Water Supply and 

Yield Study

 March 2008

U.S. Department of the Interior

Bureau of Reclamation 

Mid-Pacific Region
Mission Statements

The mission of the Department of the Interior is to protect and 

provide access to our Nation’s natural and cultural heritage and 

honor our trust responsibilities to Indian Tribes and our 

commitments to island communities.

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.
Water Supply and 

Yield Study

March 2008

U.S. Department of the Interior

Bureau of Reclamation 

Mid-Pacifi c Region

Executive Summary 

Background 

Hydrologic conditions in California 

vary greatly from year to year, 

season to season, and place to place. 

Wet years bring the threat of floods, 

and drought years put pressure on 

available water supplies. The 

majority of the state’s precipitation 

occurs in the northern third of the 

state during the winter, while much 

of the water is used in the central 

and southern portions of the state 

during the spring and summer. 

Because of this, meeting 

California’s water demands is 

complicated by the logistics of 

moving water from its source to its 

place of use, which may be over 

hundreds of miles. The availability 

of storage and conveyance facilities 

may limit California’s ability to 

deliver water to the right place at 

the right time. 

To address the difference in the 

location and timing between water 

supplies and water demands, 

federal, state, and local water 

agencies constructed various water 

supply projects. The two main water 

storage and conveyance projects in 

California are the federal Central 

Valley Project (CVP) and the State 

of California’s State Water Project 

(SWP), managed by the Department 

of Water Resources (DWR). Both 

the CVP and SWP use natural 

waterways and constructed facilities 

to convey water. To deliver this 

water to users in Central and 

Southern California, both projects 

convey water through the 

ecologically sensitive Sacramento–

San Joaquin River Delta (Delta), 

which is upstream of San Francisco 

Bay. 

Dramatic increases in statewide 

population, land use changes, and 

environmental and other regulatory 

requirements have put pressure on 

available water supplies and 

facilities to meet water demands on 

a regional basis and statewide. 

These pressures have presented 

challenges to reliably meeting yearto-year water demands. The 

availability of storage and 

conveyance facilities is another 

factor that currently limits 

California’s ability to deliver water 

to the right place at the right time. 

The availability of storage and 

conveyance facilities will continue 

to be a limiting factor in the future. 

iii 

Statewide water management systems 

include physical facilities like the 

California Aqueduct. (Source: DWR) 

Authorization and 

Purpose 

The CALFED Bay-Delta 

Authorization Act, Title 1 of Public 

Law 108-361 (the Water Supply, 

Reliability, and Environmental 

Improvement Act of 2004) directed 

the Secretary of the Interior 

(Secretary), acting through the 

Bureau of Reclamation 

(Reclamation), to conduct a study of 

available water supplies and 

existing and future needs for water 

in the State of California. 

Firm Yield Defined 

Public Law 108-361 defines firm 

yield as “...a quantity of water 

from a project or program that is 

projected to be available on a 

reliable basis, given a specified 

level of risk, during a critically 

dry period.” 

The Secretary is to prepare a report 

identifying possible projects and 

water management actions that 

could provide new firm yield and 

water supply improvements for the 

CVP. The Secretary is also required 

to incorporate and revise, as 

necessary, the results of the 1995 

Least-Cost CVP Yield Increase Plan

originally required by section 

3408(j) of Central Valley Project 

Improvement Act (CVPIA) of 1992. 

The purpose of this Water Supply 

and Yield (WSAY) Study is to 

identify the following: 

1. Opportunities for new firm 

yield and water supply 

improvements for CVP water 

service contractors (entities 

with contracts for the delivery 

of CVP water) 

2. Water management actions or 

projects that would improve 

firm yield for the CVP while 

balancing the available supplies 

with existing demands 

3. The financial costs of the water 

management actions or projects 

4. Beneficiaries and beneficiaries’ 

willingness to pay for identified 

improvements 

Study Area and 

Data Sources 

As directed by Public Law 108-361, 

the study area addressed in this 

report includes the units of the CVP, 

the area served the CVP 

agricultural, municipal, and 

industrial water service contractors, 

and the CALFED Bay-Delta 
WATER SUPPLY AND YIELD STUDY 

Program (CALFED) Solution Area 

as shown in Figure ES-1. 

Information for this study was 

primarily collected from the 

following sources: 

• Reclamation planning studies, 

Title 16, Integrated Resource 

Management Plans, and other 

special studies 

• CALFED Programmatic Record 

of Decision and Program Plans 

• DWR’s California Water Plan 

Update 2005 (Update 2005) and 

various related studies 

California’s regional differences 

make it necessary to divide the 

study area into regions for the 

purpose of discussing water 

supplies and demands. For planning 

purposes, DWR divides the state 

into 10 hydrologic regions 

corresponding to the state’s major 

drainage basins. Figure ES-2 shows 

these regions. For the purposes of 

some discussions, this report 

combines several hydrologic 

regions to delineate three 

geographic zones—North, Central, 

and South—to reflect geographic 

differences north and south of the 

Delta and within the Central Valley. 

These zones are shown in 

Figure ES-3. 

Study Results 

iv 

This WSAY Study provides the 

following information: 

• Compares available water 

supplies and demands in wet, 

average, and dry years under 

current and future levels of 

development 

• Identifies gaps between available 

water supplies and demands 

under current and future 

conditions 

• Discusses indicators of existing 

water supply reliability and 

identifies factors that affect this 

reliability 

• Describes projects and water 

management actions that may 

increase average deliveries 

and improve reliability 

during droughts 

• Estimates the financial impacts 

and range of willingness to pay 

for additional storage and 

conveyance projects and for other 

water management actions 

Supplies and Demands 

Supplies 

In an average water year, California 

receives close to 200 million acrefeet (MAF) of water from 

precipitation and imports or inflows 

from the Colorado River, Oregon, 

and Mexico. Of this total supply, 

about 50 to 60 percent is either 

consumed by natural processes 

(such as evaporation, 

evapotranspiration from native 

vegetation and forests, and 

groundwater percolation) or flows 

to Oregon, Nevada, the Pacific 

Ocean, and salt sinks like saline 

groundwater aquifers and the Salton 

Sea. The remaining 40 to 

50 percent, called dedicated supply, 

is distributed among urban uses, 

agricultural uses, used to protect 

and restore the environment, or is 

stored in surface reservoirs and 

groundwater basins for later use. 

Water supply in California is 

provided to users by statewide water 

management projects, including the 

CVP and SWP and by local 

projects. Locally owned 

groundwater wells also contribute to 

supplies, especially during dry 

years. The availability of water 

supplies depends on the availability 

of water at the source, the ability of 

conveyance facilities to transfer 

water, and the quantity and pattern 

of water demand at its place of use. 

The SWP and CVP manage, store, 

and deliver approximately 4 and 

9 percent, respectively, of the state’s 

water supplies. Local water projects 

and the Colorado River account for 

over 30 percent. However, 

deliveries vary considerably from 

year to year, and may be limited by 

available conveyance or storage 

facilities. The CVPIA and other 

environmental constraints have 

further restricted the CVP’s ability 

to meet contract deliveries. 

Current Demands and SupplyDemand Gap 

Current water demands for 

representative wet (1998), average 

(2000), and dry (2001) years were 

developed using statewide water use 

data from Update 2005. The water 

use values from Update 2005 were 

adjusted to account for a variety of 

factors, including increased 

demands in average and dry years 

caused by these factors: 

• Increased urban use resulting 

from population increases and 

drier conditions in 2001 

• Reduced irrigated acreage 

resulting from insufficient 

supplies 

• Reduced environmental flows 

resulting from insufficient 

supplies 

CVP and SWP water 

deliveries vary 

considerably from year to 

year, and may be limited 

by available conveyance or 

storage facilities. 

Current statewide water demands 

were estimated to be 60.6 MAF in 

an average year (2000) and 

57.2 MAF in a dry year (2001). 

Supply-demand gaps were 

determined by totaling unmet urban, 

agricultural, and environmental 

demands, along with the annual 

estimated amount of groundwater 

overdraft, and comparing the result 

to currently available supplies. 

Supplies and demands were 

compared on a regional basis 
EXECUTIVE SUMMARY 

FIGURE ES-1 

Study Area 

FIGURE ES-2 

DWR’s Hydrologic Regions 

FIGURE ES-3 

WSAY Study Geographic Zones 

v 
WATER SUPPLY AND YIELD STUDY 

vi 

because comparing them on a 

statewide basis does not provide an 

accurate representation of supplydemand gaps at the regional level. If 

one region has surplus supply, it 

cannot be assumed that the surplus 

water can be conveyed to fill 

another region’s supply-demand 

gap. Therefore, supplies and 

demands were compared by 

hydrologic region, and only gaps 

(not surpluses) were added to 

regional and statewide totals. 

This analysis shows that the supplydemand gap for the state as a whole 

is approximately 2.3 MAF for 2000 

(average year) and approximately 

4.2 MAF in 2001 (dry year) 

(Figure ES-4). Regional supplydemand gaps reveal that shortages 

are greatest in the Central 

Geographic Zone. 

Note that this analysis considered 

only a single dry year. The 

supply-demand gap in a drought 

year (preceded by one or more dry 

years) may be much greater. 

Future (2030) Demands and 

Supply-Demand Gap 

The projected future statewide 

water demands were estimated to be 

60.8 MAF in an average year and 

57.4 MAF in a dry year. Without 

future investment in water 

management actions or facilities, it 

is assumed that available water 

supplies in the future will remain 

about the same as under existing 

conditions. However, future 

supplies were adjusted slightly to 

reflect recent agreements regarding 

the reallocation of Colorado 

River water. 

Current statewide water 

use requires exercise of 

reservoir carryover storage 

and overdraft of 

groundwater during 

average and dry years. 

The projected gap between 

available water supplies and water 

demand in 2030 can be estimated by 

comparing future demands with 

existing supplies in average and dry 

years. Figure ES-5 shows that under 

projected future conditions, the 

supply-demand gap is approximately 4.9 MAF in average years 

and approximately 6.1 MAF in dry 

years. Regional supply-demand 

gaps reveal that shortages are 

greater in the South Geographic 

Zone under average and dry years 

FIGURE ES-4 

Existing Supply-Demand Gaps by Geographic Zone in an Average Year (2000) and Dry Year (2001) 
EXECUTIVE SUMMARY 

vii 

because of hydrologic conditions 

and facility (storage and 

conveyance) constraints. 

Population growth, agricultural-tourban land conversion, unknown 

future laws and regulations, and 

climate change add uncertainty to 

future demand estimates, and may 

increase the risk that during 

multiple-year droughts demands 

will not be met with existing 

facilities and infrastructure. 

Projects and Water 

Management Actions 

The gap between California’s water 

supply and demand is substantial, 

and this need will not be met 

without significant investments in 

new infrastructure and water 

conservation actions. A variety of 

storage and conveyance projects 

and water management actions have 

the potential to help fill this gap. 

Three categories of storage and 

conveyance projects were 

considered in this report. These 

three categories were based on the 

amount of available information, the 

level of development in the 

planning process, and the current 

understanding of the likelihood of 

those projects moving forward. The 

categories are described below and 

are not intended to signify 

implementation preference. 

Population growth, 

agricultural-to-urban land 

conversion, unknown 

future laws and 

regulations, and climate 

change add uncertainty to 

future demand estimates 

and may increase the risk 

that existing facilities and 

infrastructure will not meet 

demands during multipleyear droughts. 

• Level 1: CALFED-authorized 

storage and conveyance 

improvement studies—These 

large-scale infrastructure 

improvements have been 

proposed as part of California’s 

water resources management 

portfolio to provide more reliable 

water supplies and to meet 

competing needs for water. 

Reclamation and DWR have 

completed preliminary 

environmental studies and 

conceptual modeling, and will 

continue to formulate detailed 

alternatives for these 

improvement projects. 

• Level 2: Projects of recent 

public, agency, or political 

interest—Projects categorized as 

Level 2 have undergone past 

FIGURE ES-5 

Projected 2030 Supply-Demand Gaps by Geographic Zone for Average and Dry Years 
WATER SUPPLY AND YIELD STUDY 

viii 

FIGURE ES-6 

Projects and Water Management Actions to Help Fill the Existing Supply-Demand Gaps 

investigation that has been 

halted, delayed, or postponed 

because of changing strategies 

and priorities for water resources 

planning. As strategies and 

priorities continue to develop, 

and new challenges arise, Level 2 

projects have the potential for 

further consideration. 

• Demand management actions 

focus on reducing water demands 

and include agricultural and 

urban water use efficiency and 

land retirement. 

• Level 3: Regional 

opportunities—Many other 

project possibilities for water 

supply improvement exist outside 

the major infrastructure projects 

characterized as Level 1 or 

Level 2. 

Statewide water management 

actions consist of individual 

projects and programs that have 

potential to provide yield and water 

supply improvements for CVP 

agricultural and urban (municipal 

and industrial, or M&I) water 

service contractors. Two types of 

water management actions are 

described in this report: 

• Other actions focus on 

increasing water supply, and 

include water transfers, water 

recycling, desalination, and 

conjunctive use. 

Statewide, many of these actions are 

already being implemented as a 

result of market forces, naturally 

occurring conservation, work by 

Reclamation and DWR, ongoing 

initiatives by local water agencies 

and districts, CALFED initiatives, 

and initiatives by other entities. 

The storage and conveyance 

projects and water management 

actions identified in this report 

formed the basis of a cursory-level 

analysis to identify which projects 

and actions could fill the existing 

and projected 2030 supply-demand 

gap. Figures ES-6 and ES-7, 

respectively, show the existing and 

projected 2030 average and dry year 

supply-demand gap along with the 

projects and water management 

actions that could be used to help 

fill the gap. 

If the Level 1 storage and 

conveyance projects were 

constructed and investments in 

water management actions were 

made, the existing supply-demand 

gap could be met in average years, 

but a gap of over 0.8 MAF would 

remain in dry years. The projected 

2030 supply-demand gap would 

remain at over 1.5 MAF in average 

years and over 2.2 MAF in dry 

years. 

A diverse portfolio of 

projects and actions, 

consistent with the 

CALFED Record of 

Decision, are needed to fill 

the supply-demand gap. 
EXECUTIVE SUMMARY 

Long-term water-supply reliability 

depends on being able to meet water 

demands in dry years, and 

additional measures, such as the 

Level 2 and Level 3 storage projects 

and more aggressive investments in 

water management actions, would 

be needed to fill the 2030 supplydemand gap. Similar to current 

conditions, it is likely that 

agricultural and environmental uses 

would continue to experience water 

supply shortages in future average 

and dry years, and drought year 

shortages could be even greater. 

ix 

FIGURE ES-7 

Projects and Water Management Actions to Help Fill the Projected 2030 Supply-Demand Gaps 

Rate Impacts and 

Willingness to Pay 

The economic aspects of the 

projects identified in this study are a 

key component in determining how 

to proceed with implementation. 

Determining what effect storage and 

conveyance projects will have on 

existing rates and what beneficiaries 

would be willing to pay are 

important components of a financial 

analysis. The financial impacts from 

implementing the projects and water 

management actions were evaluated 

by relating the associated water 

charges to water contractors’ 

willingness to pay. 

This analysis focused on the Level 1 

storage and conveyance projects 

because these projects could be 

federally funded, and would be 

recovered through CVP contractor 

rate adjustments. Detailed yield and 

cost information is not available for 

the Level 2 and Level 3 projects. 

The water management actions 

would likely be funded through a 

mix of state, federal, and local 

agencies and organizations and do 

not influence the rates charged to 

CVP contractors. Therefore, these 

projects and water management 

actions were not included in this 

financial analysis. 

If the Level 1 storage and 

conveyance projects were 

constructed and 

investments in water 

management actions were 

made, the existing gap 

could be met in average 

years, but a gap of over 

0.8 MAF would remain in 

dry years. The projected 

2030 supply-demand gap 

would remain at over 

1.5 MAF in average years 

and over 2.2 MAF in 

dry years. 

The cost-of-service rate impact and 

willingness to pay analyses were 

undertaken to provide a basis for 

discussions of reimbursement policy 

changes that may be necessary for 

the construction of the Level 1 

storage and conveyance projects. 

However, final determinations of 

financial feasibility will be made as 

part of subsequent feasibility studies 

for each individual project. 
WATER SUPPLY AND YIELD STUDY 

x 

Estimated Rate Impacts 

A preliminary assessment was made 

of the cost-of-service rate impacts 

of implementing the Level 1 storage 

and conveyance projects. The 

cumulative per-acre-foot impact on 

CVP water charges from these 

projects, including capital and 

operations and maintenance costs 

allocated to water supply, is shown 

for irrigation contractors in Figure 

ES-8 and M&I contractors in 

Figure ES-9. Financing the existing 

CVP capital costs and all Level 1 

storage and conveyance projects 

would result in a cost-of-service of 

about $40 per acre-foot for 

irrigation and $70 per acre-foot for 

M&I uses when allocating 

50 percent of project costs to water 

supply. These rate estimates are for 

the period 2021 to 2030. After 

2030, initial CVP capital costs will 

be repaid, and overall rates will fall 

to slightly lower levels. 

Willingness to Pay 

Historical water transfer prices, 

water management options, and 

contractor surveys all indicate a 

positive willingness to pay for 

additional water supplies. Based on 

reasonable and foreseeable actions 

to improve supply through water 

management actions and past 

transactions to increase permanent 

supply, contractors south of the 

Delta indicate an annualized 

willingness to pay for permanent 

supply of approximately $130 per 

acre-foot for irrigation users and 

$185 per acre-foot for M&I users. 

Recent transfer negotiations indicate 

that contractors may be willing to 

pay more than these amounts for 

new, permanent water supply. 

However, it is important to note that 

not every contractor has the ability 

to pay the average willingness to 

pay amount. Some contractors will 

be unable to participate in the 

purchase of CVP water if the 

contract rates rise dramatically. 

Next Steps 

A variety of actions, programs, and 

projects are underway to improve 

statewide water supply reliability. 

Reclamation participates in some 

of these studies, such as the 

CALFED-authorized storage and 

conveyance improvement feasibility 

studies. The next steps toward 

meeting the needs for future water 

demand and reliability include the 

following: 

• Continue to support the existing 

CALFED storage and 

conveyance projects. 

• Support other surface storage and 

conveyance projects, as well as 

other statewide water 

management actions, such as 

WUE and conjunctive use, that 

could improve water supply and 

water supply reliability for CVP 

contractors. 

The supply-demand gaps identified 

in this WSAY Study were 

developed by DWR hydrologic 

region and are based primarily on 

information from DWR’s Update 

2005. These supply-demand gaps 

are based on the best information 

available within the time 

requirements stated in the WSAY 

Study’s authorization; however, 

additional data could be collected to 

develop CVP-specific supplydemand gaps. This would allow for 

the following analyses: 

• Identification of supply-demand 

gaps by CVP division 

• Identification of projects and 

water management actions to fill 

the supply-demand gap by CVP 

division 

FIGURE ES-9 

M&I Cost-of-Service Impact at 50 Percent Cost Allocation 

FIGURE ES-8 

Irrigation Cost-of-Service Impact at 50 Percent Cost Allocation 
EXECUTIVE SUMMARY 

xi 

Major Technical Results 

♦ Existing statewide water demand estimates: 

− Demands were developed for each hydrologic region and user (urban, agricultural, and environmental). 

− Demands were based primarily on information from Update 2005 and adjusted to reflect historical water 

demands rather than water use. 

− Existing statewide water demands were estimated as follows: 

− 60.6 MAF in average water years (based on water use and unmet demands in 2000) 

− 57.2 MAF in dry water years (based on water use and unmet demands in 2001) 

♦ Amount by which current statewide water demands exceed available water supplies: 

− Supply-demand gaps were calculated by totaling unmet urban, agricultural, and environmental demands 

and annual estimated groundwater overdraft. The resulting total was compared to current supplies. 

− Supply-demand gaps were determined on a regional basis, and only unmet demands (not surpluses) 

were added to regional and statewide totals. If one region has surplus supply, it cannot be assumed that 

the surplus water can be conveyed to fill another region’s supply-demand gap because of regulatory and 

infrastructure limitations on conveyance and basin-to-basin transfers. 

− Current statewide supply-demand gaps were estimated as follows: 

− 2.3 MAF in an average water year (2000) 

− 4.2 MAF in a dry water year (2001) 

♦ The largest existing water supply-demand gap is in the Central Geographic Zone. 

♦ Projected 2030 statewide water demand estimates: 

− As with existing demand estimates, projected 2030 water demands were also developed for each 

hydrologic region and user. 

− Overall projected 2030 water demands were estimated to increase for urban users, decrease for 

agricultural users, and remain the same for environmental users. 

− Projected 2030 statewide water demands were estimated as follows: 

− 60.9 MAF in average water years 

− 57.4 MAF in dry water years 

♦ Estimated amount by which projected 2030 statewide water demand exceeds available water supplies: 

− Projected 2030 supply-demand gaps were calculated using the same methodology as the existing 

supply-demand gap calculation. Future supplies were assumed to be similar to existing supplies, except 

for Colorado River supplies, which were projected to decrease to the State’s 4.4 MAF allocation. 

− Although the 2030 demands are similar to existing (2000) demands, projected increases in urban water 

demand throughout the state—especially in the central and southern portions of the state—result in an 

increased statewide water gap. Similar to the existing supply-demand gap calculation, surplus supplies in 

one region cannot be assumed to fill another region’s supply-demand gap because of regulatory and 

infrastructure limitations on conveyance and basin-to-basin transfers. 

− Projected 2030 statewide supply-demand gaps were estimated as follows: 

− 4.9 MAF in average water years 

− 6.1 MAF in dry water years 

♦ The largest projected 2030 water supply-demand gap is in the South Geographic Zone. 

♦ If the Level 1 storage and conveyance projects were constructed and the investments in foreseeable water 

management actions were made, the existing supply-demand gap could be met in average years, but a gap 

of over 0.8 MAF would remain in dry years. The projected 2030 supply-demand gap would remain at over 

1.5 MAF in average years and over 2.2 MAF in dry years. 

♦ When allocating 50 percent of project costs to water supply, the cost-of-service rate for financing the existing 

CVP capital costs and all Level 1 storage and conveyance projects is approximately $40 per acre-foot for 

irrigation users and $70 per acre-foot for M&I users. 

♦ CVP contractor annualized willingness to pay for permanent water supply south of the Delta was determined 

to be approximately $130 per acre-foot for irrigation users and $185 per acre-foot for M&I users. 

xiii 

Table of Contents

Section Page

Executive Summary.................................................................................................................. iii

Background ......................................................................................................................iii

Authorization and Purpose...............................................................................................iii

Study Area and Data Sources..........................................................................................iii

Study Results ...................................................................................................................iv

Supplies and Demands ........................................................................................iv

Projects and Water Management Actions ...........................................................vii

Rate Impacts and Willingness to Pay...................................................................ix

Next Steps........................................................................................................................ x

Acronyms and Abbreviations ............................................................................................... xvii

1 Introduction .......................................................................................................................... 1-1

Geographical and Historical Perspective ...................................................................... 1-1

Authorization ................................................................................................................. 1-3

Purpose......................................................................................................................... 1-3

Study Area and Data Sources....................................................................................... 1-4

Related Studies and Programs ..................................................................................... 1-4

CALFED Bay-Delta Program............................................................................. 1-6

California Water Plan ........................................................................................ 1-6

Central Valley Project Improvement Act............................................................ 1-7

Least-Cost CVP Yield Increase Plan................................................................. 1-7

2 Supplies and Demands ....................................................................................................... 2-1

California’s Water Supply Variability ............................................................................. 2-1

Seasonal Variability........................................................................................... 2-2

Geographic Variability ....................................................................................... 2-2

Annual Variability and Droughts ........................................................................ 2-2

Water Management and Reliability ............................................................................... 2-5

CVP Supplies .................................................................................................... 2-6

SWP Supplies ................................................................................................... 2-8

Groundwater...................................................................................................... 2-9

Current Water Use and Demands............................................................................... 2-10

Water Use Estimates....................................................................................... 2-11

Water Demand in Average and Dry Years ...................................................... 2-12

Current Supply-Demand Gaps ........................................................................ 2-14

Future Challenges....................................................................................................... 2-14

Factors Driving Future Water Demand............................................................ 2-15

Projected Future Water Demands................................................................... 2-18

Future Supply-Demand Gaps.......................................................................... 2-20

Need for Additional Water Supply Management and Infrastructure ................ 2-21

3 Projects and Water Management Actions ........................................................................ 3-1

Projects ......................................................................................................................... 3-1

Level 1: CALFED-Authorized Storage and Conveyance Improvement 

Studies.............................................................................................................. 3-1
WATER SUPPLY AND YIELD STUDY 

xiv 

Level 2: Projects of Recent Public, Agency, or Political Interest ....................... 3-7

Level 3: Regional Opportunities ........................................................................ 3-8

Water Management Actions........................................................................................ 3-10

California Water Plan Update 2005 Potential Additional Annual 

Water Supply .................................................................................................. 3-10

Common Assumptions Model Version 7 ......................................................... 3-10

Demand Management Actions ........................................................................ 3-10

Other Actions................................................................................................... 3-13

Filling the Supply-Demand Gap .................................................................................. 3-16

4 Rate Impacts and Willingness to Pay ................................................................................ 4-1

Overview .......................................................................................................................4-1

Agricultural WUE ............................................................................................... 4-2

Urban WUE ....................................................................................................... 4-2

Recycling........................................................................................................... 4-2

Desalination....................................................................................................... 4-2

CVP Rate Impacts......................................................................................................... 4-2

Federal Cost Allocation Practices ..................................................................... 4-3

Federal Reimbursement Practices .................................................................... 4-3

Ratesetting ........................................................................................................ 4-3

Estimated Rate Impacts .................................................................................... 4-4

Willingness to Pay......................................................................................................... 4-5

Willingness to Pay Estimates ............................................................................ 4-6

Willingness to Pay Results .............................................................................. 4-11

Ability to Pay.................................................................................................... 4-11

Conclusions................................................................................................................. 4-11

5 Results and Next Steps .......................................................................................................5-1

Results .......................................................................................................................... 5-1

Supply and Demand.......................................................................................... 5-1

Projects and Water Management Actions ......................................................... 5-3

Rate Impacts and Willingness to Pay................................................................ 5-3

Next Steps.....................................................................................................................5-3

6 References............................................................................................................................ 6-1 

Glossary 

Appendix 

Supply-Demand Gap Tables 
TABLE OF CONTENTS 

xv 

Tables 

1-1 California’s Ten Hydrologic Regions and Corresponding Zones 

2-1 Impact of CVPIA on CVP Deliveries in All Years and Driest Years 

2-2 Applied Statewide Water Use and Dedicated Supplies in Wet, Average, and Dry Years 

2-3 Projected Statewide Demand by User in Representative Wet, Average, and Dry Years 

2-4 Existing Supply and Demand Gap for Average and Dry Years by Geographic Zone 

2-5 Projected Statewide Demand by User in Existing and Future (2030) Conditions for Average and Dry Years 

2-6 Assumed Statewide Future (2030) Dedicated Supplies in Average and Dry Years 

2-7 Supply-Demand Gaps in Existing and Future (2030) Conditions for Average and Dry 

Years by Geographic Zone 

3-1 Summary of Level 1 Storage Projects—Preliminary Cost and Supply 

3-2 Projects and Water Management Actions to Help Fill the Existing and Projected 2030 

Supply-Demand Gaps 

4-1 Summary of CVP Wholesale Water Charges by Selected Facility 

4-2 EWA Acquisitions through 2005 

4-3 Prices Paid by Reclamation’s WAP 

4-4 Water Transfers to Westlands Water District, 2000–2004 

4-5 Recent Long-term Transfers 

4-6 Water Contract Sales 2002–2004 

4-7 Summary of SWP and CVP Contractor Survey 

4-8 2030 Water Supply Options: Southern San Francisco Bay Area and South Coast 

4-9 Estimated Range of Willingness to Pay per Acre-Foot 

5-1 WSAY Study Authorization and Compliance 

Figures 

ES-1 Study Area 

ES-2 DWR’s Hydrologic Regions 

ES-3 WSAY Study Geographic Zones 

ES-4 Existing Supply-Demand Gaps by Geographic Zone in an Average Year (2000) and Dry 

Year (2001) 

ES-5 Projected 2030 Supply-Demand Gaps by Geographic Zone for Average and Dry Years 

ES-6 Projects and Water Management Actions to Help Fill the Existing Supply-Demand Gaps 

ES-7 Projects and Water Management Actions to Help Fill the Projected 2030 

Supply-Demand Gaps 

ES-8 Irrigation Cost-of-Service Impact at 50 Percent Cost Allocation 

ES-9 M&I Cost-of-Service Impact at 50 Percent Cost Allocation 

1-1 Major CVP and SWP Storage and Conveyance Facilities 

1-2 Study Area 

1-3 DWR’s Hydrologic Regions 

1-4 WSAY Study Geographic Zones 
WATER SUPPLY AND YIELD STUDY 

xvi 

2-1 Average Monthly Precipitation in Mt. Shasta City, Sacramento, Fresno, and the 

Imperial Valley 

2-2 Variation in California Precipitation and Historical Drought Periods 

2-3 CVP and SWP Deliveries During the 1987–1992 Drought 

2-4 Change in Storage Levels in Shasta and Oroville Reservoirs During the 

1987–1992 Drought 

2-5 Components of California’s Dedicated Water Supplies in Wet and Dry Years 

2-6 Developed Surface Storage, Average Imports Inflows, and Average Exports and 

Outflows by Geographic Zone 

2-7 CVP Delivery Gap by Year Type 

2-8 Gap between CVP Water Supply Contracts and Deliveries by Year Type 

2-9 SWP Delivery Gap by Year Type 

2-10 Land Subsidence Recorded on a Telephone Pole in the Central Valley 

2-11 Distribution of Statewide Water Uses in an Average Year (2000) 

2-12 Distribution of Applied Water Uses by Geographic Zone 

2-13 Statewide Dedicated Water Supplies and Uses by Year Type 

2-14 Existing Supply-Demand Gaps by Geographic Zone in an Average Year (2000) and 

Dry Year (2001) 

2-15 California Population Growth Trend 

2-16 Geographic and Statewide Water Demand Trends from 1972 to 2030 

2-17 Distribution of Applied Water Demands in 2030 by Geographic Zone 

2-18 Projected 2030 Supply-Demand Gaps by Geographic Zone for Average and Dry Years 

3-1 Level 1 Storage Project Sites and Potential Benefits 

3-2 Potential Statewide Additional Annual Water Supply 

3-3 Statewide Conservation Level Estimates 

3-4 Projects and Water Management Actions to Help Fill the Existing Supply-Demand Gaps 

3-5 Projects and Water Management Actions to Help Fill the Projected 2030 

Supply-Demand Gaps 

4-1 Existing Cost Allocation Repayment Responsibilities 

4-2 Approximation of Total Cost of Service 

4-3 Irrigation Cost-of-Service Impact at 50 Percent Cost Allocation 

4-4 M&I Cost-of-Service Impact at 50 Percent Cost Allocation 

4-5 Irrigation Cost-of-Service Impact at 75 Percent Cost Allocation 

4-6 M&I Cost-of-Service Impact at 75 Percent Cost Allocation 
xvii 

Acronyms and Abbreviations

AF acre-foot or acre-feet 

CALFED CALFED Bay-Delta Program 

CALFED ROD CALFED Programmatic Record of Decision 

CALFED Finance Plan CALFED Bay-Delta Program Finance Plan 

CBDA California Bay-Delta Authority 

CCWD Contra Costa Water District 

CEQA California Environmental Quality Act 

cfs cubic feet per second 

CVP Central Valley Project 

CVPIA Central Valley Project Improvement Act 

Delta Sacramento–San Joaquin River Delta 

DMC Delta-Mendota Canal 

DWR California Department of Water Resources 

EWA Environmental Water Account 

Exchange Contractors San Joaquin River Exchange Contractors 

FY fiscal year 

M&I municipal and industrial 

MAF million acre-feet 

NEPA National Environmental Policy Act 

NOD north-of-Delta 

NODOS North-of-Delta Offstream Storage 

O&M operations and maintenance 

OCAP Long-Term CVP Operations Criteria and Plan 

PEIS Programmatic Environmental Impact Statement 

Reclamation Bureau of Reclamation 

ROD Record of Decision 

SBA South Bay Aqueduct 

Secretary Secretary of the Interior 

Settlement Contractors Sacramento River Settlement Contractors 

SOD south-of-Delta 
WATER SUPPLY AND YIELD STUDY 

xviii 

SWP State Water Project 

TAF thousand acre-feet 

Update 2005 California Water Plan Update 2005, Bulletin 160-05

USFWS U.S. Fish and Wildlife Service 

VAMP Vernalis Adaptive Management Plan 

WAP Water Acquisition Program 

Westlands Westlands Water District 

WSAY Water Supply and Yield 

WUE water use efficiency 
1 Introduction 

This section introduces the Water 

Supply and Yield (WSAY) Study’s 

basis and purpose. To provide 

context for the study, background 

information on the geographical and 

historical perspective of water 

resources in California begins the 

discussion. Building on this 

foundation is an overview of the 

authorization and purpose of this 

WSAY Study, the study area, data 

sources, and a description of the 

related studies and programs. 

1-1 

Statewide water management systems 

include physical facilities like the 

California Aqueduct. (Source: DWR) 

Section Highlights 

The WSAY Study’s purpose is to 

identify the following: 

♦ Opportunities for new firm 

yield and water supply 

improvements for CVP water 

service contractors 

♦ Water management actions 

or projects that would improve 

CVP firm yield while 

balancing available supplies 

with existing demands Geographical and 

Historical 

Perspective 

Contrast and diversity characterize 

California’s geography and climate. 

Precipitation varies widely—from 

place to place, season to season, and 

year to year. Annual rainfall varies 

from more than 140 inches in the 

northwestern part of the state to less 

than 4 inches in the southeastern 

part. Most precipitation and runoff 

occur in the north and in the 

mountains, much of which falls as 

snow in the winter. As the 

snowpack melts in the spring, 

runoff fills major rivers and streams 

or percolates to aquifers. 

Historically, quickly melting snow 

would flood into the Central Valley, 

located in the central portion of the 

state, creating swamps and 

marshlands, or continue to the 

Pacific Ocean through the 

Sacramento–San Joaquin River 

Delta (Delta) upstream of the San 

Francisco Bay. 

During the nineteenth century, 

farming increased in the Delta and 

Central Valley regions, which 

increased the need for a dependable 

water supply and flood control 

facilities. Farmers began draining 

land and building levees around the 

marshes and swamps to reclaim the 

land for agriculture. As agriculture 

expanded, the state’s overall 

population and major cities, 

including San Francisco and Los 

Angeles, also grew. Although the 

agricultural lands and urban areas 

have grown significantly in the 

central and southern part of the 

state, the availability of water 

decreases from north to south. 

People in the central and southern 

portion of the state recognized the 

need to augment water supplies and 

develop remote sources. 

♦ The financial costs of the 

water management actions or 

projects 

♦ The beneficiaries and 

beneficiaries’ willingness to 

pay for identified 

improvements 

The study area includes the CVP 

Service Area and the CALFED 

Solution Area. 

Primary data sources include the 

following: 

♦ Reclamation planning studies, 

Title 16, Integrated Resource 

Management Plans, and 

other special studies 

♦ CALFED Record of Decision 

(ROD) and Program Plans 

♦ The California Department of 

Water Resources’ California 

Water Plan Update 2005 and 

various related studies 

This study uses and builds upon 

the results of the 1995 

Least-Cost CVP Yield Increase 

Plan. 

To address the difference in the 

location and timing between water 

supplies and water demands, 

federal, state, and local water 

agencies constructed various water 

supply projects. The two main water 

storage and conveyance projects in 

California are the federal Central 

Valley Project (CVP) and the State 

of California’s State Water Project 

(SWP). The major CVP and SWP 

storage and conveyance facilities 

are shown in Figure 1-1. 

The Bureau of Reclamation 

(Reclamation) operates the CVP, 

one of the world’s premier water 

supply projects. The CVP extends 

some 400 miles, from the Cascade 

Mountains near Redding in the 

north to the Tehachapi Mountains 

near Bakersfield in the South. It 
WATER SUPPLY AND YIELD STUDY 

FIGURE 1-1 

Major CVP and SWP Storage and Conveyance Facilities 

1-2 
SECTION 1: INTRODUCTION 

1-3 

Public Law 108–361, Section 103(d)(1)(C) Water Supply and Yield Study 

(i) IN GENERAL.—The Secretary, acting through the Bureau of Reclamation and in coordination with the State, shall 

conduct a study of available water supplies and existing and future needs for water— 

(I) within the units of the Central Valley Project; 

(II) within the area served by Central Valley Project agricultural, municipal, and industrial water service contractors; and 

(III) within the CALFED Delta solution area. 

(ii) RELATIONSHIP TO PRIOR STUDY.—In conducting the study, the Secretary shall incorporate and revise, as 

necessary, the results of the study required by section 3408(j) of the Central Valley Project Improvement Act of 1992 

(Public Law 102–575; 106 Stat. 4730). 

(iii) REPORT.—Not later than 1 year after the date of enactment of this Act, the Secretary shall submit to the appropriate 

authorizing and appropriating committees of the Senate and the House of Representatives a report describing the 

results of the study, including— 

(I) new firm yield and water supply improvements, if any, for Central Valley Project agricultural water service 

contractors and municipal and industrial water service contractors, including those identified in Bulletin 160; 

(II) all water management actions or projects, including those identified in Bulletin 160, that would— 

(aa) improve firm yield or water supply; and (bb) if taken or constructed, balance available water supplies and 

existing demand with due recognition of water right priorities and environmental needs; 

(III) the financial costs of the actions and projects described under subclause (II); and 

(IV) the beneficiaries of those actions and projects and an assessment of the willingness of the beneficiaries to pay the 

capital costs and operation and maintenance costs of the actions and projects. 

consists of 20 dams and reservoirs, 

11 power plants, and 500 miles of 

major canals, as well as conduits, 

tunnels, and related facilities. The 

CVP manages some 9 million acrefeet (MAF) of water, annually 

delivering about 7 MAF of water 

for agricultural, urban, and wildlife 

use. Today, the CVP supplies water 

to approximately 3 million acres of 

irrigable agricultural land,1

(approximately one-third of the total 

agricultural land in California), 

2 million urban residents, and 

numerous wildlife refuges. 

The California Department of Water 

Resources (DWR) operates the 

SWP, the largest state-built, 

multipurpose water project in the 

country. The SWP consists of a 

water storage and delivery system 

of reservoirs, aqueducts, power 

plants, pumping plants, and a 

conveyance system that extends for 

more than 600 miles, or two-thirds 

the length of California. Project 

functions also include recreation 

and support of fish and wildlife. 

 

1 Of the 3 million acres of irrigable agricultural 

lands within the CVP service area, 

approximately one-third is irrigated annually 

with CVP water. The balance is irrigated by 

other sources, or is fallowed, dryland farmed, 

or used for other purposes. 

Seventy percent of the over 4 MAF 

in contracts for SWP water is for 

urban use. 

Although the capacity to manage 

water in California is significantly 

developed, the state continues to be 

vulnerable to water shortages. 

Available water supply cannot meet 

existing water demands, and with 

California’s population expected to 

grow by more than 10 million by 

2030 (California Department of 

Finance, 2004), there is a vital need 

to improve existing supply facilities 

and improve water supply 

reliability. This report is intended to 

address the adequacy of available 

water supplies to meet current and 

future demands, discuss potential 

water management actions, and 

describe the economics of meeting 

future water demands. 

Authorization 

The CALFED Bay-Delta 

Authorization Act, Title 1 of Public 

Law 108-361 (the Water Supply, 

Reliability, and Environmental 

Improvement Act of 2004) directs 

the Secretary of the Interior 

(Secretary), acting through 

Reclamation and in coordination 

with the State of California, to 

conduct a study of available water 

supplies and existing and future 

needs for water. The findings of that 

study are to be presented by the 

Secretary to the appropriate 

authorizing and appropriating 

committees of the Senate and House 

of Representatives. This WSAY 

Study satisfies the requirements of 

Public Law 108-361, Section 

103(d)(1)(C). 

Purpose 

Congress directed the Secretary to 

conduct a study of available water 

supplies and existing and future 

needs for water, and prepare a 

report identifying possible projects 

and water management actions that 

could provide new firm yield and 

water supply improvements for the 

CVP and help the state meet its 

current and future needs for water. 

The Secretary is also required to 

incorporate and revise, as necessary, 

the results of the 1995 Least-Cost 

CVP Yield Increase Plan originally 

required by section 3408(j) of the 

Central Valley Project Improvement 

Act (CVPIA) of 1992. 
WATER SUPPLY AND YIELD STUDY 

The purpose of this study is to 

identify the following: 

FIGURE 1-2 

Study Area 

1. Opportunities for new firm 

yield and water supply 

improvements for CVP water 

service contractors 

2. Water management actions or 

projects that would improve 

firm yield for the CVP while 

balancing the available supplies 

with existing demands 

3. The financial costs of the water 

management actions or projects 

4. Beneficiaries and beneficiaries’ 

willingness to pay for identified 

improvements 

Public Law 108-361 defines firm 

yield as “...a quantity of water from 

a project or program that is 

projected to be available on a 

reliable basis, given a specified 

level of risk, during a critically dry 

period.” 

Study Area and 

Data Sources 

As directed by Public Law 108-361, 

the study area addressed in this 

report includes the units of the CVP, 

the area served by CVP agricultural, 

municipal, and industrial water 

service contractors, and the 

CALFED Bay-Delta Program 

(CALFED) Solution Area as shown 

in Figure 1-2. The CALFED 

Solution Area was defined in the 

CALFED ROD to include the Bay, 

Delta, and the areas in which 

diverted/exported water is used. 

Information for this study was 

collected primarily from the 

following sources: 

• Reclamation planning studies, 

Title 16, Integrated Resource 

Management Plans, and other 

special studies 

• CALFED Programmatic Record 

of Decision (CALFED ROD) and 

Program Plans 

• DWR’s California Water Plan 

Update 2005 (Update 2005) and 

various related studies 

California’s regional differences 

make it necessary to divide the 

study area into regions for the 

purpose of discussing water 

supplies and demands. For planning 

purposes, DWR divides the state 

into 10 hydrologic regions 

corresponding to the state’s major 

drainage basins. Figure 1-3 shows 

these regions. A brief description of 

each hydrologic region is provided 

in Table 1-1. 

For the purposes of some 

discussions, this report combines 

several hydrologic regions to 

delineate three geographic zones—

North, Central, and South—to 

reflect geographic differences north 

and south of the Delta and within 

the Central Valley. These zones are 

shown in Figure 1-4. 

Related Studies and 

Programs 

The following studies and programs 

provide insight or otherwise affect 

the WSAY Study: 

• CALFED Bay-Delta Program 

• California Water Plan 

• Central Valley Project 

Improvement Act 

• Least-Cost CVP Yield Increase 

Plan 

Descriptions of each study and 

program follow. 

1-4 
SECTION 1: INTRODUCTION 

FIGURE 1-3 

DWR’s Hydrologic Regions 

FIGURE 1-4 

WSAY Study Geographic Zones 

TABLE 1-1 

California’s Ten Hydrologic Regions and Corresponding Geographic Zones 

Zone Region Description 

North Coast Klamath River and Lost River Basins, and all basins draining into the Pacific Ocean 

from Oregon south through the Russian River Basin 

North Lahontan Basins east of the Sierra Nevada crest and west of the Nevada state line, from the 

North Oregon border south to the southern boundary of the Walker River watershed 

Sacramento 

River 

Basins draining into the Sacramento River system in the Central Valley (including 

the Pit River drainage), from the Oregon border south through the American River 

drainage basin 

Central Coast Basins draining into the Pacific Ocean below the Pescadero Creek watershed to the 

southeastern boundary of Rincon Creek Basin in western Ventura County 

San Francisco 

Bay 

Basins draining into San Francisco, San Pablo, and Suisun Bays, and into the 

Sacramento River downstream from Collinsville; western Contra Costa County; and 

basins directly tributary to the Pacific Ocean below the Russian River watershed to 

the southern boundary of the Pescadero Creek Basin 

San Joaquin 

River 

Basins draining into the San Joaquin River system, from the Cosumnes River Basin 

on the north through the southern boundary of the San Joaquin River watershed 

Central 

Tulare Lake The closed drainage basin at the south end of the San Joaquin Valley, south of the 

San Joaquin River watershed, encompassing basins draining to Kern Lakebed, 

Tulare Lakebed, and Buena Vista Lakebed 

Colorado River Basins south and east of the South Coast and South Lahontan regions; areas that 

drain into the Colorado River, Salton Sea, and other closed basins north of the 

border with Mexico 

South Coast Basins draining into the Pacific Ocean from the southeastern boundary of Rincon 

Creek Basin to the international border with Mexico South 

South Lahontan The interior drainage basins east of the Sierra Nevada crest, south of the Walker 

River watershed, northeast of the Transverse Ranges, and north of the Colorado 

River Region. The main basins are the Owens and the Mojave River Basins 

1-5 
WATER SUPPLY AND YIELD STUDY 

CALFED Bay-Delta 

Program 

The CALFED Bay-Delta Program 

(CALFED) is a cooperative effort 

among federal and state agencies 

and California’s environmental, 

urban, and agricultural 

communities. The Governor of 

California and the President of the 

United States initiated work on the 

program in 1995 to address 

environmental and water 

management problems associated 

with the Bay-Delta system. 

CALFED has taken a broad 

approach to addressing 

four problem areas: 

1-6 

• Water quality 

• Ecosystem quality 

• Water supply reliability 

• Levee system integrity 

Implementation of the CALFED 

Program began after the circulation 

of the Final CALFED 

Programmatic Environmental 

Impact Statement/Environmental 

Impact Report and the signing of 

the CALFED ROD in August 2000. 

The Preferred Program Alternative 

described in the CALFED ROD 

consists of programmatic elements 

that set a long-term direction for 

CALFED consistent with the 

CALFED mission statement and 

objectives. The Preferred Program 

Alternative includes several 

interrelated programs and a series of 

actions to execute the programs. 

Implementation of CALFED 

depends on authorization and 

funding by participating federal and 

state agencies. The Preferred 

Program Alternative is expected to 

require 25 to 30 years to complete. 

Implementation is divided into 

stages, with Stage 1 lasting through 

fiscal year 2007. 

Relationship to WSAY Study 

The CALFED ROD identified five 

potential surface storage reservoirs 

being investigated by DWR, 

Reclamation, and local water 

interests. These CALFED surface 

storage projects are being planned 

as multipurpose projects for water 

supply reliability, improved water 

quality, and ecosystem restoration. 

The five surface storage projects 

include raising Shasta Dam, 

constructing Sites Reservoir, 

constructing a reservoir in the Delta, 

expanding Los Vaqueros Reservoir, 

and constructing additional surface 

storage in the Upper San Joaquin 

River drainage. These five 

CALFED surface storage projects 

are described in Section 3 of this 

report and form the basis of the 

cost-of-service and willingness to 

pay assessments in Section 4. 

California Water Plan 

Updated approximately every 

5 years, the California Water Plan

is the state’s strategic plan for 

managing and developing water 

resources statewide. Since its first 

California Water Plan, published as 

Bulletin No. 3 in 1957, DWR has 

prepared seven water plan updates, 

known as the Bulletin 160 series. 

The most current version, referred 

to as Update 2005, describes the 

roles of state and federal 

government and the expanding role 

of regional and local agencies in 

California water management. The 

purpose of Update 2005 is to 

finalize statewide policy direction 

through broad public involvement. 

Update 2005 included a roadmap 

for completing the next version of 

the California Water Plan (2010) by 

identifying the analytical tools, 

studies, and data necessary to 

quantify and evaluate future water 

demand and supply. 

Update 2005 used actual regional 

water use and supply data from 

three recent years—1998, 2000, and 

2001—to show the variance of 

water supplies and uses in recent 

typical wet, average, and dry years, 

respectively. Statewide information 

was assembled from the 

10 individual hydrologic regions. In 

some cases, numerical values in 

Update 2005 were developed by 

estimation techniques because 

measured data were not available on 

a statewide basis. Update 2005 also 

presents three future scenarios 

(Current Trends, Less Resource 

Intensive, and More Resource 

Intensive) for 2030. Each scenario 

describes a different base condition 

for 2030, to which the water 

community would need to respond 

by implementing various 

management strategies. The 

scenarios are created by various 

assumptions about important factors 

affecting water use and supplies 

(such as population growth, 

development patterns, crop markets, 

industrial productivity, and 

environmental regulations). 
SECTION 1: INTRODUCTION 

Relationship to WSAY Study 

Update 2005 does not make 

project- or site-specific 

recommendations, but it does 

provide valuable insight on 

statewide water needs and describe 

how different resource management 

strategies play a role in helping to 

meet future water needs. 

Recent statewide water use and 

supply data from Update 2005 were 

used as the basis of the current 

statewide water supply and demand 

projections in this study. The 

three future scenarios described in 

Update 2005 were used as the basis 

of the future statewide water supply 

and demands projections in this 

study. This information is presented 

in Section 2. 

1-7 

Central Valley Project 

Improvement Act 

The Central Valley Project 

Improvement Act (CVPIA) of 1992 

(Title 34 of Public Law 102-575) 

mandated changes in management 

of the CVP, particularly for the 

protection, restoration, and 

enhancement of fish and wildlife. 

The CVPIA dedicated a portion of 

the yield of the CVP to protect, 

restore, and enhance fish, wildlife, 

and associated habitats in the 

Central Valley and Trinity River 

Basins, which resulted in the 

following provisions: 

• Dedication of up to 0.8 MAF of 

supply per year to environmental 

needs, referred to as CVPIA 

3406(b)(2) water 

• Designation of additional water 

supplies to wildlife refuges 

• Re-operation of the Trinity River 

Division to increase releases in 

the Trinity River to protect and 

restore the fishery 

In 1999, Reclamation and the 

U.S. Fish and Wildlife Service 

(USFWS) completed the CVPIA 

Programmatic Environmental 

Impact Statement (PEIS) for the 

implementation of the CVPIA. The 

PEIS evaluated five alternatives that 

addressed a range of actions or 

programs to meet the CVPIA 

objectives, and analyzed the 

environmental and economic 

consequences of implementing the 

CVPIA. With regard to existing 

CVP water contractors, the PEIS 

projected reduced CVP contract 

deliveries, particularly for 

contractors located south of the 

Delta. The PEIS also projected that 

implementation of the CVPIA 

provisions would result in increased 

groundwater overdraft, agricultural 

land fallowing, loss of jobs, and loss 

of more than $150 million in annual 

agricultural revenues (Reclamation 

and USFWS, 1999). 

Relationship to WSAY Study 

The CVPIA is one of the major 

components of the legal framework 

under which the CVP operates and 

the CVPIA provisions affect when, 

where, and for what purpose CVP 

water can be used. Implementation 

of the CVPIA has affected the 

distribution of available CVP 

supplies to CVP contractors and has 

reduced the overall supply available 

to agricultural and municipal and 

industrial CVP contracts. The water 

supply impact of implementing the 

CVPIA is addressed in Section 2 of 

this study. 

Least-Cost CVP Yield 

Increase Plan 

In 1995, Reclamation, on behalf of 

the Secretary and in conjunction 

with the USFWS, developed the 

Least-Cost CVP Yield Increase Plan

and submitted it to Congress. The 

plan presented an appraisal-level 

evaluation of options that would 

need to be further refined as specific 

needs for yield increase became 

better known. Through a screening 

process, more than 100 yield 

increase options were narrowed to a 

subset of least-cost yield increase 

options with a potential yield of 

3 MAF per year. The options 

included conjunctive use, land 

fallowing, conservation, reuse, 

surface storage, and conveyance. 

The plan determined that no option 

category would likely dominate a 

refined set of options. It foresaw a 

refined plan containing a 

combination of option categories 

that would minimize reliance on a 

single yield increase type and would 

minimize any particular kind of 

adverse impact. 

Reclamation deferred subsequent 

efforts to improve the CVP water 

supply under the authority of 

section 3408(j) of the CVPIA 

because of a far-reaching and 

critical juncture in California water 

management that led to the 

development of the CALFED ROD 

and the release of the CVPIA PEIS. 
WATER SUPPLY AND YIELD STUDY 

1-8 

Relationship to WSAY Study 

A variety of changes have occurred 

since the publication of the October 

1995 Least-Cost CVP Yield 

Increase Plan. For example, the 

estimated project costs and ideas 

about implementable projects have 

changed, and portions of the leastcost actions, such as conservation 

and conjunctive management, have 

been implemented. Additionally, the 

following two significant 

documents influencing CVP 

planning decisions have been 

published: 

• The CVPIA PEIS, which 

documents the impacts of the 

CVPIA on CVP water service 

contractors 

• The CALFED ROD, which 

presents CALFED’s Preferred 

Program Alternative for 

long-term solutions to problems 

in the Delta 

The WSAY Study uses the results 

of the Least-Cost CVP Yield 

Increase Plan and builds upon these 

results by incorporating information 

from the CVPIA PEIS and the 

CALFED ROD. This WSAY Study 

identifies new firm yield and water 

supply improvements that may 

serve to minimize the impact of the 

CVPIA on CVP water service 

contractors (see Section 2 for 

additional information on the 

impact of the CVPIA).
2-1 

Section Highlights 

Seasonal, geographic, and 

annual variability in precipitation 

poses significant challenges to 

meeting statewide water 

demands. 

CVP and SWP deliveries vary 

considerably each year. 

Current water use requires 

reservoir carryover storage use 

and groundwater overdraft in 

average and dry year types. 

Current statewide demands 

exceed supplies by 2.3 MAF in 

average years and 4.2 MAF in 

dry years. 

Future (2030) statewide 

demands exceed supplies by 

4.9 MAF in average years and 

6.1 MAF in dry years. 

The needs for additional water 

supply are substantial, and will 

not be fully met without 

significant investment in new 

infrastructure and water 

conservation. 

Multiple-year droughts may 

significantly impact water 

deliveries as existing storage 

facilities are depleted of 

supplies. Increased reliability is 

needed to protect water users 

during droughts. 

2 Supplies and Demands 

Over the last 30 years, California’s 

water demand has increased as 

irrigated agricultural lands, 

population, and environmental 

considerations have grown. 

However, California’s water 

supplies and developed surface 

storage have remained relatively 

constant during those 30 years. This 

disparity has created a gap between 

available supplies and water 

demands in most years. 

As California’s population 

continues to grow, unmet water 

demands will create additional 

competition for available supplies 

among urban, agricultural, and 

environmental water users. 

Multiple-year droughts may have 

significant impacts to water 

deliveries as existing storage 

facilities are depleted of water. 

Many investment and management 

decisions must be made to secure a 

sustainable and reliable water 

supply for California through 2030 

and beyond. 

This section addresses four main 

points: 

• Statewide variation in water 

supply and population 

distribution results in significant 

regional supply-demand gaps. 

• Statewide water projects, local 

projects, and groundwater are 

managed to maximize water 

deliveries and reduce local 

supply-demand gaps. However, 

project deliveries are limited by 

available storage, conveyance 

facilities, and year-to-year 

variations in hydrologic 

conditions. 

• Use of carryover storage and 

overdraft of groundwater basins 

are required to meet water 

demands during average and dry 

water years. Regional supplydemand gaps reveal that 

shortages are greatest in the 

Central Geographic Zone and 

South Geographic Zone. 

• Supply-demand gaps are likely to 

grow in the future. Population 

growth, agricultural-to-urban 

land conversion, currently 

unknown future laws and 

regulations, and climate change 

add uncertainty to future demand 

estimates. These factors may 

increase the risk that existing 

facilities and infrastructure will 

not meet demands during 

multiple-year droughts. 

California’s Water 

Supply Variability 

Hydrologic conditions in California 

vary greatly from year to year, 

season to season, and place to place. 

Wet years bring the threat of floods, 

and drought years put pressure on 

available water supplies. The 

majority of the state’s precipitation 

occurs in the northern third of the 

state during the winter, while much 

of the water is used in the central 

and southern portions of the state 

during the spring and summer. 

Because of this, meeting water 

demands within the state is 

complicated by the logistics of 

moving water from its source to its 

place of use, which may be over 

hundreds of miles. The availability 

of storage and conveyance facilities 

may limit California’s ability to 

deliver water to the right place at 

the right time. 

As California’s population 

continues to grow, unmet 

water demands will create 

additional competition for 

available supplies among 

urban, agricultural, 

and environmental 

water users. 
WATER SUPPLY AND YIELD STUDY 

2-2 

Seasonal Variability 

The majority of California’s 

precipitation occurs in the northern 

third of the state during winter. 

During the summer, the presence of 

a cold ocean current along the 

western coast of California 

stabilizes the air, and the subsidence 

of a subtropical high pressure 

suppresses cloud development and 

precipitation. Figure 2-1 shows the 

fluctuation in precipitation over a 

typical year in Mt. Shasta City, 

Sacramento, Fresno, and the 

Imperial Valley. 

This seasonal variability is 

important to water managers. 

Although most of the state’s 

precipitation occurs in the winter 

and early spring, most water is used 

in the late spring and summer for 

agriculture and urban use, and for 

hydroelectric power generation. 

California must store water during 

the winter months to meet water 

demands throughout the summer. 

Geographic Variability 

California’s climate is dominated by 

the Pacific storm track. Figure 2-1 

shows how most precipitation 

occurs in the northern part of the 

state near Mt. Shasta City, while 

Fresno and the Imperial Valley in 

the central and southern part of the 

state receive much less rain. 

California’s numerous mountain 

ranges are another factor of 

variability; the mountains cause 

orographic lifting of clouds, 

producing precipitation mostly on 

the western slopes and creating a 

rain shadow on the eastern slopes. 

Although most precipitation falls in 

the north and in the mountains, 

demand for water is concentrated in 

the Central Geographic Zone, where 

agriculture is prevalent, and in the 

South Geographic Zone, where 

population is dense along the coast 

and important agricultural areas are 

located inland. This geographic 

variability in precipitation and water 

demand led to the development of 

facilities to store and move water 

from north to south. To move south, 

this water must pass through the 

ecologically sensitive Delta region. 

Annual Variability and 

Droughts 

Significant variability in statewide 

precipitation from year to year 

affects annual water supplies. 

Figure 2-2 illustrates precipitation 

in California over the last century. 

The annual runoff from 

precipitation in the Sacramento 

Valley in Northern California is 

graphed over time and overlaid with 

year-type classifications developed 

by the State Water Resources 

Control Board. Critical drought 

periods are highlighted. 

Precipitation runoff conditions can 

range from drought to extreme 

flooding over just a few years. 

California’s most recent dry period, 

FIGURE 2-1 

Average Monthly Precipitation in Mt. Shasta City, Sacramento, Fresno, and the 

Imperial Valley 

Geographic variability in 

precipitation and water 

demand led to the 

development of facilities to 

store and move water from 

north to south. To move 

south, this water must 

pass through the 

ecologically sensitive 

Delta region. 
SECTION 2: SUPPLIES AND DEMANDS 

2-3 

a 6-year drought between 1987 and 

1993, was followed by 5 years of 

above-normal precipitation from 

1995 through 1999. In the wettest 

year on record, 1983, precipitation 

was over 200 percent of normal. 

The driest year on record was 1977, 

when precipitation was only about 

20 percent of normal. 

Climate variability has several 

effects on California’s ability to 

deliver water. The availability of 

precipitation and runoff affects not 

only the water supply in the year it 

occurs, but also in subsequent 

years, because consecutive dry 

years reduce the ability of storage 

facilities to cushion drought 

impacts. The rate of evapotranspiration (the amount of water lost to 

both evaporation and transpiration) 

influences the demand for water, 

particularly by agriculture. The 

combination of such significant 

annual variability in precipitation 

and the growth of agriculture and 

population over the last century 

indicate that California must 

manage and store water during 

wetter years to meet demands 

during dry years. 

Storage and Conveyance 

Limitations 

Water is stored in California to 

alleviate the challenges of droughts 

and floods, and to help meet the 

seasonal and annual imbalance in 

water supplies and demands. 

Surface reservoirs may be used for 

seasonal operation (agricultural 

irrigation or urban supplies) or for 

carryover storage (storing water 

during wet years for use during dry 

years). During wet winter storms 

and in spring, when snow in the 

mountains is melting rapidly, 

surface reservoirs retain runoff near 

its source to prevent excessive 

flooding in communities 

downstream and to save water for 

later beneficial use. During summer 

months and throughout drought 

years, this stored water is available 

for downstream uses. 

When the demand for water is 

greater than the water stored in a 

single year, carryover storage is 

used to meet demands. Californians 

depend on carryover storage to meet 

demands in most years. Only during 

wet and above-normal years does 

net water storage in the state 

FIGURE 2-2 

Variation in California Precipitation and Historical Drought Periods 

In an average year, net 

water supply storage 

decreases by nearly 

6 percent, and in a single 

dry year, by as much as 

14 percent or more. 
WATER SUPPLY AND YIELD STUDY 

2-4 

increase. During an average year, 

net water supply storage decreases 

by nearly 6 percent. During a single 

dry water year, storage may 

decrease by a total of 14 percent or 

more, which affects the state’s 

ability to meet water supplies the 

following year. 

Consecutive dry years present 

additional challenges to storage. At 

the beginning of an extended dry 

period, the drought’s duration is 

unknown. To manage potential 

shortages (or deficiencies during 

droughts), water may be released 

from storage based on a 

predetermined risk analysis 

procedure. As the drought 

continues, the procedure may 

impose progressively larger 

deficiencies (DWR, 1998). 

Carryover storage was used in this 

way to supplement deliveries during 

the low-runoff years of the 

1987–1992 drought. Figure 2-3 

shows how project deliveries 

changed during this multiple-year 

drought, and Figure 2-4 illustrates 

the change in reservoir storage 

during that time. Although the 

drought lasted several years, neither 

the state or federal water project 

imposed significant delivery 

deficiencies during the first 3 years 

of the drought. When carryover 

storage was diminished by several 

consecutive dry years without 

replenishment, deliveries were 

sharply curtailed to manage the risk 

for meeting basic needs the 

following year. 

As Californians experienced in 

1991 and 1992, drought-year 

shortages produce significant social, 

economic, and environmental 

hardships. Urban water users face 

cutbacks in supply and mandatory 

rationing. Agricultural lands are 

FIGURE 2-3 

CVP and SWP Deliveries During the 1987–1992 Drought 

FIGURE 2-4 

Change in Storage Levels in Shasta and Oroville Reservoirs During the 

1987–1992 Drought 

Drought-year shortages 

produce significant social, 

economic, and 

environmental hardships. 
SECTION 2: SUPPLIES AND DEMANDS 

2-5 

fallowed, jeopardizing the state 

economy. Environmental water 

supplies are reduced, putting 

sensitive and endangered species at 

increased risk because of low flows 

or degraded water quality. The 

increasing pressure on available 

supplies makes meeting water 

demands even more difficult with 

each consecutive dry year. 

Increasing California’s ability to 

capture and store water would 

improve water supply reliability 

during future droughts. 

Water Management 

and Reliability 

In an average water year, California 

receives close to 200 MAF of water 

from precipitation and inflows from 

the Colorado River, Oregon, and 

Mexico. Of this total supply, about 

50 to 60 percent is either consumed 

by natural processes (such as 

evaporation, evapotranspiration 

from native vegetation and forests, 

and groundwater percolation) or 

flows to Oregon, Nevada, the 

Pacific Ocean, and salt sinks like 

saline groundwater aquifers and the 

Salton Sea. The remaining 40 to 

50 percent, called dedicated supply, 

is distributed among urban and 

agricultural uses, used to protect 

and restore the environment, or 

stored in surface reservoirs and 

groundwater basins for later use. 

Figure 2-5 shows how the 

contributions of precipitation, stored 

water, and groundwater to dedicated 

water supplies vary between a wet 

and dry year. 

In most years, more water is 

withdrawn from storage than is 

replenished. For example, in 2000, a 

recent average year, 82.5 MAF of 

supply was delivered to urban, 

agricultural, and environmental 

users, including Wild and Scenic 

Rivers. Of this total supply, 

carryover storage and groundwater 

overdraft accounted for about 

6.7 MAF. Therefore, even in an 

average year, 6.7 MAF more water 

FIGURE 2-5 

Components of California’s Dedicated Water Supplies in Wet and Dry Years 

FIGURE 2-6 

Developed Surface Storage, Average Imports and Inflows, and Average Exports and 

Outflows by Geographic Zone 
WATER SUPPLY AND YIELD STUDY 

2-6 

Water Year Types Defined 

Several water year type indices are used to characterize water availability depending on the amount of precipitation occurring 

in a single year or during several years. Essentially, more rain falls in some years (wet years), and less rain falls in others (dry 

years). Various agencies conducting studies for specific purposes have defined and used such terms to describe this 

phenomenon based on analytical need. This WSAY Study draws upon water year type information from several current and 

previous studies to assess water delivery reliability and demand. 

Year Type Indices Multiyear Periods Single Representative Years 

Definitions Wet Year 

Above Normal Year 

Below Normal Year 

Dry Year 

Critical Year 

Year-type classifications 

based on index ranges that 

incorporate weighted 

averages of the current 

year’s runoff and previous 

year’s indices. Refer to 

Figure 2-3 for an illustration. 

All Years

Average of the entire 73 years 

of historical hydrology: 

1922–1994 

Driest Years

Average of three historical 

drought periods: 

May 1928–Oct. 1934 

Oct. 1975–Sep. 1977 

June 1986–Sep. 1992 

Wet Year

1998 hydrologic conditions—falls 

within the SWRCB’s wet year 

classification 

Average Year

2000 hydrologic conditions—falls 

within the SWRCB’s above-normal 

year classification 

Dry Year

2001 hydrologic conditions—falls 

within the SWRCB’s dry year 

classification 

Use in this 

WSAY Study 

To illustrate the fluctuating 

nature of water availability in 

California. 

To assess CVP and SWP delivery 

capability and the impact of 

CVPIA on water deliveries. 

To assess supplies, demands, and 

supply-demand gaps. The 

considerable amount of data available 

for every hydrologic region makes 

statewide assessment possible. 

Source SWRCB Reclamation DWR 

Original 

purpose 

The Sacramento Valley 

40-30-30 Index and the San 

Joaquin Valley 60-20-20 

Index were developed in 

1995 to assess the water 

originating from the two 

primary water supply basins 

in the state. 

The terms define periods to which 

results are presented for the 

CALSIM II water system 

operations model, which 

simulates the CVP and SWP 

over a 73-year period of 

record (1922–1994). 

The 2005 Update reported on 

statewide hydrologic conditions and 

water use based on actual data from 

three recent year’s representative of 

three different water year types. 

was withdrawn from storage than 

was replenished. 

The availability of dedicated water 

supplies depends on the availability 

of water at the source, the ability of 

conveyance facilities to transfer 

water, and the quantity and pattern 

of water demand at its place of use. 

Figure 2-6 shows developed surface 

storage, water exports, and imports 

among the North, Central, and 

South Geographic Zones. As the 

figure illustrates, the North 

Geographic Zone exports water, 

while the Central and South 

Geographic Zones are net importers. 

The SWP and CVP manage, store, 

and deliver approximately 4 and 

9 percent, respectively, of the 

dedicated supplies. Local water 

projects and the Colorado River 

account for over 30 percent of the 

dedicated supply. Locally owned 

groundwater wells also contribute 

to supplies, especially during 

dry years. 

CVP Supplies 

The federal CVP is a multipurpose 

water reclamation project 

constructed and operated to regulate 

Sacramento River Basin and San 

Joaquin River Basin runoff to meet 

agricultural and urban needs in the 

Sacramento Valley, the San 

Francisco Bay Area, the San 

Joaquin Valley, and the Tulare Lake 

Basin. It is also the primary source 

of water for much of California’s 

wetlands and provides flood 

protection, navigation, recreation, 

and water quality benefits. The CVP 

plays a key role in California’s 

powerful economy, providing water 

for 6 of the top 10 agricultural 

counties in the nation’s leading 

farm state. 

Project Deliveries 

The CVP delivers water to many 

users, including the Sacramento 

River Settlement Contractors 

(Settlement Contractors), the San 

Joaquin River Exchange 

Contractors (Exchange 

Contractors), municipal and 

industrial (M&I) contractors (urban 

users), agricultural contractors in 

the San Joaquin and Tulare Basins, 

and wildlife refuges. Each CVP 

contract type has a different priority 

for water delivery. 
SECTION 2: SUPPLIES AND DEMANDS 

2-7 

The Settlement Contractors and 

Exchange Contractors have the 

highest priority based on senior 

California water rights. The 

construction and operation of the 

CVP are facilitated largely due to 

negotiated contracts with these 

users; as such, CVP water deliveries 

to the Settlement Contractors and 

Exchange Contractors are the last 

to be reduced when drought 

conditions exist. 

The next highest priority for 

deliveries belongs to CVP M&I 

contractors. During drought 

conditions, CVP agricultural 

contractors, who have the lowest 

priority, bear the greatest 

reductions during drought. 

The priority of refuge water 

supplies varies compared to other 

project deliveries. Level 2 water, the 

amount required to meet existing 

refuge management needs, has a 

priority similar to that held by the 

Settlement Contractors and 

Exchange Contractors, and may not 

be cut by more than 25 percent in 

any year. Incremental Level 4 

water, the amount needed for full 

habitat development, is purchased 

annually from willing sellers and 

takes on the priority of its 

prepurchase source, as specified by 

CVPIA, Section 3406(d)(4). 

The CVP has water service 

contracts to deliver about 

6.275 MAF per year. However, 

historical CVP deliveries have 

varied greatly from year to year 

depending on water year type and 

available water supply, pumping 

restrictions, and environmental 

demands. 

To express the long-term variation 

of CVP deliveries, CALSIM II, a 

water system operations model, was 

used to simulate the operation of 

CVP and SWP under conditions 

represented in 73 years 

(1922–1994) of historical 

hydrologic data. These simulations 

were conducted in preparation of 

The Delivery Impact of CVPIA, 

commonly referred to as the 

“Delivery Impact Report” 

(Reclamation, 2005). The results of 

the simulations were used to 

estimate the delivery gap, or the 

average difference between CVP 

contract amounts and deliveries in 

all years and in driest years. 

Under existing regulatory 

conditions (with the CVPIA), 

CALSIM II simulations show that 

the CVP delivers an average of 

4.7 MAF per year in all years and 

3.7 MAF per year in driest years. 

The overall average delivery gap is 

therefore approximately one-quarter 

of the maximum contract amount in 

all years, and over 40 percent in 

driest years. This concept is 

illustrated in Figure 2-7. 

The delivery gap varies by 

contractor group type, however, as 

shown by Figure 2-8. Agricultural 

contractors have the largest delivery 

gap in all years and in driest years, 

at approximately 64 percent and 

77 percent of their maximum 

contract amount, respectively. 

These gaps have grown to these 

levels with the passage of CVPIA, 

which has impacted CVP 

agricultural and urban (M&I) 

water supply. 

Delivery Impact of the CVPIA 

The implementation of the CVPIA 

in 1993 dedicated a portion of the 

yield of the CVP to protect, restore, 

and enhance fish and wildlife 

habitats in the Central Valley and 

FIGURE 2-8 

Gap between CVP Water Supply Contracts and Deliveries by Year Type 

FIGURE 2-7 

CVP Delivery Gap by Year Type 
WATER SUPPLY AND YIELD STUDY 

2-8 

State and Federal Refuges with CVP Supplies 

Section 3406 of CVPIA required Interior, through Reclamation and the USFWS, 

to provide firm water supplies of suitable quality to maintain and improve wetland 

habitat areas on the Central Valley refuges that receive CVP water supplies. To 

comply with the CVPIA, a Water Acquisition Program was developed as a joint 

effort by Reclamation and the USFWS. The Water Acquisition Program has 

annually purchased incremental Level 4 water supplies from willing sellers to 

fulfill CVPIA obligations and meet refuge contract quantities. 

Trinity River Basins. The CVPIA 

increased demands on the CVP by 

allocating a portion of yield to 

environmental uses instead of 

delivering this water to agricultural 

and urban uses, thereby impacting 

available water supplies and 

project deliveries. 

Several key CVPIA provisions 

directly affect the availability of 

CVP water supplies to agricultural, 

urban, and environmental 

water users: 

• Up to 0.8 MAF per year of 

supply is dedicated to 

environmental needs as CVPIA 

3406(b)(2) water. 

• Additional reliable water supplies 

are designated for use by 

wildlife refuges. 

• The reoperation of the Trinity 

River Division increases releases 

in the Trinity River to protect and 

restore the fishery. 

The Delivery Impact Report 

estimated the CVPIA’s effect on the 

CVP’s ability to deliver water to 

project contractors. This analysis 

quantified changes in the CVP’s 

water supply delivery performance 

resulting from implementation of 

the CVPIA. The impact analysis 

was conducted by performing 

two CALSIM II simulations: one 

representing pre-CVPIA conditions 

and the other representing 

post-CVPIA conditions. 

The Delivery Impact Report 

concluded that the CVPIA reduces 

water supply to CVP agricultural 

and M&I (urban) contractors by an 

average of 516 TAF per year 

(24 percent) in all years and by 

586 TAF per year (42 percent) in 

driest years. Table 2-1 compares 

CVP deliveries to north-of-Delta 

(NOD) and south-of-Delta (SOD) 

contractors under pre- and 

post-CVPIA conditions. The table 

shows that the greatest impact from 

the CVPIA is seen in deliveries to 

SOD contractors. In particular, SOD 

agricultural deliveries are reduced 

by 28 percent on average (in all 

years) and by 49 percent in 

driest years. 

The results from the Delivery 

Impact Report show that increased 

demands on the CVP affect water 

deliveries to agricultural and M&I 

(urban) contractors because more of 

the available supply is allocated to 

environmental uses. 

These delivery gaps demonstrate 

that increasing demands on the CVP 

are creating a need for reliable 

water supplies, particularly during 

driest years in the southern half of 

the state. 

SWP Supplies 

The SWP is a large water supply, 

storage, and distribution system 

authorized by an act of the 

California State Legislature in 1959. 

The SWP is operated by DWR, and 

makes deliveries to approximately 

two-thirds of California’s 

population. Of the contracted water 

supply, approximately 70 percent 

goes to urban users, and 30 percent 

goes to agricultural users. The SWP 

service area includes primarily 

agricultural users in the Tulare 

Basin and urban users in the San 

Francisco Bay Area, Central Coast, 

TABLE 2-1 

Impact of CVPIA on CVP Deliveries in All Years and Driest Years 

All Years Driest Years 

CVP Contract Deliveries 

PreCVPIA 

(TAF) 

PostCVPIA 

(TAF) 

Percent 

Change 

PreCVPIA 

(TAF) 

PostCVPIA 

(TAF) 

Percent 

Change 

NOD agricultural 279 234 -16% 169 84 -50% 

NOD M&I (urban)a

 176 167 -5% 166 145 -13% 

SOD agriculturalb

 1,588 1,137 -28% 931 471 -49% 

SOD M&I (urban) 134 122 -9% 114 96 -16% 

Total 2,176 1,660 -24% 1,381 796 -42% 

Source: Reclamation, 2005 

Note: Simulated using CALSIM II 

a For simplification, NOD M&I (urban) deliveries include American River CVP contract water and Contra Costa Water 

 District deliveries. 

b For simplification, SOD agricultural deliveries include Cross Valley Canal agricultural deliveries. 
SECTION 2: SUPPLIES AND DEMANDS 

2-9 

and Southern California Hydrologic 

Regions. 

Project Deliveries 

The SWP delivers water to 

two primary contractor groups: 

agricultural and M&I (urban). Each 

SWP contract has a Table A 

amount, which is a term used to 

represent the annual maximum 

amount of water to which each 

contractor has a contract right to 

request delivery. Previously referred 

to as entitlement, this amount is 

specified in Table A of each SWP 

contractor’s water supply contract. 

The total of all contractors’ Table A 

amounts is currently 4.173 MAF per 

year (DWR, 2006d). Nearly all 

SWP deliveries are made south of 

the Delta for a total Delta Table A 

amount of 4.133 MAF per year. 

However, similar to the CVP, SWP 

supplies can vary greatly from year 

to year depending on water year 

type and available water supply, 

pumping restrictions, and 

environmental demands. 

DWR’s Delivery Reliability Report 

2005 assessed the delivery ability of 

the SWP using several different 

CALSIM II runs covering a 73-year 

period of record (DWR, 2006d). 

The CALSIM II studies developed 

for this report indicate that, from the 

Delta, the SWP delivers an average 

of 2.8 MAF per year in all years and 

1.7 MAF per year in driest years1

compared with the SWP Delta 

Table A of 4.133 MAF per year. 

The overall average SWP delivery 

gap is therefore approximately 

32 percent of the maximum Delta 

Table A amount in all years and 

59 percent in driest years. This is 

illustrated in Figure 2-9. Originally, 

M&I (urban) contractors had a 

higher priority than agricultural 

contractors, but since the 1995 

Monterey Amendment, shortages 

are shared proportionally between 

agricultural and M&I contractors. 

These delivery gaps demonstrate the 

need for reliable water supplies, 

particularly during driest years to 

SWP contractors south of the Delta. 

Groundwater 

Groundwater provides an estimated 

30 percent of the state’s total water 

supply in an average year (DWR, 

2005). In some regions, 

groundwater provides 60 percent or 

more of the supply during dry years. 

Between 40 and 50 percent of the 

state’s population relies on 

groundwater for part of its drinking 

water supply. Many small- to 

moderate-sized communities are 

entirely dependent on groundwater 

for drinking water supplies. In 1995, 

 

1 Summarized from the data provided in the 

Delivery Reliability Report for the WSAY Study. 

Model Table A delivery for Study 4 (DWR, 

2006d). Does not include Model Article 21 

water. 

it was estimated that 14.5 MAF of 

groundwater was extracted in 

California, which represented 

20 percent of all groundwater 

extracted in the United States 

(DWR, 2005). 

Groundwater in California is 

generally being withdrawn at a 

faster rate than it is being 

replenished, resulting in overdraft 

conditions. Figure 2-10 shows an 

example of dramatic overdraftinduced land subsidence in the 

Central Valley, one of several 

negative effects caused by 

overdraft. 

In Bulletin 118, DWR estimated 

statewide groundwater overdraft at 

between 1 and 2 MAF per year 

(DWR, 2003). It further identified 

11 groundwater basins in a state of 

critical overdraft, eight of which are 

in the Central Valley. This amount 

FIGURE 2-10 

Land Subsidence Recorded on a 

Telephone Pole in the Central Valley 

(Source: USGS)

Groundwater overdraft is 

not a sustainable 

water supply 

management action. 

FIGURE 2-9 

SWP Delivery Gap by Year Type 
WATER SUPPLY AND YIELD STUDY 

2-10 

is compounded annually and has 

resulted in significant groundwater 

depletion over time. 

Update 2005, which used a different 

analytical approach, estimated that 

more groundwater was withdrawn 

than replenished in the three year 

types (wet, average, and dry) used 

in that report (DWR, 2005). 

Although modern computers allow 

rapid manipulation of groundwater 

data to determine basin conditions 

such as groundwater storage 

changes or groundwater extraction, 

a lack of essential data in some 

groundwater basins limits the ability 

to make precise calculations. 

Management approaches such as 

conjunctive use allow surface water 

supplies and groundwater supplies 

to be managed collectively. In some 

regions, groundwater is banked 

when surface water supplies are 

most plentiful, and then extracted 

and used as an important source of 

supply during droughts. However, 

groundwater overdraft can lead to a 

variety of economic and permanent 

environmental impacts, such as 

increased extraction costs, land 

subsidence, water quality 

degradation, and saltwater intrusion 

(DWR, 2003). Therefore, 

groundwater overdraft is not a 

sustainable water supply 

management action. 

Current Water Use 

and Demands 

To evaluate the adequacy of 

California’s water supplies to meet 

existing and future water demands, 

this WSAY Study estimated and 

compared available water supply, 

typical water use, and overall water 

demand in different year types. 

Each year, runoff from precipitation 

and water imported from adjacent 

states is dedicated to urban, 

agricultural, and environmental 

uses. Figure 2-11 shows the typical 

distribution of statewide water uses 

in an average year (2000). 

FIGURE 2-11 

Distribution of Statewide Water Uses in an Average Year (2000) 

FIGURE 2-12 

Distribution of Applied Water Uses by Geographic Zone 
SECTION 2: SUPPLIES AND DEMANDS 

2-11 

Wild and Scenic River flows are 

classified separately in Figure 2-11. 

Wild and Scenic Rivers are 

designated by the state and federal 

government for their extraordinary 

scenic, recreation, fishery, or 

wildlife values. These rivers or river 

segments are considered fully 

appropriated (or fully “used” by the 

environment); therefore, including 

the flow of these rivers as dedicated 

environmental water uses would be 

misleading, because Wild and 

Scenic River uses simply represent 

what is available from unimpaired 

runoff. For this reason, such flows 

were excluded from this supply and 

demand analysis. 

Uses vary significantly by 

geographic zone and hydrologic 

region. The distribution of applied 

water uses by geographic zone is 

shown in Figure 2-12. The North 

and Central Geographic Zones 

support the bulk of agricultural use 

in the state, while the majority of 

urban uses are in the South 

Geographic Zone. During an 

average year, most environmental 

flows and all Delta outflow 

requirements are met using water 

originating in the North Geographic 

Zone. Managed Delta outflows 

make up the largest environmental 

water use in the state, aside from 

Wild and Scenic River flows. 

Water Use Estimates 

Update 2005 estimated existing 

regional and statewide water use by 

compiling actual water use data 

from three recent years—1998, 

2000, and 2001—to show the 

variation of water supplies and uses 

in a typical recent wet, average, and 

dry year, respectively. Water supply 

and use data was assembled from 

the state’s 10 individual hydrologic 

regions, and no statistical 

adjustments were made to the data. 

The total statewide applied water 

uses and supplies are listed in 

Table 2-2. 

The Update 2005 estimate shows 

how water supplies and uses vary 

by year type. Figure 2-13 illustrates 

the differences between statewide 

supplies and uses in recent wet, 

average, and dry years. In a wet 

year, dedicated supplies are higher 

than the amount of water used, and 

the excess water is stored. In 

average and dry years, dedicated 

supplies and uses were equal. The 

carryover storage and groundwater 

indicated by the shaded area within 

the average and dry year supply 

boxes represents the net depletion in 

surface and groundwater storage in 

a given year type. Therefore, to 

meet some demands in average and 

dry years, more water is withdrawn 

from storage than replenished. 

Figure 2-13 also shows that 

statewide water uses in an average 

year exceed water uses in a wet or 

dry year. During a wet year, the 

demand for water is lower because 

more water is available from 

precipitation. This corresponds to 

the lower water use in a wet year. 

During dry years, when less water is 

available from precipitation, a 

TABLE 2-2 

Applied Statewide Water Use and Dedicated Supplies in Wet, Average, and 

Dry Years 

Use 

Wet Year

1998 

(MAF) 

Average Year

2000 

(MAF) 

Dry Year

2001 

(MAF) 

Urban use 7.8 8.8 8.4 

Agricultural use 27.3 33.3 32.0 

Environmental use 17.8 16.3 12.6 

Total statewide use 52.9 58.4 53.0 

Dedicated statewide supplies 58.4 58.4 53.0 

Note: Environmental use and dedicated supplies do not include Wild and 

Scenic River flows. Dedicated supplies exclude water made available from 

groundwater overdraft in order to reflect the typical, sustainable supply for 

each year type. 

FIGURE 2-13 

Statewide Dedicated Water Supplies and Uses by Year Type 

To meet some demands in 

average and dry years, 

more water is withdrawn 

from storage than 

replenished. 
WATER SUPPLY AND YIELD STUDY 

2-12 

Use and Demand Defined 

Water use is the amount of water 

delivered to and used by a user, 

which is dependent on water supply 

and is influenced by factors such as 

price, availability, and physical 

constraints. Update 2005 

determined water use. 

Water demand is an amount of 

water a user desires to apply to a 

particular use, such as crop 

irrigation, industrial processes, 

ecosystem needs, or residential 

supply, regardless of influencing 

factors such as price, available 

supply, or physical constraints. 

The WSAY Study determined 

water demand.

higher urban and agricultural 

demand is expected because of 

increased need for landscape 

watering and crop irrigation. The 

dedicated supply in a dry year may 

be insufficient to meet those 

increased needs. Therefore, during a 

dry year, it is likely that supply 

curtailments—rather than decreased 

demand—lead to the lower water 

use. Even in average water years, 

some growers forego planting and 

other agricultural operations 

because they lack a reliable water 

supply (DWR, 2005). 

Note that although 2001 was a dry 

year, it was not considered a 

drought year or critically dry year. 

The year 2001 followed six 

consecutive years designated as 

either above normal or wet. 

Reservoirs were filled prior to 2001, 

attenuating the impacts of a dry 

2001. Although 2001 does illustrate 

how uses change based on 

hydrology, this single year does not 

reflect consecutive dry years’ 

impact water supply reliability. 

The water uses developed in 

Update 2005 account for physical 

and economic considerations that 

may affect the amount of water 

delivered to users. Water demand, 

as defined in this WSAY Study, is 

the amount of water a user desires 

to apply to a particular use, 

regardless of these factors. 

To assess the actual water demand 

during average and dry years, unmet 

water needs must be accounted for. 

Forecasting future water demand 

must also include needs currently 

being unmet even in an average 

water year. The following 

discussion quantifies the existing 

gaps between water use and water 

demand in order to establish 

existing demands and forecast 

future water needs. 

Water Demand in 

Average and Dry Years 

The demand for water can be 

estimated by adjusting water use 

estimates to account for unmet 

demands and groundwater 

overdraft. Demands were 

determined for each hydrologic 

region using the following 

methodology. 

Urban (M&I) Demand 

A typical level of urban demand can 

be estimated by the level of water 

use during an average year. Urban 

demand in 2001, a dry year, likely 

increased as a result of increased 

need for landscape irrigation and an 

increase in population from the 

previous year. Incorporating the per 

capita increase in typical water use 

resulting from the increase in 

population from 2000 to 2001, 

statewide urban demand for water 

was estimated to be about 500 TAF 

greater in 2001 than in 2000, an 

average year. 

Agricultural Demand 

Agricultural water use decreased by 

19 percent from 2000 to 2001, 

primarily as a result of fewer acres 

being irrigated, likely because of 

delivery reductions under dry year 

conditions. Since the number of 

irrigated acres in 1998 and 2000 

were similar, it could be assumed 

that irrigated acreage would have 

been roughly the same in 2001 if 

there had been no delivery 

curtailments (shortages). Therefore, 

the agricultural water demand in 

2001 would have been at least as 

much as the demand in 2000. 

Environmental Demand 

Statewide, numerous environmental 

flow objectives have not been met, 

even in wet years. For Update 2005, 

Environmental Defense conducted 

an analysis of unmet environmental 

flows using actual flow data for 

water years 1998, 2000, and 2001 

(Environmental Defense, 2004). 

That analysis included a regional 

assessment of unmet environmental 

objectives and considered the 

following factors: 

• Trinity River flows consistent 

with Trinity River Mainstem 

Restoration Plan ROD 

• Additional water required to meet 

flow objectives in the Final 

Restoration Plan for the 

Anadromous Fish Restoration 

Program 

• A level of protection in the Delta 

equivalent to that specified in the 

CALFED ROD and required for 

long-term Endangered Species 

Act assurances 

• San Joaquin River flows needed 

to comply with the federal court 

order to restore the salmon 

fishery below Friant Dam 

• All Level 4 refuge supplies 

• The Ecosystem Restoration 

Program purchases identified in 

the CALFED ROD for Stage One 

implementation 

• San Joaquin River flows at 

Vernalis consistent with levels 

specified in the 1995 Water 

Quality Control Plan 

These unmet environmental flows 

did not include water needed for 

privately owned wetlands. In the 

During a dry year, it is 

likely that supply 

curtailments—rather than 

decreased demand—lead 

to lower water use. 
SECTION 2: SUPPLIES AND DEMANDS 

2-13 

Statewide Demand Simulation and CALSIM II 

Congress directed the Secretary to conduct a study of available water supplies and existing and future water needs by passing 

Public Law 108-361 (described in Section 1 of this report). This WSAY Study fulfills that need by identifying possible projects

and water management actions that could provide new firm yield and water supply improvements for the CVP and help the 

state meet current and future water needs. 

Generally, planning studies prepared by Reclamation address water supplies and needs in the integrated CVP and SWP 

service areas. However, the WSAY Study’s authorization includes the CALFED Solution Area and statewide water needs, and 

therefore broadens the scope of this WSAY Study beyond the CVP and SWP service areas. 

In many planning studies, Reclamation and DWR use a number of computer models to analyze water supply reliability, 

reservoir storage, and Delta water exports. CALSIM II, a monthly time-step planning and analysis model, is one such model 

used by both agencies to simulate operations of the CVP and SWP. CALSIM II is typically used to simulate how the CVP and 

SWP water supply systems respond to a future action, such as the addition of a new facility or implementation of a certain 

policy. CALSIM II simulates these responses over several years of historical hydrology, which is adjusted to reflect current or

simulated future water demands, facilities, and operational constraints. 

Although CALSIM II may seem appropriate to simulate future statewide water shortages, it does have limitations: 

• Model output from different scenarios is intended to be analyzed comparatively in reference to a base simulated condition. 

CALSIM II is not designed to predict discrete river flows, daily water quality conditions, or drought shortages, but instead 

provide relative magnitudes of the long-term effects of alternative planning decisions. 

• CALSIM II simulates the operations of the CVP and SWP systems and includes demands for CVP and SWP contractors. 

However, the CALSIM II model does not account for demands in areas outside of the CVP and SWP system, such as 

areas of the CALFED Solution Area and the North Coast and Central Coast. 

• Operations and calculations in CALSIM II are based on generalized monthly operational rules to reveal trends reflected as 

the long-term average and critical and dry year average deliveries. Actual operations will likely be different than those 

simulated, resulting in differences between modeled and actual conditions in a given month or year. This means that 

CALSIM II is not intended to exactly replicate recent or historical operational conditions. 

CALSIM II’s intended use and its inherent limitations prevent it from being used to provide the data necessary to fulfill the 

requirements of the WSAY Study. Therefore, this report uses the hydrologic and water use data collected by DWR for 

Update 2005 to provide a better representation of existing and anticipated future statewide conditions. 

update of the Central Valley 

Wetlands Water Supply 

Investigations Report, the Central 

Valley Habitat Joint Venture has 

preliminarily concluded that there is 

a supply shortfall of full deliveries 

to existing private wetlands in an 

average year. The update also 

concluded that there is a shortfall in 

reliable water supplies to meet 

supplemental wetland habitat goals 

originally established by the Central 

Valley Wetlands Water Supply 

Investigations Report (Ostroff, 

2006). These additional supply gaps 

increase the statewide unmet refuge 

water demand calculated by 

Environmental Defense. 

The unmet environmental demands 

developed by Environmental 

Defense and the Central Valley 

Habitat Joint Venture range from 

1.11 MAF in a representative wet 

year (1998) to approximately 

1.28 MAF in a representative dry 

year (2001). Unmet environmental 

flow objectives were also 

distributed to each applicable 

hydrologic region. To estimate the 

total environmental demand in both 

years, these unmet environmental 

flows were added to the overall 

environmental water demand in 

each year type. 

Total Water Demand 

Urban, agricultural, and environmental water demands were 

developed for each hydrologic 

region, primarily from Update 

2005 data. 

The water demand for each user 

was added to determine a total 

water demand. Total statewide 

water demands are listed in 

Table 2-3. Demands vary from 

about 54 MAF in wet years to about 

61 MAF in average years. Demand 

is lowest in wet years, when more 

water is provided by precipitation 

and runoff, and higher in average 

TABLE 2-3 

Projected Statewide Demand by User in Representative Wet, Average, and 

Dry Years 

User 

Wet Year 

1998 

(MAF) 

Average Year 

2000 

(MAF) 

Dry Year 

2001 

(MAF) 

Urban 7.8 8.9 9.0 

Agricultural 27.3 34.2 34.2 

Environmental* 18.5 17.5 14.0 

Total statewide demand 53.6 60.6 57.2 

* Does not include Wild and Scenic River flows 
WATER SUPPLY AND YIELD STUDY 

2-14 

and dry years, when less precipitation is available and more water is 

lost to evaporation. Environmental 

demands seem to decrease 

significantly during dry years 

because less runoff is available for 

instream flows. Consequently, 

unmet environmental demands are 

greatest during dry years. 

Current SupplyDemand Gaps 

Supply-demand gaps were 

determined by totaling unmet urban, 

agricultural, and environmental 

demands, as well as the annual 

estimated amount of groundwater 

overdraft2 and comparing the result 

to currently available supplies. 

Supplies and demands were 

compared on a regional basis 

because comparing supplies and 

total demands on a statewide basis 

does not provide an accurate 

representation of supply-demand 

gaps at the regional level. If 

one region has surplus supply, it 

cannot be assumed that the surplus 

water can be conveyed to fill 

another region’s supply-demand 

gap. Therefore, supplies and 

demands were compared by 

hydrologic region, and only gaps 

(not surpluses) were added to 

regional and statewide totals. 

This analysis shows that supplydemand gaps exist for all 

geographic zones in average and dry 

years. Table 2-4 lists the supplydemand gaps by geographic zones 

and for the state as a whole for 2000 

(average year) and 2001 (dry year). 

 

2 Bulletin 118’s estimate of groundwater 

overdraft was distributed to hydrologic regions 

that have areas reported to be in overdraft, 

including the Central Coast, South Coast, San 

Joaquin River, and Tulare Lake regions. 

Because overdraft is not a sustainable source 

of supply, 2 MAF was subtracted from 

statewide supplies in dry years and 1 MAF was 

subtracted in average years. 

Regional supply-demand gaps 

reveal that shortages are greatest in 

the Central Geographic Zone. 

Detailed information on existing 

supplies, demands, and gaps by 

hydrologic region is provided in the 

appendix. 

The source of each gap varies by 

year type and geographic zone, as 

shown in Figure 2-14. The gap in 

average years is primarily the result 

of unmet environmental demands, 

whereas the gap in dry years results 

from unmet urban, agricultural, and 

environmental demands. 

Regionally, in the North Geographic 

Zone, unmet environmental 

demands account for 70 to 

90 percent of the gap, whereas 

agricultural and urban demands 

account for the entire gap in the 

South Geographic Zone. Gaps exist 

in the central and southern parts of 

the state primarily because of 

hydrologic conditions and facility 

(storage and conveyance) 

constraints. Groundwater overdraft 

is greatest in the Central and South 

Geographic Zones, which is also 

reflected in the urban and 

agricultural gap for those areas. 

Significant fluctuations in state 

precipitation from year to year and 

the high demands placed on 

available water result in supplydemand gaps in average and dry 

years. Additional storage and 

conveyance infrastructure and 

facility improvements are some of 

the options available to ensure that 

enough water supplies are available 

to meet demand during average and 

dry years. 

During dry years in particular, water 

managers must balance a 

complicated set of considerations 

when deciding which demands can 

be met and how much water should 

be banked to protect against future 

droughts. Each year of a multipleyear drought presents a greater 

challenge to meeting the next year’s 

water demands, because storage is 

further depleted with each 

successive dry year. The dry year 

supply-demand gaps calculated for 

this study only begin to describe the 

challenges faced by California 

during a multiple-year drought. As 

population and other demands on 

California’s water supply increase 

in the future, it will become more 

difficult to ensure that water is 

available and reliable without 

investment in additional conveyance 

and storage facilities and 

demand-reduction options. 

Future Challenges 

Demand for water in the future will 

depend on several driving factors, 

including population growth and 

density, land use changes (such as 

conversion of agricultural areas to 

urban areas), unknown future laws 

and regulations, and the effects of 

climate change. These factors add 

uncertainty to future available 

supplies, and may increase the risk 

that existing facilities and 

infrastructure will be inadequate to 

meet demands during multiple-year 

Supply-demand gaps exist 

for all geographic zones in 

average and dry years. 

TABLE 2-4 

Existing Supply and Demand Gap for Average and Dry Years by 

Geographic Zone 

Geographic Zone 

Average Year 

2000 

(MAF) 

Dry Year 

2001 

(MAF) 

North 0.8 1.1 

Central 1.5 2.3 

South <0.1 0.8 

Total statewide gap 2.3 4.2 
SECTION 2: SUPPLIES AND DEMANDS 

2-15 

droughts. The following discussion 

explains these driving factors, 

estimates water demand in 2030, 

and describes future supply-demand 

gaps regionally and statewide. 

Factors Driving Future 

Water Demand 

Future water demand can be gauged 

by studying historical trends in 

water use on a regional and 

statewide basis. Factors that may 

drive these trends into the future 

include population growth, 

conversion of agricultural land, 

environmental regulations, and 

climate change. 

Population and Urban Growth 

It is estimated that California’s 

population will grow from 36 to 

48.1 million people by 2030 

(California Department of Finance, 

2004) (Figure 2-15). Current trends 

point to nearly a 50 percent increase 

in single-family residences and a 

35 percent increase in multifamily 

houses by 2030, resulting in 

increased urban water demand 

and potential conversion of 

agricultural land. 

Regional growth is of vital concern 

to water supply and conveyance. 

Population is expected to increase 

most in the state’s inland and 

southern areas by nearly 45 percent 

according to current trends. This 

could present a challenge to convey 

enough water from its source in the 

northern regions of the state to the 

growing demand in the south. Over 

the last 30 years, urban water use 

has nearly doubled in the South 

Coast Hydrologic Region. In 

contrast, urban water use in the 

North Coast Hydrologic Region has 

decreased by about 17 percent 

since 1980. 

Conversion of 

Agricultural Land 

California has approximately 

27.6 million acres of farmland, 

about 9 million acres of which is 

irrigated. Agricultural land has been 

gradually shifting to urban or other 

nonagricultural uses; from 1990 to 

2000, about 500,000 acres were 

converted from agricultural use to 

urban or other nonagricultural uses. 

The rate at which this land 

conversion will continue is 

uncertain, but based on current 

trends, approximately 700,000 acres 

of additional California farmland 

will be converted to urban use each 

decade. However, as a result of 

technological advances, 

multicropping, increased water 

efficiency, and production of 

higher-value crops per acre, yield 

per acre of agricultural land may 

continue to increase. 

FIGURE 2-14 

Existing Supply-Demand Gaps by Geographic Zone in an Average Year (2000) and Dry Year (2001) 
WATER SUPPLY AND YIELD STUDY 

2-16 

Environmental Water Account 

The CALFED ROD established the Environmental Water Account (commonly 

referred to as EWA) to provide water for the protection and recovery of fish beyond 

that which would be available through existing regulatory protections related to 

CVP and SWP operations. The EWA program consists of two primary elements: 

implementing fish actions that protect at-risk native fish species, and maintaining 

water supply reliability by acquiring and managing assets to compensate for the 

supply effects of fish protection actions. Actions that protect fish species consist 

primarily of seasonal and annual pumping reductions at the CVP and SWP Delta 

pumping plants to protect fish at times when they are near the pumps or moving 

through the Delta. These pumping reductions can reduce water supply reliability 

for CVP and SWP contractors, so the EWA assets are used to repay CVP and 

SWP users for water not pumped during pump reductions (CALFED, 2000c; Rust, 

2006). The EWA will be implemented through December 31, 2007. 

Environmental and Flow 

Regulations 

Prior to the late twentieth century, 

flows for environmental uses were 

rarely regulated. Trends over the 

last few decades point to more 

flows being contributed to Delta 

outflows, restoration efforts, Wild 

and Scenic Rivers, wildlife refuges, 

and the Environmental Water 

Account (EWA). However, future 

environmental water demands could 

vary depending on future land use 

changes and the effectiveness of 

current and planned ecosystem 

restoration efforts. 

These recent developments point to 

an increasing trend in dedicated 

environmental flows: 

• State Water Resources Control 

Board Water Right Decision 

1485 (D-1485), issued in 1978, 

set flow and water quality 

standards for the protection of 

beneficial uses in and from the 

Delta, and required the SWP and 

CVP to meet those standards as 

conditions of the water right 

permits for the projects. The 

Coordinated Operations 

Agreement of 1986 specified 

how the CVP and SWP would 

share the responsibility of 

meeting these Delta water 

quality standards. 

• The Water Quality Control Plan, 

adopted in 1995 by the State 

Water Resources Control Board, 

required greater amounts of CVP 

water to meet water quality 

standards. 

• Water Right Decision 1641 

(D-1641), issued in 1999, 

assigned interim responsibility to 

the CVP and SWP to meet the 

flow and water quality objectives 

in the 1995 Water Quality 

Control Plan, and addressed the 

responsibility of certain other 

water right holders for meeting 

those objectives. 

• The EWA, established in 2000, 

implemented pumping reductions 

at the Delta CVP and SWP 

export pumping plants to protect 

at-risk fish species, and used 

other assets to repay CVP and 

SWP users for water not pumped 

during the pumping restrictions. 

Pumping reductions may reduce 

water supply reliability for the 

CVP and SWP users south of 

the Delta. 

• Compliance with the Endangered 

Species Act has altered CVP and 

SWP operations. Structural and 

operational changes have been 

required to maintain flows and 

reduce water temperatures below 

Shasta Dam for the endangered 

winter-run chinook salmon, 

resulting in less water being 

available for agricultural and 

urban (M&I) users. Additionally, 

CVP and SWP diversions from 

the Delta have been reduced to 

limit losses of special-status 

species, especially Delta smelt 

and winter-run chinook salmon. 

Climate Change 

For over a decade, scientists have 

been publishing formal, 

peer-reviewed articles on the 

potential causes and effects of 

global climate change. Although the 

debate continues within the 

scientific and political communities 

regarding the extent of climate 

change impacts on California, 

programs have been established to 

develop and implement a climate 

change research plan in order to 

improve the understanding of 

physical and economic impacts 

FIGURE 2-15 

California Population Growth Trend 
SECTION 2: SUPPLIES AND DEMANDS 

2-17 

Wild and Scenic Rivers 

Passed in 1968, the National Wild and Scenic Rivers Act (Public Law 90-542 as amended; 16 U.S.C. 1271-1287), 

provides for the protection of “certain selected rivers of the Nation...with their immediate environments...be preserved 

in free-flowing condition.” Patterned after the federal act, the California Wild and Scenic Rivers Act (Public Resources 

Code Sec. 5093.50 et seq.) was passed in 1972 to preserve designated rivers possessing extraordinary scenic, 

recreation, fishery, or wildlife values. These designated rivers or river segments are considered fully appropriated, 

although flows downstream of a designated river segment may be diverted for other beneficial purposes. 

From a water supply perspective, flows in Wild and Scenic Rivers fall into two general categories: 

• Encumbered supplies, including protected rivers flowing directly to the 

Pacific Ocean that do not have impoundments, diversion, and other 

modifications at a significant level (such as the Smith and Van Duzen 

rivers). These protected “free-flowing” rivers are fully appropriated 

and unimpaired, and thus unavailable for other beneficial use. 

• Available supplies that include flows downstream of protected rivers 

or protected reaches (such as the American, Merced, and Tuolumne 

rivers). Flows downstream of protected rivers or reaches may be 

diverted for other beneficial use, and this diverted portion may be 

counted as a benefit to a water resource project. 

The state’s Update 2005 includes the unimpaired flows of Wild and Scenic 

Rivers as part of the state’s dedicated supply allocated to environmental 

uses. Both flow categories (encumbered and available) are included in the 

environmental supplies and uses. 

The WSAY analysis does not include Wild and Scenic River flows in its supply-demand gap analysis for two reasons. 

First, since required flows in Wild and Scenic Rivers and river segments are represented by what is available from 

unimpaired runoff, the demand in these segments is always met by the available supply—by definition, there is never a 

supply-demand gap. Second, including Wild and Scenic Rivers makes it possible to overstate the proportion of 

environmental demand that can be met through management, as the charts illustrate. Chart 1 shows water demands in 

three year types including Wild and Scenic Rivers, and Chart 2 shows demands excluding Wild and Scenic Rivers. 

Comparing these figures reveals that a significant portion of environmental demands in wet and average years is from 

unmanaged Wild and Scenic Rivers, and a relatively small fraction of environmental demands are met through 

management. Therefore, excluding Wild and Scenic River flows helps water managers better understand the 

environmental demands met through water management actions, such as timed reservoir releases. 

Although the WSAY Study excludes Wild and Scenic River flows and uses, flows downstream of these segments 

diverted for urban or agricultural uses (the second flow category, available supplies) are included in the analysis; this is 

achieved by using an “applied” water balance methodology to calculate the supply-demand gaps. 

Total Statewide Water Use Including Total Statewide Water Use Excluding 

Wild and Scenic River Flows Wild and Scenic River Flows 

Excluding Wild and Scenic 

River flows from the 

supply-demand gap 

analysis helps water 

managers understand the 

environmental demands 

met through water 

management actions. 
WATER SUPPLY AND YIELD STUDY 

2-18 

of climate change and to develop 

policy recommendations. The 

following discussion draws from 

Update 2005 and from the 

conclusions of two studies 

regarding the impacts of climate 

change on California’s water 

resources and associated 

infrastructure: “Climate Change and 

California Water Resources: A 

Survey and Summary of the 

Literature” (Kiparsky and Gleick, 

2003), and “Accounting for Climate 

Change” (Roos, 2005). 

Climate change may affect not only 

the availability of precipitation, but 

also the demand for water for 

agricultural uses, the demand for 

hydropower to provide electricity 

for air conditioning and 

refrigeration, and the ability to store 

and convey water and control 

flooding. Much depends on the 

degree of warming and the 

magnitude of future changes. Some 

of the potential impacts include 

altered snowpack accumulation and 

melting patterns, altered runoff 

patterns, changes in water supply 

reliability, floods and droughts, 

increased water demands, and 

higher water temperature. 

Climate change could influence 

where precipitation falls. Warming 

might push the winter storm track 

on the West Coast farther north, 

leading to a drier California. In 

contrast, some models show that 

warming may cause precipitation to 

increase, but snowpack to decrease. 

In any case, less snowfall would 

lead to less spring snowmelt. 

Consequently, reservoirs would be 

more difficult to refill during late 

spring and early summer of many 

years, potentially reducing the 

amount of surface water available 

during the dry season. Spring runoff 

in California’s major rivers 

currently yields 40 percent of the 

estimated state net demand for 

agricultural and urban water use. 

Replacing that yield would require 

increased reservoir storage capacity, 

increased conveyance facilities, and 

other measures. 

A second potential impact of 

climate change is sea level rise, 

which would result in two 

significant problems in the Delta: 

increased saltwater intrusion from 

the ocean, and increased pressure 

on levees protecting the low-lying 

land, much of which is already 

below sea level. Saltwater intrusion 

could degrade fresh water supplies 

pumped at the southern edge of the 

Delta or require more fresh water 

releases from upstream reservoirs 

to repel ocean water. Pressure on 

levees could ultimately result in a 

levee failure, potentially drawing 

saltwater into the Delta region and 

affecting overall Delta water 

quality. 

Many of the central Delta levees are 

built on unstable peat soil and are 

vulnerable to high water levels. 

Already subject to considerable 

pressure from tidal action, sea level 

rise could magnify the problem. A 

small rise can likely be tolerated by 

the levee system; a major rise of 

1 foot or more could cause 

significant problems. A breach of 

one or more of the central Delta 

levees could result in the temporary 

or long-term disruption of the water 

supply for about two-thirds of the 

state’s residents and for about half 

of the state’s irrigated agriculture. 

Levee failure can cause large 

amounts of saline ocean water to be 

drawn into the Delta. Water supply 

pumping operations in the Delta for 

the SWP, CVP, and other supply 

systems would be compromised 

because of poor export water quality 

and because of environmental and 

regulatory obligations. 

Projected Future Water 

Demands 

Understanding the potential effects 

of the factors described in the 

preceding discussion and studying 

existing water use trends makes it 

possible to predict future water 

demands and determine how 

California can prepare to meet 

those demands. 

Update 2005 projected water use in 

2030 by developing three future 

scenarios—Current Trends, Less 

Resource Intensive, and More 

Resource Intensive—for each type 

of user (urban, agricultural, and 

environmental) to estimate a range 

of future water uses that could occur 

without additional management 

intervention. The scenarios varied 

plausible water use assumptions 

related to population growth, land 

use, and naturally occurring 

conservation, and highlighted 

important categories of 

uncertainties. To estimate a total 

future water use under each 

scenario, the projections for each 

user were totaled by scenario type. 

For example, the More Resource 

Intensive scenario projections for 

urban, agricultural, and environmental users were added to 

determine the total future water 

use under the More Resource 

Intensive scenario. 

To enhance this approach, this 

WSAY Study evaluated the 

Update 2005 scenario assumptions 

for urban, agricultural, and 

environmental water use in an 

average year to ensure that full 

future water demands were 

reflected. In some cases, it was 

determined that the assumptions 

considered for one scenario better 

reflected current trends and unmet 

demands for one user than for a 

different user. For example, for 

urban users, only the Current 

Trends scenario assumes a 

population projection consistent 

with the established Department of 

Finance estimates. However, the 

same Current Trends scenario does 

A breach of one or more of 

the central Delta levees 

could result in the 

temporary or long-term 

disruption of the water 

supply for about two-thirds 

of the state’s residents and 

for about half of the state’s 

irrigated agriculture. 
SECTION 2: SUPPLIES AND DEMANDS 

2-19 

not account for unmet environmental user demands; only the 

Less Resource Intensive scenario 

accounts for full unmet 

environmental demands. 

To project total water demands in 

2030 that are consistent with 

existing trends (population, land 

use, regulatory, and climate) and 

account for the unmet demands, this 

WSAY Study applied the Update 

2005 scenarios to each type of user 

in the following manner: 

• For urban water use, the Current 

Trends scenario assumes a 

population projection consistent 

with California Department of 

Finance estimates. 

• For agricultural water use, the 

Less Resource Intensive scenario 

provides for some decrease in 

irrigated acreage consistent with 

current forecasts while 

accounting for an average 

increase in water use efficiency 

over the next 25 years. 

• For environmental water use, the 

Less Resource Intensive scenario 

is the only scenario that assumes 

that full environmental demands 

(as defined by existing 

legislation) are met. Additional 

demand is added for private 

wetlands evaluated by the Central 

Valley Habitat Joint Venture, 

which was not included in 

Update 2005. 

Adding all user demands by 

hydrologic region, the statewide 

water demand under a 2030 level of 

development is estimated to be 

60.8 MAF in an average water year 

(excluding Wild and Scenic River 

flows). Future dry year demands 

were estimated by assuming there 

would be the same proportional 

differences between average and 

dry year demands as in current 

conditions. Using this assumption, 

the future statewide water demand 

in a dry year is estimated to be 

about 57.4 MAF. Table 2-5 

summarizes total estimated 2030 

statewide demands and provides 

existing demands for comparison. 

These results follow existing 

statewide and regional trends. 

Figure 2-16 shows the trend in 

water use and demand from 1972 to 

2030 statewide and for each 

geographic zone. The trends show a 

general increase in statewide water 

use, with growth particularly in 

dedicated environmental flows and 

urban use. Agricultural water use is 

projected to decline from 2000 

to 2030. 

Future water demand in California 

will vary significantly across 

regions and water users. Although a 

decrease in agricultural water 

demand outweighs an increase in 

urban and environmental water 

demand statewide, the majority of 

regions show an increase in water 

demand, particularly urban demands 

in the south. Regional demand 

changes by geographic zone are 

shown in Figure 2-17. 

Demand projections generally show 

substantially increasing urban 

demands, particularly in southern 

coastal areas. In contrast, the 

Central Geographic Zone, 

especially the Tulare Lake 

Hydrologic Region, is likely to 

experience a decrease in agricultural 

water demand. From a statewide 

perspective, these changes in 

demand seem to be complementary 

to meeting future water supplies. 

However, increases in water 

demand must be addressed at the 

regional and local levels, because 

supplies made available in one part 

of the state as a result of reduced 

demand cannot necessarily be used 

to meet increasing demands in 

another part. The ability to transfer 

water from the Central Geographic 

Zone to meet Southern California’s 

growing demands could be 

constrained by available 

conveyance facilities, area-of-origin 

issues, environmental impacts, and 

other third-party effects. 

These trends in water demand 

indicate the need for an intensive 

focus on integrated water 

management efforts, storage 

projects, and improved conveyance 

facilities to move water from the 

Central Valley to other parts of 

the state. 

Trends in water demand 

indicate the need for an 

intensive focus on 

integrated water 

management efforts, 

storage projects, and 

improved conveyance 

facilities. 

TABLE 2-5

Projected Statewide Demand by User in Existing and Future (2030) Conditions for 

Average and Dry Years 

Average Year (MAF) Dry Year (MAF) 

User Existing Future Existing Future 

Urban 8.9 11.9 9.0 12.0 

Agricultural 34.2 31.4 34.2 31.4 

Environmental* 17.5 17.5 14.0 14.0 

Total statewide demand 60.6 60.8 57.2 57.4 

* Does not include Wild and Scenic River flows 

Trends show a general 

increase in statewide 

water use, with growth 

particularly in dedicated 

environmental flows and 

urban use. Agricultural 

water use is projected to 

decline from 2000 to 2030.
WATER SUPPLY AND YIELD STUDY 

2-20 

Future Supply-Demand 

Gaps 

Without future investment in water 

management actions or facilities, it 

is assumed that available water 

supplies in the future will remain 

about the same as they are under 

existing conditions. 

One difference in future supplies 

will result from recent agreements 

regarding the reallocation of 

Colorado River water. The 

Quantification Settlement 

Agreement established mechanisms 

to reduce California’s dependence 

on the Colorado River through 

conservation and transfers 

(CVWD et al., 2002). These 

mechanisms will effectively result 

in a decrease in agricultural supplies 

in the Colorado River Hydrologic 

Region and a decrease in urban 

supplies in the South Coast 

Hydrologic Region. Although other 

changes in supplies may be possible 

in the future, these foreseen 

differences resulting from the 

Quantification Settlement 

Agreement have been integrated 

into the assumed 2030 supplies. 

These future statewide supplies, 

without further investment in water 

management actions or facilities, 

are listed for average and dry years 

in Table 2-6. Supply-demand gaps 

in a prolonged drought would likely 

be much greater than those listed for 

a single dry year. 

The projected gap between 

available water supplies and water 

demand in 2030 can be estimated by 

comparing future demands with the 

anticipated future supplies listed in 

Table 2-6. 

Table 2-7 shows the projected 

supply-demand gaps by geographic 

zone and statewide. Existing gaps 

are shown for comparison. Detailed 

information on future supplies, 

demands, and gaps by hydrologic 

region is provided in the appendix. 

Table 2-7 also shows how future 

statewide demands exceed supplies 

in average and dry years. In dry 

years, the statewide future gap 

exceeds the existing gap. At the 

regional level, the future gap in the 

South Geographic Zone is nearly 

three times as large as the existing 

gap. In contrast, the future gap in 

the Central Geographic Zone 

slightly decreases. 

FIGURE 2-16 

Geographic and Statewide Water Demand Trends from 1972 to 2030 

TABLE 2-6 

Assumed Statewide Future (2030) Dedicated Supplies in Average and Dry Years 

Supply 

Average Year 

(MAF) 

Dry Year 

(MAF) 

Urban supply 8.4 8.0 

Agricultural supply 32.8 31.5 

Environmental supply* 16.3 12.6 

Total dedicated statewide supplies 57.5 52.1 

* Does not include Wild and Scenic River flows 

Future statewide demands 

exceed supplies in average 

and dry years. 
SECTION 2: SUPPLIES AND DEMANDS 

2-21 

Figure 2-18 displays the distribution 

of gaps by region and by use for a 

future average and dry year. The 

significant increase in the supplydemand gap in the South 

Geographic Zone results primarily 

from growth in urban demands. The 

Central Geographic Zone shows a 

decrease in agricultural water 

demand compared to current 

conditions. This follows existing 

regional trends, as discussed 

previously. 

Need for Additional 

Water Supply 

Management and 

Infrastructure 

Several factors indicate that the 

state’s existing water supplies are 

not sufficient to meet demands, and 

that additional water supply 

management activities and projects 

are necessary to augment water 

supplies and delivery reliability in 

the future: 

• Annual variability in 

precipitation and the threat of 

multiyear droughts indicate the 

need to manage and store water 

during wet years to meet 

demands during dry years. 

Seasonal variability in 

precipitation indicates the need to 

store water during wet winter 

months to meet water demands 

throughout dry summers. 

Geographic variability in 

precipitation and population 

indicates the need for adequate 

conveyance facilities to move 

water from the wetter north to the 

more densely populated south. 

• CVP and SWP water deliveries 

vary considerably from year to 

year. Project deliveries may be 

limited by available conveyance 

or storage facilities. Passage of 

the CVPIA and other environmental constraints has reduced 

the ability of the CVP to meet 

contract deliveries. Future 

institutional constraints could 

further impact this ability. 

• Current statewide water use 

requires exercise of reservoir 

carryover storage and overdraft 

of groundwater during average 

and dry years. Banked 

groundwater is an important 

source of supply during droughts, 

but groundwater overdraft is not 

a sustainable source of supply. 

FIGURE 2-17 

Distribution of Applied Water Demands in 2030 by Geographic Zone 

TABLE 2-7 

Supply-Demand Gaps in Existing and Future (2030) Conditions for Average and 

Dry Years by Geographic Zone 

Average Year 

(MAF) 

Dry Year 

(MAF) 

Geographic Zone Existing Future Existing Future 

North 0.8 1.4 1.1 1.6 

Central 1.5 1.6 2.3 2.1 

South <0.1 1.9 0.8 2.4 

Total statewide gap 2.3 4.9 4.2 6.1 
WATER SUPPLY AND YIELD STUDY 

2-22 

• Water demands exceed 

sustainable supplies in average 

and dry years. Regional supplydemand gaps reveal that 

shortages are greatest in the 

Central and South Geographic 

Zones. The South Coast and 

Tulare Lake Hydrologic Regions 

have the largest regional gaps. 

Demand gaps are larger in the 

central and southern parts of the 

state because of hydrologic 

conditions and facility (storage 

and conveyance) constraints. 

• Future statewide demands exceed 

supplies in average and dry years. 

The future gap is greater than the 

existing gap. Regional supplydemand gaps reveal that 

shortages will be greatest in the 

South Geographic Zone. Gaps 

will increase by the highest 

percentage in the South Coast 

and San Francisco Bay 

Hydrologic Regions. Increasing 

urban demands, particularly in 

coastal areas, will impact the 

ability of existing facilities to 

meet future water needs. 

• Population growth, agriculturalto-urban land conversion, 

unknown future laws and 

regulations, and climate change 

add uncertainty to future demand 

estimates and may increase the 

risk that demands will not be met 

during multiyear droughts with 

existing facilities and 

infrastructure. 

FIGURE 2-18 

Projected 2030 Supply-Demand Gaps by Geographic Zone for Average and Dry Years 
3 Projects and Water Management Actions 

3-1 

The need for additional water 

supply is illustrated in Section 2 of 

this report. This section identifies 

the projects and water management 

actions that have the potential to 

improve firm yield or water supply 

within the CALFED Bay-Delta 

Solution Area, and assist the state in 

meeting its current and future needs 

for water. 

Section Highlights 

Projects and water management 

actions are needed to help fill 

the projected 2030 water supply 

demand gap. 

Storage and conveyance 

projects would increase average 

deliveries to water service 

contractors during critical times. 

Conveyance improvements play 

a critical role in the ability to 

utilize additional storage. 

CALFED has authorized the 

study of storage and 

conveyance improvements. 

Continued investment in water 

management actions is key to 

providing a reliable water supply 

in the future. 

A wide range of estimates for 

additional water supply benefits 

and cost for both projects and 

water management actions is 

available. 

If the Level 1 storage and 

conveyance projects were 

constructed and investments in 

water management actions 

were made, the supply-demand 

gap would remain at over 

1.5 MAF in average years and 

over 2.2 MAF gap in dry years. 

Long-term water supply 

reliability depends on being able 

to meet water demands during 

dry years, and additional 

measures will be required to fill 

the dry year gap. 

Projects 

Storage and conveyance projects 

have the potential to increase water 

supply by increasing average 

deliveries to water service 

contractors during critically dry 

periods or multiyear drought. The 

projects presented are categorized 

into three levels based on the 

amount of available information, the 

level of development in the 

planning process, and the current 

understanding of the likelihood of 

those projects moving forward. The 

three categories and the projects and 

actions considered in each are as 

follows: 

• Level 1: CALFED-authorized 

storage and conveyance 

improvement studies 

• Level 2: Projects of recent public, 

agency, or political interest 

• Level 3: Regional opportunities 

Descriptions of projects under each 

level category follow. 

Level 1: CALFEDAuthorized Storage 

and Conveyance 

Improvement Studies 

The Level 1 projects are large-scale 

infrastructure improvements that 

have been proposed as part of 

California’s water resources 

management portfolio to provide 

more reliable water supplies and to 

meet competing needs for water. 

Reclamation and DWR have 

completed preliminary 

environmental impact studies and 

conceptual modeling, and will 

continue efforts to formulate 

detailed alternatives that can be 

used in decision making for storage 

and conveyance improvements. 

Storage Improvements 

Surface storage reservoirs are 

widely used in California as a 

means of balancing the timing of 

the natural runoff pattern and the 

state’s water needs. In 2000, the 

CALFED ROD identified five 

potential surface storage reservoirs 

for investigation by DWR, 

Reclamation, and local water 

interests: 

• Shasta Lake Water Resources 

Investigation 

• Sites Reservoir Investigation 

• In-Delta Storage 

• Los Vaqueros Reservoir 

Expansion 

• Upper San Joaquin River Basin 

Storage Investigation 

CALFED’s surface storage projects 

are being planned as multipurpose 

projects for water supply reliability, 

improved water quality, and 

ecosystem restoration. These 

projects can provide regional 

benefits and broad public benefits to 

California; Figure 3-1 shows the 

general location of the project sites 

and identifies which potential 

benefits are associated with the 

storage projects described. 

The following descriptions of the 

five potential storage projects 

identified in the CALFED ROD are 

based on information in the 

California Bay-Delta Authority’s 

(CBDA) CALFED Bay-Delta 

Surface Storage Investigation 

Progress Report (CBDA, 2006). 
WATER SUPPLY AND YIELD STUDY 

3-2 

Shasta Lake Water 

Resources Investigation 

Shasta Dam is located on the 

Sacramento River in Shasta County, 

9 miles northwest of Redding. The 

existing Shasta Reservoir has a 

storage capacity of 4.5 MAF and a 

dam height of 602 feet. The 

reservoir’s volume could be 

increased by 300 TAF if the dam 

were raised above its current height 

by 6.5 feet, or increased by 

635 TAF if the dam were raised 

18.5 feet. 

The primary purpose of increasing 

storage in Shasta Reservoir is 

twofold: to increase the available 

cold water pool for environmental 

needs, and to increase water supply 

capability. The increased cold water 

pool would help maintain the cooler 

water temperatures needed by 

anadromous fish (migrating salmon 

and steelhead trout) in the 

Sacramento River, helping to 

increase their survival rate. 

Increased water supply capability 

will help meet future agricultural, 

urban (M&I), and environmental 

water demands by increasing 

California’s water supply capacity 

and supply reliability. Other project 

objectives include the following: 

• Preserving and restoring 

ecosystem resources in the Shasta 

Reservoir area and along the 

Upper Sacramento River 

• Reducing flood risk along the 

Sacramento River 

• Developing additional 

hydropower capabilities at 

Shasta Dam 

A preliminary study of three 

possible dam modification scenarios 

showed that if the dam were 

increased in height by 6.5 feet, the 

enlarged Shasta Reservoir could 

provide an additional long-term 

average water supply benefit of 

40 TAF per year, and 60 TAF per 

year during the driest periods. If the 

dam were increased in height by 

18.5 feet, the reservoir could supply 

an additional long-term average 

water supply benefit of 69 TAF per 

year, and 127 TAF per year during 

the driest periods. The third 

scenario would increase the dam 

FIGURE 3-1 

Level 1 Storage Project Sites and Potential Benefits 

Shasta Dam Authority 

Authorization 

Rivers and Harbors Act of 1935, 

Rivers and Harbors Act of 1937 

(re-authorized)

Purpose 

Navigation, regulation, and flood 

control primary purposes with 

irrigation and domestic uses 

secondary 

Federal Study Authorization 

Public Law 96-375 of 1980 

authorized the Shasta Lake 

Water Resources Investigation 

for the purpose of: 

Engaging in feasibility studies 

relating to: 

(1) Enlarging Shasta Dam and 

Reservoir, or constructing a 

replacement dam on the 

Sacramento River, and 

(2) The use of the Sacramento 

River for conveying water 

from such enlarged dam. 
SECTION 3: PROJECTS AND WATER MANAGEMENT ACTIONS 

height by 18.5 feet and construct 

anadromous fish habitat. 

Anadromous fish survival could 

increase by up to 9 percent under 

this scenario, and provide an 

additional long-term average water 

supply of 85 TAF per year, and 

160 TAF per year during the driest 

periods. The long-term net energy 

production could increase by up to 

40 gigawatt hours per year for a 

dam height increase of 18.5 feet. 

Preliminary capital cost estimates 

for enlarging Shasta Dam ranged 

from $280 million to $480 million 

for different configurations. 

Sites Reservoir Investigation 

The Sites Reservoir Investigation, 

also known as the North-of-Delta 

Offstream Storage (NODOS) 

Investigation, is evaluating an 

offstream storage reservoir up to 

1.8 MAF at the proposed Sites 

Reservoir and other locations in the 

Sacramento Valley. The project is 

in the feasibility study process 

which has three milestones: Initial 

Alternatives Information Report, 

Plan Formulation Report, and 

Feasibility Report with National 

Environmental Policy Act/ 

California Environmental Quality 

Act (NEPA/CEQA) compliance. 

The proposed project will meet the 

following goals: 

• Enhance water management 

flexibility in the Sacramento 

Valley while reducing water 

diversions from the Sacramento 

River during critical fish 

migration periods 

• Increase supply reliability for a 

significant portion of the 

Sacramento Valley 

• Provide storage and operational 

benefits for other CALFED 

programs, including Delta water 

quality and the EWA or similar 

program 

The formulation of alternative plans 

is underway, but additional work is 

necessary before the alternative 

plans are fully developed and 

evaluated. Four conceptual 

scenarios for the NODOS project 

were developed to provide a 

preliminary estimate of project 

benefits. These four scenarios 

focused on a project that could 

increase water supply reliability for 

Sacramento Valley water users as 

well as the CVP and SWP 

contractors; improve Delta water 

quality; improve environmental 

health by providing water for 

ecosystem restoration purposes; and 

provide water supply and storage 

for the EWA or similar program. 

Modeling output showed that a 

NODOS project could provide 

average annual water supply benefit 

to the CVP and SWP of 81 TAF to 

259 TAF per year in the long term, 

and 315 TAF to 440 TAF per year 

during the driest periods. An 

average annual water supply benefit 

of up to 124 TAF per year in the 

long term and 147 TAF during the 

driest periods can be provided for 

the EWA or similar program. The 

quantity of water supply provided 

for the EWA is limited by the 

EWA’s north-of-Delta (NOD) 

purchase goals. With operational 

flexibility created by NODOS, 

diversions from the Sacramento 

River at Glenn-Colusa Irrigation 

District and Tehama-Colusa Canal 

intakes could be reduced to protect 

fish migration during April through 

August by 170 TAF to 230 TAF 

per year in the long term, and 

115 TAF to 235 TAF per year 

during the driest periods. However, 

additional analysis and refinement 

of water supply benefits are 

necessary once alternative plans are 

formulated during the Sites 

Reservoir Investigation Plan 

Formulation Study. 

The preliminary capital cost study 

estimated the cost of constructing 

the reservoir and conveyance 

facilities associated with the Sites 

Reservoir Investigation to be 

between $1.3 billion and 

$2.3 billion, depending on the 

configuration chosen. 

In-Delta Storage Project 

The proposed In-Delta Storage 

Project consists of converting 

two islands (Webb Tract and Bacon 

Island) in the central Delta into new 

storage islands, and two other 

islands (Holland Tract and Bouldin 

Island) into habitat islands. The 

state completed a feasibility study 

evaluating in-Delta storage. 

Congressional authorization and 

appropriations would be required 

before a federal feasibility study 

could be conducted. 

The storage islands would provide 

approximately 217 TAF of water 

capacity. The habitat islands would 

provide 9,000 acres of new 

managed habitat in the Delta. 

Together, the project could provide 

water supply reliability, operational 

flexibility, conjunctive management 

opportunities, water quality 

improvements, wildlife and habitat 

improvements, and improved 

stability of Delta levees. 

Sites Reservoir 

Study Authority 

Federal Study Authorization 

Public Law 108-7, Division D, 

Title II, Section 215, the 

Omnibus Appropriations Bill for 

Fiscal Year 2003 authorized the 

Sites Reservoir feasibility study 

to be pursued along with 

ongoing environmental projects 

in a balanced manner. 

Preliminary model results 

demonstrated that the average 

annual water supply benefits for the 

SWP and CVP for the four 

operational scenarios being 

considered vary from 52 to 77 TAF 

per year for the long term, and from 

51 to 64 TAF per year during the 

3-3 
WATER SUPPLY AND YIELD STUDY 

driest periods. An average longterm annual water supply of 14 to 

28 TAF per year can be provided 

for the EWA or similar program. 

Preliminary total capital cost 

estimates for implementing the 

In-Delta Storage Project ranged 

from $700 million to $800 million, 

depending on the configuration. 

Los Vaqueros Reservoir 

Expansion 

The existing Los Vaqueros 

Reservoir, located in Contra Costa 

County in the San Francisco Bay 

Area, was completed in 1997 to 

provide 100 TAF of offstream water 

storage for the purpose of 

improving water quality and 

providing emergency supply for 

customers of the Contra Costa 

Water District (CCWD). 

An expanded Los Vaqueros 

Reservoir could provide as much as 

400 TAF per year of offstream 

storage to CCWD and other Bay 

Area water agencies. The purposes 

of the reservoir expansion project 

are the following: 

1. Water supply reliability for Bay 

Area urban (M&I) water users 

2. Less-costly replacement for the 

long-term EWA or similar 

program 

3. Without limiting purposes 1 

and 2, improve quality of water 

delivered to Bay Area urban 

(M&I) water users 

3-4 

As presently formulated, water 

supply benefits to other areas, 

including Southern California, are 

excluded from the project 

objectives. The studies indicate that 

the average annual water supply 

benefits for the CVP and SWP for 

the different configurations being 

considered vary from 0 to 13 TAF 

per year for the long term, and from 

0 to 25 TAF per year during the 

driest periods. The average annual 

water supply of 117 TAF to 

143 TAF per year in the long term, 

and 42 TAF to 65 TAF during the 

driest periods can be provided to the 

EWA or similar program. 

Los Vaqueros 

Reservoir Authority 

Authorization 

Los Vaqueros Reservoir is a 

locally owned facility authorized 

in 1988 by the voters of the 

Contra Costa Water District. 

Purposes 

Water quality, emergency supply 

storage, recreation, and flood 

control. 

Federal Study Authorization 

Public Law 108-7, Division D, 

Title II, Section 215, the 

Omnibus Appropriations Bill for 

Fiscal Year 2003 authorized the 

Los Vaqueros Reservoir 

Enlargement feasibility study to 

be pursued along with ongoing 

environmental and other projects 

in a balanced manner. 

Friant Dam Authority 

Authorization 

Rivers and Harbors Act of 1935, 

Rivers and Harbors Act of 1937 

(re-authorized) 

Purpose 

Regulate rivers and improve 

flood control and navigation, 

provide water for irrigation and 

domestic use, and power 

generation. 

Additional purpose of providing 

water for fish and wildlife 

protection, restoration, and 

mitigation was authorized by the 

CVPIA. 

Federal Study Authorization: 

Upper San Joaquin River 

Basin Storage Investigation 

Public Law 108-7, Division D, 

Title II, Section 215, the 

Omnibus Appropriations Bill for 

Fiscal Year 2003 authorized the 

Upper San Joaquin Storage 

projects feasibility study to be 

pursued along with ongoing 

environmental and other projects 

in a balanced manner. 

Preliminary capital cost estimates 

for the Los Vaqueros Reservoir 

Expansion ranged from 

$870 million to $1.5 billion, 

depending on the configuration. 

Upper San Joaquin River Basin 

Storage Investigation 

The existing Millerton Lake, 

formed by Friant Dam, has a 

storage capacity of 520 TAF. The 

reservoir is operated to provide 

water supply to agricultural and 

urban areas within the Friant 

Division of the CVP, and to provide 

recreation and flood control along 

the San Joaquin River. 

The CALFED ROD recommends 

evaluating the effects of increasing 

water storage in the Upper San 

Joaquin River Basin at Millerton 

Lake by raising Friant Dam or 

developing a functionally equivalent 

storage program. 

Developing 130 to 1,310 TAF of 

additional storage throughout the 

Upper San Joaquin River watershed 

could contribute to the river’s 

restoration and improve its water 

quality. This increased storage 

would also facilitate additional 

conjunctive management and 

exchanges that would improve the 

reliability of water deliveries to 

urban areas. Other benefits could 

include hydropower production and 

flood control. 

Unlike the other four storage 

projects, the studies for the Upper 

San Joaquin River Basin Storage 
SECTION 3: PROJECTS AND WATER MANAGEMENT ACTIONS 

Investigation have not yet 

considered the effect of Upper San 

Joaquin Storage operations on CVP 

and SWP operations in the Delta. 

Previous study estimates described 

additional water storage benefits of 

24 to 183 TAF per year, depending 

on the storage scenario. 

3-5 

Preliminary capital cost estimates 

for the Upper San Joaquin River 

Basin Storage Investigation ranged 

from $200 million to $1 billion, 

depending on the configuration. 

Summary of Level 1 

Storage Projects 

Table 3-1, provided on the 

following page, is a summary of the 

preliminary estimated supply and 

cost for each of the five Level 1 

storage projects described. 

Conveyance Improvements 

Presently, the CVP and SWP 

systems’ ability to move water 

released by upstream reservoirs is 

limited by conveyance capacity 

through the Delta and the 

Delta-Mendota Canal (DMC) 

delivery system. The following 

specific conveyance constraints 

exist in the Delta: 

• Inadequate conveyance capacity 

of canals and sloughs leading to 

Clifton Court Forebay (SWP) and 

the Tracy Pumping Plant (CVP) 

pumping facilities 

• Delivery restrictions arising from 

endangered species movement 

through Delta channels 

• Delivery restrictions due to 

excessive vegetation interfering 

with conveyance facility 

operation 

• Endangered Species Act take 

limits 

• DMC conveyance capacity lower 

than the authorized Tracy 

Pumping Plant capacity 

• Decision 1641—water quality 

and Delta outflow requirements1

Banks Pumping Plant 

• Water quality and water levels 

for local south Delta water users 

downstream of the head of 

Old River 

• Delta Cross Channel operations 

affecting ability to meet water 

quality objectives 

Conveyance improvements alone, 

particularly those that increase the 

capacity of delivering water south of 

the Delta, may increase water supply 

by delivering water that would 

otherwise flow out of the Delta to 

San Francisco Bay. Conveyance 

improvements would significantly 

improve the yield of new storage 

facilities and the flexibility of the 

CVP and SWP. These potential 

conveyance projects are described in 

the following discussions: 

• Banks 8,500 cubic feet per 

second (cfs) Capacity and 

Permanent Operable Gates 

• DMC and California Aqueduct 

Intertie 

• Enlarged Tracy Pumping Plant 

and DMC Intertie 

Banks 8,500 cfs Capacity and 

Permanent Operable Gates 

The SWP exports water from the 

Delta through operation of the 

Banks Pumping Plant, which has a 

maximum permitted capacity of 

6,680 cfs. Water flows from the 

Delta channels into Clifton Court 

Forebay and then through the 

Skinner Fish Facility, where the 

majority of the fish are screened 

from the water. 

The proposed action, generally 

referred to as the South Delta 

Improvement Program, seeks to 

 

1 The State Water Resources Control Board 

adopted Water Right Decision 1641 on 

December 29, 1999. The Decision implements 

flow-related water quality objectives for the 

Bay-Delta Estuary, approves a petition to 

change points of diversion of the CVP and 

SWP in the southern Delta, and approves a 

petition to change places of use and purposes 

of use of the CVP. Refer to 

http://www.waterrights.ca.gov/baydelta/d1641.

htm for additional information. 

increase the maximum allowable 

diversion rate at Clifton Court 

Forebay to 8,500 cfs. However, it is 

necessary to install permanent 

operable gates at several locations 

within the south Delta before the 

pumping capacity can be increased. 

These gates are designed to fulfill 

two purposes: protect water quality 

and water levels for agricultural 

water users in the Delta, and protect 

salmon fisheries of the San Joaquin 

River, while still allowing for 

Failure to achieve the 

8,500 cfs Banks pumping 

capacity would limit the 

value of new north-of-Delta 

storage and other actions 

that make water available 

north of the Delta. 

Clifton Court Forebay and Skinner 

Fish Facility 
WATER SUPPLY AND YIELD STUDY 

TABLE 3-1 

Summary of Level 1 Storage Projects—Preliminary Cost and Supply 

Project Yield (TAF/year) 

Storage Project Name and Scenario 

Capital Cost

($ M) 

Long-term 

Averagea Driest Periods Averageb

Shasta Lake Water Resources Investigation 280−480 

6.5-foot rise: water supply 40 60 

18.5-foot rise: water supply 69 127 

18.5-foot rise: water supply and anadromous fish 85 160 

Sites Reservoir Investigation (NODOS) 1,300−2,300 

Scenario 1: water supply 259 392 

Scenario 2: water quality 177 294 

Scenario 3: environmental 220 314 

Scenario 4: environmental and the Environmental Water 

Account 87 203 

In-Delta Storage 700−800 

Scenario 1: water supply 77 64 

Scenario 2: water quality and the Environmental Water 

Account 73 61 

Scenario 3: water supply, the Environmental Water Account, 

and Ecosystem Restoration Program (CALFED) 52 51 

Scenario 4: water supply, the Environmental Water Account, 

and water quality 63 49 

Los Vaqueros Reservoir Expansionc 870−1,500 

Scenario 2: Environmental Water/SBA Water Quality 0 0 

Scenario 3: SBA water supply reliability, Environmental 

Water Account, SBA water quality 

8 17 

Scenario 4: SBA & CCWD water supply reliability, 

Environmental Water Account, SBA water quality 

13 25 

Upper San Joaquin River Basin Storage Investigationd 220−1,000 

Raise Friant Dam 25 feet 24−29e NA 

Fine Gold Reservoir 65−136e NA 

Temperance Flat River Mile 274 165−183e NA 

Temperance Flat River Mile 279 86−146e NA 

Source: CBDA, 2006 

a Long-term average is the average quantity for the period of Oct. 1922–Sep. 1994. b Driest periods average is the average quantity for the combination of periods of May 1928–Oct. 1934, Oct. 1975–Sep. 1977, and 

June 1986–Sep. 1992. c Scenario 1 is a future no-action base condition, so it provides no additional supply. d

 Unlike the other four storage projects, the Upper San Joaquin River Basin Storage Investigation has not yet modeled scenarios 

considering the effect on operations on the CVP-SWP operations in the Delta. Therefore, the yield and cost information shown have a 

different basis than the values shown for the other four storage projects. e

 Long-term average is the average quantity for the period of Oct. 1922–Sep. 1999. 

NA: not available 

SBA: South Bay Aqueduct 

3-6 
SECTION 3: PROJECTS AND WATER MANAGEMENT ACTIONS 

recreational navigational usage of 

the Delta channels. Currently, 

temporary rock barriers are installed 

on an annual basis. The installation 

of permanent gates will eliminate 

the need for annual installation of 

rock barriers, thus reducing costs 

for water users. In addition, the 

permanent gates will have greater 

operational flexibility, which would 

improve the management of the 

Delta’s salmon fisheries. 

3-7 

Initial engineering studies indicate 

that the project, under certain 

conditions, would produce 

increased delivery by 90 TAF per 

year on average for the SWP, and 

100 TAF per year on average for the 

CVP. The South Delta Improvement 

Program has recently been revised 

to defer the decision on 8,500 cfs 

capacity at Banks Pumping Plant 

until fishery issues can be resolved. 

Failure to achieve the 8,500 cfs 

Banks pumping capacity would 

limit the value of new NOD storage 

and other actions that make water 

available north of the Delta. 

DMC and California 

Aqueduct Intertie 

The CVP Tracy Pumping Plant has 

an authorized capacity of 4,600 cfs 

to pump water into the DMC. The 

capacity of the DMC was designed 

to closely match the amount of peak 

water demand expected along the 

canal. The amount, timing, and 

location of water deliveries from the 

DMC, along with the apparent canal 

subsidence, siltation, facility design, 

and other factors, have resulted in a 

mismatch between the authorized 

Tracy Pumping Plant capacity and 

the DMC conveyance capacity. 

These factors restrict the full use of 

the Tracy Pumping Plant. 

This project would provide an 

intertie from the DMC to the 

California Aqueduct so that the 

full authorized capacity of the Tracy 

pumps could be used. The intertie 

would be located at milepost 7.2 of 

the DMC and connect with 

milepost 9.1 on the California 

Aqueduct. At this location, the 

DMC and California Aqueduct are 

about 400 feet apart horizontally 

and 50 feet apart vertically. The 

intertie would allow the Tracy 

Pumping Plant to operate at 

4,600 cfs by moving approximately 

400 cfs from the DMC to the 

California Aqueduct. On infrequent 

occasions, water may be moved 

from the California Aqueduct 

to the DMC. 

Environmental compliance (NEPA 

and CEQA) analyses are currently 

underway for this project. Through 

construction, the project will cost 

about $30 million. Modeling studies 

indicate that approximately 35 TAF 

per year of yield would be restored 

for the CVP. 

Enlarged Tracy Pumping Plant 

and DMC Intertie 

Included in the CALFED Bay-Delta 

Authorization Act is the 

authorization to undertake a 

feasibility study for an enlarged 

intertie. The new feasibility study is 

investigating increasing the 

proposed intertie from 400 to 

900 cfs capacity and increasing the 

capacity at the Tracy Pumping 

Plant. The additional 500 cfs would 

use increased Tracy Pumping Plant 

capacity for export south of the 

Delta and add operational 

flexibility. An increased authorized 

capacity at the Tracy Pumping Plant 

would be needed. This option would 

also require improvements to the 

DMC between the pumping plant 

and the intertie location to provide 

conveyance up to 5,100 cfs. 

No yield or cost estimates are 

currently available. 

Delta-Mendota Canal and the 

California Aqueduct 

Level 2: Projects of 

Recent Public, Agency, 

or Political Interest 

These projects, characterized as 

Level 2, have undergone past 

investigation that has been halted, 

delayed, or postponed because of 

changing strategies and priorities 

for water resources planning: 

• Delta Isolated Facility/Dual Delta 

Conveyance 

Water deliveries and 

engineering factors have 

resulted in a mismatch 

between the authorized 

Tracy Pumping Plant 

capacity and the DMC 

conveyance capacity. 

• Auburn Dam/Folsom South 

Canal 

As strategies and priorities continue 

to develop, and new challenges 

arise, Level 2 projects have the 

potential for further consideration. 

Delta Isolated Facility/Dual 

Delta Conveyance 

Three alternative conveyance 

capacities (5,000, 10,000, and 

15,000 cfs) for the Delta Isolated 

Facility are presented in the 

CALFED Storage and Conveyance 

Components: Facility Descriptions 

and Cost Estimates (CALFED, 

1997). The alternative conveyance 

capacities described are intended to 

be combined with other Delta 

improvements to form various Dual 

Delta Conveyance configurations. 

These configurations would transfer 

a portion of the south Delta export 

demand through a Delta Isolated 

Facility and a portion through 

Delta channels. 
WATER SUPPLY AND YIELD STUDY 

The Delta Isolated Facility concept 

consists of an unlined canal, 

hydraulically isolated from the 

existing Delta channels, to convey 

Sacramento River water around the 

eastern edge of the Delta to the 

federal and state pumping plants in 

the south Delta. As proposed, the 

Delta Isolated Facility would help 

alleviate fish and water quality 

concerns in the Delta. Also, water 

quality degradation of export water 

caused by seawater intrusion and 

return flows from irrigation in the 

Delta and San Joaquin Valley would 

be eliminated. The Delta Isolated 

Facility would be combined with 

other Delta improvements to form a 

Dual Delta Conveyance system. 

The principal facilities for each 

conveyance-level alternative 

include an intake channel with 

associated works; a pumping plant; 

44 miles of unlined canal; 

11 inverted siphons for river and 

slough crossings; and 17 bridges for 

county road, state highway, and 

railroad crossings. 

Cost estimates (in 1997 dollars) 

prepared for the 5,000 cfs, 

10,000 cfs, and 15,000 cfs 

alternatives are $850 million, 

$1.1 billion, and $1.3 billion, 

respectively (CALFED, 1997). 

Auburn Dam and Reservoir, 

and Folsom South Canal 

In conjunction with other facilities 

of the CVP, Auburn Reservoir 

would control the varying flows of 

the north and middle forks of the 

American River. Releases from the 

reservoir would operate Auburn 

Power Plant and supply the Folsom 

South Canal. The dam site is on the 

North Fork of the American River, 

adjacent to the city of Auburn, 

California. 

Construction of Auburn Dam, 

Reservoir, and Power Plant was 

well underway when construction 

was halted because of concerns 

about the ability of the dam to 

withstand a major earthquake. 

Construction of the dam has been 

delayed due to environmental and 

safety concerns. 

In December 2006, Reclamation 

completed a Special Report to 

update the analysis of costs and 

associated benefits of the AuburnFolsom South Unit, Central Valley 

Project, California, authorized under 

federal Reclamation laws and the 

Act of September 2, 1965, Public 

Law 89-161, 79 Stat. 615 

(Reclamation, 2006d). 

The proposed reservoir would have 

a capacity of 2,326 TAF, and the 

power plant would contain four 

units with a total generation 

capacity of 800 megawatts. Cost 

figures in the Special Report 

represent an appraisal-level cost 

estimate for those features. 

Depending on assumptions, total 

project costs range from $6 to 

$10 billion. 

The Folsom South Canal was 

planned to be constructed in five 

reaches for a total length of 

68.8 miles. Only the first two 

reaches have been built, a total 

length of 26.7 miles, and there are 

no current plans to construct the 

remaining three reaches, about 

42 miles, which are delayed 

pending reauthorization. 

Level 3: Regional 

Opportunities 

Many other project possibilities for 

water supply improvement exist 

outside the major infrastructure 

projects characterized as Level 1 or 

Level 2. 

The CALFED’s Initial Surface 

Water Storage Screening report 

began with a list of over 

50 potential reservoir sites, which 

were screened down to sites for 

further consideration (CALFED, 

2000b). The current CALFED 

storage projects under investigation 

(refer to the previously described 

Level 1 projects) were chosen from 

the screened list as the best projects 

for continued investigation. 

The following regional descriptions 

provide an overview of areas where 

projects were considered: 

• West Side Sacramento Valley 

• East Side Sacramento Valley 

• West Side/Off-Aqueduct San 

Joaquin Valley 

• In- or Near-Delta 

• CVP Pumping at Banks Pumping 

Plant 

Sites not retained for additional 

CALFED consideration may still be 

candidates for development by 

others for other purposes, and 

further opportunities in these 

regions should not be overlooked. 

West Side Sacramento Valley 

Runoff from upstream tributaries to 

the Delta usually occurs in large 

volumes during short periods in 

winter and spring. New storage 

upstream of the Delta could store a 

portion of these flows in excess of 

instream flow requirements and 

water supply needs. While detaining 

water in storage, care must be taken 

to maintain periodic peak flow 

events in the rivers; these peak 

flows provide for natural fluvial 

geomorphic processes, including the 

moving and cleansing of gravels 

that are important to aquatic 

ecosystems. This is a more vital 

consideration associated with 

enlarged onstream storage 

compared to offstream storage; 

large amounts of water can be 

detained quickly in onstream 

storage, whereas conveyance 

capacity constraints allow only a 

minor percentage of large peak river 

flows to be diverted to offstream 

storage. 

New storage upstream of 

the Delta could store a 

portion of upstream 

tributary runoff flows in 

excess of instream flow 

requirements and water 

supply needs. 

3-8 
SECTION 3: PROJECTS AND WATER MANAGEMENT ACTIONS 

To supplement instream flows and 

water supply, water could be 

released from upstream surface 

storage when needed to meet direct 

needs or to provide additional 

benefits through exchanges. In the 

Sacramento River Basin, for 

example, water could be released 

from offstream storage directly to 

local water users, reducing existing 

diversions from the Sacramento 

River during periods critical to 

fisheries. Water released for 

environmental purposes could 

include pulse flows to help transport 

fish through the Delta. During drier 

years, water could also be released 

to provide sustained flows for 

riverine and shallow water habitats, 

and to improve water quality in 

the Delta. 

3-9 

East Side Sacramento Valley 

Upstream of the Delta, this storage 

could provide benefits similar to 

storage for the West Side 

Sacramento Valley. Runoff from 

upstream tributaries to the Delta 

usually occurs in large volumes 

during short periods in winter and 

spring. New storage upstream of the 

Delta could store a portion of these 

flows in excess of instream flow 

requirements and water supply 

needs. To supplement instream 

flows and water supply, water could 

be released from upstream surface 

storage when needed to meet direct 

needs or to provide additional 

benefits through exchanges. Water 

released for environmental purposes 

could include pulse flows to help 

transport fish through the Delta. 

During drier years, water could also 

be released to provide sustained 

flows for riverine and shallow water 

habitats, and to improve water 

quality in the Delta. 

West Side/Off-Aqueduct 

San Joaquin Valley 

A version of offstream storage, 

SOD off-aqueduct storage could be 

filled by diversions through the 

DMC or the California Aqueduct. 

Examples of existing off-aqueduct 

storage include San Luis Reservoir 

and Castaic Lake. New off-aqueduct 

storage would be filled by 

increasing Delta exports during 

periods of high flows and least 

potential harm to Delta fisheries. 

Water stored in new off-aqueduct 

storage could be released to meet 

export needs while export pumping 

from the Delta is curtailed during 

times of heightened environmental 

sensitivity in the Delta. Filling of 

off-aqueduct storage is of great 

value to export water users because 

this water can be delivered directly 

for use without Delta operational 

constraints. Off-aqueduct storage 

can significantly improve system 

operational flexibility. 

In- or Near-Delta 

A major concern in the south Delta 

is the effect of continuing exports—

specifically, entrainment and 

salvage of important fish species. 

To address this concern, CALFED 

is evaluating the concept of flexible 

operations. Flexible operations 

would allow reduced export 

pumping at times critical to fish, 

and increased export pumping at 

other times. For example, the SWP 

and CVP could reduce pumping 

when Delta inflow is low or when 

fish are present in large numbers, 

and increase pumping when Delta 

inflow is high and few fish are 

present. New in-Delta or near-Delta 

storage could significantly facilitate 

flexible operations, because during 

times that are problematic for fish 

species, it would allow pumping 

from storage rather than 

reduced-capacity pumping. 

CVP Pumping at Banks 

Pumping Plant 

Water deliveries to CVP contractors 

south of the Delta are pumped from 

the Delta through Reclamation’s 

Tracy Pumping Plant and SWP’s 

Banks Pumping Plant. Generally, 

CVP water is pumped through the 

Tracy Pumping Plant up to its 

capacity, and additional water is 

pumped through the Banks 

Pumping Plant. Pumping CVP 

water in the Banks Pumping Plant 

has a lower priority than pumping 

SWP project water or transfers by 

SWP contractors. After SWP use of 

the pumping plant, any remaining 

capacity in the Banks Pumping 

Plant is split equally between the 

CVP and the EWA. There are 

opportunities for the CVP to utilize 

more than the 50 percent remaining 

capacity if it is not used by 

the EWA. 

Water stored in new 

off-aqueduct storage could 

be released to meet export 

needs during times of 

heightened environmental 

sensitivity in the Delta. 

Additional capacity is 

available at the SWP’s 

Banks Pumping Plant in 

some months. The CVP 

could utilize this space to 

increase exports to southof-Delta contractors. 

Although the CVP currently 

operates the Tracy Pumping Plant to 

meet its water allocation targets, 

additional capacity is available in 

the Banks Pumping Plant in some 

months. The CVP could utilize this 

space to increase exports to SOD 

contractors. Potential sources of 

water for this increased pumping 

include excess Delta outflow, 

additional releases from Shasta 

Lake or Folsom Lake, or the 

additional yield that would result 

from the development of new 

surface storage north of the Delta. 

Flexible operations would 

allow reduced export 

pumping at times critical to 

fish, and increased export 

pumping at other times. 
WATER SUPPLY AND YIELD STUDY 

Water Management 

Actions 

Statewide water management 

actions consist of individual 

projects and programs that have 

potential to provide yield and water 

supply improvements for CVP 

agricultural and M&I (urban) water 

service contractors. Water 

management actions have been 

categorized as either demand 

management actions or other 

actions. Demand management 

actions focus on reducing water 

demand, and include agricultural 

water use efficiency (WUE), urban 

WUE, and land retirement. Other 

actions focus on increasing water 

supply, and include water transfers, 

water recycling, and desalination. 

3-10 

FIGURE 3-2 

Potential Statewide Additional Annual Water Supply (DWR, 2005) 

Statewide, many of these actions are 

already being implemented as a 

result of market forces, naturally 

occurring conservation, work by 

Reclamation and DWR, ongoing 

initiatives by local water agencies 

and districts, CALFED initiatives, 

and initiatives by other entities. The 

last several years have witnessed 

continual improvement in 

agricultural WUE, urban WUE, and 

water recycling.

California Water Plan 

Update 2005 Potential 

Additional Annual 

Water Supply 

DWR describes 25 “resource 

management strategies” in 

Update 2005. Several strategies 

focus on increasing water supply 

benefits by either generating new 

supplies or reducing water demand. 

Data from Update 2005, presented 

in Figure 3-2, illustrate the potential 

range of additional statewide water 

supply benefits from these 

strategies. The low end of the range 

represents the level of 

implementation likely to occur 

given current trends. The high end 

of the range is an upper boundary 

that represents what is technically 

possible but not necessarily cost 

effective in today’s market. 

Common Assumptions 

Model Version 7 

A joint effort by DWR, 

Reclamation, and the CBDA, 

Common Assumptions is a process 

to develop consistency and improve 

efficiency among the CALFED 

surface storage investigations. 

As part of the Common 

Assumptions modeling efforts, the 

characterization and quantification 

of water management actions in 

some of the hydrologic regions were 

documented in support of ongoing 

surface storage investigations. This 

included future baseline conditions 

that meet the criteria of being 

reasonably foreseeable. The 

conclusions drawn serve as an 

estimate of water supply produced 

from projects through 2030. 

Water conservation has 

become a viable long-term 

supply option. 

Demand Management 

Actions 

Californians are already leaders in 

WUE measures such as 

conservation and recycling, and 

must continue to use water 

efficiently to get maximum utility 

from limited supplies. Water 

conservation has become a viable 

long-term supply option because it 

saves considerable capital and 

operating costs for utilities and 

consumers, avoids environmental 

degradation, and creates multiple 

benefits. Demand management 

and WUE actions should continue 

to be an integral part of water 

supply planning. 

Strategies categorized as demand 

management actions focus on 

reducing water demand and include 

the following: 

• Agricultural WUE 

• Urban WUE 

• Land retirement 

Agriculture Water Use 

Efficiency 

Agricultural WUE consists of 

improvements in technology, 

hardware, and water management to 

conserve water and improve water 

quality and environmental benefits. 

Effective agricultural WUE results 
SECTION 3: PROJECTS AND WATER MANAGEMENT ACTIONS 

in increased crop production 

without increasing the amount of 

water used. 

Some conservation may reduce the 

amount of water applied to a field 

but does not produce real water 

savings. Real water savings are 

produced when irrecoverable flows

(those that go to a salt sink, such as 

a saline aquifer, or are lost to 

evaporation) are conserved. By 

contrast, recoverable flow is water 

that, without the conservation 

measure, would have returned to 

groundwater or surface streams and 

become water supply for other 

users. In Figure 3-2, agricultural 

WUE (net) refers to irrecoverable 

flows. 

3-11 

Recently, the CBDA completed a 

study that estimated the costs and 

benefits of water use as a part of the 

Year-4 Comprehensive Evaluation 

of the CALFED Water Use 

Efficiency Element final report 

(referred to as Year-4 Report) 

(CBDA, 2005b). The agricultural 

WUE annual savings from the study 

of irrecoverable losses range from 

34 to 621 TAF, depending on 

investment level. The savings would 

come from onfarm improvements 

(how the water is applied on the 

field) and water-supplier 

improvements (how the water is 

conveyed and managed before it is 

delivered to the farmer). The costs 

of the agricultural water savings are 

estimated at $3 million to 

$150 million per year for 34 to 

621 TAF, respectively. 

The CALFED Water Use Efficiency 

Technical Appendix of the 

CALFED ROD also investigated 

the benefits of agricultural WUE. 

The CALFED ROD estimated that 

the benefit for irrecoverable loss 

reduction through agricultural WUE 

ranges between 120 and 563 TAF 

annually. The total cost of achieving 

a 563 TAF annual water savings by 

year 2030 is estimated at 

$0.3 billion to $2.7 billion. 

The CALFED ROD and the Year-4 

Report used different approaches 

and assumptions. The CALFED 

ROD’s potential costs and benefits 

are based on assumed onfarm 

efficiency improvements of 

85 percent within each hydrologic 

region and consider total irrigated 

crop area, crop water use, applied 

water, and depletions. The Year-4 

Report estimates are based on crop 

water use, irrigated crop area, 

irrigation system type, and applied 

water within each Update 2005 

planning area. It uses cost and 

performance information for 

onfarm and water-supplier 

improvements to estimate costs, 

consider various levels of funding 

and local implementation, and 

account for quantifiable objectives 

developed in CALFED’s Water Use 

Efficiency Element. In addition, it 

includes an estimate of potential 

water use reduction from 

implementing a moderate level of 

regulated deficit irrigation. 

The Update 2005 data in Figure 3-2 

show a range of 200 to 800 TAF of 

potential additional annual water 

from net agricultural WUE. The 

technical documentation for 

Update 2005 indicates that the 

200 TAF low estimate is the sum of 

the irrecoverable and recoverable 

flows (185 TAF rounded to 

200 TAF). The technical 

documentation indicates that the 

800 TAF high estimate comes from 

the 621 TAF estimated in the Year4 Report plus an additional 94 TAF 

for lining the All-American and 

Coachella canals for a total of 715 

TAF, rounded upward to 800 TAF 

to include the general assumption 

that some additional water supply 

benefits would be obtained from the 

Klamath Basin areas, for which data 

are not available. 

The Common Assumptions 

investigation established a 

reasonably foreseeable conservation 

level of 74 TAF per year of 

irrecoverable flows including water 

management actions and programs 

that are either locally cost effective 

or are permitted and/or funded as of 

June 30, 2004, and are expected to 

continue being funded at the same 

rate through 2030. 

Vineyard Using Drip Irrigation 

Effective agricultural WUE 

results in increased crop 

production without 

increasing the amount of 

water used. 

The Common Assumptions 

investigation included the 

hydrologic regions of the 

Sacramento River, San Joaquin 

River, Tulare Lake, and South 

Coast. The San Francisco Bay 

region was not included in the 

agricultural WUE investigation 

because of its low concentration of 

agricultural uses. The boundaries of 

these hydrologic regions are shown 

in Figure 1-3. 

The regions investigated represent 

approximately 80 percent of the 

irrigated agricultural acreage in the 

state. Assuming that agricultural 

WUE potential is proportional to 

irrigated agriculture acreage, the 

reasonably foreseeable conservation 

level for the state would be 

approximately 95 TAF annually. 

This value is shown in Figure 3-3 

along with the Update 2005 

low estimate. 
WATER SUPPLY AND YIELD STUDY 

Urban WUE focuses on 

reducing short- and longterm per capita urban 

water demand. 

FIGURE 3-3 

Statewide Conservation Level Estimates 

Urban Water Use Efficiency 

Urban WUE focuses on reducing 

short- and long-term per capita 

urban water demand. It results from 

behavioral changes and changes to 

the hardware used in urban areas. 

Behavioral changes include 

educating the public about how to 

use less water. Examples of 

hardware changes include low-flush 

toilets, flow restrictors, and efficient 

washing machines. Urban WUE can 

improve water supply by freeing up 

water to be used for other purposes. 

Conserved water can be stored in 

reservoirs or groundwater basins to 

be used later. Other benefits of 

urban WUE include decreased 

energy use and lower capital 

operations and maintenance (O&M) 

costs for water distribution and 

treatment systems. 

The CBDA sponsored a study of 

urban water conservation potential 

as part of the Year-4 Report. This 

study estimated an applied 

(combined recoverable and 

irrecoverable flows) water savings 

ranging from 1,153 to 2,075 TAF 

annually. An additional estimate of 

annual water savings of 3,096 TAF 

was provided as a reference; this 

level of savings represents the water 

savings potential using the 

assumptions of existing 

conservation technologies and 

100 percent adoption of the 

evaluated conservation measures. 

The range of water savings is based 

on varying assumptions about local 

water agency implementation of 

conservation measures and funding 

levels for CBDA grant programs. 

The low end of the range, 

1,153 TAF annually, assumes 

historical levels of conservation and 

that grant program funding would 

consist only of remaining 

Proposition 50 funds available for 

urban conservation implementation. 

The higher end of the range, 

2,075 TAF annually, assumes that 

all locally cost-effective measures 

are implemented, and that 

remaining Proposition 50 funds plus 

an additional $40 million per year 

of funding for the period of 2005–

2014 and $10 million per year for 

the period of 2015–2030 would be 

available. Costs range from 

$223 per acre-foot to $522 per 

acre-foot, and would require an 

annual investment of between 

$99 million and $236 million. 

3-12 

The Update 2005 values provided in 

Figure 3-2 show a range of 1,200 to 

3,100 TAF of potential additional 

annual water from applied urban 

WUE. The CALFED ROD 

estimated that the applied water 

savings of existing urban WUE 

programs ranges from 800 to 

1,000 TAF annually at a cost of 

$150 to $450 per acre-foot. 

The investigation for the Common 

Assumptions model included the 

hydrologic regions of the South 

Coast and the San Francisco Bay 

Region–South. It established a 

reasonably foreseeable maximum 

applied annual water savings in the 

year 2030 of 683 TAF that results 

from regulatory codes; 

implementing best management 

practices at historical rates; and 

investment of Proposition 50, 

Chapter 7 funds. The regions 

investigated represent 

approximately 68 percent of the 

population in the state. Assuming 

that urban WUE potential is 

proportional to population, the 

Urban Water Use Efficiency Devices
SECTION 3: PROJECTS AND WATER MANAGEMENT ACTIONS 

reasonably foreseeable conservation 

level for the state would be 

approximately 1,000 TAF annually. 

This value is shown in Figure 3-3 

along with the Update 2005 

low estimate. 

Irrigated Lands Retirement 

Irrigated land retirement is the 

removal of farmland from irrigated 

agriculture. Retirement is practiced 

in one of two ways. Permanent land 

retirement is the perpetual cessation 

of land irrigation for agriculture, 

which is done for permanent water 

transfer or for solving drainagerelated water quality problems. 

Crop idling or land fallowing, the 

temporary cessation of land 

irrigation for agriculture, can be 

employed to make water available 

in dry years. The water supply 

made available to other users as a 

result of these practices is discussed 

in the Water Purchases and 

Transfers section. 

3-13 

Permanent land retirement in 

problem drainage areas would 

improve water quality and supply 

reliability. It would reduce the 

leaching of salts from soils and 

minimize the risk of selenium 

exposure to fish and wildlife in 

some areas. The total water made 

available by irrigated land 

retirement is potentially 2 to 

3.5 acre-feet annually for each 

retired acre, assuming the lands are 

receiving their water allocation. 

This resulting available water from 

reduced demand can enhance water 

supply reliability. 

Land retirement creates an 

opportunity to establish upland or 

other habitat for wildlife, but results 

in loss of lands available for 

agricultural production, which 

results in accompanying economic 

losses for the region and nation. 

In 1992, The CVPIA Land 

Retirement Program authorized the 

purchase (from willing sellers) of 

agricultural land and associated 

water rights and other property 

interests that receive CVP water. 

The program is expected to retire 

about 100,000 acres of irrigated 

farmland. The program applies to 

lands that would improve water 

conservation or improve the quality 

of an irrigation district’s agricultural 

drainage water, or that are no longer 

suitable for sustained agricultural 

production because of permanent 

damage resulting from severe 

agricultural drainage water 

management problems, groundwater 

withdrawals, or other causes. 

Reclamation initiated a Land 

Retirement Demonstration Project 

to provide site-specific scientific 

data to guide the implementation of 

the Land Retirement Program. So 

far, this program has retired about 

8,300 acres of land in the Westlands 

Water District (Westlands) and the 

Tulare Lake Basin. About 

3,000 acres of drainage problem 

lands in Westlands have been 

retired as a part of Britz v. 

U.S. Bureau of Reclamation

settlement agreements. An 

additional 33,000 acres in 

Westlands are planned to be retired 

over a 3-year period as a result of

Sumner-Peck vs. U.S. Bureau of 

Reclamation. These retirements 

would be permanent land 

retirements, and the associated 

water allocation will be given to 

Westlands under a settlement 

agreement with Reclamation. 

Other Actions 

A diverse portfolio of water 

management strategies is essential 

to providing the flexibility needed 

to cope with changing and uncertain 

future conditions. The following 

water management actions are 

additional tools that can be 

incorporated as part of a water 

supply plan to meet current and 

future water needs: 

• Water purchases and transfers 

• Water recycling 

• Desalination 

Water Purchases and 

Transfers 

Although purchase and transfer 

water for the CVP does not generate 

new water for the state, it could 

provide additional yield for the 

CVP. A transfer involves a willing 

seller who will forego a water use 

for some time, and a willing buyer 

who can make use of additional 

water. Purchase of water from water 

users outside the CVP must 

compete with several other 

programs and agencies planning to 

purchase the same water or use the 

same facilities for conveyance. 

Although purchase and 

transfer water for the CVP 

does not generate new 

water for the state, it could 

provide additional yield for 

the CVP. Irrigated lands retirement 

may make water supply 

available to other users. The California Water Code defines 

water transfers as a temporary or 

long-term change in the point of 

diversion, place of use, or purpose 

of use due to a transfer or exchange 

of water or water rights. Temporary 

water transfers have a duration of 

1 year or less [Section 1728]. 

Long-term water transfers have a 

duration in excess of 1 year 

[Section 1735].) 

Many transfers among contractors 

of the CVP or the SWP are 

generally a redistribution of water, 

not strictly transfers. Water 

transfers can occur locally, between 

districts, or across the state if the 

water can be conveyed. Water 

transfers may be a temporary or 

permanent sale of a water right by 

the water right holder, a lease of the 

right to use water from the water 

right holder, a sale or lease of a 

contractual right to water supply, 

or a long-term contract for the 
WATER SUPPLY AND YIELD STUDY 

purpose of improving long-term 

supply reliability. 

Temporary and long-term transfers 

between water districts increased 

from 80 TAF in 1985 to more than 

1,250 TAF in 2001. About 

80 percent of these transfers are 

short term and 20 percent are 

considered long term. Since 1998, 

several permanent transfers have 

occurred between the CVP and 

SWP for up to 175 TAF annually. 

3-14 

Economic studies conducted for the 

Environmental Water Account Final 

Environmental Impact Statement/ 

Environmental Impact Report 

indicate that annually, 

approximately 300 TAF in the 

Sacramento Valley and 400 TAF in 

the San Joaquin Valley could be 

made available through crop idling 

without unreasonably affecting the 

overall economy of the county that 

would lose the water (DWR, 2005). 

Statistics on water transfers should 

only be considered a snapshot in 

time, because new transfers are 

continually being negotiated. 

The investigation for the Common 

Assumptions included the entire 

state for long-term temporary 

transfers. For temporary single-year 

transfers, available transfer supplies 

were estimated for the following 

hydrologic regions: San Joaquin 

River, Tulare Lake, and Sacramento 

River, which includes the 

Sacramento, Yuba, and Feather 

River subregions. Demands for 

single-year transfers were 

determined for the San Francisco 

Bay Region–South, and the South 

Coast Region. It established a 

reasonably foreseeable maximum 

potential of water transfer supplies 

by 2030 of 645 to 890 TAF per year 

depending on water year type. 

Water Recycling 

Water recycling is a program to 

reclaim and reuse municipal, 

industrial, domestic, and 

agricultural wastewater. It can also 

include reclaiming impaired 

groundwater and surface water. The 

recycled and reclaimed water can be 

used for a variety of purposes, such 

as ecosystem restoration, fish and 

wildlife habitat, groundwater 

recharge, urban water supply, 

agricultural water supply, power 

generation, and recreation. Water 

reclamation can produce flows that 

are useful to downstream areas. The 

terms recycled water and reclaimed 

water are used interchangeably. 

Today, California’s water agencies 

recycle about 500 TAF annually of 

wastewater. Figure 3-2 shows a 

range of 900 to 1,400 TAF of 

potential additional annual water 

from recycled municipal water by 

the year 2030, as reported by 

Update 2005. In the scheme of 

California’s overall water supply, 

recycling provides new water for the 

state only in areas where wastewater 

is discharged to the ocean or to a 

salt sink. Recycling in other areas 

may provide new water for the 

water agency, but does not 

necessarily add to the state’s water 

supplies. In these locations, 

discharged wastewater in interior 

California mixes with other water 

and becomes source water for 

downstream water users. 

The estimated capital cost for the 

range of potential recycling by 2030 

is about $6 billion to $9 billion. 

Actual costs will vary based on the 

quality of the wastewater, the 

treatment level needed, and the 

availability of a distribution system. 

The majority of applications would 

cost between $300 and $1,300 per 

acre-foot of recycled water. 

Water Recycling Facility 

Canal System The investigation for Common 

Assumptions included the 

hydrologic regions of South Coast 

and San Francisco Bay. It 

established a reasonably foreseeable 

additional annual yield of 

approximately 331 TAF. 

The regions investigated for 

Common Assumptions represent 

approximately 71 percent of the 

population in the state. Assuming 

that recycling potential is 

proportional to population, the 

reasonably foreseeable conservation 

level for the state is estimated to be 

approximately 466 TAF annually. 

This value is shown in Figure 3-3 

along with the Update 2005 

low estimate. 

Desalination 

Desalination is a water treatment 

process whereby salt is removed 

from seawater, brackish 

groundwater, or wastewater so that 

the water may be available for 

beneficial use. This is accomplished 

either by thermal distillation or 

membrane filtration. One type of 

membrane filtration is reverse 

osmosis, which is the treatment 

method most commonly used 

in California. 

Recycling provides new 

water for the state only in 

areas where wastewater is 

discharged to the ocean or 

to a salt sink. 
SECTION 3: PROJECTS AND WATER MANAGEMENT ACTIONS 

Wastewater recycling projects may 

require desalination treatment in 

order to meet water quality 

standards; similarly, groundwater 

projects that result in the extraction 

of brackish groundwater must 

often treat such water for salt. 

Additionally, desalination facilities 

may be operated exclusively for 

purposes other than producing 

new yield, such as wastewater 

desalted and injected into an 

aquifer to maintain a saltwater 

intrusion barrier. 

3-15 

Desalination facilities currently 

operate in California to provide water 

for municipal purposes. The 

following descriptions of these 

facilities are based on information in 

Update 2005. 

Seven new desalination facilities, 

with a combined annual capacity 

of about 30 TAF annually, are in 

the design and construction phase. 

By 2030, it is estimated that 

19 additional desalination facilities 

will be operational in California, 

resulting in a total additional supply 

of approximately 507 TAF per year. 

Of those 26 new facilities, it is 

estimated that 12 will be brackish 

groundwater desalting facilities 

with a capacity of approximately 

91.2 TAF annually, and 14 will be 

seawater desalination plants with a 

capacity of approximately 

415.4 TAF annually. The 

Metropolitan Water District of 

Southern California alone is 

targeting 150 TAF annually in 

sustained production. Additionally, 

150 TAF annually in reclaimed 

municipal wastewater will be 

treated for salt statewide. 

Figure 3-2 shows a range of 300 to 

500 TAF of potential additional 

annual water from ocean and 

brackish desalination water by the 

year 2030, as reported in 

Update 2005. The technical 

documentation for Update 2005 

indicates that the low estimate of 

300 TAF per year is based on the 

assumption that desalination 

facilities in the design, construction, 

or planning stages will be 

constructed. Any desalination 

facilities that had reconnaissance or 

feasibility-level planning studies 

prepared or in preparation at the 

time of Update 2005’s publication 

were considered planned. The 

documentation indicates the high 

estimate of 500 TAF, which is the 

sum of 29.8 TAF under design or 

construction and 476.8 TAF for 

planned and projected. The 

resulting value of 506.6 TAF per 

year was rounded to obtain 

500 TAF per year. 

The investigation for Common 

Assumptions included the South 

Coast and San Francisco Bay 

Hydrologic Regions. It established a 

reasonably foreseeable maximum 

potential water supply by 2030 of 

53.8 TAF per year that results from 

one seawater desalination project, 

two brackish groundwater desalting 

facilities, and Proposition 50 funds. 

In this analysis, any projects 

currently operational or that have 

received 25 percent of their total 

project cost from state and federal 

funds were deemed to be reasonably 

foreseeable. For projects with some 

level of funding, current (or future) 

levels of state and federal funds 

were applied to achieve financing of 

25 percent of the total project cost. 

It is assumed that local funds will 

finance the remaining 75 percent. 

State and federal funds in excess of 

those spent to achieve 25 percent 

financing were applied to develop 

additional yield based on an average 

cost per acre-foot of developed 

capacity. This process accounts for 

a representative yield resulting from 

desalination that will be developed 

by the year 2030. 

Conjunctive Water 

Management 

Coordinated management of 

groundwater and surface water 

resources is called conjunctive water 

management. Groundwater is 

typically withdrawn during dry 

periods and replaced, or recharged, 

in wet periods, but many operational 

changes are possible depending on 

local conditions. By coordinating 

use of surface water and 

groundwater, both supply sources 

may be managed more efficiently. 

This, in turn, leads to greater yield 

and a more reliable water supply. 

Conjunctive management may also 

have the beneficial effects of 

reducing groundwater overdraft and 

land subsidence, and improving 

environmental conditions by leaving 

fish flows instream or creating 

wildlife habitat in percolation ponds 

or recharge basins. 

Desalination is 

accomplished either by 

thermal distillation or 

membrane filtration. 

Coordinating use of 

surface water and 

groundwater allows supply 

sources to be managed 

more efficiently. 

Supplies for groundwater storage 

may be obtained by diverting 

portions of storm flows in local 

rivers, transferring water from 

out-of-basin sources, or by using 

reclaimed wastewater or desalinated 

water. Supplies enter groundwater 

storage either by percolation or by 

direct recharge through basins or 

injection wells. Reverse-osmosis Equipment in a 

Desalination Facility The CALFED ROD set a target for 

500 to 1,000 TAF of additional 
WATER SUPPLY AND YIELD STUDY 

groundwater storage. To help meet 

this target, the DWR Conjunctive 

Water Management Program 

provided funds to support local 

initiatives in the total amount of 

$240 million, accounting for 

roughly 25 percent of project costs. 

The remaining 75 percent of costs 

were paid by the project proponents. 

Between fiscal years 2000 and 

2004, 146 grants and loans were 

awarded. It is important to note that 

grant funding requests far exceeded 

available funding. In the case of 

Water Bond 2000 (Proposition 13), 

requests outstripped available funds 

by more than three-to-one. This 

program produced an estimated 

additional yield of 300 TAF/year 

that could be obtained at a total cost 

of approximately $1 billion. 

Figure 3-2 shows a range of 500 TAF 

to 2 MAF, as reported in 

Update 2005. Conservative estimates 

of additional implementation of 

conjunctive management indicate the 

potential to increase average annual 

water deliveries throughout the state 

by 500 TAF with 9 MAF of “new” 

groundwater storage. More 

aggressive estimates from screeninglevel studies indicate the potential to 

increase average annual water 

deliveries by 2 MAF with about 

20 MAF of new storage. The more 

aggressive estimates are based on 

assumptions that require major 

reoperation of existing surface water 

reservoirs and require groundwater 

storage to achieve the benefits, but 

do not fully consider the conveyance 

capacity constraints for exports from 

the Delta and other conveyance 

facilities. If the Level 1 storage and 

conveyance projects 

were constructed and 

investments in water 

management actions were 

in place today, the existing 

supply-demand gap could 

be met in average years, 

but a gap of over 0.8 MAF 

would remain in dry years.

Unit costs range from $10 to 

$600 per acre-foot of additional 

annual yield, with an average of 

about $110 per acre-foot. Estimates 

from other recent grant proposals 

indicate that costs are rising, 

primarily because construction costs 

have increased. General information 

from several of the most recent 

proposals (fiscal year 2003–2004) 

for funding from Water Bond 2000 

indicates the scale and range of 

conjunctive management projects 

currently being carried out 

throughout California. 

Filling the SupplyDemand Gap 

3-16 

The existing and future gap between 

California’s water supply and 

demand is substantial, and a variety 

of projects and water management 

actions could be used to fill this 

supply-demand gap. A cursory-level 

analysis was conducted to 

determine whether these projects 

and water management actions 

could fill the existing and projected 

2030 supply-demand gap. The 

results of this analysis are 

summarized here. 

Figure 3-4 shows the existing 

average and dry year supplydemand gap along with the projects 

and water management actions that 

could be used to fill all or a portion 

of the gap if these projects were in 

place and the actions were fully 

implemented today. The values 

assumed for filling the existing 

water supply-demand gap are 

summarized in Table 3-2. If the 

Level 1 storage and conveyance 

projects were constructed and 

investments in water management 

actions were in place today, the 

existing supply-demand gap could 

be met in average years, but a gap 

of over 0.8 MAF would remain in 

dry years. 

As shown in Figure 3-4, agricultural 

and environmental uses compose 

the majority of the supply-demand 

gap. These uses generally 

experience water supply shortages 

in average and dry years, resulting 

in reduced irrigated agricultural 

land and agricultural output, and 

increased pressures on 

environmental demands. Even if the 

projects and water management 

actions shown in Figure 3-4 could 

be implemented in the near term, 

agricultural and environmental uses 

are likely to continue to experience 

water supply shortages and 

associated negative effects of these 

shortages in dry years. 

Groundwater Pump 

Figure 3-5 compares the projected 

2030 supply-demand gap along with 

the projects and water management 

actions that could be used to fill a 

portion of the gap. The values 

assumed for filling the supplydemand gap are summarized in 

Table 3-2. If the Level 1 storage 

and conveyance projects were 

If the Level 1 storage and 

conveyance projects 

were constructed and 

investments in water 

management actions were 

made, the projected 

2030 supply-demand gap 

would remain at over 

1.5 MAF in average years 

and over 2.2 MAF in dry 

years. 
SECTION 3: PROJECTS AND WATER MANAGEMENT ACTIONS 

FIGURE 3-4 

Projects and Water Management Actions to Help Fill the Existing Supply-Demand Gaps 

FIGURE 3-5 

Projects and Water Management Actions to Help Fill the Projected 2030 Supply-Demand Gaps 

3-17 
WATER SUPPLY AND YIELD STUDY 

TABLE 3-2 

Projects and Water Management Actions to Help Fill the Existing and Projected 2030 Supply-Demand Gaps 

Existing Projected 2030 

Average Year 

(TAF) 

Dry Year 

(TAF) 

Average Year 

(TAF) 

Dry Year 

(TAF) 

Conveyancea 300 300 300 300 

Desalinationa 300 300 300 300 

Recycled municipal wastewatera,b 690 690 900 900 

Conjunctive managementc 0 500 0 500 

Agricultural WUEa,d 210 200 200 150 

Urban WUEa,b 920 920 1,200 1,200 

Level 1 storage projectse 430 450 430 450 

Total 2,850 3,360 3,330 3,800 

a

 The potential water supply from conveyance, desalination, recycled municipal wastewater, agricultural WUE, and urban WUE are 

 based on the 2005 Update low estimate provided in Figure 3-2. 

b

 Values were adjusted proportionally to account for differences in existing and projected 2030 population. 

c

 Assumed to contribute to water supply during dry years and not average years. Participation in conjunctive use programs occurs in 

 all years. However, net groundwater withdrawals are assumed to occur only in dry years. 

d

 Values were adjusted proportionally to account for differences in the amount of existing and projected agricultural lands. Agricultural 

 WUE also decreased slightly in dry years as a result of reduced deliveries to agricultural users. Although more water may be 

 conserved per acre of irrigated land in a dry year, fewer acres may be irrigated in a dry year because of reduced deliveries. As a 

 result, the total water conserved would actually be less in a dry year. 

e

 The potential water supply from the Level 1 storage projects shown is the average of the storage projects alternatives listed in 

 Table 3-1. The long-term average project yield in Table 3-1 was averaged across the different scenarios for each storage project and 

 summed to obtain the average year value. A similar analysis was conducted using the driest period average in Table 3-1 to obtain 

 the dry year value. 

3-18 

constructed and investments in 

water management actions were 

made, the projected 2030 

supply-demand gap would remain 

at over 1.5 MAF in average years 

and over 2.2 MAF in dry years. 

Long-term water supply reliability 

depends on being able to meet water 

demands during dry years, and 

additional measures would be 

needed to fill this projected 

supply-demand gap. 

Under the projected 2030 

conditions, the urban gap is 

substantially larger than under 

existing conditions and accounts for 

the majority of the supply-demand 

gap. Urban uses generally take 

priority over agricultural and some 

environmental uses; therefore, it is 

likely that agricultural and 

environmental uses would continue 

to experience water supply 

shortages in future average and 

dry years. 

As shown in Figures 3-4 and 3-5, 

both the Level 1 storage and 

conveyance projects and 

investments in water management 

actions are needed to fill the 

existing and future water supplydemand gap. Implementation of the 

Level 2 and 3 storage projects and 

more aggressive investments in 

water management actions would 

be needed to fill the 2030 

supply-demand gap. 

It is important to note that this 

analysis provides a statewide 

perspective of supply-demand gaps. 

Conveyance limitations and limited 

opportunities for projects and/or 

water management actions on a 

regional basis may exacerbate 

regional water supply-demand gaps. 
4-1 

Section Highlights 

Estimated cost-of-service for 

existing and all Level 1 projects: 

♦ $40 per acre-foot for 

irrigation and $70 per 

acre-foot for M&I when 

allocating 50 percent of 

project costs to water supply 

♦ $55 per acre-foot for 

irrigation and $95 per 

acre-foot for M&I when 

allocating 75 percent of 

project costs to water supply 

CVP contractors’ annualized 

willingness to pay for permanent 

water supply south of the Delta 

is approximately $130 per 

acre-foot for irrigation and 

$185 per acre-foot for M&I. 

Recent transfer negotiations 

indicate that contractors may be 

willing to pay more than these 

amounts for new, permanent 

water supply. 

Not every contractor has the 

ability to pay the average 

willingness to pay amount. Some 

contractors will be unable to 

participate in the purchase of 

CVP water if the contract rates 

rise dramatically. 

Terminology 

For the purpose of discussing 

CVP rate impacts in this section, 

the terms M&I and irrigation are 

used in place of urban and 

agriculture, respectively, to be 

consistent with contractual 

language. This is based on the 

language used in Reclamation’s 

CVP Annual Ratebook. 

4 Rate Impacts and Willingness to Pay 

The economic aspects of the 

projects identified in this study are a 

key component in determining how 

to proceed with implementation. 

This section provides insight to 

possible financial and economic 

impacts through the following 

evaluations: 

• Identification of the financial 

impacts from implementing the 

projects and water management 

actions identified in Section 3 

• Estimation of beneficiaries’ 

willingness to pay for additional 

water deliveries 

• Development of an initial 

conclusion concerning the 

financial feasibility of the 

Level 1 storage and conveyance 

projects 

Public Law 108-361, the 

authorizing legislation for this 

WSAY Study, requires an 

assessment of the beneficiaries’ 

willingness to pay the capital 

and O&M costs of the actions 

and projects. 

Determining what effect storage and 

conveyance projects will have on 

existing rates and what beneficiaries 

would be willing to pay are 

important components of a financial 

analysis. A project is considered 

financially feasible if sufficient 

revenue can be raised to pay the 

financial costs. A project can be 

economically feasible but not 

financially feasible if the 

beneficiaries are not willing or able 

to pay the associated water charges 

or fees. 

Overview 

The projects and water management 

actions identified in Section 3 are 

financed through various sources. 

Some projects are federally funded 

by Reclamation through the CVP 

and require repayment through rate 

adjustments to CVP contractors. 

The majority of water management 

actions are funded through state, 

federal, or local agencies and 

organizations and do not influence 

the rates charged to CVP 

contractors. 

The Level 1 storage and conveyance 

projects identified in Section 3 

could be federally funded, and 

would be recovered through CVP 

contractor rate adjustments. The 

impact these projects would have on 

the CVP rates is detailed later in this 

section. The Level 2 projects 

discussed in Section 3 do not have 

detailed yield and cost information 

associated with their construction 

and operation. However, these 

facilities would impact CVP rates to 

contractors through the same 

process as Level 1 projects. 

The water management actions 

covered in Section 3 occur on a 

local level and do not have 

systemwide impacts to CVP rates. 

These water management actions 

are funded through a mix of state, 

federal, and local agencies and 

organizations. Statewide, many of 

these water management actions are 

already being implemented as a 

result of market forces, naturally 

occurring conservation, work by 

Reclamation and DWR, ongoing 

initiatives by local water agencies 

and districts, CALFED initiatives, 

and other entities. The following 

actions identified in Section 3 are 

included in the CALFED Bay-Delta 

Program Finance Plan (CALFED 

Financial Plan) (CBDA, 2005a): 

• Agriculture WUE 

• Urban WUE 

• Water recycling 

• Desalination 

Federal, state, and local funding for 

water use efficiency, including 

urban and agricultural water 

conservation, recycling, and 

desalination, is $3.15 billion over 
WATER SUPPLY AND YIELD STUDY 

4-2 

the next 10 years. The objective is 

to meet 65 percent of this total 

from local water agencies and 

organizations and the remaining 

35 percent from federal and 

state sources. 

Agricultural WUE 

Agricultural WUE consists of 

improvements in technology, 

hardware, and water management to 

conserve water and improve water 

quality and environmental benefits. 

The CALFED Finance Plan 

estimates that agricultural WUE 

over the next 10 years will be met 

by approximately 40 percent state 

and federal funding and 60 percent 

local agency and organization 

funding (CBDA, 2005a). California 

Propositions 50 and 84 are 

examples of state funding targeted 

for agricultural WUE. 

Urban WUE 

Urban WUE focuses on reducing 

short- and long-term per capita 

urban water demand. It results from 

behavioral changes and changes to 

the hardware used in urban areas. 

The CALFED Finance Plan 

estimates that urban WUE over the 

next 10 years will be met by 

approximately 60 percent state and 

federal funding and 40 percent local 

agency and organization funding 

(CBDA, 2005a). California 

Propositions 50 and 84 are 

examples of state funding targeted 

for urban WUE. 

Recycling 

Water recycling is a program to 

reclaim and reuse municipal, 

industrial, domestic, and 

agricultural wastewater. It can also 

include reclaiming impaired 

groundwater and surface water. The 

CALFED Finance Plan estimates 

that recycling targets over the next 

10 years will be met by approximately 25 percent state and federal 

funding and 75 percent local agency 

and organization funding (CBDA, 

2005a). Title 16 and California 

Proposition 84 are examples of 

funding available for recycling. 

Desalination 

Desalination is a water treatment 

process whereby salt is removed 

from seawater, brackish 

groundwater, or wastewater so that 

the water may be available for 

beneficial use. The CALFED 

Financial Plan estimates that 

desalination targets over the next 

10 years will be met by approximately 25 percent state and federal 

funding and 75 percent local agency 

and organization funding (CBDA, 

2005a). California Propositions 50 

and 84 are examples of funding 

available for desalination. 

CVP Rate Impacts 

The purpose of the rate impact 

analysis is to illustrate the 

relationship between anticipated 

increases in CVP project costs and 

future water charges. The CVP cost 

allocation repayment responsibilities for plant-in-service (capital 

costs) as of September 30, 2004, are 

provided in Figure 4-1. Each entity 

is allocated a portion of the 

approximately $3.4 billion in total 

CVP capital costs. Repayment 

methods vary by entity. For 

example, M&I and irrigation water 

users repay their share of costs 

through water rates, commercial 

power customers repay costs 

through power revenue, and state 

and federal costs are repaid using 

direct payments and federal 

taxes, respectively. 

The total preliminary capital cost 

estimates for the Level 1 storage 

and conveyance projects range from 

$3.9 billion to $6.8 billion, and 

could result in an anticipated 

average annual yield of approximately 200 to 600 TAF.1 As these 

and other water management 

actions are implemented to meet 

current and future needs, their costs 

will have a noticeable influence on 

CVP repayment responsibilities and 

contract water rates. 

The basic steps in the ratesetting 

process for capital (new plant-inservice) additions to the CVP are 

the following: 

1. Cost Allocation. Identify and 

allocate the costs of a 

multipurpose facility among the 

various authorized project 

purposes, which includes 

sub-allocating costs allocated to 

water supply among irrigation, 

M&I, and wildlife refuges. 

2. Reimbursement. Identify the 

repayment responsibility for the 

cost of each facility and 

budgeted O&M costs, O&M 

deficits/surplus, and projected 

water deliveries. 

 

1 A high-end water supply estimate of 600 TAF 

annually is used to demonstrate the 

relationship between capital costs and rate 

impacts under a best-case scenario. This yield 

estimate is based on the aggregate water 

supply objective from each of the Level 1 

storage and conveyance projects. 

Canal Lining to Prevent 

Seepage Losses 

Desalination Plant 
SECTION 4: RATE IMPACTS AND WILLINGNESS TO PAY 

4-3 

3. Ratesetting. Calculate contract 

water rates using information 

provided in the cost allocation 

and reimbursement steps. 

These basic steps are described in 

greater detail in the following 

discussion. 

Federal Cost Allocation 

Practices 

Cost allocation is the process of 

identifying and allocating the costs 

of a multipurpose project among the 

authorized project purposes. The 

purposes authorized by law for the 

CVP are typically water supply, 

water quality, flood control, 

recreation, navigation, hydropower, 

and fish and wildlife. 

For the CVP, the cost allocation 

identifies costs to be repaid to the 

federal government by water and 

power users, as well as the 

repayment obligations of nonfederal public entities, such as the 

State of California and counties. 

The allocation also identifies 

nonreimbursable costs, borne by 

federal taxpayers (Reclamation, 

2001). Reclamation annually 

updates the CVP cost allocations as 

changes occur in the uses of 

project-supplied water and power, 

and as new investments in facilities 

are completed. These updates are 

needed to provide input to the CVP 

water ratesetting process, which is 

performed by Reclamation. Cost 

allocations are also used to establish 

bases for financial feasibility studies 

when proposals are made for new 

additions to the project. 

Federal 

Reimbursement 

Practices 

Cost reimbursement refers to the 

collection of revenues to repay 

assigned costs. Funds for financing 

the initial construction of federal 

projects are appropriated from 

the general budget. The portion 

of the costs that must be repaid 

by beneficiaries varies by 

project purpose. 

The reimbursement requirements 

for costs allocated to irrigation 

differ from those for other purposes. 

Irrigation water users are required to 

pay their share of O&M costs. 

However, interest costs are not 

reimbursable for irrigation, and the 

users’ obligation to pay their 

allocated share of construction costs 

and restoration fund payments can 

be limited by a determination of 

their ability to pay, as defined by 

Reclamation law. 

M&I water users and hydropower 

users must pay their share of O&M 

and construction costs, plus interest 

during construction and during the 

repayment period. Depending on 

legislation enacting repayment, 

recreation and fish-and-wildlife 

mitigation reimbursement may also 

be required. However, the federal 

share of costs allocated to most 

recreation, fish-and-wildlife 

enhancement, navigation, flood 

control, and water quality are 

nonreimbursable. 

The water supply actions described 

in this report have been proposed by 

CALFED to be developed 

cooperatively with the State of 

California and local interests. 

Therefore, the financial analysis for 

each CALFED project cannot 

proceed using federal standards 

alone. Rather, the financial analysis 

should consider CALFED 

precedents, and state and local 

standards. However, CALFED 

precedents do not take precedent 

over state or federal laws. 

Ratesetting 

In general, the authorized CVP 

repayment period is fiscal year (FY) 

1981 to the end of FY 2030. New 

repayment periods are established 

for the capital costs of major 

rehabilitation and new facilities 

added to the CVP, such as the San 

Felipe Division out-of-basin 

facilities, which have a repayment 

period of FY 1987 to the end of 

FY 2036. However, the construction 

costs for smaller additions or 

modifications fall within the initial 

50-year repayment period. Capital 

additions (such as a new plant-inservice) are recorded in the 

Reclamation accounting system and 

reflected in contract water rates to 

the extent that they are allocated to 

irrigation and M&I water supply. 

Table 4-1 summarizes, by selected 

facility, the 2006 CVP contract 

water rates for irrigation and M&I 

water. Contract rates may vary 

significantly among facilities 

depending on the cost of capital (for 

example, capital costs may include 

capital and conveyance, pumping, 

and so on), O&M for the capital 

costs, and deficit payments. 

Table 4-1 shows that contract rates 

range from $2 to $57 per acre-foot. 

FIGURE 4-1 

Existing Cost Allocation Repayment Responsibilities 
WATER SUPPLY AND YIELD STUDY 

4-4 

Estimated Rate 

Impacts 

The data necessary for conducting a 

specific rate impact analysis are not 

yet available for the storage and 

conveyance facilities described in 

Section 3 of this report. However, 

some information is available for 

Level 1 projects, and approximations can be made on the basis of 

the limited information available. A 

simplified example of this approximation is illustrated in Figure 4-2. 

Because contract water rates are 

critical in determining the financial 

feasibility of any CVP 

improvements, a preliminary 

assessment was made of the 

cost-of-service rate impacts of 

implementing the Level 1 storage 

and conveyance projects. Both 

reimbursable and nonreimbursable 

purposes are served by the Level 1 

storage and conveyance projects, 

and these projects tend to enhance 

the reliability of water supply to all 

water users. Therefore, the allocated 

costs are spread to the entire rate 

base in this ratesetting exercise. 

The cumulative per-acre-foot 

impact on CVP water charges from 

adding storage, conveyance, 

marketing, and O&M costs 

allocated to water supply is shown 

for irrigation in Figure 4-3 and for 

M&I in Figure 4-4. In this analysis, 

costs are allocated to irrigation and 

M&I based on historical contract 

allocations. Along the x-axis, the 

costs of the additional Level 1 

storage and conveyance projects are 

added, with the least expensive 

actions tallied first. The y-axis 

identifies the cost-of-service for 

capital, conveyance, marketing, and 

O&M associated with the capital, 

based on the cost and projected 

water supply yield from each 

storage and conveyance action. 

The cost-of-service estimates were 

derived using a capital rate (total 

capital costs/total storage yield), 

conveyance rate (total conveyance 

costs/conveyance yield), and 

estimated marketing and O&M 

rates. Storage and conveyance 

capital cost, along with water yield 

from the projects, are added to 

current CVP capital and yield 

estimates to derive a total capital 

cost and projected water supply. 

Capital cost from all storage and 

conveyance projects is estimated at 

over $6 billion, and the total yield 

allocated to water supply is over 

600 TAF.2

The cost-of-service rates are for 

storage and conveyance only; no 

pumping (conveyance or direct) or 

other costs (such as deficit costs) 

are included in this analysis. O&M 

and marketing costs are estimated 

for storage only and are 

extrapolated from existing facilities. 

It is anticipated that more-refined 

and accurate estimates of the 

cost-of-service rate impacts will be 

provided in future analysis, when 

additional cost allocation 

information becomes available. 

On the basis of limited projectspecific benefits and costs, it was 

assumed that 50 percent of the total 

storage project costs (along the 

x-axis) would be allocated to 

irrigation and M&I. The remaining 

50 percent would be allocated to 

other purposes, such as environmental water supply. 

The rate impact figures highlight a 

few important points: 

• Cost-of-service rates are 

estimated to be about $40 per 

acre-foot for irrigation and 

$70 per acre-foot for M&I when 

including all of the Level 1 

projects. 

• The Level 1 projects are assumed 

to be constructed and operational 

by 2021, so the cost-of-service 

rate estimates are for the period 

 

2 A high-end water supply estimate of 600 TAF 

annually is used to demonstrate the 

relationship between capital costs and rate 

impacts under a best-case scenario. This yield 

estimate is based on the aggregate water 

supply objective from each of the Level 1 

storage and conveyance projects. 

TABLE 4-1 

Summary of CVP Wholesale Water Charges by Selected Facility 

2006 Water Contract Rate ($/AF) 

Facility Irrigation M&I 

Sacramento River 2–53 15 

Corning Canal 15–18 NA 

Tehama-Colusa Canal 14–22 23–35 

San Felipe Unit 31–32 43 

Delta-Mendota Canal 24–54 15–43 

San Luis Canal 8–34 19–48 

Friant-Kern Canal 23–30 15–57 

Source: Reclamation, 2006a 

NA: not applicable 

FIGURE 4-2 

Approximation of Total Cost of Service 
SECTION 4: RATE IMPACTS AND WILLINGNESS TO PAY 

4-5 

2021 to 2030. After 2030, initial 

CVP capital costs will be repaid 

(with the exception of the San 

Felipe Division, which will be 

repaid in 2037), and overall rates 

will fall to slightly lower levels. 

• The large increase in irrigation 

and M&I rates results from 

current total CVP capital costs 

increasing by approximately 

150 percent as a consequence of 

implementing Level 1 projects, 

while the increase in CVP 

contract water supply is 

10 percent. 

Changing the proportion of cost 

allocated to irrigation and M&I 

causes a noticeable change in the 

cost-of-service rates. For illustrative 

purposes, changing the allocation of 

capital cost to irrigation and M&I to 

75 percent increases the cost-ofservice rates by 20 to 30 percent 

(Figures 4-5 and 4-6). 

Willingness to Pay 

Willingness to pay can be used for 

two separate purposes in water 

resources planning and 

management. The first is as a 

method of measuring economic 

benefits in benefit-cost analysis or 

cost-effectiveness analysis. The 

second use is in the financial 

analysis as a measure of the project 

participants’ (for example, water 

contractors) willingness to repay the 

debt (such as water rates) incurred 

to finance the capital cost and to 

meet the O&M costs of the actions 

and projects. 

Several methods can be used to 

estimate the willingness to pay for 

additional water supplies: 

• Observation of water market 

transactions 

• Surveys of water users 

• Estimates of the value water has 

in production settings (irrigation 

or industrial) 

FIGURE 4-3 

Irrigation Cost-of-Service Impact at 50 Percent Cost Allocation 

FIGURE 4-4 

M&I Cost-of-Service Impact at 50 Percent Cost Allocation 

FIGURE 4-5 

Irrigation Cost-of-Service Impact at 75 Percent Cost Allocation 

FIGURE 4-6 

M&I Cost-of-Service Impact at 75 Percent Cost Allocation 
WATER SUPPLY AND YIELD STUDY 

4-6 

• Identification of the cost to 

implement a least-cost alternative 

(such as the cost of groundwater 

pumping to augment supply) 

When determining the willingness 

to pay for additional water supplies, 

baseline conditions are an important 

aspect to consider. Willingness to 

pay is dependent on considerations 

such as baseline deliveries, delivery 

timing, and water year type. 

Baseline conditions are implicit in 

historical transfer prices; however, 

when estimating future prices, these 

conditions may need adjustment to 

account for changing demand and 

supply for water. 

Willingness to Pay 

Estimates 

To estimate a range of willingness 

to pay for additional water supplies, 

three techniques were used: 

• Observation of transferred 

water prices. Historical transfer 

prices are a good indication of 

the willingness to pay for 

additional water supplies. 

Transfers take place in a variety 

of situations (such as spot 

market, long-term, and 

permanent contract sales), north 

and south of the Delta. 

• Survey. SWP and CVP 

contractors were surveyed to 

identify a need for water in the 

future and their willingness to 

pay for additional water. 

• Estimating the cost of water 

management options. Each 

SWP and CVP contractor has 

different opportunities to secure 

additional water supplies. These 

opportunities might include 

desalination, recycling, and 

conservation. The costs of these 

alternatives are estimated to 

provide upper limits on the 

maximum willingness to pay for 

future water supplies. 

Information obtained from these 

three methods was used to estimate 

willingness to pay for short-term, 

long-term, and permanent water 

supply north and south of the Delta. 

The following discussion describes 

the three methods in greater detail. 

Historical Transfers 

An indication of some water 

districts’ willingness to pay for 

water is provided by the prices they 

have paid in recent years for water 

transfers. The CVPIA, the Drought 

Water Bank Dry Year Purchase 

Program, and the EWA have 

spawned a large number of transfer 

transactions in recent years. In 

addition, several long-term transfers 

are pending or have been approved

(DWR, 2005). 

Most transactions are for the 

transfer of irrigation water from one 

district to another, but many 

transactions are for the transfer of 

irrigation water to environmental 

and M&I uses. In the case of CVP 

supplies, the total price paid per 

acre-foot includes the contract rate 

plus additional charges as 

applicable. Prices paid to the seller 

for irrigation use generally range 

from about $25 to more than 

$50 per acre-foot. 

The broad spectrum of irrigation 

districts purchasing water at these 

prices indicates that many are 

willing to purchase additional water 

supplies at the rates being paid by 

the selling district. The prices paid 

for transferred water described in 

the following discussion represent 

only the amount paid for the 

acquisition of the transferred water; 

they do not include additional rates 

paid, costs for conveyance, storage, 

treatment, or seepage losses 

between the point of sale and point 

of water use. 

Transferred water is priced 

depending on the volume of water 

transferred, reliability of the 

transferred water, and duration of 

the transfer. Another factor that 

determines willingness to pay for 

transfers is water year type. 

Historical water transfers are 

categorized in the following 

manner: 

• Spot market 

• Long-term water purchase 

• Water contract sales 

Water market transfer prices 

historically paid for each type 

of transfer are detailed here. 

Reported prices do not include 

conveyance costs. 

Spot Market Transfers 

Spot market transfers are 

single-year transfers arranged 

between buyers and sellers in the 

year of transfer. These short-term 

arrangements provide willingness to 

pay information for actions by the 

following programs and agencies to 

augment single-year supplies: 

• EWA 

• Reclamation 

• Westlands Water District 

Environmental Water Account 

In operation since 2001, the EWA 

water acquisition program has 

paid $75 to $100 per acre-foot for 

water from north-of-Delta (NOD) 

sources, and from $130 to 

approximately $460 per acre-foot 

from SOD sources. The prices vary 

Canal System 

Chinook Salmon 
SECTION 4: RATE IMPACTS AND WILLINGNESS TO PAY 

4-7 

by water year type. In dry and 

critically dry years, which have not 

yet occurred since the EWA’s 

inception, the price of water is 

expected to rise beyond historical 

prices paid by the EWA for 

transfers. 

The EWA water acquisition 

program separates acquisitions by 

region (NOD and SOD) and by 

water agency. Table 4-2 shows the 

EWA water acquisitions and the 

calculated average price per acrefoot for each of the 5 years. The 

FY 2000–2001 prices were higher 

than in any of the following 3 years 

because 2000–2001 was a 

drier-than-average year. 

Reclamation 

Under its Water Acquisition 

Program (WAP), Reclamation 

acquires water for Level 4 refuge 

water supply, for Vernalis Adaptive 

Management Plan (VAMP) pulse 

flows, and to meet the terms of the 

San Joaquin River Agreement. 

Water acquisitions have been 

completed every year since 1994. 

Table 4-3 summarizes prices paid in 

recent years. 

Prices paid were generally in the 

range of $60 to $150 per acre-foot. 

All purchases were from SOD water 

users, excluding 2002–2003. NOD 

prices in 2002–2003 may be lower 

than typical for the region because 

of the particular districts involved, 

and because the transfers are part of 

a water rights settlement. 

Westlands Water District 

Data on costs of water transfers 

were provided by Westlands Water 

District, a water purveyor that 

serves the primary agricultural area 

on the west side of the San Joaquin 

Valley. Table 4-4 shows costs of 

water acquired in 2000–2004. A 

large share of these transfers might 

qualify as within-CVP transfers 

facilitated by CVPIA provisions. 

Long-term Water Purchases 

Long-term water purchases provide 

the buyer with a period of water 

transfers lasting longer than a single 

year. They also provide the buyer 

with the right to use the water for a 

specified term, but do not constitute 

the sale of water right or contract. 

The higher willingness to pay for 

long-term water transfers (higher 

than the spot market) is reflected in 

the more permanent nature of the 

arrangement. However, long-term 

transfer price is still dictated by the 

reliability, volume, and duration of 

the transfer. Table 4-5 provides 

information on some of the recent 

NOD and SOD long-term transfers. 

Water Contract Sales 

Transfers that are considered 

contract sales are a permanent 

transfer of water right or contract 

right. The price represents the cost 

of obtaining the right or contract, 

but not future payment for the use 

of water under the right or contract. 

This prevents direct comparison of 

water contract sales and short- and 

long-term transfers. However, 

annualizing the contract sale price 

provides an approximation of the 

annual price paid for capital outlay. 

Selected recent contract sales are 

summarized in Table 4-6. 

Future Water Transfers 

Urban demands are expected to 

increase as population increases, 

and agricultural demands are 

expected to decline and harden 

because of declining land in 

production, and increasing 

conservation efforts and percentage 

of permanent crops (DWR, 2005). 

The willingness to pay for transfers 

in the future depends on these 

changes in demand and also on the 

statewide hydrology, which may be 

altered as a result of climate 

change. These uncertainties 

complicate future willingness to 

pay estimation.

TABLE 4-2

EWA Acquisitions through 2005

Source Year 

Total EWA Water 

Acquired (TAF) 

Average Price Paid 

($/AF)* 

2005 46 43 

2004 120 87 

2003 70 84 

2002 142 75 

NOD 

2001 105 87 

2005 90 177 

2004 35 190 

2003 145 169 

2002 97 181 

SOD 

2001 231 221 

Source: DWR, 2006a 

* Does not include conveyance costs 

TABLE 4-3

Prices Paid by Reclamation’s WAP ($ per acre-foot) 

Source 2001–2002 2002–2003 2003–2004 2004–2005 

NOD NA 30 NA NA 

SOD 60–150 63–120 60–130 65–120 

Source: Reclamation, 2006b; Reclamation, 2006c 

Note: Does not include conveyance costs 

NA: not applicable 
WATER SUPPLY AND YIELD STUDY 

4-8 

TABLE 4-4 

Water Transfers to Westlands Water District, 2000–2004 

Year 

Transfers Purchased 

by Users (AF) 

Transfers Purchased 

by District (AF) 

Total Purchased 

(AF) 

Water Cost 

($/AF)* 

2004 95,855 24,905 120,760 147 

2003 106,141 27,641 133,782 108 

2002 124,491 18,210 142,701 127 

2001 106,761 132,894 239,655 138 

2000 222,461 109,545 332,006 120 

Source: DWR, 2006b 

* Does not include conveyance costs 

TABLE 4-5 

Recent Long-term Transfers 

Source Year Buyer Seller 

Duration 

(years) 

Quantity 

(TAF) 

Reported 

Price 

($/AF)* 

2005 DWR and CVP Yuba County WA 9 63–188 25–125 

2003 City of Lodi Woodridge WD 40 6 200 

2000 Contra Costa WD East Contra Costa ID Permanent 8.2 27 

NOD 

2000 Northridge WD Placer County WA 15 12 35 

2003 Cities of Tracy, Lathrop, 

Manteca, and Escalon 

South San Joaquin ID 30 44 191 

2003 Newhall Land and 

Farming Co. 

Nickel Family 30 1.6 475 

1999 Reclamation San Joaquin River Group 

Authority 

10 11–110 27–60 

SOD 

1997 Metropolitan Arvin Edison WSD 25 50 165 

Source: Adapted from Reclamation, 2006c 

* Does not include conveyance costs 

ID: irrigation district WD: water district 

WA: water agency WSD: water storage district 

TABLE 4-6 

Water Contract Sales 2002–2004 

Source Year Buyer Seller 

Quantity 

(AF) 

Price 

($/AF) 

Annualized 

Price ($/AF)* 

NOD 2002 Zone 7 Tulare Lake Basin WSD 400 1,600 96 

2002 Zone 7 Belridge WSD 2,219 1,500 90 

2004 Westlands WD Widren WD 2,900 1,500 90 

2004 Westlands WD Centinella WD 2,500 1,400 84 

2002 City of Tracy Banta Carbona ID 2,500 1,000 60 

2002 City of Tracy West Side ID 5,000 1,000 60 

2003 Coachella Valley WD Tulare Lake Basin WSD 9,900 2,150 129 

2003 Lemoore Naval Base Tulare Lake Basin WSD 5,000 2,150 129 

SOD 

2003 West Kern WD Berrenda Mesa WD 6,000 1,000 60 

Source: Adapted from Reclamation, 2006c 

* Annualized values assume a 6 percent rate over a 

 20-year period. Does not include conveyance costs. 

ID: irrigation district 

WD: water district 

WSD: water storage district 
SECTION 4: RATE IMPACTS AND WILLINGNESS TO PAY 

4-9 

Over the last few years, the price 

paid for water contract sales has 

increased. Although this is not a 

sufficient sample of contract sales to 

estimate a trend, it does indicate that 

agencies are willing to pay upwards 

of $2,100 per acre-foot (plus the 

annual, or “use,” payment for the 

contract) for the one-time purchase 

of a permanent transfer of water. 

However, this willingness to pay for 

contract sales is dependent on the 

availability and price of spot market 

transfers. If supply and demand 

trends push the price of short- and 

long-term transfers higher, contract 

sales for permanent water rights will 

also increase. 

CVP and SWP Contractor 

Survey 

Another approach for estimating 

willingness to pay for additional 

water deliveries is through 

contractor survey. A survey 

conducted for the WSAY Study in 

June 2006 obtained current 

information from CVP and SWP 

contractors. Table 4-7 summarizes 

the survey results. Contractors were 

first asked if they anticipated a 

need for additional supplies in the 

future (2025 or 2030). They were 

then asked to estimate the 

following: 

• What they would be willing to 

pay for additional supplies 

• What type of alternatives they 

may have (such as groundwater 

or transfers) to acquire additional 

water in the future 

Most contractors surveyed were 

reluctant to provide their 

willingness to pay for additional 

water because they indicated that 

changing demand and supply 

conditions make it hard to estimate 

future willingness to pay, and 

current and future water transfer 

negotiations would be compromised 

if they stated their willingness to 

pay. Based on this response, the 

contractors were also asked to 

identify their “least-cost future 

supply options.” 

TABLE 4-7 

Summary of SWP and CVP Contractor Survey 

Project Location Question Response 

SWP NOD Need for additional 

supplies 

Contractors indicated that dry year supplies are needed now and in the 

future. Reliability is the biggest issue. 

 Willingness to pay 

for additional 

supplies 

Contactors willing to pay up to $1,500 per acre-foot during dry years 

for additional SWP Table A amounts. No interest in wet year supplies 

was indicated. In the future, groundwater is a possible source for 

additional supply during dry years. 

 SOD Need for additional 

supplies 

There is a need for additional water in dry years. Surface and 

groundwater supplement shortages when contract deliveries are 

reduced. Overdraft is a problem during dry years. Many contractors 

are interested in additional SWP supplies, and some are actively 

investigating storage opportunities (such as groundwater banking) to 

take advantage of additional supplies in wet years. 

 Willingness to pay 

for additional 

supplies 

To ensure willingness to pay, additional supplies would have to cost 

less than groundwater pumping. Local conservation, water transfers, 

and non-SWP water will provide for M&I growth, and willingness to pay 

for additional contract supplies would not exceed the cost of these 

alternatives. Contractors are looking for additional supplies from other 

water districts. 

CVP NOD Need for additional 

supplies 

Shortages occur in dry years now for some contractors and in the 

future for others. Reliability is the most significant issue. 

 Willingness to pay 

for additional 

supplies 

Willingness to pay would be no more than the cost of transferred water 

and groundwater from other districts, or the cost per acre-foot acquired 

from lining of canals. 

 SOD Need for additional 

supplies 

Reliability is the most important issue. Additional water is needed in dry 

years. This is true for some contractors now, and will be more 

important in the future. 

 Willingness to pay 

for additional 

supplies 

Transfers, groundwater, and local supplies are used in dry years. 

Willingness to pay for additional contract water supplies over the cost 

to acquire these sources is unlikely. Willingness to pay for additional 

water supply is related to the level of certainty for delivery of additional 

contract supply. 
WATER SUPPLY AND YIELD STUDY 

4-10 

TABLE 4-8 

2030 Water Supply Options: Southern San Francisco Bay Area and South Coast 

Option Potential Yield (TAF) Average Cost ($/AF)*

Southern San Francisco Bay Area 

Recycling 72 1,561 

Desalination 134 1,294 

Conservation 338 916 

South Coast 

Recycling 383 801 

Desalination 219 1,434 

Conservation 128 513 

Source: DWR, 2006c 

* 2005 dollars 

When additional water is needed in 

average or dry years, the most 

likely determinant of willingness to 

pay for additional water will be the 

contractors’ least-cost alternative 

for additional supplies. For 

example, in dry years many 

contractors have access to 

groundwater. If additional CVP 

supplies in dry years are cheaper 

than the cost to pump groundwater, 

those contractors will likely be 

willing to pay for the water. 

Each SWP and CVP contractor 

surveyed was operating under 

different conditions. Some 

contractors could use water in all 

year types, while others primarily 

needed additional supplies in dry 

years to increase reliability. 

Contractors have varying access to 

additional water. Some pump 

groundwater in dry years, while 

others rely on transfers, 

conservation, and local actions to 

secure additional supplies. 

Most contractors desire increased 

reliability in dry years. Many water 

district general managers said that 

reliability meant receiving their full 

contract allocations. Recent 

environmental regulations have 

most noticeably affected contract 

allocations to districts in dry years. 

Although contractors express a 

strong interest in reliability of dry 

year supply, the availability of 

additional water in all year types 

might reveal a demand for 

additional water in all year types. 

For example, some contractors 

(such as CCWD and Santa Clara 

Valley Water District) do not 

identify an additional need for 

water, but when additional supplies 

are made available, the contractors 

purchase them (Mann, 2006). 

Survey results indicate that each 

contractor is faced with different 

demand and supply conditions. 

Most have available alternatives for 

short-term supply, such as 

groundwater pumping. Based on 

water management options available 

to the contractors and stated 

willingness to pay, the willingness 

to pay for additional water ranges 

from $30 to $80 per acre-foot for 

irrigation contractors (for which 

groundwater pumping sets the 

maximum willingness to pay) to 

$200 per acre-foot for M&I uses. 

However, these are changes in 

temporary water supply, and water 

contract sales for permanent water 

rights that help improve long-term 

reliability have been priced over 

$2,100 per acre-foot. 

Water Management Options 

The third approach used to estimate 

willingness to pay for additional 

water deliveries identified least-cost 

alternatives available to contractors. 

Contractors can secure future water 

supply from several possible 

sources, such as groundwater 

pumping, desalination, recycling, 

and conservation. The costs for 

additional water supplies from these 

sources provide information on the 

upper limit of willingness to pay. 

Urban areas, such as the southern 

San Francisco Bay Area and the 

South Coast, have recycling, 

desalination, and conservation 

options to provide additional 

supplies. Data on the amount of 

water available in 2030 from these 

options and the costs to implement 

them were collected as part of the 

Common Assumptions effort of the 

CALFED Bay-Delta Program 

Surface Storage Investigations 

(DWR, 2006c). These cost 

estimates indicate an upper limit on 

willingness to pay for additional 

supplies in the year 2030 

(Table 4-8). 

The cost of groundwater pumping is 

a better willingness to pay indicator 

for irrigation. Although willingness 

to pay may change depending on 

reliability, groundwater pumping to 

supply water in dry years can cost 

$30 to $80 per acre-foot. The more 

groundwater pumped, the higher 

the cost. 

The costs of groundwater pumping 

change depending on the district 

and the geology of the region. It 

costs less for districts in the Central 

Valley Basin to access groundwater 

resources. Districts closer to the 

Sierra Nevada foothills deal with 

greater lift issues and other 

geological impediments that make 

groundwater pumping more costly. 

Agricultural Production 
SECTION 4: RATE IMPACTS AND WILLINGNESS TO PAY 

4-11 

Willingness to Pay 

Results 

The historical water transfer prices, 

water management options, and 

contractor surveys all indicate a 

positive willingness to pay for 

additional water supplies. Based on 

this information, an estimated range 

of willingness to pay for irrigation 

and M&I was developed. 

Willingness to pay was divided by 

region and duration (Table 4-9). 

The permanent willingness to pay 

estimates are reported as annualized 

values of capital outlay, so they are 

more representative of the annual 

fee a contractor may pay for 

increased supply. In this situation, 

contractors receive annual water 

supply for a single upfront payment. 

However, this single payment does 

not include possible future payment 

for contract supplies beyond the 

initial outlay. 

Although short-term willingness to 

pay for additional water (transfers 

and groundwater) is a good estimate 

of how contractors will react to dry 

year shortages under current 

allocations, the willingness to pay 

for permanent water supply is a 

more likely estimate of the value of 

increased storage and conveyance 

projects. Contractors were 

apprehensive about stating their 

willingness to pay for securing 

additional supplies. However, based 

on reasonable and foreseeable 

actions to improve supply through 

water management actions, and past 

transactions to increase permanent 

supply, contractors indicate an 

annualized willingness to pay for 

capital outlay of approximately 

$185 per acre-foot for M&I and 

$130 per acre-foot for irrigation. 

However, recent transfer 

negotiations within the state indicate 

that contractors may be willing to 

pay even more per acre-foot of 

water than reported here. 

Ability to Pay 

It is important to note that not every 

contractor has the ability to pay the 

amounts indicated by the estimated 

willingness to pay range. Some 

contractors will be unable to 

participate in the purchase of CVP 

water if the contract rates rise 

dramatically. This analysis assumes 

that all contractors will have the 

ability to pay the estimated 

willingness to pay. Contractors’ 

ability to pay should be addressed in 

additional analysis. 

Conclusions 

The intent of this section is to 

identify the financial impacts from 

implementing the projects and water 

management actions identified in 

Section 3, estimate the willingness 

to pay of beneficiaries for additional 

water deliveries, and use the 

information to develop an initial 

conclusion concerning the financial 

feasibility of the Level 1 storage 

and conveyance projects. 

Water management actions 

identified in Section 3 of this report 

would not have systemwide impacts 

on the CVP rates charged to 

contractors. However, the rate 

impact of implementing all the 

Level 1 storage and conveyance 

projects is significant. When 

50 percent of the project costs for 

the Level 1 storage and conveyance 

projects are allocated to water 

supply, cost-of-service rates are 

estimated to increase from the 

existing rates of about $19 per 

acre-foot to $42 per acre-foot for 

irrigation, and from $19 per 

acre-foot to $69 per acre-foot for 

M&I. The significant increase 

results from an approximate 

150 percent increase in the CVP 

capital costs and only a 10 percent 

increase in CVP yield. 

TABLE 4-9 

Estimated Range of Willingness to Pay per Acre-Foota 

Contractor NOD ($/AF) SOD ($/AF) 

Irrigation 

Short-termb 30–80c 30–80c

Long-termd

 25–125 30–500 

Permanente

 (annualized) NA 65–130 

M&I 

Short termb 30–180 60–240

Long termd

 30–210 195–200 

Permanente

 (annualized) 55–105 30–185 

a

 Estimates are in 2005 dollars and rounded to the nearest $5 increment. 

b Short-term market transfers are single-year transfers arranged between buyers and sellers in the year of transfer. c

 Short-term willingness to pay in irrigation is limited by pumping costs (approximately $30–$80 per acre-foot) d

 Long-term market transfers provide the buyer with a period of water transfers lasting longer than a single year. 

 However, long-term transfers are not a sale of water rights. 

e

 Permanent transfers are considered a permanent transfer in water right. 

NA: not applicable 
WATER SUPPLY AND YIELD STUDY 

4-12 

When 75 percent of the project 

costs for the Level 1 storage and 

conveyance projects are allocated to 

water supply, cost-of-service rates 

are estimated to increase to $53 per 

acre-foot for irrigation and $94 per 

acre-foot for M&I. However, with 

the importance of nonreimbursable 

fish-and-wildlife enhancement and 

water quality improvement in the 

ongoing plan formulation studies, a 

cost allocation of 75 percent to 

water supply is unlikely. 

The beneficiaries’ willingness to 

pay for additional water ranges from 

$30 per acre-foot for NOD spot 

market transfers to over $500 per 

acre-foot for SOD long-term 

transfers. Contractors’ willingness 

to pay is dependent on 

circumstances surrounding available 

groundwater, transfers, and other 

water management options. 

However, there is a demand for 

additional water, as detailed in 

Section 2, and contractors have 

been historically willing to pay 

for additional water to meet 

this demand. 

Based on the survey of CVP and 

SWP contractors, their most 

pressing issue is water supply 

reliability. Adding Level 1 storage 

and conveyance projects would 

increase the reliability of contract 

deliveries, similar to the purchase of 

water contracts. Because of this, 

water contract transactions are a 

reliable estimate of a contractor’s 

willingness to pay for additional 

water deliveries from storage. 

Recent transactions indicate that 

SOD contractors are willing to pay 

an annualized capital outlay value 

of $130 per acre-foot for irrigation 

and $185 per acre-foot for M&I. 

NOD contractors have paid an 

annualized capital outlay value of 

$105 per acre-foot for M&I. 

However, the total willingness to 

pay for permanent water supply is 

likely higher if payments for future 

contract deliveries and conveyance 

charges were included. 

Rate impacts from the Level 1 

storage and conveyance projects are 

below the observed annualized 

capital outlay for recent water 

contract sales. This is a good 

indication that contractors are 

willing to pay for a portion of the 

capital cost associated with the 

Level 1 storage and conveyance 

projects. Additional analysis of rate 

impacts will be possible when 

specific cost allocation information 

for the individual storage projects 

becomes available. 
5 Results and Next Steps 

5-1 

Over the past decade, continual 

improvement in agricultural WUE, 

urban WUE and water recycling, 

construction of facilities for new 

groundwater or conjunctive 

management projects, and local 

storage projects have all contributed 

to improved water delivery. 

However, an imbalance between 

supply and demand still exists. 

Section Highlights 

Current statewide water demand 

estimates: 

♦ 60.6 MAF in average years 

♦ 57.2 MAF in dry years 

Current statewide water 

demands exceed available water 

supplies by: 

♦ 2.3 MAF in average years 

♦ 4.2 MAF in dry years 

Future (2030) statewide water 

demand estimates: 

♦ 60.8 MAF in average years 

♦ 57.4 MAF in dry years 

Amount by which future (2030) 

statewide water demands 

exceed water supplies: 

♦ 4.9 MAF in average years 

♦ 6.1 MAF in dry years 

If the Level 1 storage and 

conveyance projects were 

constructed and investments in 

water management actions were 

made, the existing supplydemand gap could be met in 

average years, but a gap of over 

0.8 MAF would remain in dry 

years. The projected 2030 

supply-demand gap would 

remain at over 1.5 MAF in 

average years and over 2.2 MAF 

gap in dry years. 

Estimated cost-of-service for 

existing and all Level 1 projects: 

♦ $40 per acre-foot for 

irrigation and $70 per acrefoot for M&I when allocating 

50 percent of project costs to 

water supply 

♦ $55 per acre-foot for 

irrigation and $95 per 

acre-foot for M&I when 

allocating 75 percent of 

project costs to water supply 

CVP contractors’ annualized 

willingness to pay for permanent 

water supply south of the Delta 

is approximately $130 per 

acre-foot for irrigation and 

$185 per acre-foot for M&I. 

The following discussion 

summarizes this WSAY Study’s 

key results and provides a list of 

recommended next steps toward 

improved statewide water 

supply reliability. 

Results 

This WSAY Study’s major results 

are summarized here according to 

the order in which this report has 

addressed the needs of the study’s 

purpose: 

• Supply and demand 

• Projects and water management 

actions 

• Rate impacts and willingness 

to pay 

Table 5-1, provided on the 

following page, summarizes how 

these results comply with each 

requirement stated in the WSAY 

Study’s authorization in Public 

Law 108-361. 

Supply and Demand 

Several factors indicate that the 

state’s existing water supplies are 

not sufficient to meet demands, and 

that additional water supply 

management activities and projects 

are necessary to augment water 

supplies and delivery reliability in 

the future: 

• Annual and seasonal 

precipitation variability require 

that water be managed and stored 

in wet years and wet winter 

months to meet demands during 

dry years and dry summers. 

• Geographic variability in 

precipitation and population 

require adequate conveyance 

facilities to move water from the 

wetter north to the more densely 

populated south. 

• CVP and SWP water deliveries 

vary considerably from year to 

year, and may be limited by 

available conveyance or 

storage facilities. 

• CVPIA and other environmental 

constraints have reduced the 

ability of the CVP to meet 

contract deliveries. 

• Current statewide water use 

requires the use of carryover 

storage and groundwater 

overdraft in average and dry 

years. During droughts, banked 

groundwater is an important 

supply, but overdraft is not a 

sustainable source. 

• Water demands exceed 

sustainable supplies in average 

and dry years, and supplydemand gaps are greatest in the 

Central and South Geographic 

Zones. The South Coast and 

Tulare Lake Hydrologic Regions 

experience the greatest shortages. 

• Demand gaps are larger in the 

central and southern parts 

of the state because of 

hydrologic conditions and 

facility constraints. 

• Future statewide demands exceed 

supplies in average and dry years 

to a greater degree than the 

existing gap. 

• Future shortages will be greatest 

in the South Geographic Zone. 

Gaps will increase by the highest 

percentage in the South Coast 

and San Francisco Bay 

Hydrologic Regions. Increasing 

urban demands, particularly 
WATER SUPPLY AND YIELD STUDY 

TABLE 5-1 

WSAY Study Authorization and Compliance 

Requirement in 

Authorization How the Study Complies 

Describe new firm yield and 

water supply improvements, 

if any, for CVP agricultural 

water service contractors 

and M&I water service 

contractors, including those 

identified in Bulletin 160.* 

Description included in Section 3, Projects and Water Management Actions. These 

new water supply and water supply improvements include new storage and 

conveyance projects and other water management actions, such as agriculture and 

urban WUE, irrigated lands retirement, conjunctive use, water purchases and 

transfers, water recycling, and desalination. Projects identified in Update 2005 were 

also included in this report to the extent that they would provide water supply and 

water supply improvements within the study area (the CVP service area or 

CALFED Solution Area). 

Describe all water 

management actions or 

projects, including those 

identified in Bulletin 160,* 

that would have the 

following effects: 

• Improve firm yield or 

water supply 

• If taken or constructed, 

balance available water 

supplies and existing 

demand with due 

recognition of water right 

priorities and 

environmental needs 

New water supply and water supply improvements, including those identified in 

Update 2005, are discussed in Section 3. Many of the projects described attempt to 

balance the overall available water supplies and existing demand with due 

recognition of water right priorities and environmental needs. 

As described in Section 2, Supplies and Demands, current statewide demands 

exceed supplies by 2.3 MAF in average years and 4.2 MAF in dry years, and future 

(2030) statewide demands exceed supplies by 4.9 MAF in average years and 

6.1 MAF in dry years. An analysis was conducted to determine if the water 

management action and projects identified in Section 3 of this WSAY Study could 

fill the existing and future (2030) water supply-demand gap. Based on this analysis, 

if the Level 1 storage and conveyance projects were constructed and investments 

in water management actions were made, the existing supply-demand gap could 

be met in average years, but a gap of over 0.8 MAF would remain in dry years. The 

future (2030) supply-demand gap would remain at over 1.5 MAF in average years 

and over 2.2 MAF gap in dry years. 

Describe the financial costs 

of the actions and projects 

identified in the report. 

Where information is available, costs for projects and actions identified in this report 

are provided in Section 3 under the respective project descriptions. The impacts on 

CVP rates from constructing new storage and conveyance projects were evaluated 

in Section 4, Rate Impacts and Willingness to Pay. 

As described in Section 4, the cost-of-service analysis focused on the Level 1 

storage and conveyance projects. Based on the analysis, financing the existing 

CVP capital costs and all of the Level 1 storage and conveyance projects would 

result in the following estimated cost-of-service rates: 

• $40 per acre-foot for irrigation and $70 per acre-foot for M&I when allocating 

50 percent of project costs to water supply 

• $55 per acre-foot for irrigation and $95 per acre-foot for M&I when allocating 

75 percent of project costs to water supply 

Describe the beneficiaries 

of those actions and 

projects, and an 

assessment of the 

willingness of the 

beneficiaries to pay the 

capital costs and O&M 

costs of the actions and 

projects. 

The potential beneficiaries of the Level 1 storage and conveyance projects are 

described in Section 3. Because of uncertainty concerning the other new storage 

and conveyance projects (the Level 2 and Level 3 projects), potential beneficiaries 

were not identified for these projects. In the event that these projects proceed, 

beneficiaries would be identified in future project-specific analysis. The water 

management actions described in this study would result in both direct and indirect 

benefits to local, regional, and statewide water users and to the environment. 

However, these actions generally result in indirect benefits, making the 

identification of beneficiaries difficult at the current level of analysis. 

The willingness to pay the costs of new Level 1 storage and conveyance projects 

was evaluated in Section 4. CVP contractors’ annualized willingness to pay for 

permanent water supply south of the Delta is approximately $130 per acre-foot for 

irrigation and $185 per acre-foot for M&I. Because the other new storage and 

conveyance projects (the Level 2 and Level 3 projects) and the water management 

actions are likely to be financed through a variety of sources, including local funds, 

grants, state proposition funds, and water users, the willingness to pay for the 

Level 2 and Level 3 projects has not been identified at this time. 

* Bulletin 160 is referred to as Update 2005 in this WSAY Study. 

5-2 
SECTION 5: RESULTS AND NEXT STEPS 

5-3 

in coastal areas, will impact the 

ability of existing facilities to 

meet future needs. 

• Population growth, agriculturalto-urban land conversion, 

unknown future laws and 

regulations, and climate change 

add uncertainty to future 

demand estimates and may 

increase the risk that existing 

facilities and infrastructure will 

not meet demands during 

multiple-year droughts. 

Projects and Water 

Management Actions 

Preliminary studies indicate that 

new storage projects would provide 

new water supply and 

improvements in water supply 

reliability. Water management 

actions such as agriculture and 

urban WUE, irrigated lands 

retirement, conjunctive use, water 

purchases and transfers, water 

recycling, and desalination also 

have the potential to provide water 

supply improvements. 

If the Level 1 storage and 

conveyance projects were 

constructed and investments in 

water management actions were 

made, the existing supply-demand 

gap could be met in average years, 

but a gap of over 0.8 MAF would 

remain in dry years. The projected 

2030 supply-demand gap would 

remain at over 1.5 MAF in average 

years and over 2.2 MAF in 

dry years. 

Long-term water supply reliability 

depends on being able to meet water 

demands during dry years, and 

additional measures will be required 

to fill the dry year gap. A diverse 

portfolio of projects and actions 

consistent with the CALFED ROD 

is needed to fill the supply-demand 

gap. Projects and actions include the 

Level 1 storage and conveyance 

projects and the water management 

actions identified in Section 3 of 

this WSAY Study. Additionally, 

implementation of the Level 2 and 

Level 3 storage projects and more 

aggressive investments in water 

management actions would be 

needed to fill the 2030 supplydemand gap. Similar to current 

conditions, it is likely that 

agricultural and environmental uses 

would continue to experience water 

supply shortages in future average 

and dry years. 

Rate Impacts and 

Willingness to Pay 

The impacts on CVP rates from 

constructing new storage and 

conveyance projects were evaluated 

by relating the associated water 

charges to water contractors’ 

willingness to pay. Financing the 

existing CVP capital costs and all 

Level 1 storage and conveyance 

projects would result in these 

estimated cost-of-service rates: 

• $40 per acre-foot for irrigation 

and $70 per acre-foot for M&I 

when allocating 50 percent of 

project costs to water supply 

• $55 per acre-foot for irrigation 

and $95 per acre-foot for M&I 

when allocating 75 percent of 

project costs to water supply 

These rate estimates are for the 

period 2021 to 2030. After 2030, 

initial CVP capital costs will be 

repaid, and overall rates will fall to 

slightly lower levels. 

Based on reasonable and 

foreseeable actions to improve 

supply through water management 

actions and past transactions to 

increase permanent supply, 

contractors indicate a willingness to 

pay for permanent water supply 

south of the Delta of approximately 

$130 per acre-foot for irrigation and 

$185 per acre-foot for M&I. Recent 

transfer negotiations indicate that 

contractors may be willing to pay 

more than these amounts for new, 

permanent water supply. 

However, not every contractor has 

the ability to pay the average 

willingness to pay amount. 

Some contractors will be unable 

to participate in the purchase of 

CVP water if the contract rates 

rise dramatically. 

Next Steps 

A variety of actions, programs, and 

projects are underway to improve 

statewide water supply reliability. 

Reclamation participates in some of 

these studies, such as the 

CALFED-authorized storage and 

conveyance improvement feasibility 

studies. The next steps toward 

meeting the needs for future water 

demand and reliability include the 

following: 

• Continue to support the existing 

CALFED storage and 

conveyance projects. 

• Support other surface storage and 

conveyance projects, as well as 

other statewide water 

management actions, such as 

WUE and conjunctive use, that 

could improve water supply and 

water supply reliability for CVP 

contractors. 

The supply-demand gaps identified 

in this WSAY Study were 

developed by DWR hydrologic 

region and are based primarily on 

information from DWR’s 

Update 2005. These supply-demand 

gaps are based on the best 

information available within the 

time requirements stated in the 

WSAY Study’s authorization; 

however, additional data could be 

collected to develop CVP-specific 

supply-demand gaps. This would 

allow for the following analyses: 

• Identification of supply-demand 

gaps by CVP division 

• Identification of projects and 

water management actions to fill 

the supply-demand gap by 

CVP division. 

6 References 

Bureau of Reclamation (Reclamation). 2006a. CVP Annual Rate Books. Internet site: 

http://www.usbr.gov/mp/cvpwaterrates/ratebooks/index.html. Accessed September. 

Bureau of Reclamation (Reclamation). 2006b. 3406(b)(3) Water Acquisition Program, program 

information. Internet site: http://www.usbr.gov/mp/cvpia/3406b3_wap/info/index.html. Accessed 

September. 

Bureau of Reclamation (Reclamation). 2006c. Draft Initial Economic Evaluation for Plan Formulation. 

May. 

Bureau of Reclamation (Reclamation). 2006d. Auburn-Folsom South Unit Special Report: Benefits and 

Cost Update. Sacramento. December. 

Bureau of Reclamation (Reclamation). 2005. A CVP Yield Feasibility Investigation Report: The Delivery 

Impact of CVPIA. Sacramento. May. 

Bureau of Reclamation (Reclamation). 2001. CVP Cost Allocation Study. Draft Report. Department of the 

Interior, Bureau of Reclamation. January. Internet site: 

http://www.usbr.gov/mp/cvpwaterrates/references.html. Accessed August. 

Bureau of Reclamation and U.S. Fish and Wildlife Service (Reclamation and USFWS). 1999. Central 

Valley Project Improvement Act Programmatic Environmental Impact Statement. October. 

CALFED Bay-Delta Program (CALFED). 2000a. Final Programmatic Environmental Impact Statement/ 

Environmental Impact Report. Sacramento. July. 

CALFED Bay-Delta Program (CALFED). 2000b. Initial Surface Water Storage Screening. Integrated 

Storage Investigation Report. Sacramento. August. 

CALFED Bay-Delta Program (CALFED). 2000c. Programmatic Record of Decision. Sacramento. 

August. 

CALFED Bay-Delta Program (CALFED). 1997. CALFED Storage and Conveyance Components: 

Facility Descriptions and Cost Estimates. Report. Sacramento. October. 

California Bay-Delta Authority (CBDA). 2006. CALFED Bay-Delta Surface Storage Program Progress 

Report Update. Prepared by DWR and Reclamation. Sacramento. May. 

California Bay-Delta Authority (CBDA). 2005a. California Bay-Delta Finance Plan. Sacramento. 

January. 

California Bay-Delta Authority (CBDA). 2005b. Year-4 Comprehensive Evaluation of the CALFED 

Water Use Efficiency Element. Final Draft. Sacramento. December. 

California Department of Finance. 2004. Population Projections by Race/Ethnicity, Gender and Age for 

California and Its Counties 2000-2050. Sacramento. May. 

California Department of Water Resources (DWR). 2006a. Past water transfers. Internet site: 

http://www.watertransfers.water.ca.gov/water_trans/water_trans_index.cfm. 

California Department of Water Resources (DWR). 2006b. Draft Report on Environmental Water 

Account Price Estimation. Sacramento. January. 

California Department of Water Resources (DWR). 2006c. Common Assumptions Draft Plan 

Formulation Common Model Package. CALFED Bay-Delta Program. February. 

6-1 
WATER SUPPLY AND YIELD STUDY 

6-2 

California Department of Water Resources (DWR). 2006d. The State Water Project Water Delivery 

Reliability Report 2005. Final. Sacramento. April. 

California Department of Water Resources (DWR). 2005. California Water Plan Update 2005: A 

Framework for Action. Bulletin 160-05. Sacramento. December. 

California Department of Water Resources (DWR). 2003. California’s Groundwater. Bulletin 118 

Update 2003. Sacramento. October. 

California Department of Water Resources (DWR). 1998. California Water Plan Update.

Bulletin 160-98. Sacramento. November. 

Central Valley Joint Venture. 2000. Central Valley Wetlands Water Supply Investigations Report CVPIA 

3406 (d)(6)(A,B). Report to Congress. USFWS and Reclamation. December. 

Coachella Valley Water District (CVWD) et al. 2002. Final Program Environmental Impact Report: 

Implementation of the Colorado River Quantification Settlement Agreement. Volume I, EIR Text 

and Appendices. June. 

Environmental Defense. 2004. “Recommendations Regarding Scenarios and Application of 

Environmental Water ‘Demands’ in the State Water Plan Update & Quantification of Unmet 

Environmental Objectives in State Water Plan 2003 Using Actual Flow Data for 1998, 2000, and 

2001.” October. Memoranda as included in California Water Plan Update 2005: A Framework for 

Action. Bulletin 160-05, vol. 4, References Guide, Environment. 

Kiparsky, Michael and Peter H. Gleick. 2003. Climate Change and California Water Resources: A Survey 

and Summary of the Literature. Pacific Institute for Studies in Development, Environment, and 

Security. July. Report as included in California Water Plan Update 2005: A Framework for Action.

Bulletin 160-05, vol. 4, References Guide, Global Climate Change. 

Mann, Roger/RMEcon. 2006. Telephone call to Lucas Bair/CH2M HILL. June. 

Ostroff, Ruth/Central Valley Joint Venture. 2006. Communication with Jeanne Brantigan/CH2M HILL. 

November. 

Roos, Maurice/DWR. 2005. “Accounting for Climate Change.” Paper as included in California Water 

Plan Update 2005: A Framework for Action. Bulletin 160-05, vol. 4, References Guide, Global 

Climate Change. 

Rust, Tim/Bureau of Reclamation. 2006. Comments provided to CH2M HILL in response to the Water 

Supply and Yield Study. First Administrative Draft Final Report. November. 
Glossary 

GLOSSARY-1 

Glossary

acre-foot. A term used in measuring the volume or amount of water needed to cover 1 acre 

(43,560 square feet) 1 foot deep (325,851 gallons or 1,233.5 cubic meters). It is considered to be roughly 

the amount of water used annually by a family household of four.

agricultural water use efficiency. Agricultural WUE consists of improvements in technology, hardware, 

and water management to conserve water and improve water quality and environmental benefits. 

applied water. The amount of water from any source needed to meet the demand for beneficial use by 

the user. It includes consumptive use, reuse, and outflows. It does not include precipitation or distribution 

losses. 

aquifer. A natural underground layer of porous, water-bearing materials (such as sand and gravel) usually 

capable of yielding a large amount or supply of water. 

beneficial use. Water used for the betterment of society, such as irrigation, municipal, or environmental 

use. California’s State Water Resources Control Board identifies 24 categories of beneficial use. 

carryover storage. Water stored in surface reservoirs or in an aquifer (groundwater storage) during wet 

years for use during dry years. 

conjunctive management (or conjunctive use). Coordinated operation of surface water storage and use, 

groundwater storage and use, and conveyance facilities to maximize the efficient use of the resource. 

conveyance. Movement of water through natural or constructed facilities such as rivers, channels, 

pipelines, canals, pumps, diversions, and distribution systems. 

cost allocation. The process of distributing project costs among authorized project purposes to determine 

repayment requirements. The purposes authorized by law for the CVP are typically water supply, water 

quality, flood control, recreation, navigation, hydropower, and fish and wildlife. 

cost reimbursement. Refers to the collection of revenues to repay the costs of a project. Funds for 

financing the initial construction of federal projects are appropriated from the general budget. The portion 

of the costs that must be repaid by beneficiaries varies by project purpose. 

dedicated supply. The portion of the total supply distributed among urban and agricultural uses, 

dedicated to protect and restore the environment, or stored in surface and groundwater reservoirs for later 

use. 

desalination. The process of removing salt from seawater or brackish water, including groundwater or 

wastewater, either by natural means or by specific water treatment processes. 

drainage basin. The area of land that drains its water into a river. 

drip irrigation. An irrigation method in which water is delivered to or near each plant in small-diameter 

plastic tubing. The water is then discharged through pores or small emitters on the tubing. 

drought. Climatic condition during a defined prolonged period, greater than 1 dry year, when 

precipitation and runoff are below average. 

evapotranspiration. The amount of water transpired by plants or evaporated from adjacent soil surfaces 

in a specific time period. 
WATER SUPPLY AND YIELD STUDY 

GLOSSARY-2 

firm yield. As defined by Public Law 108-361: a quantity of water from a project or program that is 

projected to be available on a reliable basis, given a specified level of risk, during a critically dry period. 

This definition differs from current Reclamation policy, which defines firm yield as the maximum 

quantity of water that can be guaranteed with some specified degree of confidence during a specific 

critical period. The critical period is that period in a sequential record that requires the largest volume 

from storage to provide a specified yield. 

geographic zone. Geographic zones were delineated for the propose of discussion and analysis in the 

WSAY Study. Each of the three geographic zones (North, Central, and South) comprises several 

hydrologic regions. 

groundwater. Water that occurs beneath the land surface and fills the pore spaces of the alluvium, soil, or 

rock formation in which it is situated, such as in an aquifer. 

hydrologic region. For planning purposes, the California Department of Water Resources divides the 

state into 10 hydrologic regions corresponding to the state’s major drainage basins. 

recycled water. Municipal, industrial, or agricultural wastewater treated so that it can be reused. 

runoff. Precipitation, snowmelt, or irrigation in excess of what can infiltrate the soil surface. 

service area. The geographic area served by a water agency or district. 

spot market transfers. Single-year water transfers arranged between buyers and sellers within the year 

of transfer. These short-term arrangements may be used by agencies to augment single-year supplies. 

total supply. The sum of all water entering the state, which includes precipitation and inflows from the 

Colorado River, Oregon, and Mexico. 

urban water use efficiency. Urban WUE consists of improvements in methods, technology, hardware, or 

behavioral changes that result in the same beneficial residential, commercial, industrial, and institutional 

uses with less water or increased beneficial uses from existing water quantities. 

water demand. An amount of water that a user desires to apply to a particular use, such as crop 

irrigation, industrial processes, ecosystem needs, or residential supply, regardless of influencing factors 

such as price or available supply. 

water management action. A project or program that has potential to provide yield and water supply 

improvements. Water management actions are categorized as either demand management actions or other 

actions. Demand management actions focus on reducing water demand; these include agricultural water 

use efficiency (WUE), urban WUE, and land retirement. Other actions focus on increasing water supply; 

these include water transfers, water recycling, and desalination. 

water recycling. A program to reclaim and reuse municipal, industrial, domestic, and agricultural 

wastewater. It can also include reclaiming impaired groundwater and surface water. 

water transfers. Selling or exchanging water or water rights among individuals or agencies. 

water use. The amount of water delivered to and used by a user, which is dependent upon water supply 

and is influenced by factors such as price and availability.

water year type. For the purposes of water management planning, a classification system used to 

compare variation in annual precipitation and runoff. For example, water year types may include wet, 

above normal, average, below normal, dry, critical. 
GLOSSARY 

GLOSSARY-3 

water year. A calendar year used for water calculations. Different agencies may use different calendar 

periods for their water years. 

willingness to pay. Method of estimating the value of activities, services, or other goods, where value is 

defined as the maximum amount a consumer would be willing to pay for the opportunity rather than do 

without. The total willingness to pay, minus the user’s costs of participating in the opportunity, defines 

the consumer surplus and benefits. 

APPENDIX 

Supply-Demand Gap Tables 
A-1 

APPENDIX 

Supply-Demand Gap Tables 

This appendix provides details of the statewide supply-demand gaps broken down by hydrologic region 

and users in the following tables: 

Table A-1: Dry Year (2001) Supplies, Demands, and Gaps by Hydrologic Region and Statewide 

(Current Conditions) 

Table A-2: Average Year (2000) Supplies, Demands, and Gaps by Hydrologic Region and Statewide 

(Current Conditions) 

Table A-3: Wet Year (1998) Supplies, Demands, and Gaps by Hydrologic Region and Statewide 

(Current Conditions) 

Table A-4: Future Dry Year Supplies, Demands, and Gaps by Hydrologic Region and Statewide 

(2030 Conditions) 

Table A-5: Future Average Year Supplies, Demands, and Gaps by Hydrologic Region and Statewide 

(2030 Conditions) 
WATER SUPPLY AND YIELD STUDY 

A-2 

TABLE A-1 

Dry Year (2001) Supplies, Demands, and Gaps by Hydrologic Region and Statewide (Current Conditions) 

Hydrologic 

Region User 

Supply 

(TAF) 

Demand 

(TAF) 

Gap 

(TAF) 

Total Regional 

Gap (TAF)a

Urban 150 150 0 

Agricultural 630 810 180 

North Coast 

Environmental 1,730 1,830 100 

280 

Urban 1,110 1,080 0 

Agricultural 120 110 0 

San Francisco 

Bay 

Environmental 30 30 0 

0 

Urban 140 300 160 

Agricultural 760 1,020 260 

Central Coast 

Environmental 10 10 0 

420 

Urban 3,920 4,270 350 

Agricultural 760 910 150 

South Coast 

Environmental 40 40 0 

500 

Urban 880 880 0 

Agricultural 8,570 8,710 140 

Sacramento River 

Environmental 8,700 9,390 690 

830 

Urban 620 620 0 

Agricultural 7,040 7,020 0 

San Joaquin River 

Environmental 1,840 2,340 500 

500 

Urban 670 670 0 

Agricultural 9,420 10,800 1,380 

Tulare Lake 

Environmental 80 80 0 

1,380 

Urban 40 40 0 

Agricultural 430 470 40 

North Lahontan 

Environmental 110 110 0 

40 

Urban 240 280 40 

Agricultural 340 360 20 

South Lahontan 

Environmental 80 80 0 

60 

Urban 610 700 90 

Agricultural 3,900 4,010 110 

Colorado River 

Environmental 30 30 0 

200 

Urban 8,380 8,990 640 

Agricultural 31,970 34,220 2,280 

Statewideb

Environmental 12,650 13,940 1,290 

Totalc 53,000d 57,150 4,210 

a Each total regional gap is the sum of all user gaps (urban, agricultural, and environmental) for a particular hydrologic 

region. b Statewide supplies, demands, and gaps are the sum of the supplies, demands, and gaps for each hydrologic region, 

respectively. c Total supplies, demands, and gaps are the sum of statewide supplies, demands, and gaps for each user type, 

respectively. d Statewide supplies are reduced by 2 MAF in a dry year to account for Bulletin 118’s maximum estimate of 

groundwater overdraft. It is assumed that overdraft is not a sustainable source of supply. The 2 MAF is distributed 

over the supplies of applicable hydrologic basins that have reported subbasins in overdraft. 
APPENDIX: SUPPLY-DEMAND GAP TABLES 

A-3 

TABLE A-2 

Average Year (2000) Supplies, Demands, and Gaps by Hydrologic Region and Statewide (Current Conditions) 

Hydrologic 

Region User 

Supply 

(TAF) 

Demand 

(TAF) 

Gap 

(TAF) 

Total Regional 

Gap (TAF)a

Urban 150 150 0 

Agricultural 810 810 0 

North Coast 

Environmental 1,870 2,210 340 

340 

Urban 1,070 1,070 0 

Agricultural 110 110 0 

San Francisco 

Bay 

Environmental 30 30 0 

0 

Urban 300 300 0 

Agricultural 740 1,020 280 

Central Coast 

Environmental 20 20 0 

280 

Urban 4,210 4,250 40 

Agricultural 910 910 0 

South Coast 

Environmental 40 40 0 

40 

Urban 860 860 0 

Agricultural 8,710 8,710 0 

Sacramento River 

Environmental 11,460 11,870 410 

410 

Urban 600 600 0 

Agricultural 6,910 7,020 110 

San Joaquin River 

Environmental 2,540 3,060 520 

630 

Urban 650 650 0 

Agricultural 10,220 10,800 580 

Tulare Lake 

Environmental 70 70 0 

580 

Urban 40 40 0 

Agricultural 470 470 0 

North Lahontan 

Environmental 110 110 0 

0 

Urban 270 270 0 

Agricultural 360 360 0 

South Lahontan 

Environmental 90 90 0 

0 

Urban 680 680 0 

Agricultural 4,010 4,010 0 

Colorado River 

Environmental 30 30 0 

0 

Urban 8,830 8,870 40 

Agricultural 33,250 34,220 970 

Statewideb

Environmental 16,260 17,530 1,270 

Totalc 58,340d 60,620 2,280 

a

 Each total regional gap is the sum of all user gaps (urban, agricultural, and environmental) for a particular hydrologic 

region. b

 Statewide supplies, demands, and gaps are the sum of the supplies, demands, and gaps for each hydrologic region, 

respectively. c

 Total supplies, demands, and gaps are the sum of statewide supplies, demands, and gaps for each user type, 

respectively. d

 Statewide supplies are reduced by 1 MAF in an average year to account for Bulletin 118’s minimum estimate of 

groundwater overdraft. It is assumed that overdraft is not a sustainable source of supply. The 1 MAF is distributed 

over the supplies of applicable hydrologic basins that have reported subbasins in overdraft. 
WATER SUPPLY AND YIELD STUDY 

A-4 

TABLE A-3 

Wet Year (1998) Supplies, Demands, and Gaps by Hydrologic Region and Statewide (Current Conditions) 

Hydrologic 

Region 

User Supply 

(TAF) 

Demand 

(TAF) 

Gap 

(TAF) 

Total Regional 

Gap (TAF)a

Urban 140 140 0 

Agricultural 660 660 0 

North Coast 

Environmental 1,840 2,000 160 

160 

Urban 990 990 0 

Agricultural 90 90 0 

San Francisco 

Bay 

Environmental 30 30 0 

0 

Urban 260 260 0 

Agricultural 830 830 0 

Central Coast 

Environmental 20 20 0 

0 

Urban 3,620 3,620 0 

Agricultural 690 690 0 

South Coast 

Environmental 30 30 0 

0 

Urban 730 730 0 

Agricultural 6,460 6,460 0 

Sacramento River 

Environmental 13,640 13,950 310 

310 

Urban 560 560 0 

Agricultural 5,460 5,460 0 

San Joaquin River 

Environmental 1,940 2,170 230 

230 

Urban 550 550 0 

Agricultural 8,570 8,570 0 

Tulare Lake 

Environmental 60 60 0 

0 

Urban 40 40 0 

Agricultural 400 400 0 

North Lahontan 

Environmental 100 100 0 

0 

Urban 210 210 0 

Agricultural 280 280 0 

South Lahontan 

Environmental 100 100 0 

0 

Urban 700 700 0 

Agricultural 3,870 3,870 0 

Colorado River 

Environmental 30 30 0 

0 

Urban 7,800 7,800 0 

Agricultural 27,310 27,310 0 

Statewideb

Environmental 17,790 18,490 700 

Totalc 52,900 53,600 700 

a

 Each total regional gap is the sum of all user gaps (urban, agricultural, and environmental) for a particular hydrologic 

region. b

 Statewide supplies, demands, and gaps are the sum of the supplies, demands, and gaps for each hydrologic region, 

respectively. c

 Total supplies, demands, and gaps are the sum of statewide supplies, demands, and gaps for each user type, 

respectively. 
APPENDIX: SUPPLY-DEMAND GAP TABLES 

A-5 

TABLE A-4 

Future Dry Year Supplies, Demands, and Gaps by Hydrologic Region and Statewide (2030 Conditions) 

Hydrologic 

Region 

User Supply 

(TAF) 

Demand 

(TAF) 

Gap 

(TAF) 

Total Regional 

Gap (TAF)a

Urban 150 190 40 

Agricultural 630 750 120 

North Coast 

Environmental 1,730 1,830 100 

260 

Urban 1,110 1,280 170 

Agricultural 120 110 0 

San Francisco 

Bay 

Environmental 30 30 0 

170 

Urban 140 350 210 

Agricultural 760 860 100 

Central Coast 

Environmental 10 10 0 

310 

Urban 3,500 5,140 1,640 

Agricultural 760 640 0 

South Coast 

Environmental 40 40 0 

1,640 

Urban 880 1,420 540 

Agricultural 8,570 8,540 0 

Sacramento River 

Environmental 8,700 9,390 690 

1,230 

Urban 620 1,040 420 

Agricultural 7,040 6,420 0 

San Joaquin River 

Environmental 1,840 2,340 500 

920 

Urban 670 990 320 

Agricultural 9,420 9,800 380 

Tulare Lake 

Environmental 80 80 0 

700 

Urban 40 50 10 

Agricultural 430 500 70 

North Lahontan 

Environmental 110 110 0 

80 

Urban 240 440 200 

Agricultural 340 310 0 

South Lahontan 

Environmental 80 80 0 

200 

Urban 610 1,110 500 

Agricultural 3,440 3,480 40 

Colorado River 

Environmental 30 30 0 

540 

Urban 7,960 12,010 4,050 

Agricultural 31,510 31,410 710 

Statewideb

Environmental 12,650 13,940 1,290 

Totalc 52,120d 57,360 6,050 

a Each total regional gap is the sum of all user gaps (urban, agricultural, and environmental) for a particular hydrologic 

region. b Statewide supplies, demands, and gaps are the sum of the supplies, demands, and gaps for each hydrologic region, 

respectively. c Total supplies, demands, and gaps are the sum of statewide supplies, demands, and gaps for each user type, 

respectively. d Statewide supplies are reduced by 2 MAF in a dry year to account for Bulletin 118’s maximum estimate of 

groundwater overdraft. It is assumed that overdraft is not a sustainable source of supply. The 2 MAF is distributed 

over the supplies of applicable hydrologic basins that have reported subbasins in overdraft. 
WATER SUPPLY AND YIELD STUDY 

A-6 

TABLE A-5 

Future Average Year Supplies, Demands, and Gaps by Hydrologic Region and Statewide (2030 Conditions) 

Hydrologic 

Region 

User Supply 

(TAF) 

Demand 

(TAF) 

Gap 

(TAF) 

Total Regional 

Gap (TAF)a

Urban 150 190 40 

Agricultural 810 750 0 

North Coast 

Environmental 1,870 2,210 340 

380 

Urban 1,070 1,270 200 

Agricultural 110 110 0 

San Francisco 

Bay 

Environmental 30 30 0 

200 

Urban 300 350 50 

Agricultural 740 860 120 

Central Coast 

Environmental 20 20 0 

170 

Urban 3,790 5,120 1,330 

Agricultural 910 640 0 

South Coast 

Environmental 40 40 0 

1,330 

Urban 860 1,390 530 

Agricultural 8,710 8,540 0 

Sacramento River 

Environmental 11,460 11,870 410 

940 

Urban 600 1,010 410 

Agricultural 6,910 6,420 0 

San Joaquin River 

Environmental 2,540 3,060 520 

930 

Urban 650 970 320 

Agricultural 10,220 9,800 0 

Tulare Lake 

Environmental 70 70 0 

320 

Urban 40 50 10 

Agricultural 470 500 30 

North Lahontan 

Environmental 110 110 0 

40 

Urban 270 430 160 

Agricultural 360 310 0 

South Lahontan 

Environmental 90 90 0 

160 

Urban 680 1,080 400 

Agricultural 3,550 3,480 0 

Colorado River 

Environmental 30 30 0 

400 

Urban 8,410 11,860 3,450 

Agricultural 32,790 31,410 150 

Statewideb

Environmental 16,260 17,530 1,270 

Totalc 57,460d 60,800 4,870 

a

 Each total regional gap is the sum of all user gaps (urban, agricultural, and environmental) for a particular hydrologic 

region. b

 Statewide supplies, demands, and gaps are the sum of the supplies, demands, and gaps for each hydrologic region, 

respectively. 

c

 Total supplies, demands, and gaps are the sum of statewide supplies, demands, and gaps for each user type, 

respectively. d

 Statewide supplies are reduced by 1 MAF in an average year to account for Bulletin 118’s minimum estimate of 

groundwater overdraft. It is assumed that overdraft is not a sustainable source of supply. The 1 MAF is distributed 

over the supplies of applicable hydrologic basins that have reported subbasins in overdraft. 
U.S. Department of the Interior

Bureau of Reclamation 

Mid-Pacific Region

Water Supply and 

Yield Study

March 2008