has associated implications that must be considered in future planning 

and decision-making processes.

FIGURE 29

Total Annual Cost by Supply Scenario Resulting from Implementation of the Portfolios over Time 

The spread between the 25th and 75th percentile is indicated by shading. The 10th and 90th percentile values are indicated by the 

x’s.
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The intersections of cost, characteristics, and performance bound the discussion of portfolios and 

highlight the strategies used to craft each. Tradeoffs also exist with respect to portfolio costs, and 

these differ depending on the specific future conditions.As shown in figure 30, the annual cost, in 

2012 dollars, for implementing the portfolios ranges from approximately $2.5 billion to $3.5 

billion in the year 2060 when considering the median of the Observed Resampled supply 

sequences, and from $3.6 billion to $5.8 billion when considering the median of the Downscaled 

GCM Projected supply sequences. The inter-quartile ranges of cost are significantly larger.

However, because of the appraisal-level option cost estimating used in the Study, the cost values 

contain additional uncertainty not directly reflected in these estimates. 

When considering how the portfolios perform in stressing hydrologic conditions often associated 

with critical water delivery reliability vulnerabilities, the differences among the portfolios in 

terms of costs and ability to reduce vulnerability are more apparent. As conditions become less 

favorable, such as in the “Lowest Streamflow” subset of sequences (figure 30, bottom row), 

Portfolios C and A perform the best with respect to the Upper Basin Vulnerability and Portfolios 

B and A perform the best with respect to Lower Basin Vulnerabiltiy. 

Portfolio C both performs better than Portfolios B and D in terms of reducing this vulnerability 

and has a lower range of costs than Portfolios A and B. For the Lower Basin Vulnerability, 

however, Portfolio B reduces vulnerability more than Portfolios C and D and also costs less than 

Portfolio A. 

Portfolios were also evaluated for which options were implemented for each dynamic portfolio. 

Figure 31 shows the implementation frequency through time for options in each portfolio. Many 

options are common among all portfolios, but the frequency of use informs how each portfolio 

resolves the imbalance in a slightly different manner. The small vertical black line indicates the 

earliest possible date that the option could be available, assuming project feasibility is initiated 

today. Options that are implemented with high frequency shortly after becoming available 

suggest that investigation in the near future may be prudent due to the simulated short delay 

between availability and selection. In the case of Portfolio A and Portfolio C, conservation is 

implemented as soon as available in order to generate water for the Upper Basin bank. These are 

not triggered by signposts, but rather are assumed to be in place ahead of time to make this 

preventive strategy effective. In a broad sense, options such as agricultural conservation and 

transfers and M&I conservation are considerably relied upon in each portfolio because they are 

available early to address many vulnerabilities. However, as conditions become more 

challenging and the imbalance widens, there is also need for other options, such as desalination, 

reuse, and importation that may only be available in the longer term. 
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FIGURE 30 

Portfolio Cost and Percent of Upper Basin (left) and Lower Basin (right) Vulnerability for 2041–2060, by Supply Scenarios and 

Lowest Sequences

(1) Conditions in which long-term mean natural flows are less than 14 mafy and the 8-year dry period flows are less than 11 mafy. 

(2) Marker indicates the 50th percentile result and the bounds represent 25th and 75th percentile results.
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FIGURE 31 

Frequency of Option Implementation (percent of traces) for Each Portfolio
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December 2012 SR-73

Through evaluation of the option implementation results across and within portfolios, the 

following findings can be summarized: 

• Options that were frequently implemented and with a short delay from their first 

availability date: M&I Water Water Conservation (for all portfolios); Agricultural Water 

Conservation and Weather Modification (for Portfolio B); Energy Water Use Efficiency 

(for Portfolios A and B). Implementation of these options was common across portfolios 

and may require advanced planning as illustrated by the short delay in model 

implementation.

• Options that were frequently implemented and with a short delay under the Low 

Streamflow conditions (long-term flow less than 15 mafy and drought less than 13 mafy): 

Salton Sea Drainwater Desalination; Agricultural Water Conservation (all portfolios); 

Municipal Wastewater Reuse (Portfolio C and D). Implementation of these options was 

common across portfolios with short delay under low streamflow conditions. These 

options may also need advanced planning in order to hedge against these challenging 

conditions. 

• Options that were frequently implemented and with short delay under the lowest 

streamflow conditions (long-term flow less than 14 mafy and drought less than 11 mafy): 

Desalination of Brackish Water in the Yuma Area; Missouri River Imports (Portfolios A 

and B). These options may only require advanced planning to hedge against the more 

severe conditions. 

• Options that were frequently implemented, but with a longer delay under the Low 

Streamflow conditions (long-term flow less than 15 mafy and drought less than 13 mafy) 

include: Gulf of California Ocean Desalination, Pacific Ocean Desalination in California, 

Grey Water Reuse, and Dust Control, and Treatment of Local-Coal Bed Methane 

Produced Water. These options may allow for some delay in implementation.

8.2 Summary of the Evaluation of Options and Strategies

The system reliability analysis with options and strategies demonstrated that all portfolios have 

capacity to reduce vulnerabilities across resources and in doing so, making a sizeable reduction 

in the supply-demand imbalance. In the 2012 through 2026 period, reductions in vulnerabilities 

tend to be small, owing to generally low risks and lesser option availability in the near-term. In 

the latter two time windows, vulnerability reductions of 50 percent or more (relative to Baseline 

results) are seen in all resource categories. The one exception is the flood control indicator 

metric. A consequence of increased Basin yield and greater storage in reservoirs is a slight 

increase in flood control vulnerabilities. 

The four portfolios explored in the Study were shown to significantly reduce Upper and Lower 

Basin vulnerabilities, but implemented different strategies. Of the four strategies and associated 

portfolios considered, notable differences extend beyond portfolio performance. Portfolio cost is 

driven by the total potential yield considered in the portfolio, the unit cost of the options, and the 

water supply and water demand conditions for which the portfolio was evaluated. As such, by 

2060, annual portfolio costs range from approximately $2 billion to $5 billion, but could increase 

to potentially $7 billion under the Downscaled GCM Projected scenario. The differences in cost 

across portfolios result from the preference of option types versus increased ability to reduce 

vulnerabilities. Two examples of this are portfolio preferences for options with higher long-term 
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reliability and preferences for lower environmental impacts. By choosing to only consider 

options that were characterized as moderate to high long-term viability, lower unit cost 

alternatives may be excluded, but the options increased the total potential yield. In contrast, 

options characterized as having lower potential environmental impacts may come at the expense 

of yield certainty. The purpose of exploring these differences is not to identify a “best” portfolio 

or strategy, but to acknowledge that there are various approaches to address the future supply and 

demand imbalance and that each has associated implications that must be considered in the 

decision making process. 

Although the portfolios explored in the Study address water supply and demand imbalances 

differently, there are commonalities across the options implemented for each portfolio. All of the 

portfolios incorporate significant agricultural water conservation, M&I water conservation (1 

maf each of both additional M&I and agricultural conservation was implemented in all 

portfolios), energy water use efficiency, and some levels of weather modification. However, 

some options were implemented more frequently in response to challenging water supply 

conditions. For example, ocean and brackish water desalination, wastewater reuse, and 

importation options were implemented for the most challenging water supply conditions in 

portfolios in which they were included. Future planning will require careful consideration of the 

timing, location, and magnitude of anticipated future Basin resource needs. 

9.0 Study Limitations

As stated previously, the focal questions being addressed by the Study were: 

• What is the future reliability of the Colorado River system to meet the needs of Basin 

resources through 2060? 

• What are the options and strategies to mitigate future risks to these resources? 

Although the technical approach of the Study was based on the best science and information 

available, as with all studies, there are limitations.

The detail at which results are reported or the depth to which analyses were performed in the 

Study was limited by the availability of data, methods, and the capability of existing models.

Many of these limitations could not be overcome for purposes of the Study because of time and 

resource constraints. In some cases, these limitations presented opportunities for additional 

research and development and the improvement of available data. These opportunities will be 

pursued in efforts independent of the Study. Limitations exist in the areas noted below. 

9.1 Treatment of Lower Basin Tributaries

For four of the inflow points below Lees Ferry (the Paria, Little Colorado, Virgin, and Bill 

Williams rivers), CRSS uses historical inflows (not natural flows) based on USGS streamflow 

records. In addition, the Gila River is not included in CRSS. 

Many Colorado River planning studies have been completed over the past two decades where 

this treatment of the major Lower Basin tributaries was used; however, questions regarding the 

adequacy of the treatment of the Lower Basin tributaries in CRSS for the Study arose during the 

phases focused on assessing future water supply and demand. The current treatment of these 

tributaries limited the ability of the Study to fully assess the natural supply of the Basin, and the 
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December 2012 SR-75

data and methodological inconsistencies present in the CU&L Reports limited the ability of the 

Study to gain a more-complete understanding of historical consumptive use in the Basin. 

Despite these limitations, other approaches were taken in the Study to examine several important 

issues, including potential climate change impacts on the tributaries represented in CRSS, future 

demand scenarios on those tributaries, and future demand scenarios for the Colorado River from 

the Gila River Basin, factoring in other water supplies within that basin. 

Reclamation will engage in efforts to: (1) resolve and correct, in collaboration with the Basin 

States, the methodological and data inconsistencies in the CU&L Reports pertaining to all of the 

Lower Basin tributaries; (2) develop natural flows for the Little Colorado, Virgin and Bill 

Williams rivers and modify CRSS to use natural flows for those tributaries; and (3) explore the 

feasibility and usefulness of computing natural flows for the Gila River Basin and the feasibility 

and usefulness of adding that basin to CRSS. Refer to Technical Report C – Water Demand 

Assessment, Appendix C11 – Modeling of Lower Basin Tributaries in the Colorado River 

Simulation System for a more-detailed discussion of these issues. 

9.2 Treatment of Agricultural Land Use in Water Demand Scenarios

The water demand storylines were developed by the Water Demand Sub-Team which included 

participation from a broad range of stakeholders. The sub-team developed storylines based on 

key driving forces that represented a range of plausible futures regarding future demand. 

However, the assumptions in some storylines with regard to these driving forces resulted in the 

same directional changes in demand across the storylines. For example, the assumptions of 

continued conversion of agricultural land use to urban land use and lower-economic value crops 

being phased out in some areas led to overall agricultural land use (i.e., the number of irrigated 

acres) decreasing over time over all scenarios. Given recent projections of increased agricultural 

productivity necessary to meet future food needs, plausible futures should include increases in 

land use. 

The application of a scenario planning approach to project future Basin-wide demand represents 

a new paradigm in the Basin and a significant advancement in Basin long-term planning. 

Reclamation and the Basin States are committed to continued refinement of scenario planning as 

part of a robust long-term planning framework for the Basin.

9.3 Ability to Assess Impacts to Basin Resources

The ability to assess impacts to Basin resources was limited by the spatial and temporal detail of 

CRSS. Described further in Technical Report D – System Reliability Metrics, some metrics have 

limitations in their ability to be assessed quantitatively and in some cases were assessed 

qualitatively. For example, CRSS tracks shortages in the Upper Basin when the flow is 

insufficient to meet the local demands as opposed to simulating the complex water rights system 

in each state that would be needed to appropriately model shortages to individual water rights 

holders and the lack of model representation of individual tributaries. This representation 

affected the ability of the Study to assess the impacts to deliveries in the Upper Basin. Another 

example is that several ecological resources metrics were evaluated through approximations at 

larger spatial scales and longer timesteps (e.g., monthly versus daily) than preferred or required 

for more-detailed assessments. 
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In some cases, particular modeling assumptions limited the detailed analysis of certain metrics. 

For example, when water is supplied to the system in the manner assumed to determine the Lee 

Ferry defecit, the uncertainty regarding metric results increases, particularly in the Upper Basin. 

However, due to the infrequent occurrence of a Lee Ferry deficit across all traces, these results 

are not disregarded. This uncertainty, however, should be considered carefully when viewing 

metric results, particularly in the Upper Basin, that have been impacted by this modeling 

assumption. 

9.4 Options Characterization Process

The process undertaken to characterize options to help resolve potential water supply and 

demand imbalances strived to maintain an objective and consistent evaluation of the options. 

Several iterations of the option characterization were performed in an attempt to normalize 

ratings wherever possible. However, several limitations were inherently associated with the 

characterization of the over 150 options received. The limitations identified during the 

characterization process include the following: 

• Limited Level of Analysis. The intent of the characterization was to perform a high-level 

analysis of a broad range of options potentially available to resolve Basin imbalances. This 

high-level analysis added the risk that not all of the potential costs and benefits of the options 

were considered. A detailed assessment by individual location for most of the distributed 

options (e.g., M&I water conservation, agricultural water conservation, and reuse) was 

beyond the scope of the Study. 

• Potential for Subjectivity. The classification system used in the characterization process was 

relatively prescriptive; however, there was still some room for subjectivity when considering 

each option. Not all participants in the Study were in agreement with all ratings, but it was 

recognized that future efforts beyond the Study will result in a more in-depth assessment of 

the options. 

• Uncertainty. The characterization was performed based on limited and high-level analyses. 

Therefore, knowledge of items such as costs, permit requirements, and long-term feasibility 

was highly uncertain. For example, cost estimates for infrastructure-type projects were based 

on past similar projects with adjustments for parameters such as scale and location. Similar 

statements can be made related to uncertainty with characterization of the other option 

criteria. 

9.5 Consideration of Options 

Due to the legal, regulatory, and sometime technical complexity of the options submitted, not all 

categories of options submitted underwent a quantitative assessment. As such, portfolios were 

largely limited to groups of options that lend themselves to modeling implementation within the 

Study’s timeframe, i.e. those that increase supply or reduce demand, with the exception of the 

Upper Basin water bank concept. The options modeled in CRSS do not necessarily reflect the 

entire range of innovative options and strategies that should continue to be explored in future 

efforts. 
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December 2012 SR-77

10.0 Future Considerations and Next Steps 

Colorado River water managers and stakeholders have long understood that growing demands on 

the Colorado River system, coupled with the potential for reduced supplies due to climate change 

may put water users and resources relying on the river at risk of prolonged water shortages in the 

future. The magnitude and timing of these risks differ spatially across the Basin, particularly 

those areas where demand is at or exceeds available supply, are at a greater risk than others. The 

Study builds on earlier work and is the next significant step in developing a comprehensive 

knowledge base and suite of tools and options that will be used to address the risks posed by 

imbalances between Colorado River water supply and resource needs in the Basin. 

The Study confirms that the Colorado River Basin faces a range of potential future imbalances 

between supply and demand. Addressing such imbalances will require diligent planning and 

cannot be resolved through any single approach or option. Instead, an approach that applies a 

wide variety of ideas at local, state, regional, and Basin-wide levels is needed. The Study’s 

portfolio exploration demonstrated that implementation of a broad range of options can reduce 

Basin resource vulnerability and improve the system’s resiliency to dry hydrologic conditions 

while meeting increasing demands in the Basin and adjacent areas receiving Colorado River 

water. 

The Study is ultimately a call to action. The potential improvements in system performance and 

enhanced resiliency resulting from the portfolio analysis is encouraging, however a very long 

lead time is required to implement many of the portfolio options. When considering the potential 

onset of critical imbalances as early as 2025, it is imperative that the processes to further these 

concepts must begin in the near future. The next steps to begin these actions must be done 

collaboratively and continue to facilitate and build upon the broad, inclusive stakeholder process 

demonstrated in the Study. 

The call to action must be answered by all stakeholders that rely on the Colorado River or its 

tributaries. Given the uncertainty associated with future conditions in the Basin, the ability to 

increase water supply reliability is even more important. There is no one option or one path that 

will provide certainty for the future water supply and rivers of the Basin. Responding to the 

uncertainty will require understanding all potential options and taking action must be the 

responsibility of all stakeholders. The political will to take necessary action must be directed 

towards a credible process to create solutions which examines the trade-offs of using various 

options while seeking to meet a range of Basin resource goals. As the next steps are taken, all 

stakeholders must be involved in considering future options and strategies and all evaluation and 

analysis of these options must be done with a high level of transparency with independent 

scientific review and opportunities for public comment. 

The following sections describe those areas where additional steps should be taken following 

completion of the Study. These areas and recommended future actions are presented thematically 

and were developed cooperatively by Reclamation, the Basin States, tribes, and various 

conservation organizations. 

Water Use Efficiency and Reuse

Further efforts to improve water use efficiency in the M&I, agricultural and energy sectors were 

a common element across all Study portfolios in providing a cost-effective solution for resolving 

imbalances in the near-term. This is an area that municipalities and entities in the agricultural 
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sector have been and will continue to pursue. The approach taken by the Study to determine the 

potential for conservation in these sectors and their respective costs was at a Basin-wide level. 

Although appropriate for the Study, this approach does not reflect the important local differences 

in conservation potential nor does it reflect the legal issues associated with the various state 

water right policies. A key issue to be explored is the significant uncertainty related to the 

potential magnitude of conservation included in the Study. 

A recommended next step is to establish workgroups associated with municipal conservation, 

agricultural conservation, energy conservation, and reuse. These workgroups would be convened 

by Reclamation. The purpose of the workgroups would be to identify existing programs, 

projects, and policies applied to municipal, agricultural, reuse, and energy sector conservation 

and the distribution of those programs across water users throughout the Study Area. The goal 

of these workgroups would be to consider new opportunities and programs, and potentially to 

develop a scope of work for feasibility-level studies to develop new approaches to encourage 

conservation that address key uncertainties and financial impacts. The groups' objectives will 

include focusing on water use efficiency at a local level, the application of approaches 

appropriate for different locations and regions, and exploring innovative and cost-effective ways 

to encourage increased water use efficiency and reuse opportunities with the goal of 

recommending the implementation of solutions resulting in cost-effective water savings and 

reuse. 

Reclamation’s WaterSMART program provides several opportunities that could be used to 

further study and implement water conservation and reuse options. Through WaterSMART 

grants, funding could be made available for projects that save water or improve energy 

efficiency. The criteria for administering these grants could be modified to give preference to 

activities that build upon Basin Study outcomes. Through the WaterSMART Title XVI – Water 

Reclamation and Reuse Program funding could be made available for planning studies and the 

construction of water recycling projects. 

Water Banks

Water banks are a flexible and innovative solution to avoiding imbalances. Both intrastate and 

interstate water banking occurs within the Lower Basin. In the Study, a conceptual Upper Basin 

water bank was explored where the benefit was twofold: 1) the bank provided increased 

flexibility in the Upper Basin to mitigate risk of potential future Lee Ferry deficits and 2) the 

water generated through conservation for the bank enhanced ecological and recreational 

resources as it was routed to a conceptual storage facility. Although there are significant legal, 

policy, and institutional challenges associated with potential banking options, the potential 

benefits associated with this option suggest that additional exploration and analysis of this 

concept may be warranted.

Presently, some of the Upper Division States are exploring the feasibility of water banking 

concepts within the Upper Basin. A recommended next step is to continue to work with 

stakeholders in the Upper Basin regarding water banking concepts. Reclamation is committed to 

exploring creative and flexible ways to use storage facilities and other Reclamation 

infrastructure, consistent with authorized purposes and the Law of the River, in an attempt to 

accommodate appropriate water banking options. Moreover, the Upper Division States will 

engage in a broader conversation with the Lower Division States and other stakeholders, at the 

appropriate time, to discuss how an Upper Basin water bank would operate. 
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December 2012 SR-79

Water Transfers

In terms of reducing demands and as conservation options, water transfers were also 

demonstrated through the Study portfolios as being an important tool for resolving imbalances in 

the near and long-term. Voluntary water transfers can have many potential benefits and in 

particular promote flexibility in adapting to uncertain future conditions. Many of the Basin States 

have been utilizing voluntary water transfers within their respective states to meet water 

management challenges and will continue to look to transfers as an important solution. Although 

negative impacts can be associated with certain types of water transfers, such as permanent dryup of agricultural land, innovative strategies can be employed to avoid these impacts and are 

being explored by many states. The Western Governors’ Association’s (WGA) recent report on 

water transfers identifies innovative approaches and specific steps that states can consider in 

order to improve water transfer outcomes (WGA, 2012). Reclamation will engage with the Basin 

States as appropriate to improve opportunities for water transfers and develop third party impact 

reduction and mitigation techniques that can be applied throughout the Basin.

Water Supply Augmentation

Large-scale water supply augmentation projects could provide additional reliable water to meet 

future demands, although such projects face significant permitting challenges and currently are 

both expensive and energy intensive. The assessments of large-scale water supply augmentation 

projects conducted in the Study were strictly at an appraisal level; additional study is needed to 

better understand the appropriate timing of investments, effectiveness, and tradeoffs. 

Recommended next steps include identifying and defining appropriate feasibility-level studies 

for large-scale augmentation projects most likely to overcome the challenges previously noted. 

Prior to conducting feasibility-level studies, key stakeholders would come together to review 

scopes of work and develop funding and cost-sharing for the studies. 

Watershed Management

There were a number of watershed management activities that were explored in the Study. Two 

of these activities were weather modification and vegetation management. Weather modification 

is inexpensive and has the potential to increase the Basin’s supply. Several of the Basin States 

have funded weather modification activities on an ongoing basis for many years. Nevertheless, 

significant uncertainty exists related to the effectiveness of snowpack augmentation activities to 

increase available water supply. In addition, there is also significant uncertainty related to the 

long-term reliability of the option due to its reliance on current weather patterns, which may not 

persist under climate change scenarios. Enhanced understanding of weather modification is 

needed including the certainty of measured efficacy within targeted watershed. 

Recommended next steps include the application of existing operational experience and research 

to identify target watersheds for snowpack augmentation activities, and continuation of research 

to reduce water supply yield uncertainties. 

Vegetation management activities are ongoing at the state and local level. Most of these 

activities occur with the help of local partners, such as the Tamarisk Coalition. These activities 

should continue and be encouraged into the future. 

Mitigation of dust on snow as an opportunity to increase water supply is a relatively new 

concept, and bears further exploration with federal partners including the Bureau of Land 
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Management. A dialogue among the relevant federal agencies and the appropriate Landscape 

Conservation Cooperatives (LCC) should be initiated to better understand the origins and 

mitigation options for managing dust on snow. 

Tribal Water

The Indian Reserved Water Rights of the tribes of the Colorado River Basin are unique and have 

attributes that must be recognized under federal law and distinguished from state law water 

rights. The Indian Reserved Water Rights of the tribes of the Colorado River Basin account for 

approximately 2.9 million acre-feet of annual diversion rights of the total apportionment of the 

Colorado River in the United States. The Study does not fully account for Tribal water demand 

nor reflect the potential use of tribal water by others nor show the potential impact on the Basin 

water supply if a substantial amount of the presently unused or unquantified tribal water is used 

by the tribal water rights holders prior to 2060. 

Working together with the Tribes, and recognizing the unique attributes of Indian Reserved 

Water Rights, Reclamation acknowledges that the outcome of tribal water settlements must be 

accounted for in Reclamation’s analysis of water supply and demand, in order to accurately 

project imbalances in the Colorado River Basin. Indian Reserved Water Rights are unique under 

federal law, they are held in trust by the United States for the benefit of Tribes, and thus a trust 

obligation exists to protect those rights.

In particular, CRSS was intended to evaluate water availability in the Upper Basin and Lower 

Basin and potential water supply and demand imbalances through 2060. Reclamation 

acknowledges that the Study results are limited in their ability to fully account for the effects of 

tribal reserved water rights on projected supply and demand imbalances, in light of the unique 

attributes of those rights. The Study does, however, summarize quantified tribal water rights in 

Technical Report C – Water Demand Assessment, Appendix C9 – Tribal Water Demand 

Scenario Quantification, but Reclamation does not intend that the current Study be used to assess 

the future impacts to tribal water use in the Basin. 

In light of the foregoing, and in recognition of the Federal Government’s continued trust 

obligation to work with members of the Ten Tribes Partnership to protect their Tribal Reserved 

Water Rights, Reclamation and the Ten Tribes Partnership are committed to joint future planning 

efforts that build on the scientific foundation of the current Study and advance critical 

information beyond the limited assessment of tribal water in the Study. Future Reclamation 

planning efforts should include a study capable of evaluating full tribal development, control, 

and protection of tribal water resources in the Basin. This study should be conducted jointly by 

Reclamation and the Ten Tribes Partnership with involvement by interested stakeholders 

including the Basin States. Considerations should include water banking, voluntary water 

transfers, improved efficiencies, re-use opportunities, underground storage, and other options. 

These options may aid tribal and non-tribal users with developing options not presently available 

to respond to supply and demand uncertainty in the decades to come. 

Reclamation also recognizes the importance of continued dialogue with respect to tribal matters 

at a regional and local level. In particular, several issues were identified by the Inter Tribal 

Council of Arizona in their option submission to the Study and these issues warrant further 

discussion. These issues are described in Technical Report F – Development of Options and 

Strategies, Appendix F13 – Options Submitted by the Ten Tribes Partnership and the Inter Tribal 

Council of Arizona. Reclamation is committed to participating actively in discussions with tribal 
Study Report

December 2012 SR-81

leaders, continuing to seek resolution on these issues, and exploring opportunities that will bring 

the tribal perspective to bear in enhancing the management of the Basin resources.

Environmental Flows

The Study recognized the importance of considering river flows to support flow and water 

dependent ecological systems, power generation, and recreation, through its adoption of metrics 

used to approximate the performance of these resources, the inclusion of an Enhanced 

Environment water demand scenario, and the inclusion of a conceptual Upper Basin water bank 

the objective of which specifically includes improving the performance of ecological and 

recreational resources. Although these activities resulted in a good first step towards 

incorporating the needs of flow and water dependent ecological systems and exploring concepts 

to better meet those needs under a range of future conditions, exploring ways to meet ecological 

and recreational needs should continue beyond the completion of the Study. Future efforts 

should strive to better understand and quantify the needs of these systems, better reflect those 

needs in a modeling framework, and further explore solutions considered in the Study as well as 

others that promote the protection and improvement of environmental and recreational flows. 

The solutions should be explored in conjunction with those that support other management goals 

and decisions as to achieve integrated water management solutions that benefit multiple uses. 

Recommended next steps focus on identifying potential enhancements to CRSS to improve the 

modeling of ecological, recreational, and power generation flow needs. Through an LCC grant in 

which The Nature Conservancy is the principal investigator, a workshop will be held in late 

summer 2013 to explore and recommend modeling improvements to appropriately consider 

recreational and environmental flow needs. Reclamation and the Basin States are committed to 

considering the recommendations that come from this workshop and to continue the dialogue 

with interested stakeholders to explore opportunities to include recreational and environmental 

flow needs in future water management decisions. This dialogue will be continued through the 

formation of an exploratory work group of interested stakeholders to identify and assess options 

that provide multiple benefits to improve flow and water dependent ecological systems, power 

generation, and recreation. The intent of this work group is not to focus on new regulatory 

requirements, but rather to identify opportunities for infrastructure, operations, and transactions 

that could reduce projected vulnerabilities resulting from future supply and demand imbalances. 

Data and Tool Development

CRSS was the primary modeling tool utilized in the Study. Originally developed to model Lake 

Powell and Lake Mead operations, the Study demonstrated the need to improve the spatial 

resolution of CRSS, particularly in the Upper Basin. Improvements to CRSS are needed to better 

support future endeavors identified in these next steps, such as analysis of Upper Basin water 

banking concepts, enhanced modeling of environmental flows, and exploring tribal water 

development and options to resolve imbalances related to tribal water. The scoping and design of 

these improvements will occur through Reclamation’s Stakeholder Modeling Workgroup. This 

work will begin within a year of completion of the Study and may build on recommendations 

from the LCC workshop discussed above. 

The Study has resulted in enhanced tools and datasets for water resource planning in the Basin. 

The Basin States will work with Reclamation to evaluate the ability to use the tools developed 

for the Study and update water demands and supply scenarios on a five-year timeframe. The 
Colorado River Basin 

Water Supply and Demand Study

SR-82 December 2012

Basin States will work with Reclamation to support improvements in the Study’s input 

information, modeling and analytical tools. The Basin States will also work with Reclamation in 

fulfilling the commitments regarding the Lower Basin tributaries specifically described in 

Technical Report C – Water Demand Assessment, Appendix C11 – Modeling of Lower Basin 

Tributaries in the Colorado River Simulation System.

Climate Science Research

The Study used the best available science at the time it was initiated. Nonetheless, climate 

science is rapidly evolving and a new set of GCM projections will soon be available. Next steps 

include prioritizing the research agenda of Reclamation’s Hydrology Work Group to advance the 

technical foundation established by the Study regarding the use of climate projections in future 

studies. 

Partnerships

The collaborative approach adopted by the Study was paramount to its success. Next steps 

should be taken in ways that build on its momentum and dialogue to increase the effectiveness of 

partnership responses when new challenges and opportunities arise. As in the past, the Federal 

Government can provide a leadership role in appropriate processes to facilitate this dialogue. 

11.0 Summary of Next Steps

In recognition of their ongoing joint commitment to future action, Reclamation will convene the 

Basin States along with tribes, other Colorado River water entitlement holders, conservation 

organizations, and other interested stakeholders in early 2013 to conduct a workshop to review 

the recommended next steps and initiate actions to implement next steps to resolve the current 

and potentially significant future imbalances in the Colorado River system. In early 2013 

Reclamation will also consult and work with tribes regarding tribal water issues reflected in this 

report.

In summary, there are several future actions that must take place to move closer towards 

implementing solutions to resolve imbalances in the Basin. First, significant uncertainties related 

to water conservation, reuse, water banking, and weather modification concepts must be resolved 

in order to adequately implement these approaches. Second, costs, permitting issues, and energy 

availability issues relating to large-capacity augmentation projects need to be identified and 

investigated through feasibility-level studies. Third, opportunities to advance and improve the 

resolution of future climate projections should be pursued and enhancements to the operational 

and planning tools used in the Colorado River system to better understand the vulnerabilities of 

the water-dependent uses, including environmental flows, should be explored. Fourth, as 

projects, policies, and programs are developed, consideration should be given to those that 

provide a wide-range of benefits to water users and healthy rivers for all users.

12.0 References 

Bureau of Reclamation (Reclamation). 2011a. SECURE Water Act Section 9503(c) – 

“Reclamation Climate Change and Water.” 

Bureau of Reclamation (Reclamation), 2011b. Phase 4: Development and Evaluation of 

Opportunities for Balancing Water Supply and Demand – Request for Ideas. 
Study Report

December 2012 SR-83

Bureau of Reclamation (Reclamation). 2007. Colorado River Interim Guidelines for Lower Basin 

Shortages and Coordinated Operations of Lake Powell and Lake Mead Final 

Environmental Impact Statement.

Bureau of Reclamation (Reclamation). 1996. Operation of Glen Canyon Dam Final 

Environmental Impact Statement. 

Bureau of Reclamation (Reclamation). 1975. Westwide Study Report on Critical Water Problems 

Facing the Eleven Western United States. April. 

Bureau of Reclamation (Reclamation). 1964. Pacific Southwest Water Plan. January.

Bureau of Reclamation (Reclamation). 1950. Colorado River Storage Project and Participating 

Projects; Upper Colorado River Basin. September. 

California Building Standards Commission. 2010. California Plumbing Code. 

Christensen, N.S., and D.P. Lettenmaier. 2007. “A multimodel ensemble approach to assessment 

of climate change impacts on the hydrology and water resources of the Colorado River 

basin.” Hydrol. Earth Sci., 11:1417–1434. 

Colorado River Water Consultants. 2008. Study of Long-Term Augmentation Options for Water 

Supply of the Colorado River System. 

Hoerling, M., D. Lettenmaier, D. Cayan, and B. Udall. 2009. “Reconciling Future Colorado 

River Flows.” Southwest Hydrology, 8(3). 

Intergovernmental Panel on Climate Change. 2007. Climate Change 2007: Synthesis Report. 

Contribution of Working Groups I, II, and III to the Fourth Assessment Report of the 

Intergovernmental Panel on Climate Change. ISBN 92-9169-122-4. Retrieved from 

http://www.ipcc.ch/publications_and_data/publications_ipcc_fourth_assessment_report_s

ynthesis_report.htm. 

Liang, X., D.P. Lettenmaier, and E.F. Wood. 1996. Surface Soil Moisture Parameterization of 

the VIC-2L Model: Evaluation and Modification. 

Liang, X., D.P. Lettenmaier, E.F. Wood, and S.J. Burges. 1994. “A Simple Hydrologically Based 

Model of Land Surface Water and Energy Fluxes for General Circulation Models.” 

Journal of Geophysical Research, Vol. 99, 14415–14428. 

Maurer, E.P., L. Brekke, T. Pruitt, and P.B. Duffy. 2007. “Fine-resolution climate projections 

enhance regional climate change impact studies.” Eos Trans. AGU, 88(47), 504. 

Maurer, E.P., A.W. Wood, J.C. Adam, D.P. Lettenmaier, and B. Nijssen. 2002. “A Long-Term 

Hydrologically-Based Data Set of Land Surface Fluxes and States for the Conterminous 

United States.” Journal of Climate, 15(22), 3237-3251. 

Meko, D.M., C.A. Woodhouse, C.A. Baisan, T. Knight, J.J. Lukas, M.K. Hughs, and 

M.W. Salzer. 2007. “Medieval drought in the Upper Colorado River Basin.” Geophysical 

Research Letters 2007 34(5), L10705, DOI: 10.1029/2007GL029988. 

National Research Council. 2007. Colorado River Basin Water Management – Evaluating and 

Adjusting to Hydroclimate Variability. The National Academies Press. 
Colorado River Basin 

Water Supply and Demand Study

SR-84 December 2012

Nijssen, B., D.P. Lettenmaier, X. Liang, S.W. Wetzel, and E.F. Wood. 1997. “Streamflow 

simulation for continental-scale river basins.” Water Resource Research, 33, 711–724. 

Ouarda, T., D. Labadie, and D. Fontare. 1997. “Indexed Sequential Hydrologic Modeling for 

Hydropower Capacity Estimates.” Journal of the American Water Resources Association, 

Vol. 33, No. 6. December. 

Pacific Southwest Inter-agency Committee. 1971a. Comprehensive Framework Study, Lower 

Colorado Region. Prepared by the Lower Colorado Region State – Federal Interagency 

Group for the Pacific Southwest Inter-agency Committee, Water Resources Council.

June. 

Pacific Southwest Inter-agency Committee. 1971b. Comprehensive Framework Study, Upper 

Colorado Region. Prepared by the Upper Colorado Region State – Federal Interagency 

Group for the Pacific Southwest Inter-agency Committee, Water Resources Council.

June. 

Painter, T. H., A. P. Barrett, C. C. Landry, J. C. Neff, M. P. Cassidy, C. R. Lawrence, K. E. 

McBride, and G. L. Farmer. 2007. “Impact of disturbed desert soils on duration of 

mountain snow cover.” Geophys. Res. Lett., 34, L12502, doi:10.1029/2007GL030284. 

Painter T, Deems J, Belnap J, Hamlet A, Landry C, and Udall B. 2010. “Response of Colorado 

River runoff to dust radiative forcing in snow.” Proceedings of the National Academy of 

Sciences.

Painter, T. H., S. M. Skiles, J. S. Deems, A. C. Bryant, and C. C. Landry. 2012. “Dust Radiative 

Forcing in Snow of the Upper Colorado River Basin: 1. A 6 Year Record of Energy 

Balance, Radiation, and Dust Concentrations.” Water Rour. Res., 48, W07521, 

doi:10.1029/2012WR011985. 

Skiles, S. M., T. H. Painter, J. S. Deems, A. C. Bryant, and C. C. Landry. 2012. “Dust radiative

forcing in snow of the Upper Colorado River Basin: 2. Interannual variability in 

radiative forcing and snowmelt rates” Water Resour. Res., 48, W07522, 

doi:10.1029/2012WR011986. 

Stephens, J., and E. Stewart. Circa 1960. A Comparison of Procedures for Computing 

Evaporation and Evapotranspiration. International Association of Hydrologic Sciences. 

Retreived from http://iahs.info/redbooks/a062/iahs_062_0123.pdf.

Timpe, C., and M.J.J. Scheepers. 2003. SUSTELNET: A Look into the Future: Scenarios for 

Distributed Generation in Europe. 

U.S. Department of the Interior (DOI). 2007. Record of Decision for Colorado River Basin 

Lower Basin Shortages and the Coordinated Operations for Lake Powell and 

Lake Mead.
Study Report

December 2012 SR-85

Disclaimer

The Colorado River Basin Water Supply and Demand Study (Study) is funded jointly by the Bureau of 

Reclamation (Reclamation) and the seven Colorado River Basin States (Basin States). The purpose of 

the Study is to analyze water supply and demand imbalances throughout the Colorado River Basin and 

those adjacent areas of the Basin States that receive Colorado River water through 2060; and develop, 

assess, and evaluate options and strategies to address the current and projected imbalances. 

Reclamation and the Basin States intend that the Study will promote and facilitate cooperation and 

communication throughout the Basin regarding the reliability of the system to continue to meet Basin 

needs and the strategies that may be considered to ensure that reliability. Reclamation and the Basin 

States recognize the Study was constrained by funding, timing, and technological and other limitations, 

and in some cases presented specific policy questions and issues, particularly related to modeling 

and interpretation of the provisions of the Law of the River during the course of the Study. In such 

cases, Reclamation and the Basin States developed and incorporated assumptions to further complete 

the Study. Where possible, a range of assumptions was typically used to identify the sensitivity of the 

results to those assumptions.

Nothing in the Study, however, is intended for use against any Basin State, any federally recognized 

tribe, the federal government or the Upper Colorado River Commission in administrative, judicial or 

other proceedings to evidence legal interpretations of the Law of the River. As such, assumptions 

contained in the Study or any reports generated during the Study do not, and shall not, represent a legal 

position or interpretation by the Basin States, any federally recognized tribe, federal government or 

Upper Colorado River Commission as it relates to the Law of the River. Furthermore, nothing in the 

Study is intended to, nor shall the Study be construed so as to, interpret, diminish or modify the rights 

of any Basin State, any federally recognized tribe, the federal government, or the Upper Colorado River 

Commission under federal or state law or administrative rule, regulation or guideline, including without 

limitation the Colorado River Compact (45 Stat. 1057), the Upper Colorado River Basin Compact (63 

Stat. 31), the Utilization of Waters of the Colorado and Tijuana Rivers and of the Rio Grande, Treaty 

Between the United States of America and Mexico (Treaty Series 994, 59 Stat. 1219), the United 

States/Mexico agreement in Minute No. 242 of August 30, 1973 (Treaty Series 7708; 24 UST 1968), or 

Minute No. 314 of November 26, 2008, or Minute No. 318 of December 17, 2010, or Minute No. 319 

of November 20, 2012, the Consolidated Decree entered by the Supreme Court of the United States in 

Arizona v. California (547 U.S 150 (2006)), the Boulder Canyon Project Act (45 Stat. 1057), the 

Boulder Canyon Project Adjustment Act (54 Stat. 774; 43 U.S.C. 618a), the Colorado River Storage 

Project Act of 1956 (70 Stat. 105; 43 U.S.C. 620), the Colorado River Basin Project Act of 1968 

(82 Stat. 885; 43 U.S.C. 1501), the Colorado River Basin Salinity Control Act (88 Stat. 266; 43 

U.S.C. 1951) as amended, the Hoover Power Plant Act of 1984 (98 Stat. 1333), the Colorado River 

Floodway Protection Act (100 Stat. 1129; 43 U.S.C. 1600), the Grand Canyon Protection Act of 1992 

(Title XVIII of Public Law 102-575, 106 Stat. 4669), or the Hoover Power Allocation Act of 2011 

(Public Law 112-72). In addition, nothing in the Study is intended to, nor shall the Study be construed 

so as to, interpret, diminish or modify the rights of any federally recognized tribe, pursuant to 

federal court decrees, state court decrees, treaties, agreements, executive orders and federal trust 

responsibility. Reclamation and the Basin States continue to recognize the entitlement and right of 

each State and any federally recognized tribe under existing law, to use and develop the water of the 

Colorado River system.
Appendix 1 

Plan of Study

December 2012 SR1-1 

Appendix 1 — Plan of Study

Note: This document was originally published with two attachments which are not included in this appendix.

1.0 Introduction

The Bureau of Reclamation’s Upper Colorado and Lower Colorado Regions (UC and LC 

Regions), in collaboration with representatives of the seven Colorado River Basin States (Basin 

States1), submitted a proposal in June 2009 to fund the Colorado River Basin Water Supply and 

Demand Study (Study) under the Basin Study Program (Program). In September 2009, the Study 

was selected for funding under the Program. The estimated total cost of the Study is $2 million, 

with an equal cost-share of 50 percent by Reclamation and 50 percent by agencies in the Basin 

States (the non-Federal Cost-Share Partners). The Study will be conducted over a period of two 

years, beginning in January 2010. 

This Plan of Study contains: the Study’s purpose and objectives; a description of the Study 

management structure; a description of the major phases of the Study and a breakdown of the 

major tasks in each phase; a plan for public involvement throughout the Study (Attachment 1); 

and the June 2009 proposal (Attachment 2). 

1.1 Study Purpose & Objectives

The purpose of the Study is to conduct a comprehensive study to define current and future 

imbalances in water supply and demand in the Colorado River Basin (Basin) and the adjacent 

areas of the Basin States that receive Colorado River water for approximately the next 50 years, 

and to develop and analyze adaptation and mitigation strategies to resolve those imbalances.

The Study will characterize current and future water supply and demand imbalances in the Basin 

and assess the risks to Basin resources. Resources include water allocations and deliveries 

consistent with the apportionments under the Law of the River2

; hydroelectric power generation; 

recreation; fish, wildlife, and their habitats (including candidate, threatened, and endangered 

species); water quality including salinity; flow and water dependent ecological systems; and

flood control. Specific objectives of the Study include:

• Characterization of the current water supply and demand imbalances in the Basin including 

the assessment of the risks to Basin resources from historical climate variability.

• Characterization of future water supply and demand imbalances under varying water supply 

and demand conditions in the Basin including the assessment of the risks to Basin resources 

from possible future impacts of climate change. 

• Identification of potential strategies and options to resolve Basin-wide water supply and 

demand imbalances including: 

 

1 Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming. 

2 The treaties, compacts, decrees, statutes, regulations, contracts and other legal documents and agreements applicable to the allocation, 

appropriation, development, exportation and management of the waters of the Colorado River Basin are often referred to as the Law of the 

River. There is no single, universally agreed upon definition of the Law of the River, but it is useful as a shorthand reference to describe this 

longstanding and complex body of legal agreements governing the Colorado River.
Colorado River Basin 

Water Supply and Demand Study

SR1-2 December 2012

− Modifications to the operating guidelines or procedures of water supply systems;

− Modifications to existing facilities and development of new facilities;

− Modifications to existing water conservation and management programs and 

development of new programs; 

− Modifications to existing water supply enhancement programs and development of new 

programs; and 

− Other structural and non-structural solutions. 

• Identification of potential legal and regulatory constraints and analysis of potential impacts to 

water users and Basin resources for the strategies and options considered. 

• Prioritization of identified strategies and options and the recommendation for potential future 

actions, including feasibility studies, Congressional authorization, environmental compliance 

activities, demonstration programs, and/or implementation as appropriate.

1.2 Study Management

Management of the Study by the UC and LC Regions and the non-Federal Cost-Share Partners 

will be accomplished as described in the following sections. 

1.2.1 Co-Study Managers

One Co-Study Manager will be designated from Reclamation and one Co-Study Manager will be 

designated from the Non-Federal Cost Share Partners. The Co-Study Managers will sit on and 

lead the Steering Team.

1.2.2 Steering Team

The Steering Team will steer and guide the efforts of the Project Team such that the objectives of 

the Study are met in an effective, efficient manner, and within the Study’s financial and time 

constraints. The Steering Team will be comprised of one member from the UC Region, one 

member from the LC Region, one member from each Basin State, and one member from the 

Upper Colorado River Commission, for a total of 10 members. 

1.2.3 Project Team

The Project Team will ensure that the tasks that relate to the Study are completed in a costeffective, timely manner and are technically sound. Members of the Project Team provide the 

expertise, experience, and knowledge that relate to the Study’s scope and objectives. Members 

include staff from the UC and LC Regions, staff from the non-Federal Cost-Share Partners, and 

staff from other entities who may be contracted to provide specific information, knowledge, and 

support. The Co-Study Managers will lead the Project Team.

1.2.4 Sub-Teams

Various Sub-Teams will be formed as needed to perform specific tasks. Sub-Team members 

provide specific expertise required to perform those tasks. Members are comprised of Project 

Team members, additional staff from the UC and LC Regions and the non-Federal Cost-Share 
Appendix 1 — Plan of Study

December 2012 SR1-3 

Partners, and staff from contracted entities. Membership may also include representatives from 

other groups with a particular expertise sought by the Sub-Team.

1.2.5 Reclamation Management Structure

To facilitate Reclamation’s oversight responsibilities and internal coordination, the proposed 

Study management structure includes a Reclamation Oversight Team (Oversight Team) and a 

Reclamation Study Team (Study Team). The Oversight Team provides oversight for the Study 

and will guide the efforts of the Study Team to ensure that the objectives of the Study are met 

within the financial and time constraints. Members of the Oversight Team are the Regional 

Directors of the UC and LC Regions and a senior member of the Office of Policy and 

Administration in Denver. Members of the Study Team include key staff from the UC and LC 

Regions. 

1.3 Study Schedule, Phases, & Products

The Study will be technically oriented, incorporating information from the latest science, 

engineering technology, climate models, and innovations. The level of analysis of the strategies 

and options will be similar to an appraisal-level study to assist in justifying and preparing 

feasibility studies, Congressional authorization, environmental compliance activities, 

demonstration programs, and/or implementation as appropriate. 

1.3.1 Schedule

The Study will be conducted over a period of two years, beginning in January 2010. The Study 

will consist of four major phases: Water Supply Assessment, Water Demand Assessment, 

System Reliability Analysis, and Development and Evaluation of Opportunities for Balancing 

Supply and Demand. The projected timeline for these phases is provided in figure 1. The 

projected Study milestones are listed in table 1.

FIGURE 1

Projected Study Timeline

J F M A M J J A S O N D J F M A M J J A S O N D

1. Water Supply Assessment

2. Water Demand Assessment

3. System Reliability Analysis

4. Development & Evaluation of 

Opportunities for Balancing Supply & 

Demand

2nd Half 2011

Phase Name

1st Half 2010 2nd Half 2010 1st Half 2011
Colorado River Basin 

Water Supply and Demand Study

SR1-4 December 2012

TABLE 1

Projected Study Milestones

Milestone Deliverable Description

September 2010 Report describing findings from current and future water supply assessment

September 2010 Report describing findings from current and future water demand assessment

April 2011 Report describing findings from system reliability analysis

August 2011 Report describing findings of opportunities analysis

October 2011 Draft Study report and appendices available for review

December 2011 Final Study report and appendices complete

Development and review of the draft and final Study report will follow the completion of the 

fourth milestone as shown above. 

1.3.2 Phases

Table 2 provides the tasks and sub-tasks associated with the major Study phases.

TABLE 2

Overview of Study Phases

Phase 1. Water Supply Assessment. Assess the quantity and location of current and future water supplies 

throughout the Basin, including the potential effects of climate variability and climate change. Major tasks and subtasks include:

1.1 Review & Select Methods to Estimate Current Supply

1.1.1 Historic Observed Record

1.1.2 Paleo Record

1.2 Review & Select Methods to Project Future Supply

1.3 Conduct Assessment of Current Supply

1.4 Conduct Assessment of Future Supply

1.5 Enhance Modeling Capability as Needed to Incorporate Methods to Project Future Supply

1.6 Conduct Sensitivity Analysis of Selected Methods to Project Future Supply

1.7 Prepare Draft Interim Report

1.8 Peer Review Report

1.9 Prepare & Publish Interim Report
Appendix 1 — Plan of Study

December 2012 SR1-5 

TABLE 2

Overview of Study Phases

Phase 2. Water Demand Assessment. Assess the quantity and location of current and future water demands, 

including the potential effects of climate variability and climate change. Major tasks and sub-tasks include:

2.1 Review & Select Methods to Estimate Current Demands

2.2 Review & Select Methods to Project Future Demands

2.3 Conduct Assessment of Current Demands

2.4 Assessment of Future Demands

2.4.1 Update State Demand Projections

2.4.2 Analyze Temperature Effects on Projected Use

2.5 Enhance Modeling Capability to Better Represent Future Demands

2.5.1 Reservoir Evaporation

2.6 Prepare Draft Interim Report

2.7 Peer Review Report

2.8 Prepare & Publish Interim Report

Phase 3. System Reliability Analysis. Assess the capability of existing and proposed infrastructure and 

operations to meet future demands and water supply challenges. This analysis will include an assessment of the 

operational risk and reliability of the system currently and in the future. System reliability will be determined by 

describing the quantity and locations of supply/demand imbalances currently and in the future. Scenarios for 

baseline and future water supply and demand will be determined in Phases 1 and 2. Evaluate effectiveness of 

opportunities identified in Phase 4 in resolving imbalances. Major tasks and sub-tasks include:

3.1 Identify Model & System Reliability Metrics

3.2 Determine Baseline System Reliability

3.2.1 Determine Baseline Scenario Modeling Assumptions

3.2.2 Prepare Model to Simulate Baseline Scenario

3.2.3 Perform Model Simulations

3.2.4 Synthesize & Analyze Model Results

3.2.5 Summarize Model Results

3.3 Project Future System Reliability

3.3.1 Determine Future Scenario Modeling Assumptions 

3.3.2 Prepare Model to Simulate Future Scenarios

3.3.3 Perform Model Simulations

3.3.4 Synthesize & Analyze Model Results

3.3.5 Determine Modeling Assumptions for Supply/Demand Opportunities

3.3.6 Prepare Model to Simulate Future Conditions Under Supply/Demand Opportunities

3.3.7 Perform Model Simulations with Supply/Demand Opportunities

3.3.8 Synthesize & Analyze Model Results

3.4 Prepare Draft Interim Report

3.5 Peer Review Report

3.6 Prepare & Publish Interim Report
Colorado River Basin 

Water Supply and Demand Study

SR1-6 December 2012

TABLE 2

Overview of Study Phases

Phase 4. Development & Evaluation of Opportunities for Balancing Supply & Demand. Identify and quantify 

potential opportunities to address imbalances in supply and demand in order to best meet future challenges. This 

analysis will include the identification and development of both structural and non-structural opportunities. As 

opportunities are refined, an iterative modeling process will be used to determine future system reliability under 

conditions where selected opportunities are assumed to be developed and/or implemented. Opportunities include 

but are not limited to: operational changes, legal and institutional changes, water conservation and efficiency, land 

fallowing and retirement, conjunctive use, upgrades, rehabilitation or replacement of existing facilities, water 

recycling and reuse, desalination, development of new conveyance and storage facilities, weather modification, 

vegetation management, dust abatement efforts, groundwater remediation, urban runoff management, and 

importation projects. Major tasks and sub-tasks include:

4.1 Develop Opportunities

4.1.1 Identify Opportunities

4.1.2 Determine Preliminary Opportunities for Evaluation

4.1.3 Analyze Opportunities (Preliminary)

4.2 Evaluate & Refine Opportunities

4.2.1 Technical Feasibility

4.2.2 Uniform Cost Comparison

4.2.3 Environmental Impacts/Permitting Requirements

4.2.4 Economic and Socioeconomic Impacts

4.2.5 Legal and Public Policy Considerations

4.2.6 Risk and Uncertainty

4.2.7 Others

4.2.8 Assessment of Effectiveness

4.2.9 Potential Yield

4.2.10 Timeframe for Implementation

4.2.11 Agreements or Partnerships Needed

4.2.12 Cost Allocation

4.2.13 Siting

4.3 Finalize Opportunities

4.3.1 Determine Ability of Opportunities to Resolve Imbalances 

4.4 Prepare Draft Interim Report

4.5 Peer Review Report

4.6 Prepare & Publish Interim Report

Figure 2 illustrates the information transfer and coordination of tasks in the four major phases of 

the Study. 
Appendix 1 — Plan of Study

December 2012 SR1-7 

FIGURE 2

Flowchart of Major Study Phases

The first coordination occurs between Phases 1 and 2 and Phase 3 where the identification of the 

system reliability metrics in Task 3.1, in terms of spatial and temporal scale, depend upon the 

methods selected to project future supply and demand in Task 1.2 and Task 2.2. Baseline and 

future system reliability in Task 3.2 and Task 3.3, respectively, is determined based on the 

results of the assessment of current and future water supply and demand conditions in Task 1.3 

(and Task 2.3) and Task 1.4 (and Task 2.4). 

In Task 4.1, opportunities to resolve supply/demand imbalance will be identified considering the 

results of the projections of future system reliability in Tasks 3.3.1-3.3.4. The evaluation and 

refinement of those opportunities in Task 4.2 will be accomplished through re-projecting future 

system reliability under the identified opportunities in Tasks 3.3.5-3.3.8. After several iterations 

consisting of refining opportunities and projecting system reliability to determine the 

opportunities’ performance, opportunities will be finalized in Task 4.3. 
Colorado River Basin 

Water Supply and Demand Study

SR1-8 December 2012

1.3.3 Products

The primary products of the Study will be interim written reports to be integrated into a final 

report that will include the following elements:

• Assessment of quantity and location of existing and future water supplies and demands 

throughout the Basin, including the potential effects of climate variability and climate 

change,

• Assessment of efforts currently being undertaken to reduce supply and demand imbalances 

throughout the Basin, 

• Analysis of supply and demand relationships and quantification of imbalances in specific 

locations throughout the Basin, 

• Development and evaluation of options for balancing supply and demand, 

• Findings and recommendations, 

• Description of methods and research processes, including assumptions, models and data used 

in the Study, and 

• Description of stakeholder involvement. 

Other expected outcomes include the identification of collaborative strategies through the 

Study’s stakeholder involvement process. 

1.3.4 Public Involvement Plan

A Public Involvement Plan has been developed to ensure that all stakeholders in the Basin as 

well as the general public are informed and their input is sought and considered throughout the 

Study. The Public Involvement Plan is provided in appendix 4. 
Appendix 2

Previously Published Study Documents

December 2012 SR2-1

Appendix 2 — Previously Published Study 

Documents

This appendix presents a list of Colorado River Basin Water Supply and Demand Study (Study) 

reports that were previously published. Due to the inherent complexities of the Study and the 

many diverse interests and perspectives of the various stakeholders, interim reports and technical 

updates were published to reflect continual technical developments and the ongoing input of 

stakeholders. 

In June 2011, the Study published its first set of reports, Interim Report No. 1, which 

documented the Study’s progress through January 31, 2011. This publication was comprised of 

six elements:

• Executive Summary: Provided a summary of the Interim Report.

• Status Report: Provided an overview of the Study and summaries of the Technical 

Reports.

• Technical Report A – Scenario Development: Described the scenario planning 

approach used to incorporate uncertainty in future water supply and demand.

• Technical Report B – Water Supply Assessment: Described the water supply scenarios 

and presented the analysis and comparison of those scenarios.

• Technical Report C – Water Demand Assessment: Described the water demand 

scenarios currently under development and presented the historical consumptive use for 

the period 1971 through 2008.

• Technical Report D – System Reliability Metrics: Described the metrics that have been 

identified for use in the assessment of reliability of the system to meet the needs of the 

resources under future supply and demand scenarios. 

In Decmeber 2011, the Study published a report during the initiation of the final phase of the

Study: Development and Evaluation of Opportunities for Balancing Water Supply and Demand. 

This publication was comprised of one element:

Phase 4: Development and Evaluation of Opportunities for Balancing Water Supply 

and Demand: Provided relevant information to those interested in submitting input.

This report also provided a background of the past studies that have assessed future 

imbalances and explored options and strategies, and described ongoing efforts for 

balancing supply and demand.

In February 2012, the Study published updated reports to reflect the comments received on 

Interim Report No. 1, technical developments, and the ongoing input of stakeholders. This 

publication was comprised of two elements:

• Technical Report B – Water Supply Assessment: Described the water supply scenarios 

and presented the analysis and comparison of those scenarios.
Colordo River Basin 

Water Supply and Demand Study

SR2-2 December 2012

• Technical Report D – System Reliability Metrics: Described the metrics that have been 

identified for use in the assessment of reliability of the system to meet the needs of the 

resources under future supply and demand scenarios. 

In May 2012, the Study published a memorandum that updated information regarding future 

water demand scenarios previously published in narrative or “storyline” format in Technical 

Report C – Water Demand Assessment. This publication was comprised of one element:

Technical Memorandum C – Quantification of Water Demand Scenarios: Presented the 

quantification of those water demand scenarios, contained a summary of the process to 

quantify the scenarios, the resulting Colorado River demand across the scenarios, and 

updated the methods and results of assessing the potential effects of a changing climate on 

water demand. The appendices presented additional information specific to state and tribal 

demand as well as projected climate change impacts.
Appendix 3 

Summary of Past

Colorado River Basin Planning Studies 

December 2012 SR3-1 

Appendix 3 — Summary of Past Colorado 

River Basin Planning Studies

1.0 Introduction

Throughout the 20th century, the challenges and complexities of ensuring a sustainable water 

supply and meeting future demand have been recognized. These challenges are documented in 

numerous studies conducted by the Bureau of Reclamation (Reclamation) and the Colorado 

River Basin States (Basin States 1) over the past 70 years. Studies done in the early half of the 

20th century were focused on development of Colorado River resources. Starting in the 1960s, 

Basin studies continued to focus on development, but with an eye towards water supply and 

demand imbalances and potential means of resolving those imbalances. There was an increasing 

emphasis on improving the efficiency of the operation of Colorado River reservoirs and 

increasing the level of predictability needed by entities that receive Colorado River water to 

better plan for and manage available water supplies. Studies following the comprehensive 

framework studies of the early 1970s have all acknowledged an imbalance between water supply 

and demand in the Colorado River Basin (Basin). Most of these studies have not sought to 

explicitly quantify the imbalance, but rather have focused on potential solutions to various 

problems throughout the Basin, including the problems of water supply and demand imbalances, 

salinity, and federally recognized tribes (tribes) water rights, to name a few. In light of the 

attention given to some of these issues, institutional changes, such as interim operating criteria 

and the Consolidated Decree, have occurred. 

2.0 Studies 1946 - 1952 

Studies performed in the early half of the 20th century were focused on development of 

Colorado River resources. The studies coming out of this period led to legislation finalizing the 

rights of each of the seven Basin States to Colorado River water, and provided the foundation for 

development of storage projects throughout the Basin. The following sections summarize the 

studies to come out of this period. 

2.1 The Colorado River: A Comprehensive Report on the Development of the 

Water Resources of the Colorado River Basin for Irrigation, Power 

Production, and Other Beneficial Uses in Arizona, California, Colorado, 

Nevada, New Mexico, Utah, and Wyoming – 1946

The purpose of this 1946 report by Reclamation was to provide a Basin-wide perspective for 

planning water development throughout the Basin. It provided an inventory of 134 potential 

projects, and was

intended to serve as a medium through which Congress may be appraised of the 

potentialities for the development of the basin’s water resources and as a guide in 

the selection of projects that ultimately will comprise the comprehensive plan for 

 

1 Arizona, California, Colorado, New Mexico, Nevada, Utah, and Wyoming.
Colorado River Basin 

Water Supply and Demand Study

SR3-2 December 2012

the utilization of the waters of the Colorado River system for irrigation, electrical 

power, and other purposes (Reclamation, 1946). 

The report advocated for a comprehensive, Basin-wide plan for development as well as complete 

control and utilization of water of the Colorado River. It did not advocate for any particular 

projects to be authorized; however, it pointed out a number of issues that needed to be resolved 

before the selection of any projects could occur. In particular, it noted that 

...before such a selection of projects can be made it will be necessary that the 

seven Basin states agree upon their respective rights to deplete the water supply of 

the Colorado River or that the courts apportion available water among them 

(Reclamation, 1946). 

As a result, the report provided a basis for compact negotiations among the Upper Basin States, 

which resulted in the passage of the Upper Colorado River Compact (Compact) in 1948 

(63 Stat. 31). 

2.2 Final Report, Engineering Advisory Committee to Upper Colorado River 

Basin Compact Commission – 1948; and Report on Water Supply of the 

Lower Colorado River Basin, Project Planning Report – 1952

These are data-oriented reports intended to support potential development projects. After the 

1946 report was published, it was concluded that more-detailed data regarding the average 

natural flow of streams and rates of water use were needed to serve as the basis for planning 

future developments for the maximum use of available water supplies. The purpose of the reports 

was to fill a need for a comprehensive analysis of the water supply of the Upper Basin and 

Lower Basin, respectively. 

Both reports summarize data over the period 1914 to 1945. This period was chosen because it 

was believed to be a representative period of average stream flow as well as a period for which 

sufficient reliable hydrologic data were available to make a comprehensive analysis of water 

resources and stream depletions. Furthermore, the 1914 to 1945 period included the aboveaverage runoff years from 1914 to 1929, as well as the drought years from 1931 through 1940, 

and was therefore thought to be appropriate for considering storage problems of stream flow in 

drought years.

Together, these reports provide a basis for a comprehensive analysis of the water supply of the 

entire Basin. 

2.3 Colorado River Storage Project and Participating Projects, Upper Colorado 

River Basin - 1950

The Colorado River Storage Project (CRSP) and Participating Projects report outlined a plan of 

development in the Upper Colorado River Basin and recommended an initial construction 

program (Reclamation, 1950). The plan contained three fundamental elements: 1) reservoir 

storage, to conserve and regulate stream flows, and to generate power, 2) participating irrigation 

projects, made possible by the storage reservoirs, and 3) the Upper Colorado River Account, to 

be charged with scheduled payments on the construction, operations and maintenance, and 

replacement costs of the CRSP and participating projects. 
Appendix 3 — Summary of Past 

Colorado River Planning Studies

December 2012 SR3-3 

In this report, an ultimate storage plan was envisioned that would permit full utilization by the 

Upper Basin of the 7.5 million acre-feet (maf) of water apportioned to the Upper Basin under the 

Compact. The storage capacity contemplated was designed to assure that the flow of the river at 

Lees Ferry would not be depleted below 75 maf in any 10 consecutive years. The goal was to 

provide the infrastructure with which the Upper Basin could proceed safely with use of its 

waters, and the Lower Basin would be assured that its rights under the Compact were protected

(Reclamation, 1950). 

Given the analysis of Colorado River supplies (primarily taken from the 1948 report by the 

Engineering Advisory Committee, but expanded to include data through 1947) and assumptions 

of Upper Basin depletions, the greatest 10-year flow deficiency at Lees Ferry was projected to be 

20.8 maf for the period ending in 1940 (see table 1). More-detailed studies based on monthly 

data rather than on the annual data used in the table indicated an imbalance of 23 maf for the 

1931 to 1940 decade, indicating a need for that amount of storage capacity for river regulation. 

Therefore, according to the plan outlined in the CRSP report, 23 maf would be reserved in 

project reservoirs for long-time regulatory storage. The water stored would be released as needed 

in drought periods to meet the Compact obligation at Lees Ferry. 

3.0 Studies 1964 – 1972 

Starting in the 1960s, Basin studies continued to focus on development, but with an eye towards 

water supply and demand imbalances and potential means of resolving those imbalances. 

Increasing emphasis was placed on improving the efficiency of the operation of Colorado River 

reservoirs and increasing the level of predictability needed by entities that receive Colorado 

River water to better plan for and manage available water supplies. The following sections 

summarize the studies to come out of this period. 

3.1 Pacific Southwest Water Plan - 1964

The Pacific Southwest Water Plan was the first study to project a water supply and demand 

imbalance in the Basin (Reclamation, 1964). The report outlined a two-phase plan of action 

designed to meet the immediate and long-range water needs of the Pacific Southwest, defined in 

this report as the water service area of the Lower Colorado River Basin including southern 

California. In both phases, substantial emphasis was placed on the salvage of water and moreefficient water use, although the plan also called for the importation of water to make up the 

remaining imbalance. 

Based on estimates of the rate at which the Upper Basin will develop uses for its 

apportioned share of Colorado River water, it is estimated that by the year 2030, 

in the absence of measures to increase Lower Basin water supplies, the amount of 

water available from the Colorado River at and below Hoover Dam for 

consumptive use by the Lower Basin States will decrease to 5,620,000 acre-feet 

annually. This would be 1,880,000 acre-feet below the 7,500,000 acre-feet 

divided among the Lower Basin States by the recent decision of the Supreme 

Court in the case of Arizona v. California. To make up this deficiency, through 

the 7,500,000 acre-foot guarantee, the Initial Plan provides for water salvage and 

related works to yield 680,000 acre-feet annually and for import of the remaining 

deficiency of 1,200,000 acre-feet (Reclamation, 1964). 
Colorado River Basin 

Water Supply and Demand Study

SR3-4 December 2012

TABLE 1 

Determination of Active Storage Requirement 

DETERMI NATI ON OF ACTI VE STORAGE REQUI REMENT

TO PERMI T FULL UTI LI ZATI ON OF APPORTI ONED CONSUMPTI VE USE

Uni t : · 1, 000 acr e- f eet

Wat er 

year

1 2 3 4 5

Vi r gi n 

f l ow of 

Col or ado 

Ri ver at 

Lee 

Fer r y

Ul t i mat e 

use of 

upper 

basi n 

appor -

t i onment 1

Ul t i mat e 

depl et ed 

unr egul at ed 

f l ow at Lee 

Fer r y ( Col . 1 

mi nus Col . 2)

Ten- year 

movi ng 

t ot al f l ow 

at Lee Fer r y

Ten- year 

var i at i on 

f r om 75 

mi l l i on 

acr e- f eet

1914 21, 220 9, 030 12, 190

1915 14, 030 6, 910 7, 120

1916 19, 200 8, 860 10, 340

1917 24, 040 9, 530 14, 510

1918 15, 360 7, 920 7, 440

1919 12, 460 6, 560 5, 900

1920 21, 950 9, 370 12, 580

1921 23, 020 9, 470 13, 550

1922 18, 310 8, 180 10, 130

1923 18, 270 8, 450 9, 820 103, 580 +28, 580

1924 14, 200 7, 340 6, 860 98, 250 +23, 250

1925 13, 030 6, 860 6, 170 97, 300 +22, 300

1926 15, 850 7, 770 8, 080 95, 040 +20, 040

1927 18, 620 8, 630 9, 990 90, 520 +15, 520

1928 17, 280 8, 390 8, 890 91, 970 +16, 970

1929 21, 430 8, 670 12, 760 98, 830 +23, 830

1930 14, 890 7, 590 7, 300 93, 550 +18, 550

1931 7, 770 5, 330 2, 440 82, 440 + 7, 440

1932 17, 240 7, 950 9, 290 81, 600 + 6, 600

1933 11, 360 6, 500 4, 860 76, 640 + 1, 640

1934 5, 640 4, 480 1, 160 70, 940 - 4, 060

1935 11, 550 6, 450 5, 100 69, 870 - 5, 130

1936 13, 800 7, 480 6, 320 68, 110 - 6, 890

1937 13, 740 6, 710 7, 030 65, 150 - 9, 850

1938 17, 550 7, 840 9, 710 65, 970 - 9, 030

1939 11, 080 6, 260 4, 820 58, 030 - 16, 970

1940 8, 600 5, 130 3, 470 54, 200 - 20, 800

1941 18, 150 7, 700 10, 450 62, 210 - 12, 790

1942 19, 120 7, 830 11, 290 64, 210 - 10, 790

1943 13, 100 7, 070 6, 030 65, 380 - 9, 620

1944 15, 150 6, 980 8, 170 72, 390 - 2, 610

1945 13, 410 6, 740 6, 670 73, 960 - 1, 040

1946 10, 420 5, 950 4, 470 72, 110 - 2, 890

1947 15, 470 7, 510 7, 960 73, 040 - 1. 960

Means: 

1931- 40 11, 830 6, 410 5, 420

1914- 45 15, 640 7, 500 8, 140 1 Use appor t i oned by Col or ado Ri ver Compact , measur ed i n t er ms 

of man- made depl et i ons at Lee Fer r y.

Source: CRSP report, 1950

In this study, importation of water from northern California was suggested to meet the 

imbalance. The initial plan contemplated the conveyance of 1.2 maf of surplus water from 

northern to southern California to guarantee against deficiencies in water supplies available from 

the lower Colorado River (Reclamation, 1964). 
Appendix 3 — Summary of Past 

Colorado River Planning Studies

December 2012 SR3-5 

This study led to the enactment of the Colorado River Basin Project Act of September 30, 1968 

(Public Law 90-537), making the Central Arizona Project (CAP) a reality. 

3.2 Water Supplies of the Colorado River – 1965

The recommendations and requests for authorization contained within the 1964 Pacific 

Southwest Water Plan caused concern in the Upper Basin, particularly regarding the CAP. 

Consequently, the Upper Colorado River Commission sponsored a study in 1965 by consulting 

engineers Tipton and Kalmbach. The results of this study were presented in Water Supplies of 

the Colorado River (Tipton, 1965). 

This study concluded that Upper Basin consumptive use, including evaporation, would be 

limited to 6.3 million acre-feet per year (mafy). Net depletion excluding evaporation would be 

5.6 mafy. A water supply and demand imbalance was calculated to be 1.195 mafy (See figure 1). 

FIGURE 1

Analysis of Lower Basin Supply and Demand and Resulting Deficiency

Lower River Requirements:

1. Beneficial consumptive use by Arizona, 

California and Nevada 7.500 maf

2. Mexican Treaty Deliveries 1.500

3. Reservoir Evaporation 0.730

4. Losses below Hoover Dam 0.810

Total Requirements 10.540 maf

Water Supply for the Lower River:

1. Delivery at Lee Ferry 8.250 maf

2. Net Inflow Lee Ferry to Lake Mead 0.675

3. Net Inflow from Bill Williams River 0.055

4. Release from Lake Mead (drawdown 

to rated power head) 0.365

Total Water Supply 9.345

Deficiency 1.195 maf

Source: Tipton, 1965.

The study states that, although a delivery of 8.25 maf had been assumed, the amount delivered 

by the Upper Basin eventually would approximate 7.5 mafy. When the delivery from the Upper 

Basin lowered to 7.5 maf instead of 8.25 maf, then the deficiency would increase to 1.945 mafy. 

Likewise, if the provisions of Section (b) of Article IV of the Compact were invoked, Lake Mead 

could be drawn down to absolute dead storage, which would provide about 0.60 mafy of 

additional water, including a decrease in evaporation from Lake Mead. In this case, the above 

deficiencies would be reduced by about 0.60 maf (Tipton, 1965). 

Finally, the study suggested the importation of water to meet the imbalance. It comes short of 

recommending a particular source of importation, stating: 

The obvious conclusion is that a firm water supply is not available in the 

Colorado River to satisfy a basic beneficial consumptive use requirement of 7.5 
Colorado River Basin 

Water Supply and Demand Study

SR3-6 December 2012

maf from the main stem by Arizona, California and Nevada, plus delivery of 1.5 

maf of water to Mexico. If these requirements as well as Upper Basin 

requirements are to be satisfied, projects must be authorized and constructed to 

import major amounts of water into the Colorado River Basin from sources of 

surplus. Such importation is important to both the Upper and Lower Basins 

(Tipton, 1965). 

3.3 The Comprehensive Framework Studies – 1971-1972

Three Comprehensive Framework Studies were conducted that pertain to the Basin – the Lower 

Colorado Region Comprehensive Framework Study, the Upper Colorado Region Comprehensive 

Framework Study, and the California Region Comprehensive Framework Study (Pacific 

Southwest Inter-agency Committee, 1971a, 1971b, and 1972). As defined in these framework 

studies, the Lower Colorado Region consisted of those parts of the Lower Colorado River Basin 

which lies downstream of Lees Ferry except for parts of the Lower Basin lying in California 

(e.g., west of the Colorado River). Parts of California lying within the Lower Colorado Basin 

were covered in the California Region Comprehensive Framework Study. The objective of the 

framework studies was to provide a broad guide to the best use, or combination of uses, of water 

and related land resources in each region to meet foreseeable short- and long-term needs.

Each of the framework studies had multiple demand scenarios, predominantly based on 1968 

national population and demographic projections by the Office of Business Economics of 

Commerce, and the Economic Research Service, U.S. Department of Agriculture (OBERS). 

These projections were then modified to reflect local conditions. 

Each of the studies detailed the status of development as of the base year, 1965. The studies then 

presented a framework program for the development and management of the water and related 

land resources (Framework Plan) of the respective region through 2020. 

3.3.1 Lower Colorado Region Comprehensive Framework Study – 1971

Two demand scenarios were considered in the formulation of the Lower Colorado Region 

Comprehensive Framework Study: 1) the Base Plan, based on the regionally interpreted OBERS

projections, and 2) the non-modified OBERS projections. 

The basic long-range objective of this study was augmentation of the region’s water supplies in 

sufficient increments to meet future water requirements and reduce ground water overdraft. The 

Framework Plan consisted of an Early Action Program to cover short-term requirements (1965 to 

1980), and a Continuing Program to cover longer-term requirements (1981 to 2020). The most 

critical immediate need was identified as meeting the diversion requirements projected to occur 

before 1980 without increasing the groundwater overdraft. 

After implementation of the Early Action program, a water supply deficiency of about 1.5 maf

was projected to remain. Therefore, the framework program provided for the importation of 2.25 

maf of desalted sea water to the Lower Colorado Region before 2000, including 1.8 maf to 

satisfy the 1944 Treaty with Mexico Mexican Treaty requirement and 0.45 maf as a regional 

program. Imported water would be conveyed to and stored in Lake Mead. It was projected that, 

if the initial water importation were in operation at year 2000, a regional annual water deficiency 

of about 0.44 maf would remain, which would increase to about 2.1 maf annually by 2020. The 
Appendix 3 — Summary of Past 

Colorado River Planning Studies

December 2012 SR3-7 

framework recommended additional importation facilities between 2000 and 2020 to provide 

about 1.9 maf annually, reducing the annual imbalance to 0.17 maf by 2020. In the absence of an 

imported water supply, groundwater overdraft was expected to continue and the regional water 

deficiency was projected to reach 4.5 mafy by 2020. 

3.3.2 Upper Colorado Region Comprehensive Framework Study – 1971

In the Upper Colorado Region Comprehensive Framework Study, four demand scenarios were 

analyzed: 1) the Base Plan, based on the regionally interpreted OBERS, 2) the States’ alternative 

to the Framework Plan (6.55 maf level of development), 3) States’ alternative at the 8.16 maf 

level of development, and 4) States’ alternative for water supply physically available in the 

region (9.44 maf). 

Land and water supply were not considered to be limiting factors in the Framework Plan in 

meeting the regionally interpreted OBERS level of development; however, the study concluded 

that the future outflow at Lees Ferry would depend on which level of development actually 

occurred, as well as augmentation. Augmentation practices considered as possibilities included 

water-yield improvement and weather modification, which were thought to increase the water 

supply by about 1 to 2 maf. The study concluded that 1) augmentation would definitely be 

required by 2020 for the two highest levels of depletion to meet the Compact obligation to the 

Lower Basin, and 2) local shortages in the region could occur at any level of development. 

3.3.3 California Region Comprehensive Framework Study – 1972

Two subregions in the California Region Comprehensive Framework Study are pertinent to the 

Basin—the Colorado Desert and the South Coast subregions. Three demand scenarios were 

analyzed in this study: 1) the Base Plan, based on the locally interpreted OBERS projections, 2) 

the non-modified OBERS projections, and 3) Series D-1970 projections used in a California state 

study, which projected a population of 45 million (10 million less than the OBERS projections). 

A number of alternatives were presented for meeting projected needs. The report states that: 

Three general approaches were taken in developing alternatives for meeting water 

supply requirements or to produce the goods and services dependent on water 

supply. These are: first an approach that relies on surface water development; 

second, an approach that utilizes other means for providing water supply; and 

third, an approach that reduces water requirements...When programs are finally 

implemented they will likely contain elements from each of the three approaches

(Pacific Southwest Inter-Agency Committee, 1972). 

In the Colorado Desert subregion, the study noted that water, not land, is the limiting factor in 

future development. The study predicted that 675,000 acres would be under irrigation by the year 

2020; however, if water were readily available within the service area of the Colorado River, an 

additional 330,000 acres of new land could be utilized. Although the possibility of developing 

this additional acreage was not considered, it was believed that at least an additional 1.5 maf of 

water could be used in this area if it were available (Pacific Southwest Inter-Agency Committee, 

1972). 

The South Coast subregion was projected to have a water supply and demand imbalance of 1.64 

maf by 2020. The study suggested this imbalance would need to be resolved through sources 
Colorado River Basin 

Water Supply and Demand Study

SR3-8 December 2012

such as reuse of surface and ground waters, waste water reclamation, distillation, and 

development of new supplies outside of the area. Waste water reclamation of 560 thousand acrefeet per year was included as a plan element for the South Coast subregion. Importation of North 

Coastal water supplies was necessary to meet Base Plan projections, but not OBERS or Series D1970 projections. 

4.0 Studies 1975 - 2007 

Studies following the Comprehensive Framework Studies have all acknowledged an imbalance 

between water supply and demand in the Basin. Most of these studies have not sought to 

explicitly quantify the imbalance, but rather have focused on potential solutions to various 

problems throughout the Basin, including the problems of water supply and demand imbalances, 

salinity, and tribal water rights. In light of the attention given to some of these issues, 

institutional changes, such as interim operating criteria and the Consolidated Decree, have 

occurred. The following sections summarize what these more-recent Basin studies have 

concluded about water supply and demand imbalances. 

4.1 Westwide Study Report on Critical Water Problems Facing the Eleven 

Western States - 1975

The Westwide Study Report on Critical Water Problems Facing the Eleven Western States 

(Reclamation, 1975) was an interagency state-federal effort meant to provide the information 

necessary to assist the federal government in making decisions on policy, funding, and action 

programs for development of the West’s water resources.

The principal conclusions regarding water supply and demand imbalances were that the 

Colorado River should be able to meet all quantitative physical water demands for some years to 

come; however, assuming a long-term average annual supply of 14.9 maf, sometime after the 

CAP became fully operational the Colorado River would not yield enough water under normal 

circumstances to meet Upper and Lower Basin demands, Mexican Treaty obligations, and 

system losses. Therefore, the study concluded, the Basin faces future water shortages unless its 

natural flows are augmented or Basin development is curtailed. Assuming a fairly intensive level 

of future Upper Basin development and a conservative long-term hydrologic cycle, the study 

predicted the Colorado River water supply would not meet all water demands, beginning in 

about 1990, and shortages would become progressively greater thereafter. The extent and timing 

of these shortages would depend on the rate of future consumptive use development and the 

volumes of annual runoff (Reclamation, 1975). 

The study continued to discuss potential options for a total water management program. It 

envisioned a program that would include activities such as:

• Coordinated operations of all major structures and conjunctive use of surface and 

groundwater supplies 

• Increasing irrigation efficiency through such means as better on-farm system and 

management practices and improved distribution systems

• Waste water reclamation and reuse
Appendix 3 — Summary of Past 

Colorado River Planning Studies

December 2012 SR3-9 

• Increasing water yield through selective phreatophyte removal and control, reducing 

snowpack evaporation, and watershed management practices 

• Reallocation of water supplies through institutional procedures 

• Water pricing mechanisms

The study ultimately concluded: 

It is evident that a total water management program can only delay and not 

prevent water shortages from occurring eventually. When such shortages do occur 

there appears to be two alternative courses open. The first would be to accept the 

limitation in water supply and pattern the economic and social future of the basin 

to that limitation. The second option would be to augment the flows of the 

Colorado River thus increasing its water supply and permitting continued growth 

of water dependent developments (Reclamation, 1975). 

4.2 Colorado River Basin Water Problems: How to Reduce the Impact - 1979

This report, by the Government Accounting Office, described numerous water problems existing 

within the Basin and discussed the need for the states and the federal government to work 

together to solve these problems. One of the key problems addressed is that “water supply is 

insufficient to meet future demands” (Government Accounting Office, 1979). 

The study’s discussion of water supply included Reclamation’s estimate of average annual 

natural flow and three challenging estimates. Reclamation’s estimate, based on records dating 

1906 through 1977, was 14.8 mafy. Alternative estimates of average annual natural flow came 

from 1) the Upper Colorado River Commission, which stated that it considered the gauged 

records for 1922 1977 to be more reliable and accepted the estimate of 13.7 maf as the future 

annual virgin flow, 2) engineers from the Lower Basin States, who testified before Congress 

during hearings for the 1968 Colorado River Basin Project Act that the virgin river flow was 

between 13.7 and 14.0 mafy, and 3) researchers at the Laboratory of Tree Ring Research, 

University of Arizona, who used tree ring reconstructions to estimate the river’s annual flow to 

be about 13.5 mafy. 

The report quoted Reclamation studies indicating that a water supply and demand imbalance

could occur as early as 1992 and probably would occur before 2023. It concluded that after the 

CAP came online, the river would probably not yield enough water to meet all Basin demands, 

the Mexican Treaty obligations, and river system losses. It further concluded that, unless the 

water supply available to CAP were increased, farmland would have to be reduced significantly 

to balance water supply and use by 2020, assuming median growth rate in nonagricultural 

activities.

Suggested solutions to the predicted imbalance included water salvage programs, conservation, 

and various augmentation methods. Water salvage measures included dredging the river channel, 

removing vegetation along the river bank, construction of Senator Wash Dam to improve control 

of the flow of water to the United Mexican States (Mexico) by reducing excess deliveries, and 

installing wells near the border to reduce the flow of groundwater to Mexico. Conservation 

measures primarily focused on farming efficiency. Augmentation methods considered included 
Colorado River Basin 

Water Supply and Demand Study

SR3-10 December 2012

weather modification, vegetation management, desalting geothermal brines and sea water, and 

importation of water from other river basins. 

Finally, the report included three recommendations to the Secretary of Interior for addressing 

water supply and demand imbalances, referred to as shortages in the report:

1. Direct Reclamation to develop a series of water management plans that reflect various supply 

estimates and present a number of alternative actions. Coordinate these plans with all the 

Basin’s water managers.

2. Amend reservoir operating criteria by stating 1) the conditions under which a water supply 

shortage will be declared, 2) the amounts to be released during a shortage, 3) the reservoir 

storage levels to be maintained in low-flow years, and 4) the amount of water each subbasin 

must provide for the 1944 Treaty with Mexico commitment.

3. Direct Reclamation to develop a comprehensive plan specifying the conservation, water 

salvage, and augmentation techniques that will be used to prevent or minimize the adverse 

effects of shortages. This plan should identify factors that would interfere with implementing 

the plan and address how they would be resolved.

4.3 Colorado River Basin Study – 1997

This study was requested by the Western Water Policy Review Advisory Commission 

(Commission), and completed by Dale Pontius. It included analysis of the most critical issues 

projected to be facing the basin in the near future, efforts being made to address these problems,

and specific recommendations to the Commission for Basin water management and governance 

over the next 20 years. The study conceptualized a vision for the Basin for the year 2025, the 

basic premise of which was that 

...we should be working toward three general goals in developing water policy 

for the basin in the next century: they are equity, efficiency, and sustainability in 

water use and management (Pontius, 1997). 

Regarding water supply and demand imbalances, the analysis depended on previous studies for 

information, and concluded that the river was over-allocated by 20 to 30 percent, depending on 

which flow estimates were used. The report stated that for planning purposes in the Upper Basin, 

the Upper Colorado River Commission had used 6.0 mafy as full development. Based on this 

number, current depletions in the Upper Basin (including 520,000 acre-feet per year of reservoir 

evaporation) were already more than 75 percent of the available amount, and projections showed 

that the Upper Basin states would be using 90 percent of 6.0 mafy by the year 2030. The study 

further concluded that in the Lower Basin, implementation of the Arizona Water Bank would 

mean that Arizona would divert its full apportionment as early as 1998 and that Nevada would be 

using its full 300,000 af apportionment by 2010. 

Included in the recommendations to address water supply and demand imbalances were the 

following: 

• An interstate water bank should be established in the Lower Basin with maximum flexibility 

for marketing and banking water. 
Appendix 3 — Summary of Past 

Colorado River Planning Studies

December 2012 SR3-11

• The Basin States and local water managers need to develop stronger conservation programs 

to maximize conservation and reuse potential and more clearly define and regulate 

reasonable beneficial use. 

• The Secretary, Basin States, and tribes, with input from other interests, should agree on a 

plan for reservoir operation and surplus and shortage criteria that is equitable to all interests 

and meets federal statutory obligations and treaty obligations to Mexico. 

4.4 Colorado River Basin Water Management: Evaluating and Adjusting to 

Hydroclimatic Variability - 2007

This report was prepared by the Committee on the Scientific Bases of Colorado River Basin 

Water Management. The activities of this committee were overseen and supported by the 

National Research Council’s Water Science and Technology Board. The committee was asked to 

review the hydrologic and climatic bases of Colorado River water management and to consider 

broad topics of system operations and water management practices. Terms such as “population 

growth” and “water demand” did not appear in the statement of task. 

Nonetheless, as the committee proceeded, 

...it became clear that broad understanding of Colorado River management issues 

is not possible unless both water supply and demand issues are adequately 

considered. Thus [they] felt it incumbent to comment on topics of water demand, 

technologies and practices for augmenting water supplies, and programs for 

coping with drought” (Committee on the Scientific Bases of Colorado River 

Basin Water Management, 2007). 

Within the scope of its statement of task and its available resources, the committee chose to 

focus on reviewing existing scientific knowledge of hydroclimatic variability and on discussing 

the implications of hydroclimatic variability in the context of key water management challenges 

in the Basin. The committee also aimed to broadly assess key Colorado River scientific issues as 

they relate to water supply, demand, management, and drought preparedness.

The committee concluded that:

Technological and conservation options for augmenting or extending water 

supplies – although useful and necessary – in the long run will not constitute a 

panacea for coping with the reality that water supplies in the Colorado River basin 

are limited and that demand is inexorably rising (Committee on the Scientific 

Bases of Colorado River Basin Water Management, 2007). 

The report contained three major conclusions, based on the committee’s evaluation of drought 

planning strategies: 

• Interstate cooperation and initiative will prove increasingly valuable and essential in coping 

with future droughts and growing water demands. 

• A commitment to two-way conversation among scientists and water managers is important 

and necessary in improving overall preparedness and planning for drought and other water 

supply shortages. 
Colorado River Basin 

Water Supply and Demand Study

SR3-12 December 2012

• A comprehensive, action-oriented study of Colorado River region urban water practices and 

changing patterns of demand should be conducted because such a study could provide a more 

systematic basis for water resources planning across the region. The study could be 

conducted by the Basin States, a federal agency or agencies, a group of universities from 

across the region, or some combination thereof. These groups should be prepared to take 

action based on this study’s findings in order to improve the region’s preparedness for future 

inevitable droughts and water shortages. 

5.0 Summary and Conclusions

Previous studies of the Colorado River Basin reveal that water supply and demand imbalances 

have been on the radar since the 1960s. A number of useful developments have come out of 

these studies. For example, the Colorado River Interim Guidelines for Lower Basin Shortages 

and Coordinated Operations for Lake Powell and Lake Mead Final Environmental Impact 

Statement (Reclamation, 2007) partially addressed recommendations from the more-recent group 

of studies, by amending reservoir operations under low reservoir conditions for an interim 

period. 

The current Colorado River Basin Water Supply and Demand Study is the next logical step in the 

series of studies. Such a comprehensive state-federal cooperative study has been envisioned and 

recommended in several of the more recent ‘survey’ studies, and picks up where the previous 

studies have left off. 

6.0 References 

Bureau of Reclamation (Reclamation). 1946. The Colorado River: A Comprehensive Report on 

the Development of the Water Resources of the Colorado River Basin for Irrigation, 

Power Production, and Other Beneficial Uses in Arizona, California, Colorado, Nevada, 

New Mexico, Utah, and Wyoming. 

Bureau of Reclamation (Reclamation). 1950. Colorado River Storage Project and Participating 

Projects; Upper Colorado River Basin. 

Bureau of Reclamation (Reclamation). 1952. Report on Water Supply of the Lower Colorado 

River Basin: Project Planning Report. 

Bureau of Reclamation (Reclamation). 1964. Pacific Southwest Water Plan. 

Bureau of Reclamation (Reclamation). 1975. Westwide Study Report on Critical Water Problems 

Facing the Eleven Western United States. 

Bureau of Reclamation (Reclamation). 2007. Colorado River Interim Guidelines for Lower 

Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead Final 

Environmental Impact Statement. 

Committee on the Scientific Bases of Colorado River Basin Water Management. 2007. Colorado 

River Basin Water Management: Evaluating and Adjusting to Hydroclimatic Variability. 

Engineering Advisory Committee. 1948. Final Report, Engineering Advisory Committee to 

Upper Colorado River Basin Compact Commission. 
Appendix 3 — Summary of Past 

Colorado River Planning Studies

December 2012 SR3-13

Government Accounting Office. 1979. Colorado River Basin Water Problems: How to Reduce 

Their Impact. 

Pacific Southwest Inter-agency Committee. 1971a. Comprehensive Framework Study, Lower 

Colorado Region. Prepared by the Lower Colorado Region State – Federal Interagency 

Group for the Pacific Southwest Inter-agency Committee, Water Resources Council. 

Washington D.C. 

Pacific Southwest Inter-agency Committee. 1971b. Comprehensive Framework Study, Upper 

Colorado Region. Prepared by the Upper Colorado Region State – Federal Interagency 

Group for the Pacific Southwest Inter-agency Committee, Water Resources Council. 

Washington D.C. 

Pacific Southwest Inter-agency Committee. 1972. Comprehensive Framework Study, California 

Region. Prepared by the California Region State – Federal Interagency Group for the 

Pacific Southwest Inter-agency Committee, Water Resources Council. Washington D.C. 

Pontius, Dale. 1997. The Colorado River Basin Study. Prepared for the Western Water Policy 

Review Advisory Commission. 

Tipton, Royce J. 1965. Water Supplies of the Colorado River. 
Appendix 4 

Study Participants 

December 2012 SR4-1 

Appendix 4 — Study Participants

As envisioned by the Plan of Study, teams were established to facilitate the completion of the 

Study. Members of each team are presented along with their affiliation.

1.0 Steering Team Members

A list of Steering Team members and their affiliations is presented below. 

• Perri Benemelis, Arizona Department of Water Resources

• Carly Jerla, Bureau of Reclamation

• Dave Trueman, Bureau of Reclamation

• Chris Harris, Colorado River Board of California 

• Ted Kowalski, Colorado Water Conservation Board 

• Estevan Lopez, New Mexico Interstate Stream Commission 

• Kay Brothers, Southern Nevada Water Authority 

• Don Ostler, Upper Colorado River Commission 

• Robert King, Utah Division of Water Resources 

• John Shields, Wyoming State Engineer’s Office

• Cathy Condon, Ten Tribes Partnership 

• Jason John, Ten Tribes Partnership

2.0 Project Team Members

A list of Project Team members and their affiliations is presented below. 

• Perri Benemelis, Arizona Department of Water Resources 

• Don Gross, Arizona Department of Water Resources

• Deanna Ikeya, Arizona Department of Water Resources

• Les Lampe, Black & Veatch

• Klint Reedy, Black & Veatch

• Pamela Adams, Bureau of Reclamation

• Alan Butler, Bureau of Reclamation

• Carly Jerla, Bureau of Reclamation

• KayLee Nelson, Bureau of Reclamation

• Ken Nowak, Bureau of Reclamation

• James Prairie, Bureau of Reclamation

• Dave Trueman, Bureau of Reclamation

• Shana Tighi, Buruea of Reclamation 

• Chuck Cullom, Central Arizona Project 

• Mohammed Mahmoud, Central Arizona Project 

• Greg Gates, CH2M HILL

• Armin Munévar, CH2M HILL 

• Chris Harris, Colorado River Board of California 
Colorado River Basin 

Water Supply and Demand Study

SR4-2 December 2012

• Lindia Liu, Colorado River Board of California 

• Jerry Zimmerman, Colorado River Board of California 

• Dave Kanzer, Colorado River Water Conservation District 

• Ted Kowalski, Colorado Water Conservation Board 

• Bennet Raley, Front Range Water Council 

• John Carter, Imperial Irrigation District

• Mike King, Imperial Irrigation District

• Joanna Smith, Imperial Irrigation District

• Bill Swan, Imperial Irrigation District

• Kevin Flanigan, New Mexico Interstate Stream Commission

• Estevan Lopez, New Mexico Interstate Stream Commission

• Amy Haas, New Mexico Interstate Stream Commission

• Jordan Fischbach, RAND Corporation 

• David Groves, RAND Corporation 

• Halla Razak, San Diego County Water Authority 

• Kay Brothers, Southern Nevada Water Authority 

• David Donnelly, Southern Nevada Water Authority 

• Tom Maher, Southern Nevada Water Authority 

• Bruce Moore, Southern Nevada Water Authority 

• Colby Pellegrino, Southern Nevada Water Authority 

• Larry Tamashiro, Southern Nevada Water Authority 

• Bill Hasencamp, The Metropolitan Water District of Southern California

• Jan Matusak, The Metropolitan Water District of Southern California

• Demetri Polyzos, The Metropolitan Water District of Southern California

• Tom Ryan, The Metropolitan Water District of Southern California

• Robert King, Utah Division of Water Resources 

• Bob Johnson, Water Consult Engineering and Planning Consultants 

• Erin Wilson, Wilson Water Group

• John Shields, Wyoming State Engineer’s Office 

3.0 Study Team Members

A list of Study Team members and their affiliations is presented below. 

• Les Lampe, Black & Veatch

• Klint Reedy, Black & Veatch

• Pamela Adams, Bureau of Reclamation

• Alan Butler, Bureau of Reclamation

• Carly Jerla, Bureau of Reclamation

• KayLee Nelson, Bureau of Reclamation

• Ken Nowak, Bureau of Reclamation

• James Prairie, Bureau of Reclamation 

• Shana Tighi, Bureau of Reclamation 

• Dave Tueman, Bureau of Reclamation

• Greg Gates, CH2M HILL
Appendix 4 — Study Participants

December 2012 SR4-3 

• Armin Munévar, CH2M HILL 

• Jordan Fischbach, RAND Corporation 

• David Groves, RAND Corporation 

4.0 Water Supply Sub-Team Members 

A list of Water Supply Sub-Team members and their affiliations is presented below. 

• Carly Jerla, Bureau of Reclamation 

• Chuck Cullom, Central Arizona Project 

• Tapash Das, CH2M HILL 

• Armin Munévar, CH2M HILL

• Jerry Zimmerman, Colorado River Board of California 

• Robert Kirk, Navajo Nation 

• John Whipple, New Mexico Interstate Stream Commission 

• Mike Roberts, The Nature Conservancy 

• John Gerstle, Trout Unlimited

• Steve Cullinan, U.S. Fish and Wildlife Service 

• Robert King, Utah Division of Natural Resources 

Additional support in the form of supplemental analysis, review, and information was provided 

by those listed below. 

• Ben Harding, AMEC Earth & Environmental 

• Ken Nowak, Bureau of Reclamation 

• Jim Prairie, Bureau of Reclamation

• Levi Brekke, Bureau of Reclamation’s Technical Service Center

• Subhrendu Gangopadhyay, Bureau of Reclamation’s Technical Service Center 

• Tom Pruitt, Bureau of Reclamation’s Technical Service Center

• Joe Barsugli, University of Colorado and the National Oceanic and Atmospheric 

Administration

5.0 Water Demand Sub-Team Members

A list of Water Demand Sub-Team members and their affiliations is presented below. 

• Perri Benemelis, Arizona Department of Water Resources

• Jim Prairie, Bureau of Reclamation 

• Greg Gates, CH2M HILL

• Ted Kowalski, Colorado Water Conservation Board 

• Jennifer Pitt, Environmental Defense Fund 

• Jason John, Navajo Nation 

• John Whipple, New Mexico Interstate Stream Commission 

• Tom Maher, Southern Nevada Water Authority

• Bill Hasencamp, The Metropolitan Water District of Southern California

• Don Ostler, Upper Colorado River Commission 

• Andrew Hautzinger, U.S. Fish and Wildlife Service 
Colorado River Basin 

Water Supply and Demand Study

SR4-4 December 2012

Alternate and/or contributing members who participated include:

• Don Gross, Arizona Department of Water Resources

• Brian Westfall, Keller-Bliesner Engineering (consultant for the Navajo Nation) 

• Michael Foley, Navajo Nation

• Larry Tamashiro, Southern Nevada Water Authority 

• Janet Bair, U.S. Fish and Wildlife Service 

• Drew Beckwith, Western Resource Advocates

Members added in November-December 2010 include: 

• Marc Waage, Denver Water

• Carole Klopatek, Fort McDowell Yavapai Nation

• Charles Vaughn, Hualapai Tribal Nation

• Darryl Vigil, Jicarilla Apache Nation 

6.0 Metrics Sub-Team Members

A list of Metrics Sub-Team members and their affiliations is presented below. 

• Klint Reedy, Black & Veatch

• Alan Butler, Bureau of Reclamation

• Carly Jerla, Bureau of Reclamation

• Martin Einert, Bureau of Reclamation

• Kara Gillon, Defenders of Wildlife

• Jason John, Navajo Nation 

• Colby Pellegrino, Southern Nevada Water Authority 

• Jan Matusak, The Metropolitan Water District of Southern California 

• Robert Wigington, The Nature Conservancy 

• John Shields, Wyoming State Engineers Office 

Points of contact with other organizations that provided additional information are presented 

below. 

• Nathan Fey, American Whitewater

• Katrina Grantz, Bureau of Reclamation

• Robert Radtke, Bureau of Reclamation

• Jack Barnett, Colorado River Basin Salinity Control Forum 

• Norm Henderson, National Park Service

• Bill Jackson, National Park Service 

• Kent Turner, National Park Service 

• David Slick, Salt River Project

• Janet Bair, U.S. Fish and Wildlife Service 

• Tom Chart, U.S. Fish and Wildlife Service 

• Andrew Hautzinger, U.S. Fish and Wildlife Service

• Jana Mohrman, U.S. Fish and Wildlife Service 

• Mike Roberts, The Nature Conservancy 

• John Sanderson, The Nature Conservancy 
Appendix 4 — Study Participants

December 2012 SR4-5 

• Xavier Gonzalez, Western Area Power Administration 

• Sam Loftin, Western Area Power Administration 

7.0 Options and Strategies Sub-Team Members 

A list of Options and Strategies Sub-Team members and their affiliations is presented below. 

• Perri Benemelis, Arizona Department of Water Resources

• Don Gross, Arizona Department of Water Resources 

• Les Lampe, Black & Veatch

• Klint Reedy, Black & Veatch

• Alan Butler, Bureau of Reclamation

• Carly Jerla, Bureau of Reclamation

• Ken Nowak, Bureau of Reclamation

• James Prairie, Bureau of Reclamation

• Chuck Cullom, Central Arizona Project 

• Greg Gates, CH2M HILL

• Armin Munévar, CH2M HILL 

• Chris Harris, Colorado River Board of California 

• Lindia Liu, Colorado River Board of California 

• Dave Kanzer, Colorado River Water Conservation District 

• Ted Kowalski, Colorado Water Conservation Board 

• Jennifer Pitt, Environmental Defense Fund 

• John Carter, Imperial Irrigation District

• Kevin Flanigan, New Mexico Interstate Stream Commission

• Estevan Lopez, New Mexico Interstate Stream Commission

• Jordan Fischbach, RAND Corporation 

• David Groves, RAND Corporation 

• Kay Brothers, Southern Nevada Water Authority 

• Tom Maher, Southern Nevada Water Authority 

• Bruce Moore, Southern Nevada Water Authority 

• Cathy Condon, Ten Tribes Partnership 

• Jason John, Ten Tribes Partnership 

• Bill Hasencamp, The Metropolitan Water District of Southern California

• Jan Matusak, The Metropolitan Water District of Southern California

• Taylor Hawes, The Nature Conservancy

• Melinda Kassen, Trout Unlimited

• Erin Wilson, Wilson Water Group

• John Shields, Wyoming State Engineer’s Office 

8.0 Modeling Sub-Team Members

A list of Modeling Sub-Team members and their affiliations is presented below. 

• Don Gross, Arizona Department of Water Resources 

• Les Lampe, Black & Veatch
Colorado River Basin 

Water Supply and Demand Study

SR4-6 December 2012

• Klint Reedy, Black & Veatch

• Alan Butler, Bureau of Reclamation

• Carly Jerla, Bureau of Reclamation

• Ken Nowak, Bureau of Reclamation

• James Prairie, Bureau of Reclamation

• Dave Trueman, Bureau of Reclamation

• Chuck Cullom, Central Arizona Project 

• Mohammed Mahmoud, Central Arizona Project 

• Greg Gates, CH2M HILL

• Armin Munévar, CH2M HILL 

• Jennifer Pitt, Environmental Defense Fund 

• Evan Bloom, RAND Corporation 

• Jordan Fischbach, RAND Corporation 

• David Groves, RAND Corporation 

• Kay Brothers, Southern Nevada Water Authority 

• Tom Maher, Southern Nevada Water Authority 

• Colby Pellegrino, Southern Nevada Water Authority 

• Chuck Lawler, Southern Ute Indian Tribe

• Cathy Condon, Ten Tribes Partnership 

• Bill Hasencamp, The Metropolitan Water District of Southern California

• Karen Murphy, The Metropolitan Water District of Southern California

• Kevin Wheeler, Water Balance Consulting

• Erin Wilson, Wilson Water Group
Appendix 5

Public Involvement Plan

December 2012 SR5-1

Appendix 5 — Public Involvement Plan

Note: This document was originally published as an appendix to the Plan of Study.

1.0 Introduction

The Colorado River Basin Water Supply and Demand Study (Study) has been selected to be one 

of three, two-year studies funded through the Bureau of Reclamation’s Basin Study Program.

The Study will provide a comprehensive analysis of current and future imbalances in water 

supply and demand projected through 2060 in the Colorado River Basin (Basin) and the adjacent 

areas of the Basin States (Arizona, California, Colorado, Nevada, New Mexico, Utah and 

Wyoming) that receive Colorado River water; potential impacts of climate variability and 

climate change on water supply and demand; and potential adaptation and mitigation strategies 

and options to resolve those imbalances. A primary objective of the Study is prioritization of 

identified strategies and options and the recommendation for potential future feasibility studies, 

Congressional authorization, environmental compliance activities, demonstration programs, 

and/or implementation.

The Study is cost-shared on a 50/50 basis between the Study partners: Reclamation (the Federal 

Cost-Share Partner) and agencies in the Basin States (the non-Federal Cost-Share Partners).

Because the Colorado River Basin spans two Reclamation regions, Reclamation is represented 

by both the Upper Colorado Regional Office and the Lower Colorado Regional Office.

The Study partners will facilitate public involvement to solicit and incorporate stakeholder input 

throughout the study. This Public Involvement Plan (PIP) provides the framework for that effort.

1.1 Approach

Several communication methods will be employed to effectively maintain communication with 

all interested stakeholders and to provide, seek, and receive information. A response will be 

provided for all comments received. All information received regarding technical aspects of the 

Study will be considered and feedback regarding that consideration will be provided.

All outreach materials, information received, and feedback provided will be archived in a 

centralized electronic filing system. As the Study progresses, the effectiveness of the public 

involvement will be assessed periodically and adjustments will be made as necessary to ensure 

that appropriate communication and feedback is occurring.

1.2 Communication Methods

Effective communication is essential for the ongoing success of the Study. The methods of 

communication that will be used to disseminate information and accept input during the course 

of the Study include the following:

• Study website will be maintained to provide up-to-date, on-line information; 

• E-mail address will be established to facilitate communication electronically; 

• Facsimile (fax) telephone number will be established to allow communication by fax;
Colorado River Basin 

Water Supply and Demand Study

SR5-2 December 2012

• Points-of-contact will be established in the Upper Colorado and the Lower Colorado Regions 

to facilitate additional information exchange; 

• News releases and informational mailings will be provided as appropriate;

• Mailing list will be established and maintained to ensure that all interested stakeholders 

receive information;

• Public meetings will be held at strategic points throughout the Study; and

• Additional meetings with interested stakeholders groups will be held as appropriate.

Additional information on each of these methods is provided below.

1.3 Web Site

Reclamation’s Study web site will be used to post up-to-date information. Web site content will 

be updated periodically, particularly at major milestones and prior to public meetings. In 

addition, the web site will be used as a tool for soliciting input from stakeholders. The following

web page will be available no later than January 8, 2010:

http://www.usbr.gov/lc/region/programs/crbstudy.html.

1.4 E-mail

Reclamation has established a Study e-mail address to disseminate information regarding the 

Study and to receive input. The Study e-mail address is: ColoradoRiverBasinStudy@usbr.gov.

1.5 Facsimile

Input may also be submitted by facsimile at: 702-293-8156.

1.6 Points-of-Contact

For additional information, questions, or comments on the Study, Reclamation has designated an 

Outreach Coordinator:

Pam Adams at 702-293-8501 or ColoradoRiverBasinStudy@usbr.gov

1.7 News Releases and Informational Mailings

News releases and other informational mailings will occur near major milestones throughout the 

Study to inform stakeholders and the public of the Study status, provide opportunities for input, 

and provide meeting information including dates and locations of the public meetings.

1.7.1 Mailing List

Informational mailings will be sent to interested stakeholders on the Study mailing list (either 

physically, electronically, or both). During each informational mailing, the recipient will be 

asked if he or she would like to remain on the list. Individuals will be added to the mailing list 

when requested through the Study e-mail address or through attendance at a public meeting 

captured on the sign-in sheet. An initial mailing will be made in January 2010 to a list of 

Colorado River stakeholders who were involved in similar prior studies.
Appendix 5 — Public Involvement Plan

December 2012 SR5-3

1.7.2 Public Meetings

Public meetings will be held at strategic points throughout the Study, beginning with an initial 

meeting in the spring of 2010. Additionally, prior to completion of each Study phase, public 

meetings will be held to provide a summary of the results of the previous phase and to seek 

comments on the upcoming phase of the Study, thereby allowing consideration of information 

and suggestions by the public for incorporation in the Study.

Four public meetings are currently envisioned as follows:

1. Targeted for March 2010 - Meeting to discuss the Study objectives, structure, schedule, PIP, 

the proposed approach for Phase 1 (assessment of current and future water supply), and 

Phase 2 (assessment of current and future water demand);

2. Targeted for September 2010 – Meeting to discuss the results of Phases 1 and 2 and the 

proposed approach for Phase 3 (analysis of the current and future system reliability);

3. Targeted for April 2011 – Meeting to discuss the results of Phase 3 and the proposed 

approach for Phase 4 (analysis of strategies and options for resolving supply/demand 

imbalances); and

4. Targeted for August 2011 – Meeting to discuss the results of Phase 4.

1.7.3 Additional Meetings with Interested Stakeholder Groups

During the course of the Study, additional meetings may be held with interested stakeholder 

groups to solicit additional input, expertise, data, and information. As appropriate, 

representatives of interested stakeholder groups may participate in specific Study tasks to 

facilitate incorporation of such input into the Study.

Interested stakeholder groups may include, but are not limited to Federal agencies, Native 

American Tribes and communities, water districts, scientific research groups, hydropower 

agencies and other representatives of the energy industry, environmental groups, and 

representatives of the recreational industry. An initial mailing will be made in January 2010 to a 

list of interest groups who were involved in similar prior studies to gage their interest and 

capability for participating in the Study. Other interest groups are encouraged to provide their 

contact information via one of the communication methods listed above.
Appendix 6 

Outreach Activities

December 2012 SR6-1 

Appendix 6 — Outreach Activities

This appendix presents a chronology of stakeholder outreach activities conducted for the 

Colorado River Basin Water Supply and Demand Study as of December 6, 2012. As 

summarized in table 1, a total of 173 outreach activities were conducted. The activities consisted 

of meetings held at locations convenient to stakeholder groups, webinars transmitted on the 

Internet, and telephone conference calls as shown in table 1. 

TABLE 1

Stakeholder Outreach Events Conducted for Basin Study as of December 6, 2012

Meeting 

Date Participant Location Meeting Type 

3/31/2010 Conservation Organizations1 Boulder, CO Meeting

5/3/2010 Conservation Organizations Conference Call

5/25/2010

Quechan Indian Tribe, Navajo Nation, Southern Ute Indian 

Tribe Webinar

5/26/2010

Hualapai Tribal Nation, Bureau of Indian Affairs - Colorado 

River Agency Parker, AZ Meeting

5/27/2010 Navajo Nation Window Rock, AZ Meeting

5/27/2010

Fort McDowell Yavapai Nation, Inter Tribal Council of 

Arizona Phoenix, AZ Meeting

6/16/2010 WestCAS Annual Conference Pacific Beach, CA Conference

6/17/2010 U.S. Fish and Wildlife Service Webinar

6/23/2010 Bureau of Land Management Salt Lake City, UT Meeting

6/24/2010

Western States Water Council, Western Governors' 

Association Webinar

6/25/2010 National Park Service Las Vegas, NV Meeting

6/30/2010 Western Area Power Administration, Salt River Project Boulder City, NV

Meeting/

Webinar

7/9/2010 Conservation Organizations Webinar

7/15/2010 Bureau of Land Management Denver, CO Meeting

7/27/2010 Conservation Organizations Webinar

7/29/2010 Fort McDowell Yavapai Nation Tribe Conference Call

7/30/2010 Conservation Organizations Webinar

8/5/2010 Hualapai Tribal Nation Boulder City, NV Meeting

1 Defenders of Wildlife, Environmental Defense Fund, Hydros Consulting, National Parks Conservation Association, Natural Resources Defense 

Council, The Nature Conservancy, Pacific Institute, Sonoran Institute, Trout Unlimited, Water Balance Consulting, Western Resources 

Advocates
Colorado River Basin 

Water Supply and Demand Study

SR6-2 December 2012

TABLE 1

Stakeholder Outreach Events Conducted for Basin Study as of December 6, 2012

Meeting 

Date Participant Location Meeting Type 

8/10/2010 Colorado River Fish and Wildlife Council Saratoga, WY Meeting

8/11/2010 Ute Indian Tribe of the Uinta & Ouray Reservation Boulder, CO Meeting

8/18/2010 Conservation Organizations Webinar

8/19/2010

Jicarilla Apache Nation, Ute Mountain Ute Tribe, Southern 

Ute Indian Tribe Durango, CO Meeting

8/19/2010 Conservation Organizations Webinar

8/23/2010 U.S. Environmental Protection Agency Webinar

9/1/2010 Conservation Organizations Conference Call

9/3/2010 U.S. Geological Survey Denver, CO Meeting

9/21/2010 Hualapai Tribal Nation Peach Springs, AZ Meeting

9/23/2010 Colorado River Basin Study Public Meeting Webinar

10/5/2010 Colorado Water Conservation Board Denver, CO Meeting

10/5/2010 Denver Water Denver, CO Meeting

10/6/2010 Irrigation and Electrical Districts Association of Arizona Conference Call

10/7/2010 Front Range Water Council Denver, CO Meeting

10/8/2010 Inter Tribal Council of Arizona Phoenix, AZ Meeting

10/20/2010 Virgin River Watershed Conference Mesquite, NV Conference

10/28/2010 Wyoming Water Association Laramie, WY Meeting

10/29/2010 Front Range Water Council Denver, CO Meeting

11/1/2010 Conservation Organizations Conference Call

11/1/2010 Conservation Organizations Webinar

12/30/2010 Layne Hydro Conference Call

1/18/2011 Conservation Organizations Boulder, CO Meeting

1/27/11 American Meteorological Society Seattle, WA Meeting

1/28/11

Tribal Leaders Water Policy Council of the 

Inter Tribal Council of Arizona Tempe, AZ Meeting

2/8/2011 Conservation Organizations Webinar

2/8/2011 Tahoe-Baikal Institute Hydrolists group from Russia Boulder City, NV Conference

2/9/2011 Nevada Climate Change - UNLV Las Vegas, NV Conference

2/16/2011 Colorado River Indian Tribes Conference Call

2/24/2011 Family Farm Alliance Annual Conference Las Vegas, NV Conference

3/2/2011 Conservation Organizations Boulder, CO Meeting
Appendix 6 — Outreach Activities

December 2012 SR6-3 

TABLE 1

Stakeholder Outreach Events Conducted for Basin Study as of December 6, 2012

Meeting 

Date Participant Location Meeting Type 

3/8/2011

UCLA Seminar - Colorado River Reservoir Management 

Under Changing Climate Conditions Los Angeles, CA Conference

3/21/2011 Jicarilla Apache Nation Conference Call

3/30/2011 Southern Ute Indian Tribe Ignacio, CO Meeting

4/5/2011 Colorado River Indian Tribes Conference Call

4/12/2011 Conservation Organizations Conference Call

4/21/2011 Ak-Chin Indian Community Conference Call

4/21/2011 Society for Human Ecology 18th International Conference Las Vegas, NV Conference

5/13/2011 Colorado River Indian Tribes Parker, AZ Meeting

5/20/2011 Society of Women Geographers Conference Estes Park, CO Conference

5/26/2011

American Society of Engineers - Water Resources Tech 

Committee Las Vegas, NV Conference

6/7/2011 National Climate Assessment Workshop Boulder, CO Conference

6/14/2011 Public Webinar - Interim Report No. 1 Webinar

6/16/2011 Jicarilla Apache Nation Albuquerque, NM Meeting 

7/5/2011 Conservation Organizations Conference Call

7/14/2011 Colorado Fish and Wildlife Council Big Sky, MT Meeting 

8/2/2011 U.S. Fish and Wildlife Service Albuquerque, NM Meeting

8/5/2011 Tribal Leaders Water Policy Council Phoenix, AZ Meeting

8/11/2011 Tohono O'odham Nation Sells, AZ Meeting

8/17/2011 Southern Ute Indian Tribe and Ute Mountain Ute Tribe Ignacio, CO Meeting

8/18/2011 Conservation Organizations Conference Call

8/23/2011 Jicarilla Apache Nation Dulce, NM Meeting

8/26/2011 Urban Water Institute San Diego, CA Conference

9/12/2011 Gila River Indian Community Phoenix, AZ Meeting

9/15/2011 Colorado River District Annual Water Seminar

Grand Junction, 

CO Conference

9/16/2011 Conservation Organizations Conference Call

9/16/2011 Utah League of Cities and Towns Salt Lake City, UT Conference

9/19/2011 Nuestro Rio Boulder, CO Meeting

9/19/2011 Protect the Flows Webinar

9/20/2011 San Carlos Apache Nation San Carlos, AZ Meeting

9/26/2011 Ak-Chin Indian Community Phoenix, AZ Meeting
Colorado River Basin 

Water Supply and Demand Study

SR6-4 December 2012

TABLE 1

Stakeholder Outreach Events Conducted for Basin Study as of December 6, 2012

Meeting 

Date Participant Location Meeting Type 

9/27/2011 American Water Resources Association - CO Chapter Denver, CO Meeting

9/30/2011 Ten Tribes Partnership Yuma, AZ Meeting

10/6/2011 Conservation Organizations Webinar

10/14/2011 Conservation Organizations Webinar

10/17/2011 White Mountain Apache Tribe Showlow, AZ Meeting

10/28/2011 Inter Tribal Council of Arizona Phoenix, AZ Meeting

10/31/2011 The Water Center at Colorado Mesa University

Grand Junction, 

CO Conference

11/7/2011 American Whitewater Conference Call

11/8/2011 Navajo Nation Window Rock, AZ Meeting

11/10/2011 Conservation Organizations Boulder, CO Meeting

11/30/2011 American Whitewater Conference Call

12/1/2011 Conservation Organizations Boulder, CO Meeting

12/2/2011 U.S. Fish and Wildlife Service and The Nature Conservancy Conference Call

12/6/2011 Public Webinar - Options & Strategies Webinar

12/8/2011 Nuestro Rio Denver, CO Meeting

12/9/2011 Conservation Organizations Conference Call

12/12-13/

2011 Innovative Water Transfers Workshop Las Vegas, NV Conference

12/14/2011 Carpe Diem West Las Vegas, NV Meeting

12/14/2011 Ten Tribes Partnership Las Vegas, NV Meeting

12/14-16/

2011 Colorado River Water Users Association Las Vegas, NV Meeting

12/18/2011 The Nature Conservancy and Trout Unlimited Boulder, CO Meeting

1/6/2012

Harvard Law School Environmental Law Program, Harvard 

Water Security Initiative Boulder, CO Briefing 

1/10/2012 Carpe Diem West Conference Call

1/18/2012 Conservation Organizations Conference Call

1/25/2012 U.S. National Park Service Webinar

1/26/2012 Trout Unlimited Conference Call

1/27/2012 National Parks Conservation Association Conference Call

1/31/2012 Carpe Diem West Webinar

2/1/2012 Inter Tribal Council of Arizona Phoenix, AZ Meeting
Appendix 6 — Outreach Activities

December 2012 SR6-5 

TABLE 1

Stakeholder Outreach Events Conducted for Basin Study as of December 6, 2012

Meeting 

Date Participant Location Meeting Type 

2/2/2012 Nuestro Rio Boulder, CO Meeting

2/8/2012 Ten Tribes Partnership Parker, AZ Meeting

2/23/2012

American Bar Association, Section of Environment, Energy, 

and Resources’ 30th Annual Water Law Conference San Diego, CA Conference

2/24/2012 Nuestro Rio Denver, CO Meeting

2/27/2012 Conservation Organizations Conference Call

2/29/2012 U.S. Geological Survey Conference Call

3/1-2/2012 14th Annual Law of the Colorado River Conference Las Vegas, NV Conference

3/6/2012 Lake Mead Symposium Las Vegas, NV Conference

3/8/2012 Carpe Diem West Conference Call

3/15/2012 Conservation Organizations Boulder, CO Meeting

3/21/2012 Carpe Diem West Webinar

3/22/2012 U.S. Geological Survey Boulder, CO Meeting

3/27/2012 Ute of Uinta and Ouray Reservation Ft. Duchesne, UT Meeting

3/28/2012 Ten Tribes Partnership Technical Committee Albuquerque, NM Meeting

4/3/2012 Conservation Organizations Conference Call

4/4/2012 The Nature Conservancy Boulder, CO Meeting

4/11/2012 Ten Tribes Partnership Towaoc, CO Meeting

4/30/2012 Rocky Mountain Climate Organization Conference Call

5/11/2012 Conservation Organizations Boulder, CO Meeting

5/21/2012 Carpe Diem West Conference Call

5/24/2012 Conservation Organizations Conference Call

5/29/2012 Ten Tribes Partnership Albuquerque, NM Meeting

6/7/2012 Conservation Organizations Webinar

6/8/2012 Inter Tribal Council of Arizona Phoenix, AZ Meeting

6/13/2012 Ten Tribes Partnership Salt Lake City, UT Meeting

6/19/2012 Western Coalition of Arid States Conference San Diego, CA Conference

6/22/2012 Conservation Organizations Boulder, CO Meeting

7/3/2012 Western Area Power Administration Conference Call

7/3/2012 Conservation Organizations Conference Call

7/12/2012 U.S. National Park Service Webinar

7/18/2012 Carpe Diem West Conference Call
Colorado River Basin 

Water Supply and Demand Study

SR6-6 December 2012

TABLE 1

Stakeholder Outreach Events Conducted for Basin Study as of December 6, 2012

Meeting 

Date Participant Location Meeting Type 

7/24/2012 Carpe Diem West Boulder, CO Meeting

8/1/2012 Conservation Organizations Conference Call

8/2/2012 Flaming Gorge Recreation Conference Call

8/15/2012 Ute Indian Tribe of the Uinta & Ouray Reservation

Fort Duchesne, 

UT Meeting

8/17/2012 Conservation Organizations Boulder, CO Meeting

8/23/2012 Urban Water Institute San Diego, CA Meeting

8/28/2012 Conservation Organizations Webinar

8/30/2012 Colorado River Fish and Wildlife Council 

Steamboat 

Springs, CO Meeting

9/13/2012 Colorado River District Annual Water Seminar

Grand Junction, 

CO Conference

9/14/2012 Carpe Diem West Salt Lake City, UT Meeting

10/1/2012 Conservation Organizations Webinar

10/5/2012 Colorado Water Conservation Board Boulder, CO Meeting

10/10/2012 Ten Tribes Partnership Yuma, AZ Meeting

10/11/2012 Conservation Organizations Boulder, CO Meeting

10/16/2012 Carpe Diem West Conference Call

10/26/2012 Scripps Institution of Oceanography Webinar

11/1/2012 National Water Resources Association San Diego, CA Conference

11/5/2012 Carpe Diem West Los Angeles, CA Meeting

11/14/2012 Carpe Diem West Webinar

11/20/2012 Front Range Water Council Denver, CO Meeting

11/21/2012 Conservation Organizations Boulder, CO Meeting

11/26/2012 Ten Tribes Partnership Conference Call

11/28/2012 Ten Tribes Partnership Conference Call

12/4/2012 Ten Tribes Partnership Webinar

12/5/2012 Family Farm Alliance Webinar

12/6/2012 Inter Tribal Council of Arizona Conference Call

12/6/2012 Ten Tribes Partnership Conference Call
Appendix 7 

Peer Review Summary Report

December 2012 SR7-1 

Appendix 7 — Peer Review Summary Report

1.0 Introduction

The Colorado River Basin Water Supply and Demand Study (Study), initiated in January 2010, 

was conducted by the Bureau of Reclamation (Reclamation) in collaboration with the seven 

Colorado River Basin States1 (Basin States), conservation organizations, federally recognized 

tribes (tribes), and other interested parties. The Plan of Study, provided in appendix 1 of the 

Study Report, states that the purpose of the Study is to define current and future imbalances in 

water supply and demand in the Colorado River Basin (Basin) and the adjacent areas of the 

seven Basin States that receive Colorado River water over the next 50 years (through 2060), and 

to develop and analyze adaptation and mitigation strategies to resolve those imbalances. The 

Study contains four major phases to accomplish this goal: Water Supply Assessment, Water 

Demand Assessment, System Reliability Analysis, and Development and Evaluation of Options 

and Strategies for Balancing Supply and Demand. 

This document provides a summary of the Study’s peer review. 

1.1 Approach

The peer review was designed to ensure that assumptions, findings, and conclusions of the Study 

were clearly stated and supported; oversights, omissions, and inconsistencies were identified; 

and limitations and uncertainties were disclosed. The reviewers were provided with focused 

technical questions while also being directed to offer a broad evaluation of the overall product. 

Specifically, peer review goals included the following: 

• Improve Study reports by ensuring that the methodologies, processes, assumptions, and 

limitations are thoroughly described and transparent 

• Understand potential critiques to help in the development of Study next steps. 

• Identify any significant errors.

Peer review comments were considered and incorporated into the Study Report and Technical 

Reports where relevant and appropriate. This summary report includes the views of the 

reviewers, without attribution of specific comments to specific reviewers, and an explanation of 

the actions undertaken (or not) to address the reviewers’ comments.

1.2 Peer Reviewers

The peer reviewers for this Study, as a group, have expertise in climate science and associated 

hydrologic impacts and water management in the Basin. Individuals with the identified expertise 

who did not have formal involvement in the Study were asked to participate in the independent 

peer review. Peer review elements and reviewers are as follows:

 

1 Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming.
Colorado River Basin 

Water Supply and Demand Study

SR7-2 December 2012

1.2.1 Water Supply Assessment

• Kelly Redmond – Deputy Director and Regional Climatologist, Desert Research 

Institute/Western Regional Climate Center

• Jeff Arnold – Senior Climate Scientist, U.S. Army Corps of Engineers

1.2.2 Water Demand Assessment

• Jeannine Jones – Interstate Resources Manager, California Department of Water 

Resources

• Bonnie Colby – Department of Agricultural and Resource Economics, University 

of Arizona 

1.2.3 Options and Strategies

• Tom Iseman – Program Director for Water Policy, Western Governors’ 

Association

• James Heaney – Department of Environmental Engineering Sciences, University 

of Florida 

1.2.4 System Reliability

• Rosalind Bark – Resource Ecological Economist, Australia’s Commonwealth 

Scientific and Industrial Research Organization

• Holly Hartman – Director of Arid Lands Information Center, University of 

Arizona 

2.0 Summary of Comments

The following sections list the specific focus questions asked of the reviewers. They provide a 

summary of comments received, without attribution of specific comments to specific reviewers, 

and an explanation of the actions undertaken (or not) to address the reviewers’ comments. 

2.1 Water Supply Assessment

The focus of the Water Supply Assessment peer review was whether the Water Supply 

Assessment met the intent of the Study. The reviewers were asked to consider the overall 

approach, the documentation of limitations and assumptions, and the scenario planning 

framework, with particular attention to secondary bias correction. The specific focus questions 

asked of the reviewers for the Water Supply Assessment are as follows: 

1. Is purpose of the report clear? 

2. Is the approach well-designed and executed?

3. Is the approach to quantifying scenarios clearly explained?

4. Has the assessment met the report goals?

5. Are the data and information appropriately cited? 

6. Are assumptions and limitations explicit and justified?

7. Is the documentation accurate, understandable, clearly structured, and temperate in tone?

8. Are the reports compelling, useful, and relevant to stakeholders and decision makers? 
Appendix 7 — Peer Review

Summary Report

December 2012 SR7-3 

In general, the reviewers thought the Water Supply Assessment, as detailed in Technical Report 

B – Water Supply Assessment, met all the requirements set out in the Study’s focus questions. 

One reviewer wrote that the report was “impressively thorough, well-planned, and very 

professionally executed.” 

Reviewers provided specific word choice edits to clarify language and additional comments, to 

further strengthen the overall presentation of material. These comments focused on two topics. 

First, comments related to clarifying the differences between the scenario including climate 

change projections and three other supply scenarios based on observed or paleo-reconstructed 

streamflow. Additional discussion was added to clarify that rising temperature and transient 

downward-trending supply were present only in the climate change scenario. In addition, 

discussion was added to further clarify the uncertainty associated with the future climate 

projections and the use of this information in water planning. 

Second, comments focused on the treatment and discussion of climate teleconnections (such as 

the Southern Oscillation Index, El Niño Southern Oscillation, and Pacific Decadal Oscillation) 

and their impacts on Basin supply. In response to these comments, additional language was 

added to the report to elaborate and clarify the discussion on Pacific Decadal Oscillation in 

particular. To address general issues of clarity, additional descriptions for several figures were 

added, as was additional discussion on uncertainty. 

2.2 Water Demand Assessment

The focus of the Water Demand Assessment peer review was whether the Water Demand 

Assessment met the intent of the Study. The reviewers were asked to consider the overall 

approach, the approach to quantifying scenarios, the documentation of limitations and 

assumptions, the scenario planning framework, and the assessment of climate impacts on 

demands. The specific focus questions asked of the reviewers for the water demand assessment 

are as follows:

1. Is purpose of the report clear? 

2. Is the approach well-designed and executed?

3. Is the approach to quantifying scenarios clearly explained?

4. Has the assessment met the report goals?

5. Are the data and information appropriately cited? 

6. Are assumptions and limitations explicit and justified?

7. Is the documentation accurate, understandable, clearly structured, and temperate in tone?

8. Are the reports compelling, useful, and relevant to stakeholders and decision makers? 

In general, the reviewers thought the Water Demand Assessment, as detailed in Technical Report 

C – Water Demand Assessment, met all the requirements set out in the Study’s focus questions. 

One reviewer wrote, “Commendable and formidable effort to account for numerous uncertainties 

confronting the Basin and to integrate information from many sources pertinent to changing 

demand by water use sector and geographic area.”

The reviewers specified a number of perceived limitations in the Water Demand Assessment. 

First, reviewers pointed out that the use of conventional demographic forecasting did not 

consider impacts on population distribution resulting from climate change. Second, reviewers 

found it problematic that the use of the practically irrigable acreage approach did not consider 
Colorado River Basin 

Water Supply and Demand Study

SR7-4 December 2012

that agricultural production (i.e., acreage and crop types) is driven by crop markets. The 

reviewers thought an econometric evaluation would complement the approach used in the Study. 

In particular, the reviewers critiqued the exclusion of price elasticity with respect to demand, 

despite available studies that could have been referenced. These comments were not necessarily 

viewed as limitations, because the impacts on population distribution resulting from climate 

change, as well as the practically irrigable acreage approach, while used in academia, are not 

ready for use in Basin-wide planning. Although climate change was not explicitly considered 

with respect to demographics, the demand scenarios did include lower-growth scenarios and 

reflect a range of potential future populations and demographic models. The Basin States did not 

use practically irrigable acreage for development of agricultural demands. Agricultural demands 

were projected by state agencies and irrigation districts. In some cases, land use-based models 

were used that incorporated urban population growth and other factors. Demand elasticity was 

not considered explicitly in the Study; however, it was included implicitly as part of the water 

demand options included in the Study. 

Additional comments were received requesting that the Study Report explain the reliance on 

demand information provided by the Basin States. Comments questioned whether limitations in 

the Study prevented gathering of independent information from sources other than state agencies 

on projected population, irrigated acreage, and other parameters. These comments suggested that 

Reclamation commit to future work to refine demand estimates through more-intensive modeling 

efforts of future water demands associated with agriculture and energy production. Although 

demand information provided by the Basin States was relied on heavily, it was not the only 

source of this information. Additional regional and local data were collected to supplement and 

support the information provided by the Basin States – particularly in consideration of alternative 

demand scenarios. Furthermore, the Basin States, specifically the Basin States’ representatives 

who were formally involved in the Study, are entrusted with the responsibility of demand 

planning and management in the region, and therefore were the best available resource for 

demand planning. 

2.3 Options and Strategies for Balancing Supply and Demand

The primary focus of the peer review of the options and strategies was whether the analysis met 

the intent of the Study. Reviewers were asked to consider the overall approach taken for options, 

the development and use of characterization criteria, the development and use of portfolios, and 

the documentation of limitations and assumptions associated with characterization. The specific 

focus questions asked of the reviewers for the options and strategies are as follows: 

1. Is purpose of the report clear? 

2. Is the approach well-designed and executed?

3. Is the approach to option development clearly explained? 

4. Is the development and use of characterization criteria clearly explained?

5. Is the development and use of portfolios clearly explained?

6. Are the data and information appropriately cited? 

7. Are assumptions and limitations explicit and justified?

8. Is the documentation accurate, understandable, clearly structured, and temperate in tone? 

9. Are the reports compelling, useful, and relevant to stakeholders and decision makers? 
Appendix 7 — Peer Review

Summary Report

December 2012 SR7-5 

In general, the reviewers thought the options and strategies, as detailed in Technical Report F – 

Development of Options and Strategies, met all the requirements set out in the Study’s focus 

questions. One reviewer wrote of a “sense that the Study was open-minded and receptive to new 

ideas and made an honest effort to provide an objective analysis.” 

A number of comments on this report related to the characterization of options and development 

of portfolios. Other comments focused on the general clarity of the report. Reviewers suggested 

that summary results be provided first in order to prevent the loss of the ‘big picture.’ They also 

thought the report would benefit from more citations, to help clarify assumptions. These changes 

were made to the final technical report. 

The reviewers thought that the use of scoring criteria for the characterization of options was an 

overall useful exercise; however, the scoring of criteria felt “squishy” and overly precise. They 

pointed out that select options appeared to score more favorably than they might have deserved. 

For example, reviewers thought the yield estimates for weather modification and dust control 

options seemed high, and were surprised to see as much water yield in municipal reuse as in 

agricultural conservation. Additionally, reviewers thought it was not always clear which options 

were more tested and reliable than others. They believed that some options that had little, if any, 

testing or documentation scored better in terms of yield than the feasibility or reliability might

suggest. 

To address these comments, the report was modified to present additional summary information 

about the options, to aid in comparison and add clarity. With respect to specific options, in some 

cases, limited data were available to characterize items such as yield or cost, and there was 

significant uncertainty in these scores. However, the criteria associated with quantity of yield 

was specifically separated from those criteria associated with technical feasibility and long-term 

viability. Options with significant feasibility or long-term reliability concerns were rated low for 

these criteria, and were subsequently limited in their inclusion in portfolios that were analyzed. A 

risk-adjusted yield was not developed in the Study. 

A number of the comments reflected a desire to know which option was “best;” however, the 

intent of Technical Report F was to enumerate and characterize the options without specific 

preferences or overall ratings. Preferences for certain option characteristics were included in the 

development of portfolios and the performance of these portfolios was evaluated in Technical 

Report G – System Reliability Analysis and Evaluation of Options and Strategies. In addition, 

the criteria were intended to be broad and represent a number of different viewpoints. 

Characterization alone could not determine which options were “best.” The analytical framework 

applied in the Study was intended to be essentially preference-based.

Comments regarding the development of the portfolios requested that the report explicitly define 

reliability, risk, and uncertainty. Reviewers thought the report was missing discussion on the 

methodology used for filtering through the range of choices, and requested that the report better 

explain the use of the Portfolio Development Tool. Last, reviewers thought that unit costs needed 

to be defined more precisely by including the incidence of the benefits and costs. 

In order to address comments on reliability, risk, and uncertainty, the text was modified to 

specifically define uncertainty and refined to replace references to “risk” with “uncertainty” 

where the intent was the same. Discussion on the methods employed to filter and characterize 

options was added, and references to the Portfolio Development Tool were removed and 
Colorado River Basin 

Water Supply and Demand Study

SR7-6 December 2012

replaced with discussion of the methods of filtering options based on the characterization criteria. 

As noted previously, this report did not attempt to define the efficacy or benefits of specific 

options, but rather provided an initial characterization that facilitated development of a set of 

exploratory portfolios reflecting different strategies for addressing potential future imbalances. 

The results of modeling the implementation of these options and strategies are defined in 

Technical Report G – System Reliability Analysis and Evaluation of Options and Strategies. In 

addition, significant additional text was added to clarify the cost discussion. 

2.4 System Reliability Analysis

The primary focus of the System Reliability Analysis peer review was whether the analysis met 

the intent of the Study. Reviewers were asked to consider the overall approach; whether there 

was a broad-enough set of system reliability metrics, (resource metrics, indicator metrics, 

signposts, and vulnerable conditions); use of system reliability metrics; and the documentation of 

limitations and assumptions. The specific focus questions asked of the reviewers for the System 

Reliability Analysis are as follows:

1. Is purpose of the report clear? 

2. Is the approach well-designed and executed?

3. Are a broad set of system reliability metrics presented?

4. Are the uses of indicator metrics, signposts, and vulnerable conditions clearly explained? 

5. Has the analysis met the intent of the report? 

6. Are the data and information appropriately cited? 

7. Are assumptions and limitations explicit and justified?

8. Is the documentation accurate, understandable, clearly structured, and temperate in tone?

9. Are the reports compelling, useful, and relevant to stakeholders and decision makers? 

Technical Report G – System Reliability Analysis and Evaluation of Options and Strategies

received the most extensive comments from peer reviewers. Reviewers found it particularly 

problematic that qualitative evaluation and discussions lacked for topics that do not lend 

themselves to quantitative evaluation. One reviewer thought that next steps in the analysis should 

include discussion on governance feasibility of options, the United Mexican States (Mexico) 

particularly, its role in planning its future and the desire for collaborative work between the two 

countries, and outstanding water rights settlements associated with tribes. Another reviewer 

criticized the neglect of qualitative discussion of two classes of options: system operation and 

governance/implementation. This reviewer wrote, “This is a major short-coming because the 

report anchors discussion on the options that are quantitatively evaluated. Just because some 

options are more readily analyzed does not make them more preferred, more practical, or even 

more deserving of further investments (i.e., additional study), especially if choices have to be 

made about what options should be studied next.” 

The Study acknowledges that certain options are more difficult to characterize in a structured 

rating approach and, in response to comments, expanded the discussion for those options that 

were qualitatively addressed in Technical Report F – Development of Options and Strategies. 

The Study Report also includes a broader discussion of the opportunities and constraints 

associated with the options that were qualitatively characterized in the Study. The Study Report

includes a section on next steps that outlines the need for a cooperative approach in future 

efforts, including discussion on governance feasibility of options, to continue what could only be 
Appendix 7 — Peer Review

Summary Report

December 2012 SR7-7 

discussed qualitatively in this Study. Including discussions with Mexico and tribes and 

communities will be critical to the success of such an approach. At the time of the peer reviews, 

the Study Report was not yet complete or available to reviewers.

Additional comments were received that were related to other areas. First, reviewers found it 

problematic that results were presented in probabilistic terms, when the analysis should focus on 

frequency. Second, reviewers found it problematic that the analysis combined scenarios and then 

evaluated results that use the median as a central tendency. The reviewers thought that the use of 

combined scenarios for simple screening was acceptable, but not for evaluations of median 

behavior. Last, reviewers believed there were unanswered questions in the report, such as who 

would pay for the options to reduce vulnerability. To address reviewers’ comments and to 

improve the clarity of the discussion, results from the System Reliability Analysis were modified

to ensure that they were presented from the point of view of a frequency analysis. References to 

probability were removed where inappropriately applied. Within the discussion of System 

Reliability Analysis without options and strategies, the combined analysis was removed and only 

the 48 individual scenario combinations for supply, demand, and post-2026 Lake Powell and 

Lake Mead operation assumptions were presented. Clarifying language was added through the 

report to ensure that readers understand that the results do not describe probabilistic outcomes. 

Instead, they describe plausible ranges and distributions for the Baseline or a portfolio 

corresponding to a wide range of plausible hydrologic, demand, and management traces. The 

underlying traces are the same across all portfolios and therefore enable a consistent comparison 

of outcome differences across the portfolios. 

In addition, system reliability results were presented as summaries by water supply scenario and 

vulnerable conditions to allow for a broader understanding of the conditions that lead to good or 

poor performance. Technical Report G was substantially improved based on the peer review 

comments and subsequent revision and analysis. 

3.0 Conclusions 

The peer review process was found to be a useful exercise and provided good, independent 

review that resulted in improvements to the technical reports included in the Study. The 

documents were generally well-received; the only major change was the restructuring of 

Technical Report G. The peer review process may have been improved by incorporating a staged 

review process which would engage reviewers earlier in the development of technical 

approaches and methods. 

In general, the peer review comments indicated that the assessments had been performed 

adequately and the analyses met the intent of the Study. Many comments dealt with the clarity of 

the discussion. To address issues of clarity, discussion was added to the reports and description 

was added to figures and tables as necessary. Study limitations (both in terms of scope and 

length) prevented the more in-depth supplemental analyses that were suggested by the reviewers.

Several suggestions for additional analysis are incorporated in the next steps described in the 

Study Report.