California Water Plan Update 2005

9 6 Volume 3 Regional Reports

problems. These include groundwater contamination from 

septic tank discharges in urban subdivisions near Susanville 

and Eagle Lake, and MTBE contamination in South Lake 

Tahoe. Drinking water quality has also become a greater issue 

for many surface water systems around Lake Tahoe, forcing 

many of the smaller private systems to consolidate or change 

ownership because they are unable to afford the new monitoring and treatment regulatory requirements. South Tahoe Public 

Utility District, the largest water purveyor in the Tahoe basin, is 

also experiencing some difficulty in meeting these water quality 

requirements. The abandoned Leviathan Mine, a Superfund site 

in the upper reaches of the Carson River watershed, impacts 

local creeks with acid mine drainage water. The top water quality issues emerging from the Lahontan Regional Water Quality 

Control Board’s (RWQCB’s) 2003 Triennial Review included 

proposals to revise the waste discharge prohibition for piers in 

Lake Tahoe, and sodium standards for the Carson and Walker 

Rivers and their tributaries.

Lake Tahoe is the subject of its own chapter in the region’s 

basin plan, and receives many specific and extraordinary 

water quality protections. The Porter-Cologne Water Quality 

Control Act bans the discharge of domestic wastewater from 

California in the Lake Tahoe Basin; the same ban is in effect 

in Nevada by executive order, resulting in the export of all 

domestic wastewater from the basin. Discharges of industrial 

wastewater, wastes from boats and marinas, food wastes, and 

solid waste are also prohibited in the Tahoe basin. Lake Tahoe’s 

clarity has declined as development has increased around the 

shoreline, increasing the sediment load and nutrients reaching 

the lake and its tributaries. In the late 1960s, the clarity of the 

lake – as measured by the depth to which a Secchi disk (a small 

white disk of specific size) is visible – was about 100 feet; but in 

recent years, the average Secchi disk visibility has been closer 

to 70 feet. Nutrients, such as nitrogen and phosphorous used 

in landscaping fertilizers, can enter the lake via storm water 

runoff, promoting growth of algae and thereby reducing clarity. Nitrogen pollution in the basin is primarily due to vehicles, 

while phosphorous is mostly derived from erosion and dust 

(phosphate-based detergents are banned). 

Roads and road maintenance, including snow removal and 

de-icing, are the focus of new restrictions that are intended to 

reduce erosion and other water quality impacts into the streams 

that enter Lake Tahoe. The traditional use of salt for road deicing had resulted in adverse impacts to the trees and plants 

which help prevent erosion and sediment from flowing into the 

lake. Forest fires, grazing, and logging also present a threat to 

the lake’s water clarity due to related and subsequent erosion 

into the stream systems. The use of agricultural pesticides in the 

Lake Tahoe Basin is prohibited, and the Tahoe Regional Planning Agency has more recently banned the use of two-stroke 

engines in all boats on Lake Tahoe, to prevent contamination 

from gasoline components such as benzene and MTBE. Other 

restrictions on land development and soil disturbances are used 

in the continuing efforts to maintain or improve the lake’s water 

quality, and programs that purchase and preserve sensitive lands 

are being implemented. Lake Tahoe is now extensively monitored 

by many federal and State agencies, and researchers such as 

the University of California, Davis, Tahoe Research Group, and 

the University of Nevada Desert Research Institute.

Local California interests in the northern part of the Lahontan 

Region have been apprehensive for several years about plans 

and proposals from northern Nevada interests in the Reno 

area that have envisioned the development of additional 

water supplies from the northeastern California watersheds. 

In the late 1980s, the Silver State Plan triggered concerns 

about water exports to Nevada from as far north as Modoc 

County, more than 150 miles north of Reno. The plan proposed building a pipeline north nearly to the Oregon border 

to tap groundwater basins, some of which extend across the 

California-Nevada line. More recently, the proposed Truckee 

Meadows Project has generated concern about potential 

depletion of California groundwater supplies in the Honey 

Lake and Long Valley Creek areas. To date, none of these 

proposals have been finalized or implemented. 

Accomplishments

Years of disputes over the waters of the Truckee and Carson 

rivers led to the enactment of the Truckee-Carson-Pyramid 

Lake Water Rights Settlement Act (Public Law 101-618) in 

1990. Provisions of the Settlement Act, including interstate 

water allocation, will not take effect until several conditions 

are completed, which include the negotiation and approval 

of a new Truckee River Operation Agreement (TROA). The 

act specifies an interstate allocation of the waters between 

California and Nevada, provides for the settlement of Native 

American water rights claims at Pyramid Lake, and provides water supplies for specified environmental purposes 

in Nevada. When it is implemented the act will allocate to 

California 23,000 acre-feet of surface water annually in the 

Lake Tahoe Basin, and 32,000 acre-feet of surface water 

annually in the Truckee River Basin below Lake Tahoe. In the 

Carson River Basin California will receive water allocations 

that correspond to existing water uses, and the remainder of 

the water supplies from both watersheds will be allocated to 

uses in Nevada.

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Negotiation of a proposed Truckee River Operating Agreement 

began in 1991, involving California and Nevada, the U.S. 

Department of Interior, the Pyramid Lake Paiute Indian Tribe, 

Sierra Pacific Power Company, and local water users in both 

California and Nevada. The language for this 220-page draft 

operating agreement was finalized in October 2003, and the 

draft EIR/EIS for implementation of the TROA was released in 

mid-2004. After the final EIS/EIR is completed and certified, the 

negotiating parties will sign TROA. When executed, the TROA 

would establish new daily river operations procedures to meet 

water rights on the Truckee River and to enhance spawning flows 

in the lower Truckee River for the threatened fishery species of 

cui-ui and Lahontan cutthroat trout. TROA would provide for 

management of water in the Truckee basin in California, including instream flow requirements and reservoir storage for fishery 

and recreation uses, and would include procedures for coordinating releases and exchanges of water among the watershed’s 

reservoirs. TROA would become the exclusive federal regulations 

governing water stored in Lake Tahoe, Martis Creek, Prosser 

Creek, Stampede, and Boca reservoirs. The agreement would 

also provide an accounting procedure for surface and groundwater diversions in California’s part of the Truckee Basin and 

would enhance streamflows for recreational purposes. 

Programs to manage and restore the water quality and clarity 

of Lake Tahoe are making progress by regulating development 

within the basin and by working to reduce surface water pollutants from entering the lake. The Tahoe Regional Planning 

Agency is a bistate agency created by Congress with authority 

to set regional environmental standards, issue land use permits, 

including conditions to protect water quality, and take enforcement actions throughout the basin. TRPA’s regional plan includes 

specific goals and timetables for accomplishing environmental 

objectives, and this bi-state agency also implements capital 

improvement programs to repair environmental damage and 

restore water quality. TRPA has identified nearly $500 million 

in capital improvements that are needed to achieve the regional 

plan’s environmental targets. Federal, state, and local governments have invested nearly $90 million in erosion control, storm 

water drainage, stream zone restoration, public transit, and 

other capital projects. The USFS’s Lake Tahoe Basin Management Unit controls more than 70 percent of the land in the Lake 

Tahoe Basin. The LTBMU has begun a watershed restoration 

program and a land acquisition program to prevent development of sensitive private lands. Within the California side of this 

basin, the Lahontan Regional Water Quality Control Board has a 

major role in protecting Lake Tahoe, by actively monitoring and 

enforcing surface water quality for all uses and discharges. In 

recent years, federal and state agencies have increased funding 

to protect the environment of Lake Tahoe. Nevada approved a 

$20 million bond measure to perform erosion control and other 

measures on the east side of the lake. In California, Proposition 

204 recently provided $10 million in bond funds for land acquisition and programs to control soil erosion, restore watersheds, 

and preserve environmentally sensitive lands. 

On the Carson and Walker rivers, the California Department of 

Fish and Game is also concerned about maintaining instream 

flows and reservoir pools to restore and preserve the fishery. In 

conjunction with American Land Conservancy, a private land 

trust organization, DFG has been acquiring lands and water 

rights at Heenan Lake in the upper watershed of the East Fork 

of the Carson River. This small reservoir was originally built to 

supply irrigation water for Nevada, but it is now being used by 

DFG to raise Lahontan cutthroat trout to stock in other locations 

throughout the Sierra Nevada. Selected sections of the upper 

Carson River tributaries are managed by DFG as wild trout 

waters, where stocking of hatchery fish is not allowed. The goal 

of these efforts is to maintain and preserve the trout fishery in 

both the upper Carson and Walker rivers, which are recognized as some of the best trout fishing in the state. 

Relationship with Other Regions

Because the river channels of the Truckee, Carson and Walker 

rivers’ naturally flow into Nevada, a large amount of the 

surface water from these watersheds has historically been 

reserved for use by Nevada interests under various interstate 

water rights settlements and agreements. Most of the surplus 

flows from these three rivers also flow into Nevada, where it 

is used for a variety of purposes. There are two small historic 

exports of surface water out of the North Lahontan hydrologic 

region to the Sacramento River region. At Echo Lakes in the 

upper Lake Tahoe Basin, an average of about 2,000 acre-feet 

per year is exported through a tunnel into the south fork of 

the American River in conjunction with a hydroelectric power 

development that began in 1876. Another water export of 

about 6,000 acre-feet per year is taken from the upper reaches 

of the Little Truckee River for irrigation use in Sierra Valley (a 

part of the Feather River Basin within the Sacramento River 

region). Near the southern end of the North Lahontan region 

another small water diversion exists, providing surface water 

from the upper tributaries of the Walker River to the Mono 

Lake Basin for summer irrigation purposes. 

The only water import into the North Lahontan region occurs 

in northern Lassen County, where an average of about 3,000 

acre-feet is imported from a tributary of the South Fork Pit 

River (Sacramento River Region) for irrigation in the Madeline 

Plains area.

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9 8 Volume 3 Regional Reports

Looking to the Future

The northern part of this hydrologic region contains portions of 

Modoc, Lassen and Sierra counties, in which no major changes 

in water use are anticipated in the near future. A small amount 

of agricultural expansion may be possible in areas that can 

support additional groundwater development. Likewise, the 

modest need for additional municipal and irrigation supplies 

can be met by some expansion of present surface systems or 

by increased use of groundwater. 

Concern for protecting the limited groundwater resources of 

the region has led to establishment of formal groundwater 

management programs in the Honey Lake and Long Valley 

basins. In Modoc County, similar groundwater proposals are 

being considered for the Surprise Valley region. At present, 

neither the Honey Lake nor Long Valley groundwater management districts are active, but can be activated when needed. In 

the Lake Tahoe and Truckee River basins, the proposed Truckee 

River Operating Agreement (TROA) interstate allocation would 

also establish limits on groundwater procedures and withdrawal 

limits from these areas.

The interstate surface waters of the Truckee, Carson and Walker 

rivers are controlled by federal watermasters according to 

existing federal court decrees. Each of these legal decrees may 

be revised to some degree within the next decade, as a result 

of TROA implementation on the Truckee River and through 

mediation regarding the Walker River water uses. Since further 

water development in these basins may be limited, especially in 

Nevada, water transfers are expected to play an increasing role 

to meet changing and higher-priority needs. In Nevada, such 

water transfers have already occurred through the acquisition 

of agricultural lands and water rights which are then transferred 

to meet municipal needs in Reno/Sparks region. 

Within the Placer and Nevada county portions of the North 

Lahontan region, several large residential and commercial 

developments are being proposed for the Truckee and Martis 

Valley regions. If these developments are completed, it is likely 

that significant new demands will be placed on the groundwater supplies and sewage disposal capabilities of this region. 

Water Portfolios for Water 

Years 1998, 2000, and 2001

Water year 1998 was a wet year for this region, with annual 

precipitation at 142 percent of normal, while the statewide 

annual precipitation was 171 percent of average. Year 2000 

represents approximately normal hydrologic conditions with 

annual precipitation at 89 percent of average for the North 

Lahontan region. 2001 reflected dry-water-year conditions with 

annual precipitation at 49 percent of average. For comparison, 

statewide average precipitation in year 2001 was 72 percent 

of normal. Table 9-1 provides more detailed information about 

the total water supplies available to this region for these three 

specific years from precipitation, imports and groundwater, and 

also summarizes the uses of all of the water supplies. The data 

in Table 9-1 shows that more water from these three interstate 

rivers flows into Nevada than is consumptively used in the North 

Lahontan region.

A more detailed tabulation of the dedicated portion of the 

total available water used for urban, agricultural and environmental purposes is presented in Table 9-2. Because most of 

the North Lahontan region is largely undeveloped, dedicated 

environmental water uses are a larger component of the total 

developed water uses in this region. Table 9-2 also provides 

detailed information about the sources of the developed water 

supplies, which are obtained from a mix of both surface water 

and groundwater supplies. The water portfolio tables at the 

end of this chapter summarize the detailed regional water 

accounting for all agricultural, urban and dedicated environmental water uses of the region. Graphical representations 

of the regions water supplies and uses are also presented in 

the water portfolio diagrams in Figures 9-4 and 9-5. 

Selected References

2002 California 305(b) Report on Water Quality, State 

Water Resources Control Board 

California’s Groundwater Bulletin 118-03, Update 2003, 

California Department of Water Resources 

Nonpoint Source Program Strategy and Implementation Plan, 

1998-2013, State Water Resources Control Board, California 

Coastal Commission, January 2000 

Strategic Plan, State Water Resources Control Board, Regional 

Water Quality Control Boards, November 15, 2001 

Truckee River Operation Agreement, Draft October 2003 

Water Quality Control Plan, Regional Water Quality 

Control Board 

Watershed Management Initiative Chapter, Regional Water 

Quality Control Board

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Chapter 9 North Lahontan Hydrologic Region 9 9

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Water Entering the Region 

Precipitation 10,655 6,708 3,756

 Inflow from Oregon/Mexico 0 0 0

 Inflow from Colorado River 0 0 0

 Imports from Other Regions 3 3 3

Total 10,658 6,711 3,759

Water Leaving the Region 

Consumptive Use of Applied Water * 263 327 307

 (Ag, M&I, Wetlands) 

 Outflow to Nevada 1,391 754 552

 Exports to Other Regions 12 12 9

 Statutory Required Outflow to Salt Sink 180 141 113

 Additional Outflow to Salt Sink 83 92 92

 Evaporation, Evapotranspiration of Native 

 Vegetation, Groundwater Subsurface Outflows, 8,572 5,493 3,223

 Natural and Incidental Runoff, Ag Effective 

 Precipitation & Other Outflows 

Total 10,501 6,819 4,296

Storage Changes in the Region

 [+] Water added to storage

 [-] Water removed from storage 

 Change in Surface Reservoir Storage 147 -66 -430

 Change in Groundwater Storage ** 10 -42 -107

Total 157 -108 -537

Applied Water * (compare with Consumptive Use) 432 524 490

*Footnote for applied water

Consumptive use is the amount of applied water used and no longer available as a source of supply. Applied water is 

 greater than consumptive use because it includes consumptive use, reuse, and outflows. 

**Footnote for change in Groundwater Storage

Change in Groundwater Storage is based upon best available information. Basins in the north part of the 

state (North Coast, San Francisco, Sacramento River and North Lahontan regions and parts of Central 

 Coast and San Joaquin River regions) have been modeled – spring 1997 to spring 1998 for the 1998 

 water year and spring 1999 to spring 2000 for the 2000 water year. All other regions and year 2001 were 

 calculated using the following equation: 

GW change in storage =

 intentional recharge + deep percolation of applied water + conveyance deep percolation - withdrawals

This equation does not include the unknown factors such as natural recharge and subsurface inflow and outflow.

 Water Year (Percent of Normal Precipitation) 

1998 (142%) 2000 (89%) 2001 (49%)

Table 9-1 North Lahontan Hydrologic Region Water Balance Summary - TAF

Water Entering the Region – Water Leaving the Region = Storage Changes in Region

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9 10 Volume 3 Regional Reports

 Applied Net Depletion Applied Net Depletion Applied Net Depletion

Water Use Water Use Water Use Water Use Water Use Water Use

1998 2000 2001

WATER USE

DEDICATED WATER SUPPLIES

Table 9-2 North Lahontan Hydrologic Region Water Use and Distribution of Dedicated Supplies (TAF)

Urban

Large Landscape 2.3 2.6 2.6

Commercial 9.0 9.7 9.3

Industrial 12.5 12.5 12.5

Energy Production 0.0 0.0 0.0

Residential - Interior 7.9 9.0 8.7

Residential - Exterior 6.2 6.3 7.2

Evapotranspiration of Applied Water 8.8 8.8 8.7 8.7 9.4 9.4

Irrecoverable Losses 0.0 0.0 0.0 0.0 0.0 0.0

Outflow 14.9 14.9 16.1 16.1 16.5 16.5

Conveyance Losses - Applied Water 0.0 0.0 0.0

Conveyance Losses - Evaporation 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Losses - Irrecoverable Losses 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Losses - Outflow 0.0 0.0 0.0 0.0 0.0 0.0

GW Recharge Applied Water 0.0 0.0 0.0

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Urban Use 37.9 23.7 23.7 40.1 24.8 24.8 40.3 25.9 25.9

Agriculture

On-Farm Applied Water 375.1 462.4 428.4

Evapotranspiration of Applied Water 241.1 241.1 301.3 301.3 281.1 281.1

Irrecoverable Losses 19.5 19.5 20.2 20.2 12.5 12.5

Outflow 66.8 66.8 75.8 75.8 74.7 74.7

Conveyance Losses - Applied Water 23.5 13.4 6.2

Conveyance Losses - Evaporation 2.3 2.3 1.7 1.7 1.0 1.0

Conveyance Losses - Irrecoverable Losses 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Losses - Outflow 1.5 1.5 1.1 1.1 0.0 0.0

GW Recharge Applied Water 0.0 0.0 0.0

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Agricultural Use 398.6 331.2 331.2 475.8 400.1 400.1 434.6 369.3 369.3

Environmental

Instream

 Applied Water 84.6 85.0 84.5

 Outflow 84.6 84.6 85.0 85.0 84.5 84.5

Wild & Scenic

 Applied Water 404.1 233.3 152.5

 Outflow 95.6 95.6 56.2 56.2 28.7 28.7

Required Delta Outflow

 Applied Water 0.0 0.0 0.0

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Managed Wetlands

 Habitat Applied Water 18.7 25.9 20.5

 Evapotranspiration of Applied Water 13.2 13.2 19.8 19.8 16.9 16.9

 Irrecoverable Losses 0.2 0.2 0.3 0.3 0.2 0.2

 Outflow 0.0 0.0 0.6 0.6 0.0 0.0

 Conveyance Losses - Applied Water 0.0 0.0 0.0

 Conveyance Losses - Evaporation 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Losses - Irrecoverable Losses 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Losses - Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Total Managed Wetlands Use 18.7 13.4 13.4 25.9 20.7 20.7 20.5 17.1 17.1

 Total Environmental Use 507.4 193.6 193.6 344.2 161.9 161.9 257.5 130.3 130.3

TOTAL USE AND LOSSES 943.9 548.5 548.5 860.1 586.8 586.8 732.4 525.5 525.5

Surface Water

 Local Deliveries 501.4 501.4 501.4 469.5 469.5 469.5 311.8 311.8 311.8

 Local Imported Deliveries 0.3 0.3 0.3 0.3 0.3 0.3 3.3 3.3 3.3

 Colorado River Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 CVP Base and Project Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 Other Federal Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 SWP Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 Required Environmental Instream Flow 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Groundwater

 Net Withdrawal 41.8 41.8 41.8 112.0 112.0 112.0 189.6 189.6 189.6

 Artificial Recharge 0.0 0.0 0.0

 Deep Percolation 46.7 49.6 45.3

Reuse/Recycle

 Reuse Surface Water 348.7 223.7 161.6

 Recycled Water 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0

TOTAL SUPPLIES 943.9 548.5 548.5 860.1 586.8 586.8 716.6 509.7 509.7

Balance = Use - Supplies 0.0 0.0 0.0 0.0 0.0 0.0 -15.8 -15.8 -15.8

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Water Portfolios

North Lahontan Hydrologic Region

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Table 9-3 North Lahontan region water portfolio (TAF)

 ID North Lahontan North Lahontan North Lahontan

Number: Flow Diagram Component (see legend) 1998 2000 2001

 1 Colorado River Deliveries - - -

 2 Total Desalination - - -

 3 Water from Refineries - - -

 4a Inflow From Oregon - - -

 b Inflow From Mexico - - -

 5 Precipitation 10,654.6 6,708.3 3,755.9

 6a Runoff - Natural N/A N/A N/A

 b Runoff - Incidental N/A N/A N/A

 7 Total Groundwater Natural Recharge N/A N/A N/A

 8 Groundwater Subsurface Inflow N/A

 9 Local Deliveries 501.1 464.6 381.9

 10 Local Imports 0.3 0.3 0.3

 11a Central Valley Project :: Base Deliveries - - -

 b Central Valley Project :: Project Deliveries - - -

 12 Other Federal Deliveries - - -

 13 State Water Project Deliveries - - -

 14a Water Transfers - Regional - - -

 b Water Transfers - Imported - - -

 15a Releases for Delta Outflow - CVP 

 b Releases for Delta Outflow - SWP 

 c Instream Flow Applied Water 84.6 85.0 84.5

 16 Environmental Water Account Releases - - -

 17a Conveyance Return Flows to Developed Supply - Urban - - -

 b Conveyance Return Flows to Developed Supply - Ag - - -

 c Conveyance Return Flows to Developed Supply - Managed Wetlands - - -

 18a Conveyance Seepage - Urban - - -

 b Conveyance Seepage - Ag 5.8 3.6 2.1

 c Conveyance Seepage - Managed Wetlands - - -

 19a Recycled Water - Agriculture 5.0 5.0 5.0

 b Recycled Water - Urban - - -

 c Recycled Water - Groundwater - - -

 20a Return Flow to Developed Supply - Ag - - -

 b Return Flow to Developed Supply - Wetlands - - -

 c Return Flow to Developed Supply - Urban - - -

 21a Deep Percolation of Applied Water - Ag 19.8 28.9 29.3

 b Deep Percolation of Applied Water - Wetlands 0.3 0.4 0.3

 c Deep Percolation of Applied Water - Urban 12.8 13.3 12.6

 22a Reuse of Return Flows within Region - Ag 27.9 36.2 30.8

 b Reuse of Return Flows within Region - Wetlands, Instream, W&S 313.5 181.9 126.9

 24a Return Flow for Delta Outflow - Ag - - -

 b Return Flow for Delta Outflow - Wetlands, Instream, W&S - - -

 c Return Flow for Delta Outflow - Urban Wastewater - - -

 25 Direct Diversions N/A N/A

 26 Surface Water in Storage - Beg of Yr 853.2 903.5 837.6

 27 Groundwater Extractions - Banked - - -

 28 Groundwater Extractions - Adjudicated - - -

 29 Groundwater Extractions - Unadjudicated 88.8 162.0 183.8

 23 Groundwater Subsurface Outflow N/A N/A N/A

 30 Surface Water Storage - End of Yr 1,000.0 837.6 407.8

 31 Groundwater Recharge-Contract Banking - - -

 32 Groundwater Recharge-Adjudicated Basins - - -

 33 Groundwater Recharge-Unadjudicated Basins - - -

 34a Evaporation and Evapotranspiration from Native Vegetation N/A N/A N/A

 b Evaporation and Evapotranspiration from Unirrigated Ag N/A N/A N/A

 35a Evaporation from Lakes 294.6 313.6 317.6

 b Evaporation from Reservoirs 175.5 213.7 267.6

 36 Ag Effective Precipitation on Irrigated Lands 62.6 32.5 12.2

 37 Agricultural Water Use 374.8 457.6 428.4

 38 Managed Wetlands Water Use 18.7 25.9 20.5

 39a Urban Residential Use - Single Family - Interior 3.2 4.3 3.6

 b Urban Residential Use - Single Family - Exterior 5.2 5.0 5.8

 c Urban Residential Use - Multi-family - Interior 4.0 4.3 4.6

 d Urban Residential Use - Multi-family - Exterior 1.0 1.1 1.2

 40 Urban Commercial Use 8.3 9.0 8.5

 41 Urban Industrial Use 14.3 14.3 14.4

 42 Urban Large Landscape 2.2 2.4 2.5

 43 Urban Energy Production - - -

 44 Instream Flow 84.6 85 84.5

 45 Required Delta Outflow - - -

 46 Wild and Scenic Rivers 95.6 56.2 28.7

 47a Evapotranspiration of Applied Water - Ag 241.1 298.2 281.1

 b Evapotranspiration of Applied Water - Managed Wetlands 13.2 19.8 16.9

 c Evapotranspiration of Applied Water - Urban 8.6 8.5 9.2

 48 Evaporation and Evapotranspiration from Urban Wastewater - - -

 49 Return Flows Evaporation and Evapotranspiration - Ag 19.5 20.2 12.5

 50 Urban Waste Water Produced 25.1 27 27.1

 51a Conveyance Evaporation and Evapotranspiration - Urban - - -

 b Conveyance Evaporation and Evapotranspiration - Ag 2.3 1.7 1

 c Conveyance Evaporation and Evapotranspiration - Managed Wetlands 0.2 0.3 0.2

 d Conveyance Outflow to Mexico N/A

 52a Return Flows to Salt Sink - Ag 68 75.2 74.7

 b Return Flows to Salt Sink - Urban 15.3 16.6 16.9

 c Return Flows to Salt Sink - Wetlands - 0.6 -

 53 Remaining Natural Runoff - Flows to Salt Sink 180.2 141.2 113.2

 54a Outflow to Nevada 1390.6 753.9 551.9

 b Outflow to Oregon - - -

 c Outflow to Mexico - - -

 55 Regional Imports 3.0 3.3 3.3

 56 Regional Exports 11.9 11.8 10

 59 Groundwater Net Change in Storage 9.8 -41.5 -107.2

 60 Surface Water Net Change in Storage 146.8 -65.9 -429.8

 61 Surface Water Total Available Storage 1,181.2 1,181.2 1,181.2

 

 Inflows Outflows Green number signifies included in summary boxes 

EE-RM-PET-100 C0MMENT 01A
Figure 9-4 North Lahontan region - illustrated water flow diagram

INFLOWS

SUMMARY

OUTFLOWS

8

15a,b

21

27

31

45

48

51

5

6

46

14 16

33

28

29

32

39- 43

59

50

18

9

51

34

47b

38

35

51

26

30

60

61

11

12

13

15c

54

56

7

1

4

55

10 44

36

47a

49

51

37

17

20

47c

22

25 24

31

23

2

3

52

53

19

In this illustration of Table 9-3, key components of the flow diagram are shown as characteristic elements of the hydrologic cycle. Circled numbers correspond to the identification number of flow diagram components in the table; its color indicates whether the component is water input, output, or summary.

52

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EE-RM-PET-100 C0MMENT 01A
SUMMARY

OUTFLOWS

INFLOWS

Figure 9-5 North Lahontan region - schematic flow diagram

In schematic of Table 9-3, key components of the flow diagram are shown as boxes and connectors in a flow chart. Circled numbers correspond to the identification number of flow diagram components in the table; box color indicates whether the component is water input, output or summary. 

Blank boxes are flow diagram components not relevant to the region. 

WILD & SCENIC RIVERS NET 

USE:

RUNOFF:

NATURAL: INCIDENTAL: 

PRECIPITATION: TOTAL STREAM 

FLOW: 

AG EFFECTIVE 

PRECIPITATION ON 

IRRIGATED LANDS: 

LOCAL IMPORTED 

DELIVERIES:

LOCAL 

DELIVERIES:

WATER DEPOSITS: 

SURFACE WATER: 

GROUNDWATER: 

RECYL & DESAL: 

TRANSFERS:

TOTAL GROUNDWATER NATURAL RECHARGE: 

GROUNDWATER CHANGE IN STORAGE: 

BANKED:

ADJUDICATED: 

UNADJUDICATED: 

GW EXTRACTIONS: 

CONTRACT BANKS: 

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

EVAPOTRANSPIRATION 

OF APPLIED WATER: 

AG:

WETLANDS:

URBAN:

WATER USE (APPLIED): 

AGRICULTURAL: 

WETLANDS:

URBAN:

RECYCLED WATER: 

AG: URBAN:

GW: 

URBAN

WASTEWATER 

PRODUCED:

INCIDENTAL E & ET 

AG RETURN FLOWS: 

AG & WETLANDS 

RETURN FLOWS:

RETURN FLOWS TO SALT 

SINKS:

AG: WETLANDS:

URBAN:

REMAINING NATURAL 

RUNOFF

FLOW TO SALT SINKS: 

OUTFLOW TO NEVADA: 

DEEP PERC OF APPLIED 

WATER: 

AG: WETLANDS:

URBAN:

RETURN FLOW TO 

DEVELOPED

SUPPLY: 

AG:

WETLANDS:

URBAN:

EVAP FROM: 

LAKES:

RESERVOIRS: 

E & ET FROM: 

NATIVE VEGETATION: 

UNIRRIGATED AG: 

RELEASES FOR 

INSTREAM USE: 

CONVEYANCE E&ET, 

RETURN FLOWS, & 

SEEPAGE:

URBAN: AG: 

WETLANDS:

CONVEYANCE E & ET: 

URBAN: AG: 

WETLANDS:

CONVEYANCE RETURN 

FLOWS:

URBAN: AG: 

WETLANDS:

CONVEYANCE SEEPAGE: 

URBAN: AG: 

WETLANDS:

RETURN FLOW FOR 

DELTA OUTFLOW: 

AG:

WETLANDS:

URBAN : 

EVAPORATION AND EVAPOTRANSPIRATION OF APPLIED WATER, 

PRECIPITATION AND CONVEYANCE: 

GW RECHARGE:

CONTRACT BANKING: 

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

TO E & ET: 

SUBSURFACE GW 

INFLOW: 

SUBSURFACE 

GROUNDWATER 

OUTFLOW: 

#REF!

REGIONAL 

TRANSFER IN: 

INSTREAM NET USE: 

SURFACE WATER IN 

STORAGE: 

 Beg of Yr: 

End of Yr: 

DIRECT 

DIVERSIONS:

Service Area

Return 

Flow within

Return of

Required Instream 

Flows

Return of

Required Wild & 

Scenic Flows

1

2

5

4

3

55

6

13

11

19

12

10

9

7

20

21

45

29

26

30

35

39 to 43

37

38

53

54

46

14

34 36

28

52

16

24

17

18

25

47

50

49

48

27

31

32

33

23

8

15C

15A

15B

56

44

16

51

22

9 14 Chapter 9 North Lahontan Region Volume 3 Regional Reports

California Water Plan Update 2005

EE-RM-PET-100 C0MMENT 01A
Chapter 10 South Lahontan Hydrologic Region 

Volume 3 

EE-RM-PET-100 C0MMENT 01A
Chapter 10 South Lahontan Hydrologic Region 10 i

California Water Plan Update 2005

Chapter 10 South Lahontan Hydrologic Region

Contents

Chapter 10 South Lahontan Hydrologic Region .......................................................................................................10-1 

Setting ............................. 10-1

Climate ............................ 10-1

Population ....................... 10-2

Land Use ......................... 10-2

Water Supply and Use ...... 10-2

State of the Region ........... 10-5 

 Challenges .................. 10-5

 Accomplishments ......... 10-8

Relationship with Other Regions ........................................................................................................................10-9

Looking to the Future ........ 10-9

Regional Planning ............ 10-9

Water Portfolios for Water Years 1998, 2000, and 2001 ..................................................................................10-11

 Water Year 1998 ....... 10-11

 Water Year 2000 ....... 10-11

 Water Year 2001 ....... 10-11

Selected References ........ 10-12

Boxes

Box 10-1 Death Valley Temperatures .....................................................................................................................10-1

Box 10-2 Mojave River Adjudication .....................................................................................................................10-9

Figures

Figure 10-1 South Lahontan Hydrologic Region (map) ............................................................................................ 10-ii

Figure 10-2 South Lahontan Hydrologic Region population .....................................................................................10-4

Figure 10-3 South Lahontan region water balance for water years 1998, 2000, 2001 (2 bar charts) .........................10-6

Figure 10-4 South Lahontan region - illustrated water flow diagram .......................................................................10-15

Figure 10-5 South Lahontan region - schematic flow diagram ................................................................................10-16

Tables

Table 10-1 South Lahontan Hydrologic Region water balance summary ...................................................................10-3

Table 10-2 South Lahontan Hydrologic Region water use and distribution of dedicated supplies .................................10-7

Table 10-3 South Lahontan region water portfolios ...............................................................................................10-14

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California Water Plan Update 2005

Flow in TAF

1998

917

2000

1,509

2001

1065

Tulare Lake Region

California Aqueduct (SWP)

Flow in TAF

1998

1

2000

1

2001

1

North Lahontan Region

Virginia Creek

Flow in TAF

1998

1,286

2000

1,695

2001

1,255

South Coast Region

Los Angeles Aqueduct

California Aqueduct (SWP)

Some Statistics

Area -26,732 square miles (16.9% of State)

 Average annual precipitation - 7.8 inches

 Year 2000 population - 721,490

 2030 population projection - 1,266,375

 Total reservoir storage capacity - 459 TAF

 2000 irrigated crop area - 65,080 acres

.

.

.

.

.

.

INYO

KERN

LOS ANGELES

SAN BERNARDINO

MONO

Figure10-1 South Lahontan Hydrologic Region

The South Lahontan Hydrologic Region contains the Eastern Sierra and the Mojave Desert and includes both the highest point (Mount Whitney) 

and lowest point (Death Valley) in the lower 48 states. Arrows indicate annual flows entering and leaving the region for water years 1998, 

2000, and 2001. 

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Chapter 10 South Lahontan Hydrologic Region 10 1

California Water Plan Update 2005

Chapter 10 South Lahontan Hydrologic Region

any significant agricultural areas. The floodwaters eventually 

flow south to a low-lying area near Silver Lake and Soda 

Lake, which is also the terminus for the Mojave River. 

Climate

The climate of the South Lahontan region is generally arid. 

Annual average precipitation is less than 10 inches, except 

for the higher mountains. Annual average precipitation in the 

higher elevations of the Sierra Nevada ranges from 25 to 50 

inches, which can generate significant snow accumulations 

for spring runoff. Some of the central and eastern portions of 

the Mojave Desert average 4 inches of precipitation annually. 

Death Valley receives a little less than 2 inches of rain on the 

average, but just a few tenths of an inch falls in some years (see 

Box 10-1). Daytime temperatures in the winter are generally 

cold in the mountains and mild in the desert valleys.

Precipitation for the region is summarized as part of regional 

water uses and supplies for recent years 1998, 2000 and 

2001 in Table 10-1. Year 1998 was a very wet year in the 

South Lahontan region with 188 percent of normal precipitation (compared to 171 percent statewide). For year 2000 

statewide precipitation was average (97 percent of normal), 

but the South Lahontan region was very dry with only 66 

percent of normal precipitation. In the generally dry year 

2001, the annual precipitation in this region was 91 percent 

of normal, while the statewide amounts averaged 72 percent 

of normal precipitation. 

Setting

Although the South Lahontan hydrologic region brings to mind 

images of desert with Joshua trees, sand dunes, and dry lakes, 

it also contains the glacier-carved topography of the eastern 

slopes of the Sierra Nevada and the eastern slopes of the San 

Gabriel and San Bernardino mountains. The northern half of 

the region includes Mono Lake, Owens Valley, Panamint Valley, 

Death Valley, and the Amargosa River Valley. The Mojave Desert 

occupies the southern half of the region, and is characterized 

by many small mountain ranges and valleys with playas, or dry 

lakes. The region has the highest and lowest elevation points in 

the continental United States: Mount Whitney with an elevation 

of 14,495 feet and Death Valley at 282 feet below sea level. 

The region includes all of Inyo County and parts of Mono, San 

Bernardino, Kern, and Los Angeles counties (Figure 10-1).`

The South Lahontan region has fewer permanent rivers and 

streams due to the dryer hydrology on the east side of the 

Sierra Nevada. The largest river in this region is the Owens 

River, which flows from north to south over the length of 

Owens Valley. This river drains both the east side of the Sierra 

Nevada and the western slopes of the White Mountain range, 

and flowed into Owens Lake until 1913, when most of its flow 

was diverted for use in Los Angeles. Another important river 

in the region is the Mojave River. Although seldom seen flowing on the surface, it has significant underground flow that 

supports nearly all the groundwater-supplied agriculture and 

urban population in the Mojave River Valley. The Amargosa 

River is the only other significant river in the region, but it only 

generates surface flows during flash floods and does not serve 

Box 10-1 Death Valley Temperatures

Death Valley experiences an oven-hot environment in the summer, when daytime maximum temperatures routinely 

reach the 110s and low 120s. Most seasons even see a few searing days with temperatures reaching the middle and 

upper 120s. A reading of 134 degrees was attained on a July day in 1913, the record for the western hemisphere. 

EE-RM-PET-100 C0MMENT 01A
California Water Plan Update 2005

10 2 Volume 3 Regional Reports

Population

Although the South Lahontan region covers 16.9 percent of the 

land mass of the state, its year 2000 population was 721,490, 

roughly 2 percent of California’s total population. Nearly 

450,000 people now live in the southern portion of the region, 

in the areas of Antelope, Apple, and Victor valleys. The cities of 

Palmdale and Lancaster were among the fastest-growing cities 

in the state in the 1990s. Rapid population growth is projected 

to continue over the next 25 years, based on projections from 

the State department of Finance. Figure 10-2 provides a graphical depiction of the South Lahontan region’s total population 

from 1960 through 2000, with current projections to 2030. 

Land Use

The region supports a variety of urban and agricultural 

uses, including a moderate amount of agricultural acreage 

and several growing cities. Much of the land in the region 

remains undeveloped and is under protected or managed 

status for recreational, scenic, environmental, or military 

purposes. Even though 18,000 acres in the Antelope Valley 

remain agriculturally productive, that area and Victor Valley 

have now become highly urbanized. Other than these two 

valleys and the cities of Barstow and Ridgecrest, the rest of 

the region is rural and generally consists of widely scattered 

small towns with populations of less than 8,000. Agricultural 

land uses are concentrated in the Antelope and Owens valleys 

and along the Mojave River. Of the 65,000 acres of crops 

harvested in 2000, alfalfa and pasture grass constituted 

about 75 percent of the total acreage, while truck crops, 

mostly carrots and onions, represent about 12 percent. 

Water Supply and Use

The Los Angeles Aqueduct is the region’s major water development feature. In 1913, the initial 223-mile-long aqueduct was 

completed by the Los Angeles Department of Water and Power 

(LADWP) and began transporting water from Owens Valley to 

the city of Los Angeles. The aqueduct was extended 115 miles 

The northern half of the South Lahontan region includes Mono Lake (in photo), Owens Valley, Panamint Valley, Death Valley, and the Amargosa River Valley. 

The Mojave Desert occupies the southern half of the region. (DWR photo)

EE-RM-PET-100 C0MMENT 01A
Chapter 10 South Lahontan Hydrologic Region 10 3

California Water Plan Update 2005

Water Entering the Region 

Precipitation 20,409 7,476 9,741

 Inflow from Oregon/Mexico 0 0 0

 Inflow from Colorado River 0 0 0

 Imports from Other Regions 918 1,510 1,066

Total 21,327 8,986 10,807

Water Leaving the Region 

Consumptive Use of Applied Water * 259 321 316

 (Ag, M&I, Wetlands) 

 Outflow to Oregon/Nevada/Mexico 0 0 0

 Exports to Other Regions 1,286 1,695 1,255

 Statutory Required Outflow to Salt Sink 80 67 58

 Additional Outflow to Salt Sink 111 150 126

 Evaporation, Evapotranspiration of Native 

 Vegetation, Groundwater Subsurface Outflows, 19,745 7,055 9,352

 Natural and Incidental Runoff, Ag Effective 

 Precipitation & Other Outflows 

 Total 21,481 9,288 11,107

Storage Changes in the Region 

[+] Water added to storage

 [-] Water removed from storage 

 Change in Surface Reservoir Storage 72 -8 -1

 Change in Groundwater Storage ** -226 -294 -299

 Total -154 -302 -300

Applied Water * (compare with Consumptive Use) 480 612 570

*Footnote for applied water

Consumptive use is the amount of applied water used and no longer available as a source of supply. Applied water is 

 greater than consumptive use because it includes consumptive use, reuse, and outflows. 

**Footnote for change in Groundwater Storage

Change in Groundwater Storage is based upon best available information. Basins in the north part of the 

state (North Coast, San Francisco, Sacramento River and North Lahontan regions and parts of Central 

 Coast and San Joaquin River regions) have been modeled – spring 1997 to spring 1998 for the 1998 

 water year and spring 1999 to spring 2000 for the 2000 water year. All other regions and year 2001 were 

 calculated using the following equation: 

GW change in storage =

 intentional recharge + deep percolation of applied water + conveyance deep percolation - withdrawals

This equation does not include the unknown factors such as natural recharge and subsurface inflow and outflow.

 Water Year (Percent of Normal Precipitation) 

1998 (188%) 2000 (66%) 2001 (91%)

Table 10 -1 South Lahontan Hydrologic Region water balance summary - TAF

Water Entering the Region – Water Leaving the Region = Storage Changes in Region

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10 4 Volume 3 Regional Reports

north into the Mono Basin in 1940 and additional water was 

diverted. A second, 137-mile-long pipeline was completed in 

1970. More recently, exports have been modifi ed and reduced 

as a result of litigation to preserve Mono Lake and to mitigate 

the dust problems that resulted from the diversion of water 

from Owens Lake.

There are eight small reservoirs in the Los Angeles Aqueduct 

system with a combined storage capacity of about 323,000 

acre-feet. These reservoirs were built to store and regulate 

fl ows in the aqueduct. The northernmost reservoir is Grant Lake 

in Mono County. Six of the eight reservoirs are in the South 

Lahontan region. Bouquet and Los Angeles Reservoirs are in 

the South Coast region. Water from the aqueduct system passes 

through 12 hydropower plants on its way to Los Angeles. The 

annual energy generated is more than 1 billion kilowatt-hours, 

enough to supply the needs of 220,000 homes.

The only dam on the Mojave River, at the base of the San Bernardino Mountains, is the Mojave River Forks Dam. This U.S. 

Corps of Engineers fl ood control facility provides a maximum reservoir storage capacity of 179,400 acre-feet. The lower Mojave 

River is seldom seen fl owing on the earth’s surface. Instead it exists 

as groundwater underfl ow which supports much of the agriculture crops and urban population in the Mojave River Valley.

Groundwater provides about 41 percent of the average annual 

water supply in the region. Groundwater is used conjunctively 

with surface water in the more heavily pumped basins. Seventysix groundwater basins underlie about 55 percent of this hydrologic region. The total estimated demand met by groundwater in 

the region is about 239,000 acre-feet, according to the 2003 

update of DWR Bulletin 118 California’s Groundwater. Most 

of the groundwater production is concentrated, along with the 

population, in basins in the southern and western parts of this 

hydrologic region. Many other areas of this hydrologic region 

are designated as public land and have low population density. As such, many of the groundwater basins have not been 

signifi cantly used, and there is thus little data available about 

groundwater volume and quality.

Five water agencies in the southwest portion of this region 

have contracts with the State Water Project for a total of 

about 250,000 acre-feet of surface water annually. The East 

Branch of the SWP California Aqueduct brings imported water 

into the region. Some of this SWP water is used to recharge 

groundwater in the Mojave River Valley. The Mojave Water 

Agency (MWA) has taken little of its SWP contract entitlement 

to date, although that may change in the near future as the 

water agency seeks ways to reduce the over-pumping of the 

groundwater basin. 

Figure 10-2 South Lahontan Hydrologic Region population

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1960 1970 1980 1990 2000 2010 2020 2030

Data from California Department of Finance provide decadal population from 1960 to 2000 and population projection for 2030 

for South Lahontan region.

EE-RM-PET-100 C0MMENT 01A
Chapter 10 South Lahontan Hydrologic Region 10 5

California Water Plan Update 2005

The Mojave Water Agency is developing a Regional Water 

Management Plan Update that will provide a regional framework for managing water resources and ensuring reliable water 

for the future of the MWA desert region. While MWA relies 

predominately on groundwater, it also receives water from the 

California Aqueduct as one of 29 SWP contractors. The RWMP 

Update will address population growth, water demand projections, stakeholder needs and issues, facilities needed to replenish 

groundwater supplies, and revenue alternatives.

Antelope Valley-East Kern Water Agency (AVEK) is the largest 

SWP water contractor in this region and one of the largest in 

the state. AVEK provides water to five major municipal agencies, 

16 smaller water service agencies, Edwards Air Force Base, 

Palmdale Air Force Plant 42, and the U.S. Borax and Chemical 

Facilities. AVEK was formed to bring imported surface water 

from the SWP into this region. 

The 2,700 acre-feet capacity Littlerock Reservoir provides water 

to Littlerock Creek Irrigation District and to Palmdale Water District (PWD). PWD recently funded most of a seismic rehabilitation 

of the original dam (constructed in 1924) in exchange for control 

of the water supply for the next 50 years. Water from Littlerock 

Reservoir is released into a canal that conveys flows to PWD’s 

Lake Palmdale, a 42,000 acre-foot storage reservoir. 

In the San Bernardino Mountains, Lake Arrowhead, owned by 

the Arrowhead Lake Association, is a 48,000 acre-foot reservoir 

providing recreational opportunities and water for Arrowhead 

Woods property owners. Figure 10-3 provides a graphical 

summary of all the water supply sources that are used to meet 

the developed water uses in this hydrologic region for years 

1998, 2000, and 2001.

In the northern part of the South Lahontan region, the town of 

Mammoth Lakes provides water from surface and groundwater 

sources to a permanent population of about 5,000, an average daily population of about 13,000, and a peak weekend 

and holiday period population of up to 30,000 people per 

day. In communities that are popular tourist destinations, 

this pattern of peak population and water use that is several 

times the permanent base level is a common water supply and 

distribution problem. 

Most of the quantified environmental water demands (listed in 

Table 10-3) are in the northern part of this hydrologic region, 

and involve the restoration of the water surface elevation for 

Mono Lake. The required inflows are the result of several years 

of court litigation, and have resulted in improving water surface 

elevations in recent years. Another identified environmental 

water demand involves current and proposed, releases into the 

Owens River to restore flows that were previously intercepted for 

use in Los Angeles after 1913, and for use in restoring surface 

water to Owens Lake. 

Alfalfa produced in the region uses groundwater as the primary 

source of irrigation water. In the Mono and Owens valleys, 

water supplies from the Los Angeles Aqueduct are sometimes 

used for flood irrigation of fields for improved production of 

native pasture grass. Ground and surface water is not the only 

source of water available to grow alfalfa. In the Antelope Valley 

region of Los Angeles County, 680 acres of alfalfa have been 

irrigated for the past 14 years with municipal effluent water. 

The treated water comes from the Lancaster Water Reclamation 

Plant owned and operated by County Sanitation District No. 14 

of Los Angeles County. 

The water balance data shown in Table 10-1 and Table 10-2 

summarize the detailed regional water accounting contained 

in the water portfolio data sets for years 1998, 2000 and 

2001. These tabulated water supplies and uses provide a 

comparison of how the patterns of water use and distribution can change from a very wet year (1998) to a dryer year 

(2000), and for an average water year such as 2001. 

State of the Region

Challenges

Many of the rapidly developing urban parts of this region 

are susceptible to shortfalls in available water supplies. For 

example, a recent study by the Antelope Valley Water Group 

concluded that the valley has low reliability to meet demands 

from existing and future groundwater supplies, the SWP, Littlerock Reservoir, and recycling. The report further stated that 

the region could only expect to meet full 1998 water demands 

about half the time without overdrafting the groundwater 

resources. The capability to meet water demands for projected 

growth and development is a concern for many water agencies 

in the southern portions of the South Lahontan region. There 

is concern that overdrafting the groundwater resources will 

generate adverse environmental impacts, such as diminished 

flows in springs and surface streams that support wildlife.

The quality of the limited surface water resources is excellent 

in the region, and is greatly influenced by snowmelt from 

the eastern Sierra Nevada. However at lower elevations, 

groundwater and surface water quality can be degraded, both 

naturally from geothermal activity, and as a result of activities 

such as recreational uses and cattle grazing. Nutrients entering 

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10 6 Volume 3 Regional Reports

Figure 10-3 South Lahontan region water balance for water years 1998, 2000, 2001

0

100

200

300

400

500

600

700

800

1998 2000 2001

Thousand Acre-Feet

Dedicated

Environ

Reuse &

Recycle

Ground Water

State Project

Local Projects

0

100

200

300

400

500

600

700

800

1998 2000 2001

Thousand Acre-Feet

Instream Flow

Irrigated

Agriculture

Urban

Dedicated Water Supplies

Applied Water Uses

Three years show a marked change in the amount and relative proportions of water delivered to South Lahontan region’s urban and 

agricultural sectors and water dedicated to the environment (applied water, top chart), where the water came from, and how much 

water was reused among sectors (dedicated water supplies, bottom chart).

EE-RM-PET-100 C0MMENT 01A
Chapter 10 South Lahontan Hydrologic Region 10 7

California Water Plan Update 2005

 Applied Net Depletion Applied Net Depletion Applied Net Depletion

Water Use Water Use Water Use Water Use Water Use Water Use

1998 2000 2001

WATER USE

Table 10-2 South Lahontan Hydrologic Region Water Use and Distribution of Dedicated Supplies (TAF)

DEDICATED WATER SUPPLIES

Urban

Large Landscape 8.4 6.6 5.3 

Commercial 27.8 19.0 20.1 

Industrial 8.1 4.7 5.6 

Energy Production 6.3 6.3 6.3 

Residential - Interior 86.4 137.0 113.5 

Residential - Exterior 62.9 77.2 75.3 

Evapotranspiration of Applied Water 71.3 71.3 83.8 83.8 80.6 80.6

E&ET and Deep Perc to Salt Sink 30.5 30.5 40.4 40.4 34.5 34.5

Outflow 32.0 32.0 49.5 49.5 35.6 35.6

Conveyance Applied Water 4.9 5.1 4.8 

Conveyance Evaporation & ETAW 4.9 4.9 5.1 5.1 4.8 4.8

Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Outflow 0.0 0.0 0.0 0.0 0.0 0.0

GW Recharge Applied Water 6.4 12.9 5.6 

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Urban Use 211.2 138.7 138.7 268.8 178.8 178.8 236.5 155.5 155.5

 Agriculture

On-Farm Applied Water 280.6 361.0 344.0 

Evapotranspiration of Applied Water 187.8 187.8 237.7 237.7 235.0 235.0

E&ET and Deep Perc to Salt Sink 5.7 5.7 7.3 7.3 6.7 6.7

Outflow 51.7 51.7 65.4 65.4 60.0 60.0

Conveyance Applied Water 0.0 0.0 0.0 

Conveyance Evaporation & ETAW 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Outflow 0.0 0.0 0.0 0.0 0.0 0.0

GW Recharge Applied Water 0.0 0.0 0.0 

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Agricultural Use 280.6 245.2 245.2 361.0 310.4 310.4 344.0 301.7 301.7

Environmental

Instream

 Applied Water 98.4 88.8 78.4 

 Outflow 79.8 79.8 67.4 67.4 57.8 57.8

Wild & Scenic

 Applied Water 0.0 0.0 0.0 

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Required Delta Outflow

 Applied Water 0.0 0.0 0.0 

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Managed Wetlands

 Habitat Applied Water 0.0 0.0 0.0 

 Evapotranspiration of Applied Water 0.0 0.0 0.0 0.0 0.0 0.0

 E&ET and Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Applied Water 0.0 0.0 0.0 

 Conveyance Evaporation & ETAW 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Total Managed Wetlands Use 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 Total Environmental Use 98.4 79.8 79.8 88.8 67.4 67.4 78.4 57.8 57.8

 

 TOTAL USE AND OUTFLOW 590.2 463.7 463.7 718.6 556.6 556.6 658.9 515.0 515.0 

 

Surface Water

 Local Deliveries 56.6 56.6 56.6 58.1 58.1 58.1 46.8 46.8 46.8

 Local Imported Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 Colorado River Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 CVP Base and Project Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 Other Federal Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 SWP Deliveries 73.1 73.1 73.1 108.0 108.0 108.0 81.9 81.9 81.9

 Required Environmental Instream Flow 79.8 79.8 79.8 67.4 67.4 67.4 57.8 57.8 57.8

Groundwater

 Net Withdrawal 226.2 226.2 226.2 294.1 294.1 294.1 299.0 299.0 299.0

 Deep Percolation of Surface and GW 107.9 140.6 123.3 

Reuse/Recycle

 Reuse Surface Water 18.6 21.4 20.6 

 Recycled Water 28.0 28.0 28.0 29.0 29.0 29.0 29.5 29.5 29.5

TOTAL SUPPLIES 590.2 463.7 463.7 718.6 556.6 556.6 658.9 515.0 515.0

Balance = Use - Supplies 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

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10 8 Volume 3 Regional Reports

Crowley Reservoir, on Owens River south of Mono Lake, have 

contributed to low dissolved oxygen levels in the reservoir. 

Water quality and quantity are inherently related in the Owens 

River watershed because of the large exports of surface and 

groundwater to the city of Los Angeles. Arsenic, a known 

human carcinogen, is a health concern in the basin, and 

therefore, in Los Angeles as well, especially with the recently 

proposed lower drinking water standard for this chemical. The 

vast majority of public water supply wells do meet drinking 

water standards. However, in places where these standards 

are exceeded, it is most often for TDS, fluoride, or boron. 

Several domestic water supply wells in the Barstow area have 

been closed due to historical contamination from industrial 

and domestic wastewater. Three military installations in the 

southwestern part of the region are on the federal Superfund 

National Priorities List because of volatile organic compounds 

and other hazardous contaminants, and the PG&E chromium 

groundwater contamination site in Hinkley is also within this 

region. In its triennial review, the Lahontan Regional Water 

Quality Control Board identified the need for site-specific 

ammonia objectives for Paiute Ponds and Amargosa Creek 

in Los Angeles County. Also, the monitoring and cleanup of 

chromium in groundwater and the cleanup of sites contaminated by mining wastes are additional water quality needs 

for this region.

In the Owens Valley, a restoration project is in operation to 

mitigate for dust generated as a result of the City of Los Angeles 

diverting water from the Owens Lake into its aqueduct. The 

barren playa on Owens Lake at one time regularly exceeded 

federal standards for airborne particulate pollution due to 

the prevailing winds moving across the dry lakebed. After 

years of litigation, the Los Angeles Department of Water and 

Power is using water from the aqueduct to irrigate large tracts 

of lakebed to reduce the dust hazard in the area. To date 

significant reductions in airborne pollution have dramatically 

improved conditions at Owens Lake. The full implementation 

measures are expected to occur by January 2007. 

In the vicinity of Ridgecrest, the Indian Wells Valley Water 

District has been involved in a cooperative study and project 

to alleviate declining groundwater levels and to manage water 

quality problems. The proposal is evaluating the availability 

and use of imported water for groundwater recharge. Studies 

are being conducted to determine where recharge would be 

most feasible. Additional studies will also attempt to determine 

the age and source of deep groundwater aquifers, which 

may contain higher levels of minerals and potential water 

quality issues. 

Accomplishments

The region has developed solutions to two major water issues 

during the past 10 years, which are the overuse of the Mojave 

River Valley groundwater basin and changes to water diversions 

from the Owens River/Mono Basin by the city of Los Angeles. 

The Mojave River groundwater basin was in overdraft since the 

early 1950s, which led to court adjudication in 1996 and the 

appointment of the Mojave Water Agency as the basin watermaster (see Box 3-2). The Los Angeles Department of Water 

and Power is involved with many restoration projects for the 

Owens River and Mono Basin. In 1993, LADWP began final flow 

releases to restore Mono Lake to a water surface elevation of 

6,392 feet. By 2003, Mono Lake elevation had reached 6,382, 

a level where LADWP can export 16,000 acre-feet per year. 

LADWP has developed plans to help ranchers manage grazing 

practices in the Crowley Lake tributary area. The Owens Gorge 

Rewatering Project and the Lower Owens River Project are two 

other significant restoration programs being implemented by 

LADWP to restore the river after 50 years of dewatering. 

In 1994, Mojave Water Agency completed its Morongo Basin 

project, which is a 70-mile pipeline from the East Branch of the 

SWP to the Morongo Basin. This system has a capacity of 100 

cubic feet per second or nearly 72,300 acre-feet per year to 

the Mojave River, and then reduces to a capacity of 15,700 

acre-feet per year to Morongo Basin and Johnson Valley. The 

pipeline allows MWA to bring SWP water into part of its almost 

5,000-square-mile service area. MWA has been delivering 

about 3,500 acre-feet per year to the Hi-Desert Water District 

since completion of the Morongo Basin Pipeline. In 1997, MWA 

began construction of another 61-mile Mojave River Pipeline 

with 67,900 acre-feet per year capacity to bring imported water 

to the Barstow area and neighboring communities downstream 

to the Newberry Springs area. This 61-mile pipeline has been 

built to a recharge facility along the river near the community of 

Daggett. Recharge facilities have also been built along the river 

near the communities of Hodge and Lenwood. When completed, 

the final reaches of the pipeline will extend to a groundwater 

recharge facility in the Newberry Springs area. 

Mojave Water Agency has entered into a creative multiyear 

groundwater banking and exchange agreement with the 

Solano County Water Agency in northern California. During 

any wet year, SCWA can bank up to 10,000 acre-feet of its 

annual SWP water in MWA’s groundwater basin, not to exceed 

a total balance of 20,000 acre-feet. During droughts, SCWA 

can take part of MWA’s SWP water by exchange, using the 

North Bay Aqueduct to divert the water from the SacramentoSan Joaquin Delta. MWA has developed the ability to store 

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Box 10-2 Mojave River Adjudication

The Mojave River Groundwater basin has experienced overdraft since the early 1950s, with the largest increase in 

groundwater overdraft occurring in the 1980s. In January 1996, the Riverside County Superior Court issued a final 

ruling on the adjudication of this basin (the case having been transferred out of San Bernardino County). The court 

ruling confirmed that the area had been in overdraft for decades, and directed that the Mojave Water Agency must 

alleviate overdraft through conservation and the purchase of supplemental water. MWA was appointed as the basin 

watermaster. Some parties challenged the Stipulated Judgment in the 4th District Court of Appeal, which partially 

overturned the Superior Court’s decision. The MWA petitioned the California Supreme Court to accept review of the 

Court of Appeal’s decision, which resulted in the case being heard by the California Supreme Court in August 2000. 

The higher court affirmed the stipulated judgment with regard to the parties involved, but determined that some of the 

appellants held overlying water rights that are not subject to the judgment. Consequently, this final judgment has been 

implemented in the Mojave Basin Area.

The adjudication stipulated that any party pumping more than 10 acre-feet per year of groundwater must become 

a party to the judgment and be bound by it. The judgment stated that each party has a right to its base annual 

groundwater production, which was determined from the highest usage between 1986 and 1990. The judgment also 

required the watermaster to initially reduce this amount by at least 5 percent each year for four years as one way to 

achieve a physical solution to the longstanding overdraft. Any party exceeding its annual allotment must purchase 

replenishment water from MWA or from other parties to the judgment. If there is still overdraft after the end of the first 

five years of the judgment, water use in overdrafted subareas will be further reduced. The judgment recognized five 

basin subareas and required that if an upstream subarea does not meet its water obligation to a downstream subarea, 

then the upstream area must pay for supplemental water. 

more imported supplies in the Mojave River Basin at MWA’s 

Rock Springs groundwater recharge facility and is considering more recharge facilities in other areas. Several other 

districts are also studying potential groundwater recharge 

and exchange projects. Funds from loan and grant programs, 

especially for drought relief, will play an important role in the 

continued development of water projects for this region. 

Relationship with Other Regions

While most of Mojave Water Agency’s service area is in the 

South Lahontan region, a portion of its service area does 

extend into the Colorado River Hydrologic Region (Lucerne 

and Johnson valleys and the Morongo Basin). This includes the 

community of Yucca Valley, which has an allocation for up to 

7,200 acre-feet of MWA’s surface water from the SWP.

As described in previous sections, imported State Water 

Project water is used to recharge groundwater supplies in 

the Mojave River Valley basins. Some of these surface water 

and groundwater supplies are also exported from the Owens 

and Mono portions of South Lahontan Hydrologic Region 

to the South Coast Hydrologic Region by the Los Angeles 

Department of Water and Power, using the Los Angeles 

Aqueduct. Recent exports through these facilities to the South 

Coast region were 442,000 acre-feet in 1998, 294,000 

acre-feet in year 2000, and 272,000 acre-feet in 2001. 

Looking to the Future

To address the needs of expanding urban areas in the southern 

portion of the region, many water districts have taken a proactive approach to the water reliability problems by initiating 

studies and projects that could provide partial or complete 

solutions. These include water conservation programs, water 

recycling projects, groundwater exchanges and recovery, 

water marketing, and other water supply augmentation strategies. Agricultural practices and water uses in rural areas are 

anticipated to remain at current levels for the near future. 

Regional Planning

Mojave Water Agency is updating its previous 1994 Regional 

Water Management Plan, which will allow it to identify and 

prioritize future water supply projects. This update process 

began in 2002 and is expected to be completed in 2005. 

As an example of regional planning, MWA has initiated a 

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10 10 Volume 3 Regional Reports

demonstration project in the Oro Grande Wash south of the city 

of Victorville to evaluate the effectiveness of off-river artificial 

groundwater recharge using State Water Project water. The project site is located several miles away from the main stem of the 

Mojave River and intends to supply imported surface water for 

groundwater recharge. When needed, the local water purveyors 

would subsequently pump this stored groundwater for use in the 

rapidly growing urban areas. This project is the first of several 

off-river recharge projects that the agency considers as the next 

major phase in water supply infrastructure development. 

With a growing population and increasing demands on the 

limited supplies of fresh water for its service area, Victor Valley 

Wastewater Reclamation Authority (VVWRA) has been planning 

a program with new facilities that would recycle millions of gallons of wastewater daily. The current wastewater flows are about 

9 MGD from more than 100,000 residents, and are expected to 

increase to more than 18.7 MGD by the year 2020. In 1997, the 

VVWRA completed a feasibility study that projected population 

growth and wastewater treatment requirements, and identified 

potential reclamation strategies and costs through 2020. These 

strategies included potential uses of the fully-treated effluent for 

beneficial purposes such as landscape irrigation and industrial 

process water. In 2000, VVWRA adopted amendments to the 

plan, which projected future wastewater flows within it’s service 

area with greater accuracy, and recommended the completion of 

four sub-regional wastewater reclamation facilities by the year 

2010. In 2002 VVWRA also completed an interim expansion 

of its treatment plant to accommodate wasteflows of up to 11 

million gallons-per-day. 

The VVWRA Board of Commissioners also approved a draft 

policy to sell the recycled water at the current river discharge 

location to stipulated parties from the Mojave Adjudication, and 

held a public hearing on the policy in 2001. Under the proposed 

policy, recycled water would be sold and credited to individual 

parties for use in meeting makeup water or replacement water 

requirements as specified by the Mojave River adjudication. 

However, the board has delayed approval of this proposed 

policy until legal challenges to the Mojave Adjudication are 

settled by the Superior Court.

The Antelope Valley Water Group (AVWG) was formed in 

1991 to provide coordination among valley water agencies 

and other planning groups. AVWG members include the 

cities of Palmdale and Lancaster, Edwards Air Force Base, 

AVEK, Antelope Valley United Water Purveyors Association, 

Los Angeles County Waterworks Districts, PWD, Rosamond 

Community Services District, and Los Angeles County. AVWG 

then completed the Antelope Valley Water Resource Study in 

1995 to address regional water management issues. That study 

evaluated the valley’s existing and future water supplies from 

groundwater, the SWP, Littlerock Reservoir, and recycling, and 

then compared those supplies with projected water demands. 

The study concluded that there is a low level of water supply 

reliability in the study area, and concluded that full 1998 water 

demands could only be met half of the time without overdrafting groundwater resources. The report recommended water 

conservation, recycling, and conjunctive use as strategies to 

reduce expected water shortages, and identified three potential 

sites (two on Amargosa Creek and one on Littlerock Creek) with 

high potential as groundwater recharge spreading ponds. The 

study also identified several potential groundwater injection 

sites within existing Los Angeles County Waterworks and PWD 

municipal well fields, and treated SWP water was identified as a 

potential recharge source. AVWG agencies are now developing 

individual programs and projects based on the recommendations from that 1995 water resource study.

In 2001, Palmdale Water District adopted a water facilities 

master plan for its service area, which updated previous 1989 

and 1996 master plans. PWD relies on three water sources: 

Littlerock Reservoir, local groundwater, and SWP surface water. 

The master plan highlights PWD’s desire to maintain the capability to obtain 40 percent of its water supply from groundwater. 

However, because declining groundwater levels are an ongoing concern in the Palmdale area, there is uncertainty about 

whether the groundwater basin’s perennial yield could support 

the desired level of pumping. In addition, this plan indicated that 

existing supplies would not be insufficient to meet demands in 

drought periods, and projected possible water supply shortfalls 

during normal years by 2010.

To help meet future demands, the PWD plan recommended 

building up to six new wells and modifications to four existing 

cased wells, so that they could be used to help meet potable 

water demands. The Draft Environmental Impact Report for the 

plan identified a continuing decline in groundwater levels as 

an unavoidable effect from building new wells and pumping 

additional groundwater, as desired to maintain groundwater 

as 40 percent of PWD’s total supply. Mitigation measures have 

been developed which recommend more water conservation, 

drought-year reductions in water demands, more conjunctive 

use programs, the acquisition of additional SWP surface water, 

participation in water marketing and transfers, and the expansion of available uses for recycled water. 

In 2002, the Quartz Hill Water District constructed six wells 

in order to develop the capability to participate in future conjunctive use projects. Only four of these wells were equipped 

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with groundwater pumps because the water yield from the 

other two wells was too small. Quartz Hill WD is also planning to add groundwater injection equipment to some of 

it’s wells, so that recharge of the groundwater basin can 

occur whenever surplus SWP water supplies are available. 

Water Portfolios for Water 

Years 1998, 2000, and 2001

Water Year 1998

Water year 1998 was a wet year for this region, with annual 

precipitation at 188 percent of normal, while the statewide 

annual precipitation was 171 percent of average. The reservoirs 

in the region increased storage by about 72,000 acre-feet as 

a result of the additional rainfall and runoff, but the regions 

groundwater basins were drawn down by about 226,000 

acre-feet. The expanding urban developments in the southern 

portion of this region have become dependent on the use of 

groundwater to meet water demands, because significant 

surface water resources and facilities do not exist. As a result 

more groundwater is pumped and used annually than can be 

recharged, even during the wetter years. 

The primary agricultural water use in the region is irrigation of 

alfalfa and pasture grass for raising beef. Smaller amounts of 

land are dedicated to truck crops, such as carrots and onions, 

and still less is used for grain crops and orchards. As shown in 

Table 10-3 the total agricultural applied water use for 1998 in 

this region was 280,600 acre-feet, which is about 48 percent of 

the total developed use of 590,200 acre-feet. Agricultural water 

use in 1998 was less than in years 2000 and 2001 because 

the significant amount of rainfall in this wet year reduced the 

need for irrigation. 

Total urban applied water use for the region was 211,200 acrefeet in 1998, which represents about 36 percent of all water use. 

The wet winter of 1998 also reduced the amount of urban water 

use compared to years 2000 and 2001 (as shown in Table 10-

3), because this category also includes outdoor landscape, parks 

and recreation facilities which generally require less water in a 

wetter year. Total environmental water use for this region was 

98,400 acre-feet, primarily for uses related to the preservation 

of Mono Lake and Owens River flows.

In 1998 about 442,000 acre-feet of surface water was exported 

from this region to the South Coast through the Los Angeles 

Aqueduct, as a result of the wet winter and abundant water 

supplies. SWP water deliveries into the South Lahontan region 

were 73,000 acre-feet from the California Aqueduct. An additional 844,000 acre-feet of SWP surface water flowed through 

this region in the California Aqueduct, passing from the Tulare 

Lake region for deliveries to the South Coast region. These 

regional imports and exports are summarizedon the regional 

map in Figure 10-1.

Water Year 2000

Year 2000 was dry in the South Lahontan region with annual 

precipitation at 66 percent of average, while the state as a whole 

received near normal rainfall. The lack of rainfall increased the 

need to apply water to crops, resulting in a total agricultural 

applied water use of about 361,000 acre-feet, which is about 

50 percent of the total developed use of 718,600 acre-feet. As 

shown in Table 10-3, urban water use also increased in year 

2000 (compared to 1998), and the 269,000 acre-feet of urban 

use represented about 37 percent of total applied water uses. 

Dedicated environmental water uses in the region declined 

slightly in year 2000 compared to 1998, and represent about 

13 of the total applied water uses.

During year 2000, total storage in the surface reservoirs 

decreased by 8,000 acre-feet as more water was released 

for use than was available for storage. Net groundwater storage declined by roughly 294,000 acre-feet, as more water 

is pumped to meet demands in a dryer water year. Only 

294,000 acre-feet of surface water was diverted from the 

South Lahontan region through the LA Aqueduct to the South 

Coast region, which is significantly less than the 1998 amount. 

However more SWP water from the California Aqueduct 

flowed through the region, with 108,000 acre-feet diverted 

to meet local uses and 1,401,000 passed to the South Coast 

region (see Figure 10-1). 

Water Year 2001

Year 2001 produced slightly below normal water supply 

conditions in the South Lahontan region with annual precipitation at 91 percent of average. For comparison, statewide 

average precipitation in year 2001 was only 72 percent of 

normal. Because the South Lahontan region is a relatively 

arid part of the State (average annual precipitation is less 

than 10 inches), a single storm event can significantly alter 

the regional average in comparison to statewide precipitation. The reduced amounts of rainfall in other regions of the 

State resulted in lower SWP deliveries to water contractors, 

and SWP imports to the South Lahontan region were about 

82,000 acre-feet. As shown in Table 10-3, urban, agricultural 

and environmental water uses were all slightly less than in 

year 2000, and accounted for roughly the same percentages 

of the total developed water supply.

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About 272,000 acre-feet of surface water was exported 

through the L.A. Aqueduct to the South Coast region in 

2001, which is slightly less than in year 2000. An additional 

983,000 acre-feet of SWP surface water flowed through this 

region in the California Aqueduct, passing from the Tulare 

Lake region for deliveries in the South Coast region. As shown 

in Table 10-1, the region’s surface reservoir storage in 2001 

remained nearly the same as in year 2000, but the amount 

of groundwater in storage continued to decline, by 299,000 

acre-feet during this year. 

A more detailed tabulation of the developed urban, agricultural and environmental water uses and water depletion is 

presented in Table 10-3. This table also provides details about 

the sources of the developed water supplies, which include 

surface water, groundwater and some SWP water imports from 

other regions. The three water portfolio data sets included in 

Table 10-3 and the companion water portfolio flow diagrams 

(Figures 10-4 and 10-5 ) provide more detailed information 

about how the available water is routed, distributed and used 

throughout this region.

Selected References 

2002 California 305(b) Report on Water Quality, State Water 

Resources Control Board 

Antelope Valley Water Resource Study by Kennedy/Jenks 

Consultants Engineers and Scientists for Antelope Valley 

Water Group, November 1995 

California’s Groundwater Bulletin 118-05, Update 2003, 

California Department of Water Resources 

Draft Environmental Impact Report and Statement for the West 

Mojave Plan, Bureau of Land Management, May 2003 

Lancaster Water Reclamation Plant 2020 Plan EIR, District 14, 

Antelope Valley Los Angeles County, September 2003 

Nonpoint Source Program Strategy and Implementation Plan, 

1998-2013, State Water Resources Control Board, 

California Coastal Commission, January 2000 

Mojave Water Agency Regional Water Management Plan, 

June 1994, Bookman-Edmonston Engineering, Inc., 

Glendale California 

Palmdale Water District Final Water System Master Plan 

Update, March 2001, Montgomery Watson 

Strategic Plan, State Water Resources Control Board, Regional 

Water Quality Control Boards, November 15, 2001 

Technical Memorandum, Establishing Objectives and Standards 

based on Existing Management Framework Owens Lake 

Groundwater Evaluation, Inyo County, CA, December 1998 

Technical Memorandum, Description of Existing Investigations 

and Data Relevant to the Owens Lake Groundwater 

Evaluation, Inyo County CA, Camp, Dresser & McKee, 

March 29, 1999 

Water Quality Control Plan, Regional Water Quality Control Board 

Watershed Management Initiative Chapter, Regional Water 

Quality Control 

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Water Portfolios

South Lahontan Hydrologic Region

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10 14 Volume 3 Regional Reports

Table 10-3 South Lahontan region water portfolio (TAF)

 ID South Lahontan South Lahontan South Lahontan

Number: Flow Diagram Component (see legend) 1998 2000 2001

 1 Colorado River Deliveries - - -

 2 Total Desalination - - -

 3 Water from Refineries - - -

 4a Inflow From Oregon - - -

 b Inflow From Mexico - - -

 5 Precipitation 20,409.3 7,476.1 9,740.9

 6a Runoff - Natural 

 b Runoff - Incidental 

 7 Total Groundwater Natural Recharge 

 8 Groundwater Subsurface Inflow N/A

 9 Local Deliveries 56.6 58.1 46.8

 10 Local Imports - - -

 11a Central Valley Project :: Base Deliveries - - -

 b Central Valley Project :: Project Deliveries - - -

 12 Other Federal Deliveries - - -

 13 State Water Project Deliveries 73.1 108.0 81.9

 14a Water Transfers - Regional - - -

 b Water Transfers - Imported - - -

 15a Releases for Delta Outflow - CVP 

 b Releases for Delta Outflow - SWP 

 c Instream Flow Applied Water 98.4 88.8 78.4

 16 Environmental Water Account Releases - - -

 17a Conveyance Return Flows to Developed Supply - Urban - - -

 b Conveyance Return Flows to Developed Supply - Ag - - -

 c Conveyance Return Flows to Developed Supply - Managed Wetlands - - -

 18a Conveyance Seepage - Urban - - -

 b Conveyance Seepage - Ag - - -

 c Conveyance Seepage - Managed Wetlands - - -

 19a Recycled Water - Agriculture - - -

 b Recycled Water - Urban 28.0 29.0 29.5

 c Recycled Water - Groundwater - - -

 20a Return Flow to Developed Supply - Ag - - -

 b Return Flow to Developed Supply - Wetlands - - -

 c Return Flow to Developed Supply - Urban - - -

 21a Deep Percolation of Applied Water - Ag 35.4 44.2 42.1

 b Deep Percolation of Applied Water - Wetlands - - -

 c Deep Percolation of Applied Water - Urban 66.1 83.5 75.6

 22a Reuse of Return Flows within Region - Ag - - -

 b Reuse of Return Flows within Region - Wetlands, Instream, W&S 18.6 21.4 20.6

 24a Return Flow for Delta Outflow - Ag - - -

 b Return Flow for Delta Outflow - Wetlands, Instream, W&S - - -

 c Return Flow for Delta Outflow - Urban Wastewater - - -

 25 Direct Diversions 

 26 Surface Water in Storage - Beg of Yr 329.4 326.2 317.8

 27 Groundwater Extractions - Banked - - -

 28 Groundwater Extractions - Adjudicated 61.8 61.8 61.8

 29 Groundwater Extractions - Unadjudicated 272.3 372.9 360.5

 23 Groundwater Subsurface Outflow N/A N/A N/A

 30 Surface Water Storage - End of Yr 401.5 317.8 316.5

 31 Groundwater Recharge-Contract Banking - - -

 32 Groundwater Recharge-Adjudicated Basins - - -

 33 Groundwater Recharge-Unadjudicated Basins - - -

 34a Evaporation and Evapotranspiration from Native Vegetation 

 b Evaporation and Evapotranspiration from Unirrigated Ag 

 35a Evaporation from Lakes 162.4 163.7 163.4

 b Evaporation from Reservoirs 45.1 45.1 42.1

 36 Ag Effective Precipitation on Irrigated Lands 33.5 9.9 7.2

 37 Agricultural Water Use 280.6 361.0 344.0

 38 Managed Wetlands Water Use - - -

 39a Urban Residential Use - Single Family - Interior 74.5 109.0 100.8

 b Urban Residential Use - Single Family - Exterior 55.8 68.6 68.4

 c Urban Residential Use - Multi-family - Interior 11.9 28.0 12.7

 d Urban Residential Use - Multi-family - Exterior 7.1 8.6 6.9

 40 Urban Commercial Use 27.8 19.0 20.1

 41 Urban Industrial Use 8.1 4.7 5.6

 42 Urban Large Landscape 8.4 6.6 5.3

 43 Urban Energy Production 6.3 6.3 6.3

 44 Instream Flow 79.8 67.4 57.8

 45 Required Delta Outflow - - -

 46 Wild and Scenic Rivers - - -

 47a Evapotranspiration of Applied Water - Ag 187.8 237.7 235

 b Evapotranspiration of Applied Water - Managed Wetlands - - -

 c Evapotranspiration of Applied Water - Urban 71.282 83.791 80.591

 48 Evaporation and Evapotranspiration from Urban Wastewater - - -

 49 Return Flows Evaporation and Evapotranspiration - Ag 5.7 7.3 6.7

 50 Urban Waste Water Produced 29.34 36.14 33.34

 51a Conveyance Evaporation and Evapotranspiration - Urban 8.51 10.6 8.81

 b Conveyance Evaporation and Evapotranspiration - Ag - - -

 c Conveyance Evaporation and Evapotranspiration - Managed Wetlands - - -

 d Conveyance Outflow to Mexico 

 52a Return Flows to Salt Sink - Ag 51.7 65.4 60

 b Return Flows to Salt Sink - Urban 58.89 84.41 66.1

 c Return Flows to Salt Sink - Wetlands - - -

 53 Remaining Natural Runoff - Flows to Salt Sink 79.8 67.4 57.8

 54a Outflow to Nevada - - -

 b Outflow to Oregon - - -

 c Outflow to Mexico - - -

 55 Regional Imports 917.7 1,509.7 1,065.7

 56 Regional Exports 1286 1695.0 1255

 59 Groundwater Net Change in Storage -226.2 -294.1 -299.0

 60 Surface Water Net Change in Storage 72.1 -8.4 -1.3

61 Surface Water Total Available Storage 458.9 458.9 458.9

 

 Inflows Outflows Green number signifies included in summary boxes 

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Figure 10-4 South Lahontan region - illustrated water flow diagram

INFLOWS

SUMMARY

OUTFLOWS

8

15a,b

21

27

31

45

48

51

5

6

46

14 16

33

28

29

32

39- 43

59

50

18

9

51

34

47b

38

35

51

26

30

60

61

11

12

13

15c

54

56

7

1

4

55

10 44

36

47a

49

51

37

17

20

47c

22

25 24

31

23

2

3

52

53

19

In this illustration of Table 10-3, key components of the flow diagram are illustrated as characteristic elements of the hydrologic cycle. Circled numbers correspond to the identification number of flow diagram components in the table; its color indicates whether the component is water input, output, 

or summary.

52

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SUMMARY

OUTFLOWS

INFLOWS

Figure 10-5 South Lahontan region - schematic flow diagram

In schematic of Table 10-3, key components of the flow diagram are shown as boxes and connectors in a flow chart. Circled numbers correspond to the identification number of flow diagram components in the table; box color indicates whether the component is water input, output, or summary. 

Blank boxes are flow diagram components not relevant to the region. 

1

2

5

4

3

55

6

13

11

19

12

10

9

7

20

21

45

29

26

30

35

39 to 43

37

38

53

54

46

14

34 36

28

52

16

24

17

18

25

47

50

49

48

27

31

32

33

23

8

15C

15A

15B

56

44

16

51

22

RUNOFF:

NATURAL: INCIDENTAL: PRECIPITATION: TOTAL STREAM 

FLOW: 

AG EFFECTIVE 

PRECIPITATION ON 

IRRIGATED LANDS: 

LOCAL

DELIVERIES:

SWP DELIVERIES: WATER DEPOSITS: 

SURFACE WATER: 

GROUNDWATER: 

RECYL & DESAL:

TRANSFERS:

TOTAL GROUNDWATER NATURAL RECHARGE: 

GROUNDWATER CHANGE IN STORAGE: 

BANKED:

ADJUDICATED: 

UNADJUDICATED: 

GW EXTRACTIONS:

CONTRACT BANKS:

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

EVAPOTRANSPIRATION 

OF APPLIED WATER: 

AG:

WETLANDS:

URBAN:

WATER USE (APPLIED): 

AGRICULTURAL: 

WETLANDS:

URBAN:

RECYCLED WATER: 

AG: URBAN:

GW: 

URBAN

WASTEWATER 

PRODUCED:

INCIDENTAL E & ET 

AG RETURN FLOWS: 

AG & WETLANDS 

RETURN FLOWS:

RETURN FLOWS TO SALT 

SINKS:

AG: WETLANDS:

URBAN:

REMAINING NATURAL 

RUNOFF

FLOW TO SALT SINKS: 

DEEP PERC OF APPLIED 

WATER: 

AG: WETLANDS:

URBAN:

RETURN FLOW TO 

DEVELOPED

SUPPLY: 

AG:

WETLANDS:

URBAN:

EVAP FROM: 

LAKES:

RESERVOIRS:

E & ET FROM:

NATIVE VEGETATION: 

UNIRRIGATED AG: 

RELEASES FOR 

INSTREAM USE: 

CONVEYANCE E&ET, 

RETURN FLOWS, & 

SEEPAGE:

URBAN: AG:

WETLANDS:

CONVEYANCE E & ET: 

URBAN: AG:

WETLANDS:

CONVEYANCE RETURN 

FLOWS:

URBAN: AG:

WETLANDS:

CONVEYANCE SEEPAGE: 

URBAN: AG:

WETLANDS:

RETURN FLOW FOR 

DELTA OUTFLOW: 

AG:

WETLANDS:

URBAN : 

EVAPORATION AND EVAPOTRANSPIRATION OF APPLIED WATER, 

PRECIPITATION AND CONVEYANCE: 

GW RECHARGE:

CONTRACT BANKING:

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

TO E & ET: 

SUBSURFACE GW 

INFLOW: 

SUBSURFACE 

GROUNDWATER 

OUTFLOW: 

OTHER REGIONAL 

TRANSFER OUT: 

REGIONAL

TRANSFER IN: 

INSTREAM NET USE:

SURFACE WATER IN 

STORAGE: 

 Beg of Yr: 

End of Yr: 

DIRECT 

DIVERSIONS:

Service Area

Return 

Flow within

Return of

Required Instream 

Flows

Return of

Required Wild & 

Scenic Flows

10 16 Chapter 10 South Lahontan Region Volume 3 Regional Reports

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Chapter 11 Colorado River Hydrologic Region 

Volume 3 

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Chapter 11 Colorado River Hydrologic Region

Contents

Chapter 11 Colorado River Hydrologic Region ........................................................................................................11-1

Setting .............................. 11-1

Climate ............................. 11-1

Population ........................ 11-1

Land Use .......................... 11-1

Water Supply and Use ....... 11-4

State of the Region .......... 11-11

 Challenges ................ 11-11

 Accomplishments ....... 11-14

Relationship with Other Regions .......................................................................................................................11-14

Looking to the Future ....... 11-16

Water Portfolios for Water Years 1998, 2000, and 2001 ...................................................................................11-17

Selected References ......... 11-20

Box

Box 11-1 Acronyms Used in the Colorado River Regional Report ..............................................................................11-2

Box 11-2 Salton Sea Description ..........................................................................................................................11-11

Box 11-3 Salton Sea Ecosystem ............................................................................................................................11-12

Box 11-4 Key Elements of California’s Colorado River Quantification Settlement Agreement .....................................11-16

Figures

Figure 11-1 Colorado River Hydrologic Region (map) ..............................................................................................11-ii

Figure 11-2 Colorado River Hydrologic Region population .......................................................................................11-3

Figure 11-3 Colorado River region water balance for water years 1998, 2000, 2001 (2 bar charts) ..........................11-6

Figure 11-4 Colorado River region - illustrated water flow diagram ........................................................................11-25

Figure 11-5 Colorado River region - schematic flow diagram .................................................................................11-26

Tables

Table 11-1 Key elements of the Law of the River .......................................................................................................11-5

Table 11-2 Annual apportionment of use of Colorado River water (interstate/international) ........................................11-7

Table 11-3 Annual apportionment of water from the Colorado River mainstream to the lower basin states ...................11-7

Table 11-4 Annual intrastate apportionment of water from the Colorado River mainstream within California under the 

Seven Party Agreement ..... 11-8

Table 11-5 QSA for Priorities 1-3 annual use of Colorado River water by California agencies ....................................11-8

Table 11-6 SWP contractors in the Colorado River region ........................................................................................11-9

Table 11-7 Existing Colorado River region water conservation actions/agreements since 1980 .................................11-15

Table 11-8 Colorado River Hydrologic Region water balance summary ...................................................................11-18

Table 11-9 Colorado River region water use and distribution of dedicated supplies ..................................................11-19

Table 11-10 Colorado River region water portfolios ...............................................................................................11-24

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Some Statistics

 Area - 19,962 square miles (12.6% of State)

 Average annual precipitation - 5.7 inches

 Year 2000 population - 606,535

 2030 population projection -1,166,550

 Total reservoir storage capacity - 620 TAF

 2000 irrigated crop area - 731,890 acres

.

.

.

.

.

.

Flow in TAF

1998

4,986

2000

5,349

2001

5,197

Colorado River

Flow in TAF

1998

1,081

2000

1,296

2001

1,250

South Coast Region

Colorado River Aqueduct

Figure 11-1 Colorado River Hydrologic Region

The Colorado River Hydrologic Region is in the southeastern corner of California and includes the Imperial and Coachella valleys, known for 

year-round agricultural production. Arrows indicate annual flows entering and leaving the region for water years 1998, 2000, and 2001. 

SAN BERNARDINO

RIVERSIDE

SAN DIEGO IMPERIAL

Inflow From 

Mexico

1998

182

2000

166

2001

155

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Chapter 11 Colorado River Hydrologic Region

to 90 percent of the maximum possible sunshine each year, 

the highest value in the United States. Winter maximum temperatures are mild, but summer conditions are generally very 

hot, with more than 100 days with temperatures of over 100 

degrees Fahrenheit each year in the Imperial Valley. 

Population

In 2000, the population for the region was about 606,000, 

which represented an increase of 31 percent from the 

1990 population. More than half of the region’s population 

resides in the Coachella Valley, where significant urbanization has occurred. Most of the remaining population is in 

the Imperial Valley and in the corridor between the cities 

of Yucca Valley and Twenty-nine Palms along Highway 62. 

From 2000 to 2030, the California Department of Finance 

projects that the regional population will almost double 

to 1,166,550 people. Figure 11-2 provides a graphical 

depiction of the Colorado River region’s total population 

from 1960 through 2000, with projections to 2030. 

Land Use

The region is a land of unequalled agricultural bounty with a 

growing urban sector, and large expanses of open, wild terrain. The U.S. Bureau of Land Management (BLM) administers 

a large portion of the region’s land, but many other entities 

also oversee significant areas. (See Box 11-1 for acronyms 

used in this chapter.)

Famous parks in the region include Joshua Tree National 

Park, the Mojave National Scenic Preserve, Anza-Borrego 

Desert State Park, and the Salton Sea and the Picacho state 

recreation areas. There are also several areas set aside for 

preservation or other land management purposes, including 

national recreation and wilderness areas, wildlife refuges, 

Indian tribal reservations and U.S. Navy facilities.

Setting

The Colorado River hydrologic region covers the southeast 

portion of California and contains 12 percent of the state’s 

land area. The Colorado River forms most of the region’s 

eastern boundary and the international boundary with Mexico 

forms its southern boundary (Figure 11-1 is a map and table 

of statistics that describe this region). The region includes 

all of Imperial County, about the eastern one-fourth of San 

Diego County, the eastern two-thirds of Riverside County, 

and the southeastern one-third of San Bernardino County. It 

has a variety of arid desert terrain that includes many bowlshaped valleys, broad alluvial fans, sandy washes, and hills 

and mountains. 

The Colorado River region includes a large portion of the 

Mojave Desert, primarily in that part of the region in San 

Bernardino County and eastern Riverside County. The area 

to the east and south of the Mojave Desert is a portion of 

the Sonoran Desert. Elevations in the region generally range 

from 1,000 to 3,000 feet in the Mojave Desert, to less than 

1,000 feet along the Colorado River. The lowest areas in 

this region are more than 200 feet below mean sea level 

in the Coachella and Imperial Valleys. Mountain peaks 

attain elevations of 6,000 to 7,000 feet. Many of these 

arid valleys contain playas (dry lake beds), some of which 

are quite large. Bristol Dry Lake, near the Mojave National 

Preserve, is a playa that covers more than 50 square miles.

Climate

Nearly all of the Colorado River region has a subtropical 

desert climate with hot summers and generally mild winters. 

Average annual rainfall is very low and precipitation ranges 

between 3 to 6 inches per year, most of which occurs in the 

winter months. However, summer storms do occur and can 

generate significant rainfall in some years. Clear and sunny 

conditions typically prevail, and the region receives from 85 

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Despite the arid conditions, significant areas of agricultural 

and urban land use exist in the region. Agriculture is the most 

prominent land use, with more than $1.5 billion of agricultural 

commodities produced in the region each year. Over 600,000 

acres of land are farmed each year. The largest agricultural 

area occurs in the Imperial Valley where over 450,000 acres of 

land are farmed annually. More than 93,000 acres are farmed 

in the Palo Verde Valley, followed by 60,000 acres in the 

Coachella Valley. Smaller, but equally important agricultural 

operations also exist in the Bard and Mojave valleys.

Despite its arid conditions, the region produces more than $1.5 billion of agricultural commodities annually. The largest water body in the Colorado River 

region is the Salton Sea (in photo background), a saline body of water about 50 feet deep. (DWR photo)

Box 11-1 Acronyms Used in the Colorado River Regional Report

BWD Bard Water District 

CVWD Coachella Valley Water District 

DFG California Department of Fish and Game 

DWA Desert Water Agency 

DWR California Department of Water Resources 

IID Imperial Irrigation District 

LCR MSCP Lower Colorado River Multi-Species Conservation 

Program 

maf million acre-feet 

MWD Metropolitan Water District of Southern California 

PVID Palo Verde Irrigation District 

QSA Quantification Settlement Agreement of 2003 

SGPWA San Gorgonio Pass Water Agency 

SDCWA San Diego County Water Authority 

SSAM Salton Sea Accounting Model 

SWP State Water Project 

USBR US Bureau of Reclamation 

USFS US Fish and Wildlife Service

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A wide variety of crops are planted and harvested in the 

region, some of which are grown only during specifi c times of 

the year. In terms of acres, alfalfa is the leading crop produced 

in the Colorado River region. Almost 250,000 acres were 

grown in 2000, of which 180,000 acres were in the Imperial 

Valley. Although constrained by summer climate, winter and 

spring vegetables, which include carrots, broccoli, lettuce, 

onions, and melons, rank second in overall acres. Of the 

150,000 acres harvested, almost 100,000 acres of the vegetables harvested in 2000 came from the Imperial Valley. 

The Coachella and Bard valleys are noteworthy for citrus and 

subtropical fruit production, especially dates. The table grape 

industry is also well established in the Coachella Valley.

The cattle industry in the Imperial Valley is extremely important 

to the region’s $1 billion per year agricultural production. 

In 2001, the cattle industry, with a value of $243 million, 

ranked as the third highest-value commodity produced in 

the Imperial Valley. Vegetable and melon crops were ranked 

fi rst with a value of $403 million, while fi eld crops were the 

second-ranked commodity worth $285 million.

Other important crops grown in the Colorado River region 

include wheat, sugar beets, and Sudan grass. Although less 

cotton is grown now than at its peak in the early 1980s, some 

cotton is still grown, mostly in the Palo Verde Valley.

Multiple-cropping is the prevalent agricultural practice in the 

Imperial, Palo Verde, Coachella, and Bard valleys. During 

2000, it was estimated that over 100,000 acres were doublecropped in the region.

Urban land uses and acreage are expanding, and co-exist 

with agriculture in the region. In the northern Coachella Valley, 

urbanization continues to expand between the Cities of Palm 

Springs and Indio. Other growing cities in the Coachella 

Valley include Palm Desert, Rancho Mirage, and La Quinta. 

This corridor is characterized by the presence of numerous 

extensively landscaped residential developments, expansion 

of local business and consumer service centers, construction 

of luxury hotels and resort properties, and the operation of 

over 100 private and public golf courses. Upscale commercial 

and residential expansion, which has been under way for 

several decades, is continuing at a robust pace. This expansion 

supports the region’s recreation and tourism industry and its 

growing number of wealthy retirees and part-time residents.

Figure 11-2 Colorado River Hydrologic Region population

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1960 1970 1980 1990 2000 2010 2020 2030

Data from California Department of Finance provide decadal population from 1960 to 2000 and population projection for 2030 

for Colorado River region.

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Although smaller in scale, the region’s urban areas in the corridor between the cities of El Centro and Imperial and around 

the city of Calexico have also been expanding. Business and 

consumer services there support the population of the Imperial 

Valley and the neighboring Mexicali Valley. In 2001 a third 

port of entry across the border with Mexico opened, which 

generates increased traffic resulting from NAFTA-related 

business activity.

In the Imperial and Palo Verde valleys and the southern 

one-half of the Coachella Valley, small to moderately sized 

cities and communities provide support for the surrounding agricultural and non-agricultural activities. There are 

also numerous single-family residential dwellings scattered throughout the region. Many of the business and 

industrial sectors in the cities of Blythe, Brawley and Indio 

provide services that also support this type of lifestyle. 

Water Supply and Use

About 85 percent of the region’s urban and agricultural water 

supply comes from surface water deliveries from the Colorado 

River. Water from the river is delivered into the region through 

the All-American and Coachella canals, local diversions, and 

the Colorado River Aqueduct by means of an exchange for 

State Water Project (SWP) water. The Colorado River is an 

interstate and international river whose use is apportioned 

among the seven Colorado River Basin states and Mexico by a 

complex body of statutes, decrees, and court decisions known 

collectively as the “Law of the River” (Table 11-1). Local surface 

water, groundwater, and the SWP provide the remainder of 

water to the region. In addition, many of the alluvial valleys 

in the region are underlain by groundwater aquifers that are 

the sole source of water for local communities. There are other 

alluvial valleys that have poor quality water that is not suitable 

for potable use. Figure 11-3 presents two bar charts that summarize all of the dedicated and developed urban, agricultural 

and environmental water uses and the sources of supply within 

this hydrologic region for years 1998, 2000 and 2001. 

In California, the Seven Party Agreement of 1931 established 

local agencies’ apportionments of Colorado River water, which 

were further defined in the Quantification Settlement Agreement of 2003 (Tables 11-2, 11-3, 11-4, and Table 11-5). The 

Secretary of the Interior apportions water to California water 

users according to the Seven Party and the Quantification 

Settlement Agreement (QSA). Water use that occurs within a 

state is charged to that state’s Colorado River apportionment. 

Thus, federal water uses, including uses associated with federal 

reserved rights (for example, tribal water rights), must also 

be accommodated within California’s basic apportionment of 

4.4 million acre-feet per year plus one-half of any available 

surplus water.

Neither Coachella Valley Water District (CVWD) nor Desert 

Water Agency (DWA) has facilities to take direct delivery 

of SWP water. Instead, both agencies have entered into 

exchange agreements with the Metropolitan Water District of 

Southern California (MWD), whereby MWD releases water 

from its Colorado River Aqueduct into the Whitewater River 

for storage in the upper Coachella Valley groundwater basin. 

In exchange, MWD takes delivery of an equal amount of the 

agencies’ SWP water. San Gorgonio Pass Water Agency 

(SGPWA), which serves the Banning-Beaumont area, also 

lacks the facilities to take delivery of SWP water into the 

portion of its service area that is within the Colorado River 

region. However, SGPWA is currently delivering SWP water 

into the Santa Ana planning area of the South Coast Hydrologic Region. When Phase 2 of the East Branch Extension is 

eventually completed, SWP water will be delivered into the 

Colorado River Hydrologic Region. However, the California 

Department of Water Resources (DWR) is still developing plans 

for this Phase 2 extension project. (See Table 11-6 for SWP 

contractors in the Colorado River region.)

Groundwater provides about 7.5 percent of the region’s 

applied water supply in normal years and about 7.7 percent 

in drought years (DWR 1998). Groundwater storage capacity has been estimated for 40 of the region’s 57 groundwater 

basins and totals more than 175 million acre-feet. The largest water-using area in the region, the agricultural area of 

the Imperial Valley, is located mostly over a saline basin and 

therefore lacks usable groundwater.

In the Coachella Valley, groundwater levels began declining 

in the late 1920s due to extensive pumping. Since 1948, 

imported water supplies have been brought into this area 

from the Colorado River via the Coachella Canal. These 

surface water deliveries have enabled decreased pumping 

of groundwater in the southeastern portion of the valley and 

have thus helped recharge the basin. As a result, groundwater 

levels rose in this part of the valley until the 1980s. Since then 

the groundwater levels have again declined because of urban 

development and increased groundwater pumping.

Local water districts in the Coachella Valley have been working 

to address the decline in groundwater levels. The agreement 

between CVWD and DWA to bring SWP supplies into the 

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Document Date Main Purpose

Colorado River Compact 1922 The Upper Colorado River Basin and the Lower Colorado 

 River Basin are each provided a basic apportionment of 7.5 

 maf annually of consumptive use. The Lower Basin is given 

 the right to increase its consumptive use an additional 1 

 maf annually.

Boulder Canyon Project Act 1928 Authorized USBR to construct Boulder (Hoover) Dam and the

 All-American Canal (including the Coachella Canal), and 

 gave congressional consent to the Colorado River Compact. 

 Provided that all users of Colorado River water stored in Lake 

 Mead must enter into a contract with USBR for use of the water.

California Limitation Act 1929 Limited California's share of the 7.5 maf annually appor-

 tioned to the Lower Basin to 4.4 maf annually, plus no more 

 than half of any surplus waters.

Seven Party Agreement 1931 An agreement among seven California water agencies/

 districts to recommend to the Secretary of the Interior how to 

 divide use of California's apportionment among the 

 California water users. 

U.S. - Mexican Treaty 1944 Apportions Mexico a supply of 1.5 maf annually of Colorado

 River water except under surplus or extraordinary drought 

 conditions.

U.S. Supreme Court Decree in 1964 Apportions water from the mainstream of the Colorado River

Arizona v. California, et al. among the Lower Division states. When the Secretary 

 determines that 7.5 maf of mainstream water is available, it 

 is apportioned 2.8 maf to Arizona, 4.4 maf to California, 

 and 0.3 maf to Nevada. Quantifies tribal water rights for 

 specified tribes, including 131,400 af for diversion in 

 California.

Colorado River Basin Project Act 1968 Authorized construction of the Central Arizona Project (CAP). 

 Requires Secretary of the Interior to prepare long-range 

 operating criteria for major Colorado River reservoirs.

U.S. Supreme Court Decree in 1979, Quantifies Colorado River mainstream present perfected

Arizona v. California, et al. 1984, rights in the Lower Basin states.

supplemental decrees 2000

Quantification Settlement Agreement 2003 Complex package of agreements that, among other things, 

and Related Agreements further quantifies priorities established in the 1931 Seven-

 Party Agreements and enables specified water transfers in 

 California.

Table 11-1 Key Elements of the Law of the River

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Figure 11-3 Colorado River region water balance for water years 1998, 2000, 2001

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

1998 2000 2001

Thousand Acre-Feet

Managed

Wetlands

Irrigated

Agriculture

Urban

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

1998 2000 2001

Thousand Acre-Feet

Reuse &

Recycle

Ground Water

State Project

Colorado

Project

Local Projects

Dedicated Water Supplies

Applied Water Uses

Three years show a marked change in the amount and relative proportions of water delivered to Colorado River region’s urban and 

agricultural sectors and water dedicated to the environment (applied water, top chart), where the water came from, and how much 

water was reused among sectors (dedicated water supplies, bottom chart).

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California Water Plan Update 2005

Table 11-2 Annual apportionment of use of Colorado River water

(amounts represent consumptive use)

Upper Basin. Required to deliver 75 maf over a 10-year period measured at Lee Ferry.

(small portion of Arizona, Colorado, New Mexico, Utah, and Wyoming) 7.5 maf

Lower Basin 7.5 maf

(portions of Arizona, California, Nevada, New Mexico, and Utah draining below Lee Ferry) plus 1 maf

Republic of Mexico a 1.5 maf

Total 17.5 maf b

a. Plus 200 taf of surplus water, when available as determined by the United States. Water delivered to Mexico must meet 

specified salinity requirements. During an extraordinary drought or other cause resulting in reduced uses in the United States, 

deliveries to Mexico would be reduced proportionally with uses in the United States.

b. The total volume is (7.5 + 7.5 + 1.0 + 1.5) = 17.5 maf/yr. Note that this total refers to all waters of the Colorado River 

System, which is defined as that portion of the Colorado River and its tributaries in the United States.

Interstate/International

Arizona 2.8 maf

Nevada 0.3 maf

California 4.4 maf

Total 7.5 maf

Table 11-3 Annual Apportionment of Water from the Colorado River Mainstream to the Lower Basin

 (amounts represent consumptive use)

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Table 11-4 Annual Intrastate Apportionment of Water from the Colorado River 

Mainstream within California under the Seven Party Agreement c

(amounts represent consumptive use)

Priority 1 Palo Verde Irrigation District for beneficial use on 104,500 acres of lands within the Palo Verde Valley.

Priority 2 USBR’s Yuma Project in California for beneficial use on up to 25,000 acres of lands within said Project

Priority 3 Imperial Irrigation District and lands served from the All American Canal in Imperial and Coachella Valleys, 

and Palo Verde Irrigation District for use on 16,000 acres in the Lower Palo Verde Mesa.

Priorities 1 through 3 collectively are not to exceed 3.85 maf/yr. The Seven Party Agreement did not quantify the division 

of this volume among the three priorities. Priorities 1-3 were further defined in the 2003 Quantification Settlement Agreement.

Priority 4 Metropolitan Water District of Southern California (MWD) for coastal plain of Southern California – 550 taf/yr.

Priority 5 An additional 550 taf/yr to MWD, and 112 taf/yr for the City and County of San Diego d.

Priority 6e Imperial Irrigation District and lands served from the All-American Canal in Imperial and Coachella Valleys 

and Palo Verde Irrigation District for use on 16,000 acres in the Lower Palo Verde Mesa, for a total not to 

exceed 300 taf/yr.

Total of Priorities 1 through 6 is 5.362 maf/yr.

Priority 7 e All remaining water available for use in California, for agricultural use in California's Colorado River Basin.

c. Indian tribes and miscellaneous present perfected right holders that are not encompassed in California’s Seven Party 

 Agreement have the right to divert up to approximately 90 taf/year (equating to about 50 taf/yr of consumptive use) within 

 California’s 4.4 maf/yr basic apportionment. Present consumptive use under these miscellaneous and Indian present 

 perfected rights is approximately 15 taf/yr. 

d. Subsequent to execution of the Seven Party Agreement, MWD, SDCWA, and the city of San Diego executed a separate 

 agreement transferring its apportionment to MWD.

e. Under the 2003 Quantification Settlement Agreement, MWD (& SDCWA) gained access to water that may be available 

 under Priority 6 and 7,

Table 11-5 Quantification Settlement Agreement for Priorities 1- 3

Annual Use of Colorado River Water by California Agencies

(amounts represent consumptive use)

 Priority 3 Approved Net Approved Net

 Quantification Consumptive Consumptive

 Use in 2003 a Use in 2003 a

Priority 1,2, and 3b – Based on historical average 

use; deliveries above this amount in a given year will 

be deducted from MWD’s diversion (order) for the 420 taf 420.0 taf 420.0 taf

next year; as agreed by MWD, IID, CVWD, and 

Secretary of the Interior (PVID & Yuma Project are 

not signatories to the QSA and are unaffected by it) 

Imperial Irrigation District 3,100 taf 2972.2 taf 2607.8 taf

Coachella Valley Water District 330.0 taf 347.0 taf 424.0 taf

Total Priority 1-3 Use 3,850 taf 3745.0 taf 3466.3 taf

Remainder of 3.85 for use by MWD (& SDCWA) 

through priority rights and transfer agreements 0 taf 105.0 taf b 383.7 taf b

a. Consumptive use is defined in the QSA as “the diversion of water from the main stream of the Colorado River, 

 including water drawn from the main stream by underground pumping, net of measured and unmeasured 

 return flows.” 

b. Includes miscellaneous present perfected rights, federal rights reserved, and decreed rights.

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California Water Plan Update 2005

valley was an important fi rst step. In 1984, another agreement was reached among CVWD, DWA, and MWD which 

allowed for the advanced deliveries of Colorado River water 

into the Coachella Valley during periods of high fl ows on the 

river. These supplies helped speed the pace of groundwater 

replenishment of the basin and provided water for future 

uses. However, groundwater levels still continue to decline in 

much of the basin.

Under the 1984 agreement, MWD was also permitted to bank 

up to 600,000 acre-feet of surface water in the groundwater 

basin. When withdrawals are needed, MWD will use its Colorado River surface water along with CVWD’s SWP allocations, 

and CVWD will then use the banked groundwater until the 

volume stored under this agreement is gone.

In 2000, the estimated applied water demands for urban, 

agriculture, and the environment for the Colorado River region 

totaled 4,727,000 acre-feet. The estimated applied water 

demand for agriculture was 4,013,000 acre-feet, or about 85 

percent of the total. In accordance with the terms of the October 2003 QSA and related agreements, actual agricultural 

water use is expected to be reduced in future years. 

Almost all of the agricultural demands in the region occur in 

the three major agricultural areas previously described, the 

Imperial, Palo Verde, and Coachella valleys. The Imperial 

Valley, with more than 500,000 acres of crops harvested 

each year (including double cropping), accounts for almost 70 

percent of the total applied water demands for the region. In 

the Imperial and Palo Verde valleys, all agricultural demands 

are met with water from the Colorado River. In the Coachella 

Valley, agricultural demands are supplied by a combination 

of Colorado River surface water and groundwater.

Urban applied water demands account for about 15 percent 

of the overall totals for the Colorado River region. In 2000, 

total urban applied water was estimated to be 683,000 acrefeet. Most of these urban demands occur in the Coachella 

Valley, amounting to 527,000 acre-feet in year 2000 which 

is almost 80 percent of the total urban applied water for the 

region. Established housing and commercial uses have been 

augmented by large housing tracts with intensive landscaping, 

hotels, shopping centers, country clubs, golf courses, and polo 

fi elds. Landscape irrigation demands in the Coachella Valley 

are large because of the expanse of turf grass and landscaping that have occurred in the past two decades.

Despite the availability of a reliable and inexpensive water 

supply, water districts and users are well aware of the importance 

of water conservation programs to effi ciently use and manage 

water. The agricultural growers in all of the districts do precision land forming for specifi c crops and use plastic and other 

mulches to reduce evapotranspiration and improve productivity.

Table 11-6 SWP contractors in the Colorado River region

Maximum

Annual

Deliveries (taf)

23.1

38.1

75.8

17.3

153.3

SWP

Deliveries in

2000 (taf)

42.3

58.2

11.2

0

111.7

Agency

Coachella Valley 

Water District

Desert Water

Agency

Mojave Water 

Agency (a)

San Gorgonio Pass 

Water Agency

Total SWP Delivery 

a Maximum Annual Amounts include amounts for both the South Lahontan and Colorado 

River Regions; 7.3 taf of this amount is allocated to Colorado River Region.

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For the past 50 years, the Imperial Irrigation District (IID), the 

region’s largest irrigation district, has implemented programs 

and completed projects designed to improve the efficiency 

of its water conveyance system. Under the 1988 IID/MWD 

Water Conservation Agreement and the Approval Agreement 

in 1989, 15 new projects were completed. These included the 

construction of three lateral interceptors serving more than 

83,400 acres, the building of two regulatory reservoirs and 

four interceptor reservoirs, concrete-lining of nearly 200 miles 

of lateral canals, installation of new hardware and software to 

upgrade the existing telemetry control on the IID conveyance 

system, and completion of a new, state-of-the-art Water Control 

Center. These infrastructure upgrades complemented existing 

IID programs including farmer-initiated measures, canal lining, 

canal seepage recovery, and regulatory reservoirs. 

In addition to the improvements to its water conveyance system, 

IID also implemented 13-Point and 21-Point Water Conservation 

Programs. IID also provides training and technical assistance to 

its agricultural customers through its Irrigation Management and 

Monitoring program. Its most valued service has been the dissemination of information to farmers and irrigation personnel about 

methods to improve their irrigation operations. These programs 

actively promote the use of technical methods and instruments to 

improve irrigation efficiencies; including level basin drip systems, 

level basin laser-leveling, irrigation scheduling, portable pumpback and tailwater return systems, salinity assessment, and soil 

moisture sensors. IID also has a training program that it uses to 

provide growers with flow records, based on metering of the water 

delivered and tailwater runoff, for any particular irrigation site.

In addition to the water supply savings in the IID/MWD agreement, improvements to IID’s water distribution system and other 

water conservation activities conserve more than 525,000 

acre-feet of water annually. Of this amount, the IID estimates that 

385,000 acre-feet of the savings are attributable to the efforts 

by its agricultural customers.

CVWD has also made important improvements to its water conveyance system. Water is delivered to its agricultural customers 

through metered, underground pipelines. The conveyance system 

is computerized, which adds to the system’s efficiency. In addition 

to the infrastructure improvements, CVWD provides technical 

services in efficient irrigation management to its agricultural and 

residential customers.

The districts have also examined their water operation policies 

and procedures. This review has resulted in modifications in the 

delivery procedures that have improved efficiencies and assisted 

farmers in their irrigation scheduling.

Palo Verde Irrigation District (PVID) has installed telemetry 

controls for more than 132 key control structures, which has 

improved the management of water in its canals. Most of the 

fields in the PVID and other district service areas have been laserleveled. Flattened fields help improve the uniform distribution of 

water. All deliveries to the PVID’s retail agricultural customers 

are measured, as are IID’s and CVWD’s.

PVID, IID, and CVWD, in cooperation with the University of 

California Cooperative Extension and DWR, have installed 

California Irrigation Management Information System (CIMIS) 

stations to collect the climatological data that agricultural water 

users need to estimate crop evapotranspiration of applied 

water (ETAW) and to develop irrigation schedules. Water users 

are made aware of improvements in irrigation management 

and crop growing procedures through local water conservation boards and farm advisory boards.

To assist CVWD, PVID entered into an emergency six-month 

fallowing program in 2003. More than 16,417 acres of 

farmland were idled and the unused water, 41,000 acre-feet, 

was made available to CVWD.

IID, PVID, and CVWD signed a Memorandum of Understanding Regarding Efficient Water Management Practices 

by Agricultural Water Suppliers in California. By signing 

the MOU, the districts demonstrated their intention to adopt 

and use agricultural water management plans that would 

improve agricultural water management and have beneficial 

environmental impacts within their service areas. IID’s 2002 

Agricultural Water Management Plan has been endorsed by 

the Agricultural Water Management Council that oversees 

the MOU.

Growers in the major agricultural areas use the latest irrigation hardware and management techniques to increase both 

the efficiencies of their operations and crop yields. In the 

Imperial Valley, it is common to see drip, micro-sprinklers, 

and drip tape systems being used along with the traditional 

systems of furrow, basin, and hand-move sprinklers. Drip tape 

is most commonly used for high-market value crops such as 

vegetables. Drip and micro-sprinkler systems are commonly 

used to irrigate the citrus and subtropical fruit orchards. Currently, less than 1 percent of the total orchard acreage, mainly 

date palms, is flood irrigated.

In the Coachella Valley most irrigation operations with vegetables and truck crops use drip tape and hand-move sprinklers. Some furrow irrigation is still used. Citrus and subtropical 

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fruit orchard irrigation is done with drip and micro-sprinklers; 

although flood or basin irrigation is still used for mature 

date palms. Almost all the vineyards are being irrigated by 

some type of drip system; only a very small portion still rely 

on furrow irrigation. The use of overhead sprinkler systems 

is a common sight in vineyards throughout the valley, where 

they are used for frost protection and the inducement of vine 

dormancy for earlier fruit-sets.

Although most of the water conservation has been directed 

to agriculture, water districts in the Coachella Valley provide 

technical assistance to the managers of large landscaped 

areas, such as golf courses, to evaluate and offer suggestions about irrigation hardware and operations. CVWD also 

provides loans to its retail customers for irrigation upgrades. 

Desert Water Agency offers classes in English and Spanish to 

homeowners, property managers, and government and school 

personnel on irrigation efficiency strategies and tools.

The largest water body in the region is the Salton Sea, a saline 

body of water about 50 feet deep. (See Box 11-2 Salton 

Sea Description.) Today’s surface water elevation is about 

229 feet below sea level. The Salton Sea has a concentration of total dissolved solids of about 46,000 mg/L, which 

is about 33 percent greater than that of ocean water. Most 

of the environmental water demands in the region are for 

the Sonny Bono Salton Sea National Wildlife Refuge, DFG 

Imperial Wildlife Area, wetland areas on the shore of the 

Salton Sea, and to maintain the viability of the sea under the 

QSA through 2017. To meet conditions for the IID/SDCWA 

transfer approved under the 2003 Colorado River QSA, 

from 2003 through 2017, IID will fallow enough ground to 

provide 800,000 acre-feet to the Salton Sea as mitigation 

for transferring water to San Diego. The Salton Sea ecosystem is considered a critical link on the international Pacific 

Flyway, providing wintering habitat for migratory birds, 

including some species whose diets are based exclusively on 

fish. The expected average annual inflows to the Salton Sea 

during the 25-year time frame of the California Water Plan 

Update 2005 are expected to be about 962,000 acre-feet 

per year, based on estimates using the Salton Sea Accounting Model (SSAM). This estimate has a standard deviation 

sensitivity range of about +/- 100,000 acre-feet per year. 

State of the Region

Challenges

Threatened or endangered fish species on the mainstem of the 

Colorado River include the Colorado pikeminnow, razorback 

sucker, humpback chub, and bonytail chub. Efforts to protect 

these fish may impact reservoir operations and streamflow in 

the mainstem and tributaries, which is critically important to 

California’s ability to store and divert Colorado River water 

supplies. Other species of concern in the basin include the 

bald eagle, Yuma clapper rail, black rail, southwestern willow 

flycatcher, yellow warbler, vermilion flycatcher, yellow-billed 

cuckoo, and Kanab ambersnail.

In 1993, the UFSWS published a draft recovery implementation plan for endangered fish in the upper Colorado River 

Basin. The draft plan included protecting instream flows, 

restoring habitat, reducing impacts of introduced fish and 

sportsfish management, conserving genetic integrity, monitoring habitat and populations, and increasing public awareness 

of the role and importance of native fish. 

Box 11-2 Salton Sea Description

The present day Salton Sea was formed in 1905, when Colorado River water flowed through a break in an irrigation 

diversion structure that had been constructed along the U.S./Mexican border to divert the river’s flow to agricultural 

lands in the Imperial Valley. Until that break was repaired in 1907, the uncontrolled diversions of river water drained 

into the Salton Sink, a closed interior basin whose lowest point is about 278 feet below sea level. 

Historically, the Colorado River’s course has changed several times. At times, the river discharged to the Gulf of 

California as it does today. At other times it flowed into the Salton Sink. Lake Cahuilla, the name used for any of the 

several prehistoric lakes to have occupied the Salton Sink, dried up some 300 years ago. In the past 2000 years, 

archaeological records indicate that the Colorado River actually headed northwest into the Salton Sink or Trough more 

often than it headed south into the Gulf of California. 

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Problems facing native fish in the mainstem Colorado River 

and its tributaries will not be easily resolved. For example, two 

fish species most in danger of extinction, the bonytail chub and 

razorback sucker, are not expected to survive in the wild. In 

recent years, most stream and reservoir fisheries in the basin 

have been managed for non-native fish. These management 

practices have harmed residual populations of native fish. However the native fish species are readily propagated in hatcheries, 

such that recovery plans include captive broodstock programs 

to maintain the species. 

Reestablishing wild populations from hatchery stocks will have to 

be managed in unison with programs that manage river habitat. 

For example, although 15 million juvenile razorback suckers 

were planted in Arizona streams from 1981through 1990, the 

majority of these planted fish were likely eaten by introduced 

predators. In 1994, the states of Colorado, Wyoming, and Utah 

reached an agreement with USFWS on protocols for stocking 

non-native fish in the Upper Basin. Stocking protocols are 

consistent with native fish recovery efforts. In a program which 

began in 1989, USBR and other federal and state agencies have 

cooperated to capture, rear, and successfully reintroduce about 

15,000 razorback sucker larvae in Lake Mojave. 

Instream flows in the mainstem and key tributaries are being 

evaluated as components of native fish recovery efforts. State 

and federal agencies are conducting studies to estimate base 

flow and flushing flow needs for listed and sensitive species in 

various river reaches. 

In the Lower Colorado River Basin, representatives of the three 

states, federal agencies, several Native American tribes, and 

Colorado River water and power users have completed and 

signed the Lower Colorado River Multi-Species Conservation 

Program (LCR MSCP). The LCR MSCP is intended to provide 

long-term compliance with the federal and California Endangered Species Acts, as well as the fully protected species statutes 

in California.

The LCR MSCP is a 50-year program that is designed to provide 

more than 8,100 acres of high quality aquatic, wetland, and 

native broadleaf riparian habitat along the Lower Colorado 

River from Lake Mead to Mexico. The restored and maintained 

habitats are expected to provide ecological benefits and mitigate 

potential impacts to 26 covered species being addressed within 

the LCR MSCP. Some of the proposed habitat restoration may 

involve the conversion of existing agricultural lands to native 

riparian habitats, as well as removal of non-native salt cedar 

(tamarisk) and replacement with native broadleaf riparian 

habitat – cottonwood, willow, and mesquite, for example.

Box 11-3 Salton Sea Ecosystem

The Salton Sea, a saline lake with a total dissolved solids of approximately 46,000 ppm (mg/L) - 33 percent greater 

than that of ocean water is California’s largest (surface area) lake and has been famous for its sport fishing and other 

recreational uses. It is also a federally designated repository to receive and store agricultural, surface, and subsurface 

drainage waters from the Imperial and Coachella valleys. The Salton Sea has a water surface elevation of about 229 

feet below mean sea level. 

Wildlife and aquatic species, which are dependent upon habitat created by the discharge of agricultural return flows, 

are threatened by the increasing salinity of the sea, as salts in the water are concentrated through evaporation. The 

sea’s importance to wildlife has grown because about 95 percent of California’s wetlands in other areas have disappeared through changes in land use. 

The Salton Sea ecosystem, including the Sonny Bono Salton Sea National Wildlife Refuge and adjacent agricultural 

lands, is considered a critical link on the International Pacific Flyway for migratory birds. The amount of freshwater 

inflow available to the Sea will be affected by water transfers to the South Çoast region as well as by water conservation 

in Mexico. As specified by the State Water Resources Control Board, IID is required to provide a defined freshwater 

inflow for mitigation from 2003 through 2017. 

By the end of 2006, the California Resources Agency is required to complete a Salton Sea ecosystem restoration study 

and an environmental document to idenntify a preferred alternatiive for Salton Sea Restoration.

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Additionally, the LCR MSCP participants plan to rear and reintroduce more than 660,000 razorback suckers and 620,000 

bonytail to the mainstream of the Colorado River during 

the 50-year LCR MSCP. More than 360 acres of backwater 

habitats are to be created along the Lower Colorado River to 

provide nursery habitat for juvenile native fish and additional 

wetland habitat for marsh species and migratory waterfowl.

Several California water and power agencies that use Colorado River water were participants in the LCR MSCP planning 

process and are signatories to the plan. The LCR MSCP is 

expected to begin implementation in early 2005. The USBR, 

in conjunction with representatives of the three states and the 

U.S. Fish and Wildlife Service, will be the agency primarily 

responsible for implementing the LCR MSCP.

The Salton Sea, with its increasing salinity, selenium contamination, and eutrophication, is the primary focus of water quality issues within this hydrologic region. The largest sources of 

surface water inflow to the sea are the New and Alamo rivers 

and the Imperial Valley agriculture drains, all of which contribute pesticides, nutrients, selenium, and silt. The New River has 

been described as the most polluted river in the United States. 

Originating in Mexicali, Mexico, the New River flows across 

the border, through the city of Calexico, and then north, and 

empties into the Salton Sea. It conveys urban runoff, untreated 

and partially treated municipal and industrial wastes from 

the Mexicali Valley, and agricultural runoff from the Mexicali 

and Imperial valleys. These pollution sources contribute pesticides, pathogens, silt, nutrients, trash, and volatile organic 

compounds (the latter, primarily from Mexican industry) to the 

sea. The Alamo River, which originates just two miles south 

of the border and also flows north to the Salton Sea, consists 

mainly of agricultural drainage from the Imperial Valley. The 

Coachella Valley Stormwater Channel, which also drains to the 

sea, at its north end is heavily contaminated with pathogens 

from municipal wastewater plants in the Coachella Valley and 

agricultural drainage.

A multiagency group, The Citizen’s Congressional Task 

Force on the New River, was created in 1997. Its mission 

is to improve agricultural drain water quality that flows into 

the New River and, ultimately, to the Salton Sea. Participating agencies include IID, Desert Wildlife Unlimited, County 

of Imperial, USBR, U.S. Geological Survey, USFS, DFG, 

California Regional Water Quality Control Board, USEPA, 

Ducks Unlimited, and U.C. Riverside. In 2000, the Task Force 

constructed two pilot wetland projects, a seven-acre site near 

Brawley and a 68-acre site near Imperial, to test the effectiveness of constructed wetlands in lowering non-point source pollutants. Due to the success of the pilot sites, up to 30 additional 

wetland sites are proposed on both the New and Alamo rivers. 

Additional information on this program can be found on the 

Task Force web site at www.newriverwetlands.com.

Contamination in the Salton Sea presents threats to migrating birds on the Pacific Flyway. At certain times of the year, 

nutrient loading to the sea supports large algal blooms that 

contribute to odors, as well as low dissolved oxygen levels 

which adversely affect fisheries. Selenium is a more recent 

constituent of concern,and has the potential to adversely affect 

fish and wildlife. 

The relatively saline Colorado River provides irrigation and 

domestic water to much of Southern California. Of recent concern to human health is the presence of low levels of perchlorate 

in the Colorado River from a Kerr-McGee chemical facility in the 

Las Vegas Wash, the nation’s largest perchlorate contamination 

site. In addition high levels of hexavalent chromium occur in 

groundwater wells near the town of Needles, resulting from a 

PG&E natural gas compressing station. Septic systems at recreational areas along the river are also a concern for domestic and 

recreational water uses. Other important water quality issues 

in this region include increasing levels of salinity, nitrates and 

other substances in groundwater associated with animal feeding 

and dairy operations and septic tank systems, especially in the 

Desert Hot Springs area and in the Cathedral City Cove area. 

In the Coachella Valley, high levels of nitrates restrict the use of 

several domestic water supply wells.

To address the issue of declining groundwater levels, CVWD 

prepared a water management plan for the lower Coachella 

Valley. The plan considered alternatives that include basin 

adjudication, water conservation, water recycling and direct 

or in lieu recharge with water imported from the Colorado 

River or from the SWP. This plan was completed and approved 

in 2002.

As a result of a 1964 U.S. Supreme Court decree in Arizona v. 

California, California’s basic apportionment of Colorado River 

water was quantified and five lower Colorado River Indian tribes 

were awarded 905,000 acre-feet of annual diversions, 131,400 

acre-feet of which were allocated for diversion in and chargeable to California pursuant to a later supplemental decree. In 

1978, the tribes asked the court to grant them additional water 

rights, alleging that the U.S. failed to claim a sufficient amount of 

irrigable acreage, called omitted lands, in the earlier litigation. 

The tribes also raised claims called boundary land claims for 

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more water based on allegedly larger reservation boundaries 

than had been assumed by the court in its initial award. In 1982, 

a Special Master appointed by the Supreme Court to hear these 

claims recommended that additional water rights be granted to 

the tribes. In 1983, however, the U.S. Supreme Court rejected 

the claims for omitted lands from further consideration and ruled 

that the claims for boundary lands could not be resolved until 

disputed boundaries were finally determined. 

Three of the five tribes – the Fort Mojave Indian Tribe, the Fort 

Yuma-Quechan Indian Tribe, and the Colorado River Indian 

Tribe – are pursuing additional water rights related to the 

boundary lands claims. A settlement has been reached on the 

claims of the Fort Mojave Indian Tribe and the Colorado River 

Indian Tribe. The settlements as approved by the U.S. Supreme 

Court provide 5,122 acre-feet of additional diversions to these 

two tribes. An agreement has also been reached to settle the 

claim of the Fort Yuma - Quechan Indian Tribe, which is currently 

before the U.S. Supreme Court.

In 2003 legislation was enacted to enable the QSA’s local 

agency signatories to reach agreement on how to reduce their 

use of Colorado River water to California’s basic interstate 

apportionment of 4.4 million acre-feet annually. As a result of 

this legislation the State accepted significant responsibilities and 

liabilities for mitigation of QSA environmental impacts and for 

restoration of the Salton Sea ecosystem, The QSA implementation legislation is contained in three approved bills, SB 277 

(Ducheny), SB 317 (Kuehl), and SB 654 (Machado), which 

were chaptered in 2003. Among other things, the legislation 

establishes State policy with respect to Salton Sea, stating the 

intent of the Legislature that the State would undertake the restoration of Salton Sea ecosystem and permanent protection of its 

fish and wildlife. It provides that no further funding obligations 

or in-kind contributions for Salton Sea restoration would be 

required of IID, CVWD, MWD, or SDCWA. Any future actions 

to restore Salton Sea would be the sole responsibility of the 

State. Additionally, IID is held harmless from Salton Sea impacts 

resulting from transfers of conserved water.

With respect to QSA implementation, the legislation authorizes DFG to issue incidental take permits for California’s fully 

protected species, and provides that DFG chair a joint powers 

authority whose other members are SDCWA, IID, and CVWD. 

The three local agencies are to contribute $133 million to the 

joint powers authority for QSA environmental mitigation, with 

the State being responsible for mitigation in excess of that 

amount. The three local agencies are also to contribute $30 

million to the Salton Sea Restoration Fund managed by DFG. 

The legislation provides for a conditional transfer of conserved 

water from IID to MWD of up to 1.6 million acre-feet of Colorado River water, under specified terms. Proceeds from sale of 

the water – estimated at up to $300 million – are to go to the 

Salton Sea Restoration Fund. The Secretary for Resources is 

directed to prepare a Salton Sea ecosystem restoration study 

and environmental documentation, and identify a preferred 

alternative by the end of 2006. The study, to be conducted in 

consultation with a legislatively mandated advisory committee 

and with the Salton Sea Authority, is to include a proposed 

funding plan for implementing the preferred alternative. 

Accomplishments

Over the past 20 years, several large-scale water conservation actions involving Colorado River water users have 

been completed, as shown in Table 11-7. Since 1993, 

development and implementation of these programs and 

projects have included consideration of environmental issues and environmental justice values. 

Relationship with Other Regions

After eight years of negotiations, the signing of the Quantification Settlement Agreement on October 10, 2003, facilitated a 

second long-term water transfer from the Imperial Irrigation 

District in the Colorado River Hydrologic Region to urban 

water users in the South Coast Hydrologic Region. It will 

also make possible the transfer of additional water to be 

obtained through lining of the All American and the Coachella 

canals. The water transfer from IID will help stabilize MWD’s, 

SDCWA’s and CVWD’s water supplies, satisfy outstanding 

miscellaneous and Indian water rights, and provide funding 

that IID and farmers in the Imperial Valley will use for additional water conservation measures once the required interim 

fallowing period is completed.

Although the facilities to deliver SWP water supplies to the 

region have yet to be built, CVWD and DWA receive their 

annual allocations of SWP water through an exchange agreement with the South Coast region’s largest water wholesale 

agency, MWD. These districts are also participants in another 

agreement that delivers and stores water from the Colorado 

River into the Coachella Valley’s largest groundwater basin 

during periods of high flows.

Water districts in both regions are also cooperating in water 

conservation and land fallowing programs. The 1988 IID/

MWD Water Conservation Agreement resulted in conservation 

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Year Action Participants Comments/Status Estimated Savings

1980 Line 49 miles USBR, CVWD, Project completed. 132 taf/yr

 of Coachella 

 Canal 

1990 IID distribution IID, MWD Project completed. Under QSA agreement Conservation verification in 1998 - 

 system extends through 2037 (2047, if not 107 taf

 improvement terminated by SDCWA; 2077, if renewed

 and on-farm by mutual consent of IID / SDCWA)

 water Conservation projects - canal lining,

 management regulatory reservoirs, lateral spill

 projects interceptor canals, tailwater return

 designed to systems, non-leak gates, 12-hour water

 conserve 100 delivery, drip irrigation, and system

 taf/yr. automation.

 MWD funded $96.5 million (1988$) for 

 program costs; pays O&M for duration 

 of agreement. 

1992 Groundwater MWD, Central Test program to bank up to 300 taf. MWD and SNWA have stored 139 

 banking in Arizona WCD, taf in Arizona groundwater basins.

 Arizona So. Nevada WA

1992 PVID land PVID, MWD Project completed. Two-year land fallowing 186 taf were made available, but

 fallowing test program. Covered 20,215 acres in the water was subsequently spilled

 PVID.MWD paid $25 million to farmers from Lake Mead when flood control

 over a two-year period. releases were made from the reservoir.

1995 Partnership USBR, CVWD Provides, among other things, for studies N/A

 agreement to optimize reasonable beneficial use of

 water in the district. 

2003 Water transfer IID, SDCWA, Initial term of 35 years; 45 years if not ter- In 2003, SDCWA receives 10 taf and

 agreement CVWD minated by SDCWA; 75 years if renewed the Salton Sea receives 5 taf. By 2017,

 by mutual consent of IID / SDCWA. SDCWA amount increases to100 taf

 SDCWA pays for water transferred & and the Salton Sea amount increases 

 to Sea. to 150 taf. From 2018 through the

 remainder of agreement (2077, if 

 extended), SDCWA would receive 200 

 taf (from 2001 on) and the Salton Sea 

 would receive 0 acre-feet. For CVWD, 

 it receives 4 taf in 2008 and 103 taf 

 by 2024. This decreases to 100 taf in 

 2039, if agreement is extended.

2003 Land lease PVID, PVID conserved and transferred water 40.6 taf in 2003.

 agreement CVWD supplies to CVWD. 

2003 Canal Lining IID, CVWD, Portions of the All American Canal and 67.7 taf/yr - All American Canal 

 San Luis Rey the Coachella Canal will be lined. 26 taf/yr - Coachella Canal

 River Indian SDCWA pays for construction and O&M.

 Water Authority, 16 taf will be provided for the San Luis 

 other Indian Rey Indian water rights settlement.

 tribes

Table 11-7 Existing Colorado River Region Water Conservation Actions / Agreements Since 1980

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Box 11-4 Key Elements of California’s Colorado River Quantification Settlement Agreement

The California Colorado River Quantification Settlement Agreement and related agreements will have the 

following effects: 

• Permit the utilization of interim surplus water. 

• Transfer as much as 30 million acre-feet of water from farms to cities in Southern California for up to the 75 year 

 term of the agreement. 

• Settle potential lawsuits between the Imperial Irrigation District and the U.S. Department of the Interior. 

• Obligate California with the sole responsibility for restoration of the Salton Sea ecosystem. 

• Provide for cooperation on the environmental review and mitigation for the Imperial Irrigation District/ San 

 Diego County Water Authority Transfer Agreement, IID/ Coachella Valley Water District Acquisition 

 Agreement, and Salton Sea habitat conservation plan/natural community conservation plan. 

• Fund a $200 million project to line with concrete a portion of the earthen All-American Canal 

 and a portion of the earthen Coachella Canal. Water conserved by reducing seepage will be transferred to San 

 Diego and the San Luis Rey Indian Tribes, who will pay proportionally for operation and maintenance costs. 

• Quantify, for the first time, the total Colorado River apportionments in California.

of water supplies from the construction of new facilities, water 

system automation, and the implementation of technical assistance programs for farmers within the IID water service area. 

The conserved water is delivered to MWD and CVWD.

As part of an on-going agreement, MWD will provide 

technical and financial assistance to the PVID for the 

construction of facilities and implementation of programs to conserve water supplies within the PVID service 

area. MWD will be permitted to divert conserved water 

supplies resulting from these projects and programs. 

Looking to the Future

On October 10, 2003, MWD, IID, CVWD, SDCWA, and 

the Secretary of the Interior signed the Colorado River Water 

Delivery Agreement: Federal Quantification Settlement Agreement (QSA) for the purpose of Section 5(B) of the Interim 

Surplus Guidelines. This agreement specifies, how, over time, 

California will reduce its use of Colorado River water to its 

basic apportionment of 4.4 million acre-feet per year in all 

years, except for those years in which the Secretary of the 

Interior declares a surplus of water on the Colorado River. 

The QSA will remain in effect for 35 years, or 45 years if not 

terminated by SDCWA, or 75 years if renewed by mutual 

consent of IID and SDCWA. The QSA is expected to achieve 

the objective sought by the other Colorado River Basin states 

and the federal government of reducing California’s use of 

Colorado River water to its annual basic apportionment of 

4.4 million acre-feet. This reduction will be achieved through, 

among other practices, transfer of water use from IID to 

SDCWA and to CVWD. While it is the intent of IID to transfer 

water saved through conservation, from 2003 through 2012 

all of the water transferred to SDCWA will come from land 

fallowing. Fallowing for this transfer will decrease from a high 

of 90,000 acre-feet per year in 2012, until by 2017 all water 

transferred to SDCWA will come from efficiency conservation 

measures. At the same time, additional land fallowing will 

occur to meet flow requirements (5,000 acre-feet per year in 

2003, growing to 150,000 acre-feet in 2017 unless reduced 

or eliminated as a result of “Salton Sea Restoration”) for environmental mitigation as a result of the reduced agricultural 

drainage to the Salton Sea. 

At its peak, land fallowing in the IID service area is anticipated to be up to 40,000 acres, as needed to provide up to 

150,000 acre-feet of mitigation water to the Salton Sea in 

2017. After 15 years, it is expected that improvements in 

water use efficiency will be sufficient to meet the terms of the 

QSA, and land fallowing would no longer be needed for 

environmental mitigation. One of the long-term assumptions 

in MWD’s Integrated Resources Plan is that MWD’s Colorado 

River supply will be maximized through water transfers from 

agricultural water users in the Colorado River hydrologic 

region (IID and PVID) to urban water users in the South Coast 

hydrologic region (SDCWA and MWD).

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The agricultural water purveyors in the region (IID, PVID, 

CVWD, and Bard Water District) will continue to implement 

Efficient Water Management Practices. Water districts in the 

Coachella Valley will continue with their efforts to provide 

technical assistance to the managers of large landscape areas 

to help improve the efficiencies of irrigation.

CVWD and DWA will continue to work together to address 

declining water levels in the Coachella Valley’s largest groundwater basin, the Indio sub-basin. CVWD is operating an active 

groundwater recharge program for the upper end of the 

Coachella Valley, generally, the urbanized part of the valley. 

CVWD recharges groundwater with imported Colorado River 

water and with Whitewater River flows using percolation ponds. 

CVWD and DWA levy extraction fees on larger groundwater 

users in the upper Coachella Valley.

With support from the Quechan Indian Reservation and from 

the Southern Low Desert Resource Conservation and Development Council, Bard Water District (BWD) is undertaking an 

$8 million project for capital improvements on the Reservation Division of the USBR’s Yuma Project. This improvement 

project is mostly funded by a $4 million matching grant from 

the North American Development Bank. The Quechan Indian 

Reservation contributed $2 million of the matching funds and 

$2 million was raised by BWD customers. BWD is rehabilitating about 10 miles of earthen canals with concrete lining 

and pipeline in 2004 and an additional 10 miles are to be 

rehabilitated in 2005. BWD will also be replacing more than 

100 irrigation gates and structures. These improvements will 

greatly increase the effectiveness of its system by reducing 

canal seepage and evaporation.

Over the years, the USBR and others have considered potential 

solutions to stabilize the Salton Sea’s salinity and elevation. 

Most recently, the Salton Sea Authority has been performing 

appraisal level evaluations of some of the frequently suggested 

alternatives, such as large scale pump-in, pump-out pipelines 

to the Pacific Ocean. The authority is investigating integrated 

strategies where a smaller, lower salinity lake with a stable water 

surface would be coupled with treatment/desalination of some 

brackish inflows. The treated water could then be sold or could 

be part of a water transfer that would help fund the project.

Under direction contained in the QSA implementing legislation, 

the Secretary of the California Resources Agency is undertaking a study of alternatives for restoration of the Salton Sea. 

A deadline of December 31, 2006 was established for the 

completion of the study and submittal to the legislature.

The Colorado River Quantification Settlement Agreement (QSA), finalized and signed in October 2003, 

outlines key elements for California to operate within its 

basic annual allotment of 4.4 million acre-feet from the 

Colorado River, as summarized in Box 11-4. 

Water Portfolios for Water Years 

1998, 2000, and 2001

Above average rainfall occurred during water year 1998 in 

Blythe, with near average rainfall elsewhere in the region. 

For water years 2000 and 2001, rainfall totals were below 

average; and 2000 could also be considered as a dry year. 

In water year 1998, rainfall totals were 176 percent above 

average for the National Weather Service station in Blythe, 

104 percent of average for the El Centro 2 SSW station and 

108 percent of average for Palm Springs. 

Water year 2000 was very dry. Rainfall totals measured by the 

Blythe station for the year were only 17 percent of average; 

for El Centro, 10 percent of normal; and for Palm Springs, 

35 percent of normal. Conditions improved slightly for water 

year 2001. The Blythe station measured rainfall that was 120 

percent of normal. For El Centro, it was 78 percent of normal. 

For Palm Springs, it was 74 percent. 

Tables 11-8 through 11-10 present actual information about 

the water supplies and uses for the Colorado River hydrologic 

region for these three years. About 85 percent of the region’s 

water comes from surface deliveries from the Colorado River. 

The high level of agricultural activity in the region is reflected 

by the large agricultural water demand relative to other water 

uses. In 2000, agricultural water demand was 85 percent of all 

developed applied water uses in the region. By contrast, urban 

water use only accounted for 14 percent of total demand. 

The Water Portfolio Flow Diagrams (Figures 11- 4 and 11-5) 

provide a graphical presentation of how water supplies are 

distributed and used throughout this region.

Despite the climatological conditions, demands for water 

supplies by the region’s urban and agricultural users and 

the environment did not exhibit any large fluctuations during 

the years between 1998 and 2001. The total applied water 

demand for 1998 was 4,602,000 acre-feet. For 2000, the 

demand increased slightly to 4,726,900 acre-feet. In 2001, 

it decreased to 4,536,800 acre-feet.

EE-RM-PET-100 C0MMENT 01A
California Water Plan Update 2005

1811 Volume 3 Regional Reports

Water Entering the Region 

Precipitation 9,455 3,034 4,770

 Inflow from Mexico 182 166 155

 Inflow from Colorado River 4,986 5,349 5,197

 Imports from Other Regions 0 0 0

Total 14,623 8,549 10,122

Water Leaving the Region 

Consumptive Use of Applied Water * 2,814 2,865 2,775

 (Ag, M&I, Wetlands) 

 Outflow to Oregon/Nevada/Mexico 0 0 0

 Exports to Other Regions 1,081 1,296 1,250

 Statutory Required Outflow to Salt Sink 0 0 0

 Additional Outflow to Salt Sink 1,185 1,252 1,228

 Evaporation, Evapotranspiration of Native 

 Vegetation, Groundwater Subsurface Outflows, 9,646 3,320 5,049

 Natural and Incidental Runoff, Ag Effective 

 Precipitation & Other Outflows 

Total 14,726 8,733 10,302

Storage Changes in the Region

[+] Water added to storage

 [-] Water removed from storage 

 Change in Surface Reservoir Storage -15 -19 1

 Change in Groundwater Storage ** -88 -165 -181

Total -103 -184 -180

Applied Water * (compare with Consumptive Use) 4,107 4,288 4,174

*Footnote for applied water

Consumptive use is the amount of applied water used and no longer available as a source of supply. Applied water is 

 greater than consumptive use because it includes consumptive use, reuse, and outflows. 

**Footnote for change in Groundwater Storage

Change in Groundwater Storage is based upon best available information. Basins in the north part of the 

state (North Coast, San Francisco, Sacramento River and North Lahontan regions and parts of Central 

 Coast and San Joaquin River regions) have been modeled – spring 1997 to spring 1998 for the 1998 

 water year and spring 1999 to spring 2000 for the 2000 water year. All other regions and year 2001 were 

 calculated using the following equation: 

GW change in storage =

 intentional recharge + deep percolation of applied water + conveyance deep percolation - withdrawals

This equation does not include the unknown factors such as natural recharge and subsurface inflow and outflow.

 Water Year (Percent of Normal Precipitation) 

1998 (154%) 2000 (50%) 2001 (80%)

Table 11-8 Colorado River Hydrologic Region Water Balance Summary - TAF

Water Entering the Region – Water Leaving the Region = Storage Changes in Region

EE-RM-PET-100 C0MMENT 01A
Chapter 11 Colorado River Hydrologic Region 1911

California Water Plan Update 2005

 Applied Net Depletion Applied Net Depletion Applied Net Depletion

Water Use Water Use Water Use Water Use Water Use Water Use

1998 2000 2001

WATER USE

Table 11-9 Colorado River Region Water Use and Distribution of Dedicated Supplies (TAF)

DEDICATED WATER SUPPLIES

Urban

Large Landscape 156.9 148.8 122.4 

Commercial 71.4 123.5 145.0 

Industrial 3.3 4.6 4.6

Energy Production 76.7 76.7 76.7 

Residential - Interior 170.0 170.3 159.1 

Residential - Exterior 65.2 59.1 75.1 

Evapotranspiration of Applied Water 222.1 222.1 207.9 207.9 196.5 196.5

E&ET and Deep Perc to Salt Sink 76.6 76.6 82.8 82.8 84.6 84.6

Outflow 124.7 124.7 129.9 129.9 131.0 131.0

Conveyance Applied Water 0.0 0.0 0.0

Conveyance Evaporation & ETAW 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Outflow 0.0 0.0 0.0 0.0 0.0 0.0

GW Recharge Applied Water 156.4 100.6 24.1 

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Urban Use 700.0 423.4 423.4 683.5 420.6 420.6 606.9 412.1 412.1

 Agriculture

On-Farm Applied Water 3,531.8 3,674.6 3,561.7 

Evapotranspiration of Applied Water 2,560.4 2,560.4 2,627.3 2,627.3 2,548.5 2,548.5

E&ET and Deep Perc to Salt Sink 80.3 80.3 86.8 86.8 83.5 83.5

Outflow 723.3 723.3 778.9 778.9 752.1 752.1

Conveyance Applied Water 338.6 338.6 338.6 

Conveyance Evaporation & ETAW 64.0 64.0 64.0 64.0 64.0 64.0

Conveyance Deep Perc to Salt Sink 167.6 167.6 167.6 167.6 167.6 167.6

Conveyance Outflow 107.0 107.0 107.0 107.0 107.0 107.0

GW Recharge Applied Water 0.0 0.0 0.0

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Agricultural Use 3,870.4 3,702.6 3,702.6 4,013.2 3,831.6 3,831.6 3,900.3 3,722.7 3,722.7

 Environmental

Instream

 Applied Water 0.0 0.0 0.0

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Wild & Scenic

 Applied Water 0.0 0.0 0.0

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Required Delta Outflow

 Applied Water 0.0 0.0 0.0

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Managed Wetlands

 Habitat Applied Water 31.6 30.2 29.6 

 Evapotranspiration of Applied Water 31.6 31.6 30.2 30.2 29.6 29.6

 E&ET and Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Applied Water 0.0 0.0 0.0

 Conveyance Evaporation & ETAW 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Total Managed Wetlands Use 31.6 31.6 31.6 30.2 30.2 30.2 29.6 29.6 29.6

 Total Environmental Use 31.6 31.6 31.6 30.2 30.2 30.2 29.6 29.6 29.6

 TOTAL USE AND OUTFLOW 4,602.0 4,157.6 4,157.6 4,726.9 4,282.4 4,282.4 4,536.8 4,164.3 4,164.3

 

Surface Water

 Local Deliveries 6.6 6.6 6.6 6.3 6.3 6.3 4.0 4.0 4.0

 Local Imported Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 Colorado River Deliveries 3,905.1 3,905.1 3,905.1 4,053.0 4,053.0 4,053.0 3,946.6 3,946.6 3,946.6

 CVP Base and Project Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 Other Federal Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 SWP Deliveries 156.4 156.4 156.4 100.6 100.6 100.6 24.1 24.1 24.1

 Required Environmental Instream Flow 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Groundwater

 Net Withdrawal 73.4 73.4 73.4 105.3 105.3 105.3 171.7 171.7 171.7

 Deep Percolation of Surface and GW 313.6 311.0 237.1 

Reuse/Recycle

 Reuse Surface Water 130.8 133.5 135.3 

 Recycled Water 16.1 16.1 16.1 17.2 17.2 17.2 17.9 17.9 17.9

 TOTAL SUPPLIES 4,602.0 4,157.6 4,157.6 4,726.9 4,282.4 4,282.4 4,536.7 4,164.3 4,164.3

Balance = Use - Supplies 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

EE-RM-PET-100 C0MMENT 01A
California Water Plan Update 2005

2011 Volume 3 Regional Reports

Minor reductions in the irrigated crop acres occurred from 

1998 to 2000, followed by a slight increase for 2001. Total 

crop acreage for the region (including double-cropping) 

was 761,760 acres in 1998, 731,890 acres for 2000, and 

739,830 for 2001. Noticeable declines were observed for 

irrigated grains and other field crop categories. A steady 

increase in production acreage has been observed for the 

vegetables crops classified in the “other truck” category.

Selected References

2002 California 305(b) Report on Water Quality, State Water 

Resources Control Board. 

Agency for Toxic Substances and Disease Registry. “Toxicological Profile for Chromium”. May 25, 2001. 

www.atsdr.cdc.gov/toxprofiles/tp7.html 

Associated Press. “Key elements of Colorado River water 

deal.” October 17, 2003. 

California Environmental Protection Agency (EPA) website. 

www.calepa.ca.gov/ 

 o List of Drinking Water Contaminants and MCLs. 

o Drinking Water Contaminant Candidate List. 

 o Regulations and Guidance. 

California’s Groundwater Bulletin 118 (Draft), Update 2003, 

California Department of Water Resources. www.ground 

water.water.ca.gov/bulletin118/index.cfm 

Chemical & Engineering News, “Rocket-Fueled River<” 

August 18, 2003. www.pubs.acs.org/cen/coverstory/ 

8133/8133perchlorates.html 

Coachella Valley Water District. www.cvwd.org/ 

Colorado River Basin Regional Water Quality Control Board. 

www.waterboards.ca.gov/coloradoriver/ 

Colorado River Board of California. www.crb.ca.gov/ 

Colorado River Water Delivery Agreement: Federal Quantification Settlement Agreement for Purposes of Section 

5(B)of Interim Surplus Guidelines. October 10, 2003. 

www.saltonsea.water.ca.gov/crqsa/index.cfm 

[DHS] California Department of Health Services, “Drinking 

Water Standards”. www.dhs.ca.gov/ps/ddwem/publica 

tions/Regulations/regulations_index.htm 

DHS. “Chemical Contaminants in Drinking Water”. July 3, 2003. 

www.dhs.ca.gov/ps/ddwem/chemicals/chemindex.htm 

DHS. “Drinking Water Action Level, Chemicals with Recent 

 Detections”. June 12, 2003. 

DHS. “Drinking Water Action Levels, Historic Action Levels 

and Action Levels for Contaminants Detected Infrequently”. 

June 30, 2003. 

DHS. “Specific Contaminants of Current Interest: arsenic, 

chromium-6, manganese, methyl tertiary butyl ether 

(MTBE), N-nitrosodimethylamine (NDMA), perchlorate, 1, 

2, 3-trichloropropane. 

DHS. “Perchlorate in California Drinking Water: Status of 

Regulations and Monitoring”. July 2, 2003. 

DHS. “Chromium-6 in Drinking Water: Background Information”. 

April 8, 2003. 

DHS. “Chromium-6 in Drinking Water: Regulation and 

Monitoring Update”. July 16, 2003. 

Groundwater Resources Association of California. “Perchlorate 

and NDMA: Rocket Fuel Contaminants a Serious Challenge 

to Drinking Water Suppliers”. News release. April 4, 2002. 

www.grac.org/pernewsrelease.html 

Imperial Irrigation District. www.iid.com/water/ 

Lower Colorado River Multi-Species Conservation Program 

Web site. www.lcrmscp.org 

Metropolitan Water District of Southern California. 

www.mwdh2o.com/ 

Nonpoint Source Program Strategy and Implementation Plan, 

1998-2013, State Water Resources Control Board, 

California Coastal Commission, January 2000. 

www.coastal.ca.gov/nps/npsndx.html 

Palo Verde Irrigation District. www.citlink.net/~davegun/pvid.html 

“Presentation by staff of the State Water Resources Control 

Board and staff of the Department of Toxic Substances 

Control”. 2003. 

Salton Sea Authority. www.saltonsea.ca.gov/ 

State Water Resources Control Board. “Perchlorate Contamination of California’s Groundwater Supplies”. www.swrcb. 

ca.gov/rwqcb4/html/perchlorate.html 

Strategic Plan, State Water Resources Control Board, Regional 

Water Quality Control Boards, November 15, 2001. 

www.waterboards.ca.gov/strategicplan/index.html

US Bureau of Reclamation. www.usbr.gov/ 

US Fish and Wildlife Service. www.fws.gov/ 

US Geological Survey National Water Quality Assessment 

Program. www.water.usgs.gov/nawqa/ 

US Geological Survey online publications. 

www.pubs.usgs.gov/products/ 

US EPA. Ground Water & Drinking Water website. “Perchlorate”. 

January 23, 2003. www.epa.gov/safewater/ 

US EPA. “Perchlorate Environmental Contamination: Toxicological Review and Risk Characterization (External Review 

Draft)”. 2002. www.cfpub.epa.gov/ncea/cfm/recordis 

play.cfm?deid=24002 

EE-RM-PET-100 C0MMENT 01A
Chapter 11 Colorado River Hydrologic Region 2111

California Water Plan Update 2005

Water Quality Control Plan, Regional Water Quality Control 

Board. www.swrcb.ca.gov/rwqcb3 

Water Quality Control Plan, Regional Water Quality Control 

Board. www.swrcb.ca.gov/rwqcb3 

Watershed Management Initiative Chapter, Regional Water 

Quality Control Board. www.waterboards.ca.gov/lahon 

tan/WMI/WMI_Index.htm 

Western Regional Climate Center website. www.wrcc.dri.edu/ 

EE-RM-PET-100 C0MMENT 01A
Chapter 11 Colorado River Hydrologic Region 2311

California Water Plan Update 2005

Water Portfolios

Colorado River Hydrologic Region

EE-RM-PET-100 C0MMENT 01A
California Water Plan Update 2005

2411 Volume 3 Regional Reports

Table 11-10 Colorado River region water portfolio (TAF)

 ID Colorado River Colorado River Colorado River

Number: Flow Diagram Component (see legend) 1998 2000 2001

 1 Colorado River Deliveries 3,905.1 4,053.0 3,946.6

 2 Total Desalination - - -

 3 Water from Refineries - - -

 4a Inflow From Oregon - - -

 b Inflow From Mexico 182.4 165.6 154.7

 5 Precipitation 9,454.8 3,033.9 4,769.9

 6a Runoff - Natural N/A N/A N/A

 b Runoff - Incidental N/A N/A N/A

 7 Total Groundwater Natural Recharge N/A N/A N/A

 8 Groundwater Subsurface Inflow N/A

 9 Local Deliveries 6.6 6.3 4.0

 10 Local Imports - - -

 11a Central Valley Project :: Base Deliveries - - -

 b Central Valley Project :: Project Deliveries - - -

 12 Other Federal Deliveries - - -

 13 State Water Project Deliveries 156.4 100.6 24.1

 14a Water Transfers - Regional - - -

 b Water Transfers - Imported - - -

 15a Releases for Delta Outflow - CVP 

 b Releases for Delta Outflow - SWP 

 c Instream Flow Applied Water - - -

 16 Environmental Water Account Releases - - -

 17a Conveyance Return Flows to Developed Supply - Urban - - -

 b Conveyance Return Flows to Developed Supply - Ag - - -

 c Conveyance Return Flows to Developed Supply - Managed Wetlands - - -

 18a Conveyance Seepage - Urban - - -

 b Conveyance Seepage - Ag - - -

 c Conveyance Seepage - Managed Wetlands - - -

 19a Recycled Water - Agriculture - - -

 b Recycled Water - Urban 16.1 17.2 17.9

 c Recycled Water - Groundwater - - -

 20a Return Flow to Developed Supply - Ag - - -

 b Return Flow to Developed Supply - Wetlands - - -

 c Return Flow to Developed Supply - Urban - - -

 21a Deep Percolation of Applied Water - Ag 47.8 48.8 44.6

 b Deep Percolation of Applied Water - Wetlands - - -

 c Deep Percolation of Applied Water - Urban 109.4 161.6 168.4

 22a Reuse of Return Flows within Region - Ag 130.8 133.5 135.3

 b Reuse of Return Flows within Region - Wetlands, Instream, W&S - - -

 24a Return Flow for Delta Outflow - Ag - - -

 b Return Flow for Delta Outflow - Wetlands, Instream, W&S - - -

 c Return Flow for Delta Outflow - Urban Wastewater - - -

 25 Direct Diversions N/A N/A

 26 Surface Water in Storage - Beg of Yr 580.8 585.4 566.9

 27 Groundwater Extractions - Banked - - -

 28 Groundwater Extractions - Adjudicated - - -

 29 Groundwater Extractions - Unadjudicated 387.0 416.3 408.8

 23 Groundwater Subsurface Outflow N/A N/A N/A

 30 Surface Water Storage - End of Yr 566.3 566.9 568.3

 31 Groundwater Recharge-Contract Banking -14.7 -59.2 -8.9

 32 Groundwater Recharge-Adjudicated Basins - - -

 33 Groundwater Recharge-Unadjudicated Basins - - -

 34a Evaporation and Evapotranspiration from Native Vegetation N/A N/A

 b Evaporation and Evapotranspiration from Unirrigated Ag N/A N/A

 35a Evaporation from Lakes 1555.5 1552.5 1552.4

 b Evaporation from Reservoirs 120 121.5 120.6

 36 Ag Effective Precipitation on Irrigated Lands 146.6 14.1 76.2

 37 Agricultural Water Use 3,531.8 3,674.6 3,561.7

 38 Managed Wetlands Water Use 31.6 30.2 29.6

 39a Urban Residential Use - Single Family - Interior 144.2 154.6 123.1

 b Urban Residential Use - Single Family - Exterior 57.1 55.8 67.4

 c Urban Residential Use - Multi-family - Interior 25.9 15.7 36.0

 d Urban Residential Use - Multi-family - Exterior 8.1 3.3 7.7

 40 Urban Commercial Use 71.4 123.5 145.0

 41 Urban Industrial Use 3.3 4.6 4.6

 42 Urban Large Landscape 156.9 148.8 122.4

 43 Urban Energy Production 76.7 76.7 76.7

 44 Instream Flow - - -

 45 Required Delta Outflow - - -

 46 Wild and Scenic Rivers - - -

 47a Evapotranspiration of Applied Water - Ag 2560.4 2627.3 2548.45

 b Evapotranspiration of Applied Water - Managed Wetlands 31.6 30.2 29.6

 c Evapotranspiration of Applied Water - Urban 222.102 207.9 196.48

 48 Evaporation and Evapotranspiration from Urban Wastewater - - -

 49 Return Flows Evaporation and Evapotranspiration - Ag 80.3 86.8 83.5

 50 Urban Waste Water Produced 61.9 67.6 69.2

 51a Conveyance Evaporation and Evapotranspiration - Urban 13.91 14.42 14.6

 b Conveyance Evaporation and Evapotranspiration - Ag 64 64 64

 c Conveyance Evaporation and Evapotranspiration - Managed Wetlands - - -

 d Conveyance Outflow to Mexico N/A N/A

 52a Return Flows to Salt Sink - Ag 997.9 1053.5 1026.7

 b Return Flows to Salt Sink - Urban 187.39 198.28 201

 c Return Flows to Salt Sink - Wetlands - - -

 53 Remaining Natural Runoff - Flows to Salt Sink - - -

 54a Outflow to Nevada - - -

 b Outflow to Oregon - - -

 c Outflow to Mexico - - -

 55 Regional Imports 4,986.0 5,349.0 5,197.0

 56 Regional Exports 1081 1296 1250

 59 Groundwater Net Change in Storage -88.1 -164.5 -180.6

 60 Surface Water Net Change in Storage -14.5 -18.5 1.4

 61 Surface Water Total Available Storage 620.4 620.4 620.4

 

 Inflows Outflows Green number signifies included in summary boxes 

 

EE-RM-PET-100 C0MMENT 01A
Figure 11-4 Colorado River region - illustrated water flow diagram

INFLOWS

SUMMARY

OUTFLOWS

8

15a,b

21

27

31

45

48

51

5

6

46

14 16

33

28

29

32

39- 43

59

50

18

9

51

34

47b

38

35

51

26

30

60

61

11

12

13

15c

54

56

7

1

4

55

10 44

36

47a

49

51

37

17

20

47c

22

25 24

31

23

2

3

52

53

19

In this illustration of Table 11-10, key components of the flow diagram are shown as characteristic elements of the hydrologic cycle. Circled numbers correspond to the identification number of flow diagram components in the table; its color indicates whether the component is water input, output, 

or summary.

52

Volume 3 Regional Reports Chapter 11 Colorado River Region 11 25

California Water Plan Update 2005

EE-RM-PET-100 C0MMENT 01A
SUMMARY

OUTFLOWS

INFLOWS

Figure 11-5 Colorado River region - schematic flow diagram

In schematic of Table 11-10, key components of the flow diagram are shown as boxes and connectors in a flow chart. Circled numbers correspond to the identification number of flow diagram components in the table; box color indicates whether the component is water input, output, or summary. 

Blank boxes are flow diagram components not relevant to the region. 

1

2

5

4

3

55

6

13

11

19

12

10

9

7

20

21

45

29

26

30

35

39 to 43

37

38

53

54

46

14

34 36

28

52

16

24

17

18

25

47

50

49

48

27

31

32

33

23

8

15C

15A

15B

56

44

16

51

22

COLORADO R 

DELIVERIES:

RUNOFF:

NATURAL: INCIDENTAL: PRECIPITATION: TOTAL STREAM 

FLOW: 

AG EFFECTIVE 

PRECIPITATION ON 

IRRIGATED LANDS: 

INFLOW FROM 

MEXICO:

LOCAL

DELIVERIES:

SWP DELIVERIES: WATER DEPOSITS: 

SURFACE WATER: 

GROUNDWATER: 

RECYL & DESAL:

TRANSFERS:

TOTAL GROUNDWATER NATURAL RECHARGE: 

GROUNDWATER CHANGE IN STORAGE: 

BANKED:

ADJUDICATED: 

UNADJUDICATED: 

GW EXTRACTIONS:

CONTRACT BANKS:

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

EVAPOTRANSPIRATION 

OF APPLIED WATER: 

AG:

WETLANDS:

URBAN:

WATER USE (APPLIED): 

AGRICULTURAL: 

WETLANDS:

URBAN:

RECYCLED WATER: 

AG: URBAN:

GW: 

URBAN

WASTEWATER 

PRODUCED:

INCIDENTAL E & ET 

AG RETURN FLOWS: 

AG & WETLANDS 

RETURN FLOWS:

RETURN FLOWS TO SALT 

SINKS:

AG: WETLANDS:

URBAN:

REMAINING NATURAL 

RUNOFF

FLOW TO SALT SINKS: 

DEEP PERC OF APPLIED 

WATER: 

AG: WETLANDS:

URBAN:

RETURN FLOW TO 

DEVELOPED

SUPPLY: 

AG:

WETLANDS:

URBAN:

EVAP FROM: 

LAKES:

RESERVOIRS:

E & ET FROM:

NATIVE VEGETATION: 

UNIRRIGATED AG: 

CONVEYANCE E&ET, 

RETURN FLOWS, & 

SEEPAGE:

URBAN: AG:

WETLANDS:

CONVEYANCE E & ET: 

URBAN: AG:

WETLANDS:

MEXICO:

CONVEYANCE RETURN 

FLOWS:

URBAN: AG:

WETLANDS:

CONVEYANCE SEEPAGE: 

URBAN: AG:

WETLANDS:

RETURN FLOW FOR 

DELTA OUTFLOW: 

AG:

WETLANDS:

URBAN : 

EVAPORATION AND EVAPOTRANSPIRATION OF APPLIED WATER, 

PRECIPITATION AND CONVEYANCE: 

GW RECHARGE:

CONTRACT BANKING:

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

TO E & ET: 

SUBSURFACE GW 

INFLOW: 

SUBSURFACE 

GROUNDWATER 

OUTFLOW: 

OTHER REGIONAL 

TRANSFER OUT: 

REGIONAL

TRANSFER IN: 

SURFACE WATER IN 

STORAGE: 

 Beg of Yr: 

End of Yr: 

DIRECT 

DIVERSIONS:

Service Area

Return 

Flow within

Return of

Required Instream 

Flows

Return of

Required Wild & 

Scenic Flows

11 26 Chapter 11 Colorado River Region Volume 3 Regional Reports

California Water Plan Update 2005

EE-RM-PET-100 C0MMENT 01A
Chapter 12 Sacramento-San Joaquin Delta Region 

Volume 3 

EE-RM-PET-100 C0MMENT 01A
Chapter 12 Sacramento-San Joaquin Delta Region i12

California Water Plan Update 2005

Chapter 12 Sacramento-San Joaquin Delta Region

Contents

Chapter 12 Sacramento-San Joaquin Delta Region ..................................................................................................12-1

Setting ............................. 12-1

 Topography and Climate ...............................................................................................................................12-1

 Land Use ..................... 12-2

 Population ................... 12-2

 Water Use ................... 12-2

 Water Exported from the Delta ......................................................................................................................12-4

 Water Standards .......... 12-5

CALFED Bay-Delta Program ...............................................................................................................................12-6

State of the Region ............ 12-7

 Water Supply Reliability  12-9

 Water Quality .............. 12-9

 Salinity .................. 12-9

 Mercury ................ 12-9

 Dissolved Oxygen (DO) ........................................................................................................................12-10

 Organic Carbon (TOC) .........................................................................................................................12-10

 Selenium ............. 12-11

 Pesticides ............. 12-11

 Toxicity of Unknown Origin ...................................................................................................................12-12

 Ecosystem Restoration . 12-12

 Levee System Integrity . 12-13

 Recreation .................. 12-13

Looking to the Future ....... 12-14

 Water Supply Reliability ..............................................................................................................................12-15

 Delta Improvements Package .................................................................................................................12-16

 In-Delta Storage Project ........................................................................................................................12-15

 Los Vaqueros Reservoir Expansion .........................................................................................................12-15

 Water Quality ............ 12-16

 Delta Improvements Package .................................................................................................................12-15

 Delta Region Water Quality Management Plan .......................................................................................12-18

 DWR MWQI Program ..........................................................................................................................12-18

 CALFED Storage Projects ......................................................................................................................12-18

 Ecosystem Restoration . 12-18

 Delta Improvements Package .................................................................................................................12-18

 Delta Region Farmland Preservation and Private Lands Stewardship Program ...........................................12-19

 Other CALFED ERP Projects ...................................................................................................................12-19

 Levee System Integrity . 12-19

 Oversight ............. 12-19

 Funding ............... 12-19

 Ecosystem Integration ...........................................................................................................................12-20

 Recreation .................. 12-20

 Other Activities ........... 12-20

Selected References ......... 12-21

EE-RM-PET-100 C0MMENT 01A
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EE-RM-PET-100 C0MMENT 01A
Chapter 12 Sacramento-San Joaquin Delta Region iii12

California Water Plan Update 2005

Boxes

Box 12-1 California Bay-Delta Authority .................................................................................................................12-7

Box 12-2 Organic Carbon ... 12-11

Box 12-3 Ongoing Planning Efforts ......................................................................................................................12-14

Box 12-4 Franks Tract Description ........................................................................................................................12-17

Figures

Figure 12-1 Delta water balance for year 2000 ..................................................................................................... 12-iv

Figure 12-2 Delta region population .......................................................................................................................12-3

Figure 12-3 CALFED objectives ..............................................................................................................................12-5

Figure 12-4 Proposed Delta gates map ...................................................................................................................12-8

Figure 12-5 Delta Improvements Program map ......................................................................................................12-10

Figure 12-6 In-Delta Storage Project (map) ...........................................................................................................12-16

Tables

Table 12-1 Crop acreage and applied water demand in the Delta service area as of 2000 .........................................12-4

Table 12-2 Water balance for the Delta region ........................................................................................................12-6

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Figure12-1 Delta water balance for year 2000 

Water entering the Delta

Water leaving the Delta

Delta Boundary - Section 12220 of the Water Code

Delta Service Area - The area that is irrigated from

 nearby Delta channels

Delta Uplands - Those lands above the five-foot contour 

 which area served from the Lowland Delta channels

Delta Lowlands - Those lands approximately at the 

 five-foot countour and below

0 2 4

Scale

6 Miles

Delta Water Balance

Average Water Year 2000

NORTH BAY AQUEDUCT

50

580

205

5

5

80

80

4

4

120

99

99

12

12

12

113

220

160

160

84

RIVER

SACRAMENTO

SAN

JOAQUIN

RIVER

LODI

SACRAMENTO

RIO VISTA

UPLANDS

UPLANDS

DELTA SERVICE AREA

DELTA BOUNDARY

LOWLANDS

Yolo Bypass

2,956 TAF

North Bay Aqueduct (SWP)

47 TAF

Outflow

18,144 TAF

Contra Costa Water District

126 TAF

Consumptive Use

1,690 TAF

Precipitation

954 TAF

Sacramento River

18,327 TAF

Eastside Tributaries

1,076 TAF

San Joaquin River

2,841 TAF

Central Valley Project

2,482 TAF

Banks Pumping Plant (SWP)

3,666 TAF Tracy

Pumping

Plant

Banks

Pumping

Plant

Delta water balance for water year 2000 includes key annual Delta inflows, exports, precipitation, consumptive use, and Net Delta Outflow.

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Chapter 12 Sacramento-San Joaquin Delta Region

The region’s resources must be managed for generations 

to come. The overarching challenge involves finding ways 

for all the interests who benefit from the Delta to integrate 

a vast array of projects intended to improve water quality, 

ecosystem health, levee stability, and water supply in ways 

that provide long-term, sustainable benefits at reasonable 

costs to everyone. 

This regional report for the Delta Region is an overview of 

recent efforts to carry out actions that will help the region to 

continue to serve society’s demand for farm products, fishing, 

recreation, and water—all while protecting the Delta’s ecosystem and water quality. The intent of the profile is to give readers 

a sense of the region’s water resource management priorities 

and outline major efforts to integrate water resource management activities in the Delta. For more detailed information 

about actions and projects mentioned in this profile, consult 

the selected references noted at the end of this chapter.

Topography and Climate

The Delta is a unique and valuable resource and an integral 

part of California’s water system. Located at the confluence of 

the Sacramento and San Joaquin Rivers, the Delta is part of the 

largest estuary system on the West Coast and is the keystone 

to operation of the two largest water projects in California 

the SWP and the federal Central Valley Project (CVP). The 

region extends from the confluence of the two rivers inland to 

Sacramento and Stockton and spans roughly 750,000 acres. 

A large part of this land is below sea level, and relies on more 

than 1,100 miles of levees for protection against flooding 

along the hundreds of miles of interlaced waterways. 

The Delta’s network of waterways conveys runoff toward San 

Francisco Bay and the Pacific Ocean from over 40 percent of 

California’s land area. Major tributaries include the Sacramento, San Joaquin, Calaveras, Cosumnes, and Mokelumne 

rivers. These rivers plus their tributaries carry 47 percent of 

the state’s total annual runoff. 

Setting

Until 1850, the Sacramento-San Joaquin Delta (Delta) was 

wild, a tidal marsh with islands and river channels that 

changed according to nature’s will. By the 1870s, settlers had 

built levees and turned marshland into farmland. Farming 

on a commercial scale became a way of life. The 1870s and 

1880s saw the arrival of commercial fisheries that introduced 

nonnative species—striped bass and American shad. As 

decades passed, commerce grew, and ocean shipping began 

using Delta ports to transport goods between California and 

foreign markets. Along with international shipping came 

invasive aquatic species unintentionally carried to the Delta 

in the ballast water of these vessels. By 1951, with completion 

of the Delta-Mendota Canal, the Delta was forever changed. 

This federal project for moving water to California’s Central 

Valley farms was the start of large-scale water supply infrastructure that would, with the addition of the State Water 

Project (SWP) and other smaller projects, evolve into today’s 

multibillion dollar system. 

The Delta was formally defined in the Delta Protection Act of 

1959 (California Water Code Section 12220) and is composed of The Uplands Zone (lands above the 5-foot elevation 

contour) and the Lowlands Zone (lands at or below the 5-foot 

contour line). The statutory Delta Boundary that defines the 

Legal Delta is shown in Figure 12-1. 

This massive network of canals, levees, pumps, and fish screens 

moves water to farms, industries, and residents hundreds of 

miles from the Delta. What was once a continually changing 

tidal marsh with a rich variety of thriving, native species is 

now a complex maze of natural and man-made resources 

providing multiple benefits to the California economy. 

The challenge the region faces in the 21st century is how to 

sustain the viability of these resources while demand for them 

continues to grow.

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Land Use

The vast majority of the Delta land is agricultural (about 538,000 

acres). These acres are among the most highly productive in the 

world. Open water covers about 60,000 acres, while urban and 

commercial property comprises approximately 64,000 acres. 

The remainder of the region presently consists of undeveloped 

natural plant vegetation. 

Population

The legal Delta encompasses portions of six counties: Alameda, Contra Costa, Sacramento, San Joaquin, Solano and 

Yolo. According to the census figures used in the 1995 Sacramento-San Joaquin Delta Atlas, the population in the Delta 

was an estimated 410,000 in 1990. A more recent estimate 

was obtained using data from the California State Census Data 

Center for areas of these counties within the legal Delta, indicating that about 462,000 people resided in the Delta region as 

of the 2000 Census. Figure 12-2 shows a map of population 

estimates for each of the county areas within the legal Delta. 

Rapid growth is occurring in urban areas in and surrounding 

the Delta, especially in Elk Grove (27.0 percent growth per year 

– the highest growth rate in California), Tracy (5.9 percent per 

year), Brentwood (12.3 percent per year), and Rio Vista (11.1 

percent per year)1

. 

Water Use

Water use in the Delta region is mostly agricultural, with over 

4,000 cubic feet per second of surface water diversions used 

to irrigate crops during peak summer months. Irrigation diversions from about 1,800 sites in the Delta total about 1 million 

acre-feet annually. The main crops grown in the Delta are corn, 

alfalfa, other grains, tomatoes, and safflower. Grapes are being 

harvested in increasing numbers within the Delta region, and 

are quickly becoming one of the primary crops. Table 12-1 

shows the approximate number of acres planted in various crops 

within the Delta Service Area and the associated applied water 

demand, as of year 2000. 

The Delta is at the confluence of the Sacramento and San Joaquin rivers. Its network of waterways conveys runoff toward San Francisco Bay and the Pacific 

Ocean to the west. (Photo courtesy of NASA)

1 Growth rates are for the period between Jan. 1, 2003, and Jan. 1, 2004, and are from the California Department of Finance, E-1 City Population Estimates, May 5, 2004.

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County People

Delta Region Population

(Estimate - Year 2000)

Legal Delta 

Boundary

Alameda

Contra Costa

Sacramento

San Joaquin

Solano

Yolo

Total

 173

175,011

 57,707

205,481

 1,353

 22,055

461,780

SOLANO

CONTRA COSTA

SACRAMENTO

ALAMEDA

SAN JOAQUIN

YOLO

Figure 12-2 Delta region population

Data from California Department of Finance provide decadal population from 1960 to 2000 and population projection for 

2030 for Sacramento-San Joaquin Delta.

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Most Delta farms use water taken directly from Delta sloughs 

and rivers under riparian water rights, and drainage water 

from the islands is pumped back into the Delta waterways. 

Small communities in the Delta primarily use groundwater 

wells for their water needs, and urban water use in the Delta 

only accounts for a small percentage of the total developed 

supply2. The remaining portion of water in the Delta is either 

used by other forms of evapotranspiration or contributes to 

Delta outfl ow, through which it can provide wildlife habitat 

and salinity control benefi ts. Recreation water uses do not 

have a large affect on the Delta water balance, but are still 

important in the Delta, with an estimated 12 million “user 

days”3 recorded each year for recreation purposes. 

Water Exported from the Delta

The Delta is the major source of fresh water to the San Francisco Bay and provides a portion of the water supply for 

many other communities in the bay region. Water from the 

Delta supplies drinking water for over two-thirds of the state’s 

population (over 23 million people) and irrigation water for 

more than 3-million acres of farmland statewide. The largest 

source of water for the Delta is the Sacramento River, which 

transports about 18.3 million acre-feet into the Delta in an 

average year. Additional fl ows from the Yolo Bypass and the 

San Joaquin River bring in an average of 5.8 million acre-feet, 

with precipitation adding about another 1 million acre-feet. 

Larger diversions in the Delta include the SWP (Banks PumpTable 12-1 Crop Acreage and Applied Water Demand in the Delta Service Area as of 2000 (DWR Central Dist. 2004)

Crop 1,000 Acres Applied Water (TAF)

Corn 113.2 325

Alfalfa 55.1 298

Other Grains 47.2 51

Processed Tomatoes 36.2 117

Safflower 33.8 26

Pasture 32.4 192

Vine Crops (grapes) 23.6 42

Other Truck Crops (strawberries, chili, etc.) 21.4 56

Other Deciduous Crops (apples, etc.) 18.3 78

Dry Beans 10.2 26

Other Field Crops 9.2 24

Fresh Market Tomatoes 6.6 16

Sugar beets 6.5 28

Cucurbits (cucumbers, gourds, melons, pumpkins) 4.7 10

Potatoes 3.9 12

Almonds, Pistachios 1.8 7

Rice 0.9 5

Onion and Garlic 0.6 2

Subtropical Crops (citrus, kiwis, etc.) 0.1 0.3

TOTAL1 425.7 1,315.3

1 The total crop acreage listed here (425,700 acres) is less than the 538,000 acres of agricultural land listed in the Delta Atlas (1991 land

survey) for several reasons. The 2000 level in Table 12-1 only includes planted irrigated acres while the 1991 number includes other types of 

agricultural land, and the 2000 data is for the Delta Service Area – a smaller area than the Legal Delta used in the Delta Atlas. Urbanization 

of agricultural lands and weather conditions at the time of surveys are among the other reasons.

2 One important exception is the Contra Costa Water District, which provides treated Delta surface water to roughly 500,000 people, but not all of the serviced population is within the Legal Delta. 

3 A “user day” is a measure of the number of people visiting or using a site over part or all of a given day. Since some recreation users will visit recreation 

areas more than once each year, the total number of people using recreation facilities over a year in the Delta is less than 12 million. 

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ing Plant and the North Bay Aqueduct), CVP (Tracy Pumping 

Plant), and Contra Costa Water District, which withdraw about 

3.7 million, 2.5 million, and 126 thousand acre-feet in an 

average year, respectively. Figure 12-1 shows the primary 

locations and amounts of Delta infl ows, outfl ows and exports, 

as they occurred in water year 2000. Table 12-2 summarizes 

the Delta water balance for years 1998 (wet), 2000 (average), 

and 2001 (a dry year) and identifi es the major water inputs 

and outputs for the Delta. 

Water Standards

Requirements of the State Water Resource Control Board 

(SWRCB) govern the release of upstream fl ows and curtailment 

of export pumping to maintain Delta water quality and outfl ow 

requirements for the San Francisco Bay. The fi rst water quality 

standards for the Delta were adopted in May 1967, when the 

State Water Rights Board (predecessor to the SWRCB) released 

Water Right Decision 1275, approving water rights for the 

SWP while setting agricultural salinity standards as terms and 

conditions. These requirements were altered in 1971 under 

SWRCB Decision 1379 (D-1379), which added standards 

that the CVP and SWP are to meet for non-consumptive uses 

(water dedicated to fi sh and wildlife), along with agricultural, 

municipal, and industrial consumptive use standards. In 1978, 

the SWRCB issued D-1485 and the 1978 Delta Plan, which 

together revised fl ow and salinity standards and required the 

US Bureau of Reclamation (USBR) and Department of Water 

Resources (DWR) to reduce pumping, release stored water 

upstream, or both when needed to meet the standards. 

Figure 12-3 CALFED objectives

Water Supply 

Reliability

Levee System 

Integrity

Water Quality Ecosystem 

Restoration

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In 1986, Congress passed the CVP-SWP Coordinated Operation 

Agreement (Title I of Public Law 99-546), requiring that the CVP 

be operated in coordination with the SWP to meet state water 

quality standards. Also in 1986, the Supreme Court upheld the 

Racanelli Decision, which recognized SWRCB authority and 

discretion over water rights and water quality issues, including 

authority over CVP operations. As a result of increasing use 

of Delta waters combined with escalating environmental and 

fi shery problems, the SWRCB adopted a new Bay-Delta Plan in 

1991, which included objectives for salinity, dissolved oxygen, 

and temperature. The United States Environmental Protection 

Agency (EPA) followed with federal standards for the Estuary 

through EPA regulations in 1994. In December of 1999, the 

SWRCB issued a new Decision 1641 as a part of the1995 BayDelta Water Quality Control Plan, which replaced earlier Delta 

standards and conditioned the water rights permits of the SWP 

and CVP to implement the new objectives. The requirements 

set in D-1641 covered Phases 1 – 7 of the Bay-Delta Water 

Rights Hearings. In April of 2001, the SWRCB went on to adopt 

Water Rights Order 2001-05, which facilitates negotiations 

to settle the responsibilities for implementing and maintaining the 1995 WQCP. 

Currently the SWP and the CVP coordinate project operations to maintain the standards established by D-1641, by 

releasing water from upstream reservoirs for Delta outfl ow 

requirements, and by curtailing export pumping at the 

SWP Banks and CVP Tracy Pumping Plants during specifi ed 

time periods. This combination of Delta outflow requirements and export pumping limitations impose the most diffi cult challenges to the process of transporting water from 

upstream reservoirs to meet water needs in the San Joaquin 

Valley, San Francisco Bay Area, and Southern California.

CALFED Bay-Delta Program

The mission of the CALFED Bay-Delta Program is to develop 

and implement a long-term, comprehensive plan that will 

restore ecological health and improve water management for 

benefi cial uses of the Sacramento – San Joaquin Bay-Delta 

system. The plan was adopted by CALFED agencies when 

they signed the Record of Decision on August 28, 2000, 

approving a 30-year comprehensive plan. The ROD identifi es 

priorities for implementing the plan for the fi rst seven years 

and describes additional actions complementary to the plan. 

Since the ROD was adopted, CALFED agencies have been 

investing in collaborative regional projects that provide local 

benefi ts while helping achieve overall program objectives. 

Table 12-2 Water Balance for the Delta Region (IEP Dayflow Data TAF)

Water Entering the Region 1998 (wet) 2000 (average) 2001 (dry)

Precipitation 1,421 954 762

 Sacramento River 28,964 18,327 10,499

 Yolo Bypass (incl. Sac. Weir spill 

 and South Putah Cr.) 8,980 2,956 366

 San Joaquin River 8,441 2,841 1,729

 Cosumnes River 785 372 116

 Mokelumne River 969 360 127

 Misc. Eastside Tribs. 339 344 128

 Total 49,899 26,155 13,727

Water Leaving the Region

Consumptive Use (Gross Channel Depletion 

 for Ag, M&I, Wetlands, ET) 1,688 1,690 1,688

 SWP Exports 

 Banks Pumping Plant 2,111 3,666 2,599

 North Bay Aqueduct 39 47 45

 CVP Exports 2,470 2,482 2,328

 Contra Costa WD Exports 160 126 104

 Outflow to Bay/Ocean 43,430 18,144 6,963

 Total 49,899 26,155 13,727

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Some of the major water-related challenges facing the Delta 

have been summarized by the Bay-Delta Authority as “priorities and issues” for the region: 

• Restore healthy ecosystems to benefit native species. 

• Preserve a viable agricultural base.

• Maintain strong levees.

• Protect water quality for agricultural and urban water 

users in and around the Delta.

• Protect and increase recreational opportunities.

These goals incorporate the four broad CALFED resource 

management objectives of water supply reliability, water 

quality, ecosystem restoration, and levee system integrity, and 

respond to concerns expressed by stakeholders in the Delta 

and other regions of the state (Figure 12-3). 

Authorized by the Delta Protection Act of 1992, the Delta Protection Commission (DPC) is the regional entity charged with 

protecting the natural, agricultural, and recreational resources 

of the Delta. The Act required the DPC to develop and adopt a 

resource management plan for the primary zone of the Delta 

(defined in Public Resources Code Section 29728). The DPC’s 

mission is to guide the protection of the Delta’s unique natural 

quality, cultural viability, economic viability, and recreational 

opportunities using three main objectives:

• Protection, maintenance, and enhancement and restoration of the overall quality of the Delta environment 

including agriculture, wildlife habitat, and recreational 

activities;

• Assurance of orderly, balanced conservation and development of Delta land resources; and

• Improvement of flood protection to ensure an increased 

level of public health and safety. 

The CALFED Program, its implementing agencies, and the DPC 

recognize that activities of the CALFED Ecosystem Restoration, 

Conveyance, Storage, and Levee System Integrity program 

elements must be in concert with the Delta region’s land use 

and recreation objectives. Therefore, CALFED and the DPC 

coordinate activities on a regular basis.

State of the Region

The Delta is a focal point for water management, ecosystem 

restoration, land use planning, and other major initiatives in 

California. The Delta Improvements Package, which has been 

identified as a critical CALFED implementation mechanism, 

is focused on actions within the Delta. Over $155 million 

has already been spent on ecosystem projects, studies, and 

acquisition within the Delta through this Bay-Delta Program. 

Urban encroachment in the Delta is becoming a critical issue, 

and some of the fastest growing communities in the state can 

be found within and around the Legal Delta. Concerns over 

increased water diversions from northern to southern California are based on pumping operations within the Delta. The 

Delta is, and will likely continue to be, a hot spot for both controversy and innovation in terms of resource management.

Two of the agencies identified with key planning roles in the 

Delta are the California Bay-Delta Authority and the Delta 

Protection Commission (DPC). The Bay-Delta Authority is 

responsible for implementing the Bay-Delta Program (Box 

12-1) . The DPC comments on applications for CALFED ecosystem restoration grants that affect the Delta and participates 

in meetings with other CALFED agencies to provide input to 

CALFED Program management decisions. DPC staff also provides input to the following BDPAC subcommittees: Working 

Landscapes Subcommittee (created to pursue partnerships 

with private landowners in meeting CALFED ecosystem, water 

quality, levee, and water supply reliability goals); the Delta 

Levees and Habitat Advisory Committee; and the Ecosystem 

Restoration Subcommittee. Many projects and programs 

are being carried out to address local and statewide needs 

related to the Delta. The stakeholders involved in Delta implementation issues are increasingly aware of how complex and 

interrelated solutions must be to avoid adverse impacts to 

other stakeholders and to provide long-term, comprehensive 

management of Delta land and water resources. Some of the 

major implementation issues and achievements to date are 

summarized below.

Box 12-1 California Bay-Delta Authority

The California Bay-Delta Authority officially became a State agency in January 2003. The authority oversees implementation 

of the CALFED Bay-Delta Program to improve water supplies in California and the health of the San Francisco Bay–Sacramento/San Joaquin River Delta. The organization and focus of this Authority is being reviewed and changed in 2005.

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Figure 12-4 Proposed Delta gates map

Freeport Regional

Water Project

(Not on this map)

Delta Cross Channel and4

through delta conveyance

Stockton Ship Channel

dissolved oxygen

improvements

Agricultural

barriers

Fish barrier

Lower San Joaquin River

water quality and flow

improvements

Central Valley 

Project pumps

Central Valley Project/

State Water Project Intertie

State Water

Project pumps

Old River and Rock Slough

water quality improvements

Franks

Tract

San Luis low point

(not on this map)

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Water Supply Reliability

Because water users within the Delta divert directly from adjacent 

channels running through the Delta, they normally have immediate access to water. However, water levels in these channels 

are influenced by river inflows, ocean tidal levels, and CVP and 

SWP operations, especially diversions at the south Delta export 

pumps. Lower water levels in the south Delta channels can make 

it difficult for local irrigators to pump or siphon the water from 

the channels to their farmlands. In addition, the flow of water 

to the export pumps can sometimes draw water with a higher 

salinity into the south Delta from the western Delta.

To help address these water level problems, CALFED agencies 

provide assistance in creating temporary barriers in portions 

of the Delta to raise water levels and improve water quality for 

irrigators. The Environmental Water Account helps improve 

water supply reliability by acquiring water from willing sellers to 

compensate for lost supplies during periods of export pumping 

curtailment for fish protection. 

Longer-term solutions involving the installation of flow control 

gates are being analyzed as part of the South Delta Improvements Program(see figure 12-4), which would eventually make 

possible increased pumping operations at Banks Pumping Plant 

to 8,500 cubic feet per second during acceptable periods of the 

year. Design and environmental reviews of the SDIP are ongoing. Other water supply activities in the Delta currently under 

investigation by CALFED include: adding an intertie between 

the CVP and SWP canals south of the Delta; re-operating the 

Delta Cross-Channel (DCC) for the benefit of fish and water 

quality; and feasibility studies for an in-Delta storage project. 

Thus far, modeling studies for the CVP-SWP intertie and two 

years of research experiments on DCC re-operation have been 

completed. In addition, a draft report about the engineering 

feasibility of the in-Delta storage project has been published 

for review and consideration.

Water Quality

The Delta is a source of drinking water for over 23 million Californians, which underscores the importance of carefully managing water quality in the region. Key drinking water constituents 

that are of concern are bromide and organic carbon, because 

they are known to contribute to the production of trihalomethanes 

(THMs) during the drinking water chlorination process. There are 

a wide range of water quality issues in the Delta, and several 

different initiatives have been organized in response.

Salinity

The impact of salinity on water quality in the Delta is important and directly related to water supply reliability. The balance between ocean tides, river outflows, salinity input from 

agricultural and urban drainage, export pumping rates, and 

other factors directly impacts aquatic health in the Delta and 

the public health of those who use Delta drinking water. One 

problematic component of water salinity is bromide, which 

is known to produce trihalomethanes (THMs) during drinking 

water chlorination. THMs are known carcinogens and are 

subject to strict federal drinking water quality standards. South 

Delta agricultural diverters are often faced with high levels of 

water salinity, which can damage crops and reduce productivity. DWR’s South Delta Temporary Barriers Project is designed 

to limit saltwater intrusion into areas with agricultural diversions, while also raising Delta water levels (Figure 12-5).

Mercury

Mercury can be found in waterways throughout the Delta as 

a result of historical mining activities that were widespread 

throughout the Sacramento Valley, such that the entire Delta is 

presently on the SWRCB’s 303(d) list4 for sources of mercury. 

Miners used mercury to separate gold from rock in the Coast 

Range, and abandoned gold and mercury mines continue to 

leach mercury today. While mercury in its natural form is usually not easily transmitted into living organisms, some natural 

processes encourage conversion to methyl mercury, which is 

a powerful neurotoxin that accumulates in fish tissue and is 

harmful to animals and humans. Restoration of wetlands has 

faced increasing scrutiny because the conversion of mercury 

to methylmercury (that is, methylation) may be encouraged 

by certain natural wetland processes. 

In response to this threat, research is now under way to study 

mercury transport, how to reduce the risks associated with 

human exposure, and potential methods to reduce methylation—particularly in restoration activities. The CALFED 

Ecosystem Restoration Program (ERP) has invested over $4 

million in two research projects that investigated a wide variety 

of mercury issues, and culminated in a “mercury strategy” 

developed by a team of independent mercury experts. The 

new strategy includes recommendations for how to carry out 

future restoration work while minimizing methylation impacts. 

A more intensive follow-up study is now under way to expand 

on this knowledge and reduce the levels of uncertainty. 

4 The Clean Water Act requires that states and territories identify impaired and threatened water bodies that are not expected to meet water quality 

standards, as outlined in Section 303(d) of the Act. These lists result in the development of Total Maximum Daily Loads (TMDLs), which establish the 

maximum amount of pollutants the water body can receive while still meeting water quality standards.

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The Department of Conservation with assistance from ERP has 

created two workgroups to deal with mercury source issues 

related to abandoned mines. A “fi sh consumption workgroup” 

has also been organized to coordinate funding and management efforts between the various agencies in order to educate 

people about reducing consumption risks resulting from mercury 

contamination. Other agencies and organizations working to 

address mercury include the Delta Tributary Mercury Council, 

the Central Valley Regional Water Quality Control Board, 

the San Francisco Bay Regional Monitoring Program, the 

Offi ce of Environmental Health Hazard Assessment (OEHHA), 

the Department of Health Services, the San Francisco Bay 

Regional Water Quality Control Board, EPA, the Sierra Trinity 

Abandoned Mine Lands Agency Group, and the Bay-Delta 

Public Advisory Subcommittee on Environmental Justice.

Dissolved Oxygen (DO)

Current water quality standards call for at least 5 milligrams 

per liter of dissolved oxygen in Delta water to protect aquatic 

organisms (including fi sh), allow for successful fi sh reproduction 

and juvenile rearing, and prevent odor problems. Discharges 

into the San Joaquin River and the Delta sometimes contain 

material with a high biochemical oxygen demand or a high 

nutrient level, which can encourage algae growth and trigger 

subsequent oxygen depletion. These discharges, along with 

depleted freshwater fl ows, channel confi guration, and water 

temperatures, have resulted in isolated areas in the Delta with 

DO levels below the current standard. On the San Joaquin River, 

low DO levels may pose a barrier to fall-run salmon migrating 

upstream to spawn. 

The DO problem is not a new phenomenon, and has been studied 

for some time. DWR and the Inter-agency Ecological Program 

(IEP) have maintained monitoring efforts on the San Joaquin 

River and the Stockton Deep Water Channel since the 1980s. 

CALFED ERP expenditures of about $4 million have been spent 

on monitoring and research activities related to DO, including 

development of models to better understand thermal stratifi cation 

in the San Joaquin River. ERP has also begun a feasibility study for 

using water aeration techniques to increase DO levels, and several aeration and nonaeration methods are under development. 

Organic Carbon (TOC)

Organic carbon is itself not a harmful constituent—In fact it 

is essential for aquatic life (Box 12-2). Problems occur when 

water containing high levels of organic carbon is treated in 

 Figure 12-5 Delta Improvements Program

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drinking water treatment plants, which use chemicals to inactivate harmful pathogens. Some forms of organic carbon react 

with these beneficial disinfection agents, such as chlorine, and 

produce potentially carcinogenic disinfection byproducts (for 

example, trihalomethanes). Since wetland restoration efforts 

could potentially increase the level of vegetation and organic 

carbon in Delta water supplies, there may be conflicting objectives between ecosystem restoration and water quality initiatives, 

as is also the case with mercury. 

Because some organic carbon processes are still poorly understood, much of the current work is focused on investigating how 

carbon is used in the aquatic food web and how natural and 

anthropogenic factors affect the type and amount of organic 

carbon released into the system. As part of approximately $10 

million in funds designated for CALFED ERP organic carbon 

projects, one research project, funded jointly with the CALFED 

Drinking Water Quality Program, is attempting to determine 

if coagulants could be used to remove organic carbon from 

Delta island drainage. The U.S. Geological Survey (USGS) 

is spearheading much of the organic carbon efforts, working 

in conjunction with ERP. The CALFED DWQ Program is also 

involved, investing $1.7 million in 2003 in four drinking water 

quality projects to monitor and assess organic carbon sources 

and processes in the Delta. DWR’s Municipal Water Quality Investigations (MWQI) Program has also funded organic 

carbon projects in the Delta, including real-time monitoring, 

source assessment, and studies of byproduct formation potential. 

Selenium

Selenium enters the Delta region from multiple sources, 

including groundwater discharges from selenium-containing 

soils, agricultural runoff, and refinery water input from the 

San Francisco Bay. Selenium, like mercury, bioaccumulates in 

aquatic life and has been shown to have negative affects on 

fish and waterfowl. High selenium concentrations could cause 

disruptions in drinking water and agricultural water deliveries, 

and are often correlated with high salinity levels as well.

CALFED’s ERP is currently implementing several projects to 

study the sources, transport, and biological affects of selenium 

in the Delta. One ERP project is also examining the potential for 

using bacteria to reduce selenium contamination in agricultural 

return water. The DWQ Program is also coordinating projects 

that focus on selenium in irrigation drainage water from the 

San Joaquin Valley.

Other agencies involved with the selenium issue include the 

USGS, which has worked on ERP projects and other initiatives to 

forecast selenium discharges and study its affects on the aquatic 

environment. In the San Joaquin Valley, USBR and the San Luis 

& Delta Mendota Water Authority have successfully developed 

the Grasslands Bypass Project to reduce selenium loads in agricultural drainage water before it enters the San Joaquin River. 

Both the Central Valley and San Francisco Regional Water Quality Control Boards are now developing Total Maximum Daily 

Loads (TMDLs) for the San Joaquin River and San Francisco Bay, 

respectively. The University of California, Davis has also participated in selenium research, particularly with bioaccumulation 

and the use of microalgae to treat agricultural drainage water.

Pesticides

Pesticides include insecticides, herbicides, fungicides, and 

other substances used to prevent, destroy, repel, or prevent 

pests. In the Delta, several types of chemical pesticides are 

widespread, including organophosphates, organochlorines, 

and pyrethroids. Each of these materials has certain risks for 

humans and aquatic organisms because they are, by design, 

meant to disrupt biological processes5.

Organophosphates (also called organophosphorous pesticides) affect the nervous system and were used in World War 

II as nerve agents in addition to being used as insecticides 

(such as chlorpyrifos and diazinon). While usually not persistent in the environment, organophosphates have been found 

in the Bay-Delta watershed and could impact the distribution 

and abundance of aquatic species. Organochlorines, which 

Box 12-2 Organic Carbon

Organic carbon can be found in different forms in nature, including dissolved organic carbon (DOC) and particulate organic 

carbon. Total organic carbon (TOC) is a measurement of all forms of organic carbon, and is usually primarily made up 

of DOC. The sources and fate of DOC and TOC are nearly identical, and the terms are often used interchangeably.

5 Much of the pesticide information is taken from U.S. EPA Pesticide Program Web site (www.epa.gov/pesticides).

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include DDT and chlordane, were used extensively in the past 

but now are much less widely used because of their toxicity 

and persistence. Like mercury, organochlorines accumulate 

in fish tissue and could contaminate humans and animals 

who consume them. Pyrethroids are synthetic versions of a 

naturally occurring pesticide in chrysanthemums, and some 

forms can be extremely toxic to the nervous systems of fish 

and invertebrates. Pyrethroids are becoming more widely 

used, but current monitoring equipment is unable to measure 

concentrations in the environment.

Several projects are now under way to evaluate practices that 

could reduce pesticide and fertilizer use in the Delta, limit urban 

pesticide applications in Sacramento and Contra Costa counties, and to study the impact of pesticides on aquatic life. CALFED 

ERP is involved with many of these efforts, along with a study to 

develop water quality criteria for the organophosphates diazinon and chlorpyrifos. 

Toxicity of Unknown Origin

In addition to the above described constituents that are known 

to impact organisms in the Delta, there is the possibility that 

other substances yet to be identified may be contributing to 

toxicity problems. The CALFED ERP is funding several projects 

to monitor and attempt to identify the source of certain episodes of toxicity in the Delta. Studies regarding splittail and 

delta smelt exposures to unknown toxics are being conducted 

as part of the ERP projects. An implementation plan is also 

being developed to reduce toxicity associated with these asof-yet unknown materials.

There are many other constituents and issues related to water 

quality that are important in the Delta region. Like some forms 

of organic carbon, bromide, which is a component of salinity, can produce disinfection byproducts when treated with 

certain, necessary disinfection processes used in domestic 

water treatment plants. Various pathogens are also present in 

Delta waterways, and the CALFED DWQ Program is leading 

several projects to assess pathogen fate and transport from 

human and animal sources, including animal feeding operations and recreational water use. DWR’s MWQI Program is 

also funding pathogen studies related to hydrostatic pressure, 

pathogen survivability, and confined animal feeding operations. Sediment is another issue of concern, particularly with 

respect to dredging operations to maintain the Stockton and 

Sacramento deepwater ports, which may re-suspend contaminants (from sediment) that are toxic to aquatic life. The US 

Forest Service has been involved in projects to reduce sediment 

loading, along with the CALFED watersheds, DWQ, and ERP 

programs. In addition, studies are under way to model and 

evaluate water quality improvements that could achieved from 

proposed Delta conveyance and storage alternatives.

Ecosystem Restoration

Over the past century, the health of the Delta ecosystem has 

declined in response to the reduction of habitat for both 

aquatic and terrestrial biota. Remaining habitat quality has also 

declined due to several factors including water diversions, toxic 

pollutants, and the introduction of exotic species. In fact, few 

aquatic ecosystems in North America have been invaded and 

changed by as many exotic species as those in the Bay-Delta. 

The Delta no longer provides the broad diversity or quality of 

habitat necessary to maintain ecological functions and support 

healthy populations of native plants and animals. Conversion 

of agricultural land to accommodate ecosystem improvements 

under the Bay-Delta Program could provide some relief, but these 

actions are also a major concern for Delta agricultural interests, 

who rely on the land for their economic survival.

During the past several decades, as water diversions and the 

recognition of environmental water needs have increased, so 

have the conflicts among different interests. Water flow and 

timing requirements have been established for certain fish and 

wildlife species in response to declining fish and wildlife populations. These requirements restrict the amount of water that can be 

diverted from the Delta, and constrain the time over which these 

withdrawals can be made. Over the past decade, a number 

of other protective actions have been implemented to protect 

fish and wildlife, including the Central Valley Project Improvement Act (CVPIA) and the 1994 Bay-Delta Accord. While the 

programs that have resulted have helped provide flows and 

habitat essential to endangered and threatened species, they 

have also reduced the ability of the CVP and SWP to meet the 

water demand of their contractors at the time of year that supplies are needed. This timing issue has contributed to the false 

perception of a zero-sum game, in which ecosystem or water 

supply interests can only benefit to the other’s detriment, and 

has created heightened tension between various groups.

To address ecosystem health issues, the CALFED ERP has 

invested in cooperative projects such as wildlife-friendly agricultural practices, which have shown that different interest 

groups do not have to compete against each other to prosper 

in the Delta. Other ecosystem efforts underway include wetlands 

protection studies, invasive species eradication initiatives, and 

fish studies to monitor the effects of pesticides on aquatic health. 

About $155 million has been spent on 107 ecosystem projects 

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in the Delta, representing one of the largest investments in ecosystem restoration in the United States. The ERP has also funded 

major studies to examine the effects of pesticides on fish in the 

Bay-Delta system and the release of dissolved organic carbon 

and methyl mercury from restored wetlands. 

Closely associated with ERP, the CALFED Multi-species Conservation Strategy (MSCS) is a comprehensive regulatory plan for 

the CALFED Program developed in accordance with the federal 

Endangered Species Act (ESA), the California ESA (CESA), and 

the Natural Community Conservation Planning Act (NCCPA). 

The MSCS establishes the programmatic State and federal 

regulatory requirements for numerous species and habitat types 

within the MSCS-ERP Focus Area. By implementing and adhering to the MSCS, the CALFED Program can be implemented in 

compliance with the ESA, CESA, and NCCPA.

Levee System Integrity

The Delta levees confine flow to channels and protect Delta lands 

from daily flooding by the tidal fluctuations. Without the levees, 

the Delta would be a 740,000-acre brackish inland sea. In the 

late 1800s and early 1900s, levees were originally built using 

the peat soils native to the Delta. This material is weak and highly 

compressible, which has left many of the levees vulnerable to 

failure, especially during earthquakes or floods. 

The high organic content in the soil contributes to rapid decomposition and settling, and decreases the integrity of the levee 

structures and their ability to hold back water flows. Delta 

island farmland, residential land and homes, wildlife habitat, 

and critical infrastructure could be flooded as a result of a 

levee failure. Flooding in the Delta has historically resulted in 

millions of dollars of damages. The State formed a partnership 

with local agencies in 1986 to improve the condition of the 

extensive Delta levee system. As a result of that partnership, a 

new levee maintenance assistance program was implemented, 

and incidents of levee failure from winter floods have decreased 

compared to prior years. 

Levee failures during the summer (the most recent in June 3, 

2004) or fall that inundate islands under non-flood conditions 

can also cause impacts by pulling salty water into the Delta from 

San Francisco Bay. The resulting increased salinity in the Delta 

could shut down CVP and SWP exports from the Delta until fresh 

water inflows return. Increased salinity in the Delta would be of 

particular concern in a low water year, when less freshwater 

is available to flush the salt out of the Delta. This damaging 

scenario occurred in 1972, when the Brannan-Andrus Island 

levee failed, resulting in the depletion of about 400,000 acre-feet 

of water supplies and requiring the removal of about 50 tons 

of salt. Long-term flooding of specific Delta islands could also 

affect water quality over a longer time horizon by changing the 

rate of saltwater intrusion and the area of the mixing zone. A 

long interruption of water supply for in-Delta uses and exports 

would affect both urban and agricultural users, until the salt 

water could be flushed from the Delta channels.

CALFED’s Levee System Integrity efforts work in conjunction with 

the DWR Delta Levees Program to maintain and strengthen the 

levee system. DWR in turn works with local groups and agencies, 

particularly with reclamation boards, to assist in the planning 

and funding of levee projects. Under Base Level Protection 

efforts, non-project levees6 are maintained and strengthened, 

with the ultimate goal of bringing all appropriate levies to a 

uniform base level of protection. DWR also provides partial funding and assistance for CALFED’s Special Improvement Projects, 

which help establish protection above base level standards in 

regions with particular public interests – such as highly populated islands. Special cost share requirements are used with levee 

projects, which allocate costs between the local participants and 

the State, and DWR oversees two funding mechanisms that are 

used to provide the State contribution.

In addition to levee maintenance and enlargement, other leveerelated efforts include levee subsidence studies, emergency 

response coordination (including the distribution of flood fight 

boxes containing emergency materials such as sandbags and 

hand tools), analysis of levee risks associated with seismic events, 

and dredged material management. The Levee System Integrity 

efforts have incorporated a number of ecosystem-related projects, such as the habitat development work currently underway 

at Decker Island, and certain provisions of the Program require 

that levee activities must result in net habitat improvement. Other 

agencies involved with the Delta Levee efforts include the U.S. 

Army Corps of Engineers and the California Department of 

Fish and Game, which serve along with DWR as Implementing 

Agencies of the Levee System Integrity Program.

Recreation

According to figures used in the 1995 Sacramento-San Joaquin Delta Atlas, the Delta is estimated to support more than 

12 million recreational user days a year. According to surveys 

conducted in 1996 by the Delta Protection Commission (DPC) 

and the Department of Parks and Recreation (DPR), 23.5 

6 A “non-project” levee is defined by State Water Code as “a local flood control levee in the delta that is not a project facility under the State Water Resources 

Law of 1945”.

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percent of registered boat owners and 23 percent of licensed 

anglers in the State of California participated in recreation 

activities within the Delta. Fishing, cruising, water skiing, 

swimming, and sailing are all popular ways of recreating 

in the Delta, as well as sightseeing and wildlife viewing. As a 

result of the growing population within the Delta and across the 

State, the popularity and use of the Delta as a major recreational 

location is expected to increase. 

The DPC, DPR, and the Department of Boating and Waterways 

(DBW) have important oversight and regulatory roles for Delta 

recreation. In addition to the 1996 surveys, DBW cooperated 

with DPC’s Recreation Citizen’s Advisory Committee in December of 2002 to produce a Boating Needs Assessment, which 

inventoried existing recreational boating infrastructure in the 

Delta and projected future boating needs. 

This assessment followed a 1995 Report conducted by DPC, 

which made recommendations to improve recreation conditions and access. A detailed Delta Recreation Master Plan 

is currently being prepared by the Delta Protection Commission, with assistance from DPR and the California Coastal 

Commission. The first phase of this study addresses Delta 

user and facility needs for water-based and water-enhanced 

recreation. The resulting estimates of recreation use in the 

Delta confirm that recreation is a key component in management of Delta resources. When completed, the second phase 

of this master plan will focus more on land-based recreation 

needs, and present a “big picture” summary of all recreation 

within the Delta. As a public resource and economic benefit, recreation opportunities in the Delta are highly valued. 

Looking to the Future 

On a long-term continuing basis, a wide variety of studies 

and projects are being undertaken to protect water quality, 

maintain and improve ecosystem health, maintain the stability 

of levees, and improve water supply reliability (Box 12-3). 

Most of these activities are being conducted by state and 

federal agencies in partnership with local landowners and 

Delta interests, and many of the major projects are critical to 

implementing the CALFED Bay-Delta Program Plan. 

Efforts are continuing to develop major programs and projects that are intended to address long-standing Delta water 

management issues. Interest groups and government agencies 

are grappling with how to package interdependent actions 

and programs in a manner that will protect the Delta’s water 

quality and ecosystem, and keep the levee system stable. 

Among the many challenges facing this effort is the issue of 

how to reconcile the engineering and technical realities with 

the economic and political realities.

CALFED implementing agencies, in conjunction with other 

Delta interests, are attempting to move critical projects forward 

through the Delta Improvements Package. These projects are 

outlined in the CALFED Bay-Delta Program Record of Decision 

(ROD), which calls for balanced implementation of CALFED 

program elements. In the Delta Region, implementation of the 

CALFED resource management objectives includes the following 

priorities: improving the environment so that threatened and 

endangered species populations can recover; making continual 

improvements in Delta water quality; increasing conveyance 

Box 12-3 Ongoing Planning Efforts

• American Farmland Trust study of Delta agriculture.

• Delta Regional Ecosystem Restoration Implementation Plan (DRERIP) for the Delta, lead by DFG.

• SAFCA study of new flood control projects for Sacramento and West Sacramento in Yolo Bypass.

• Yolo Flyway Center – proposed public education facility adjacent to Yolo Bypass.

• Delta Science Center – proposed public education facility at Big Break Regional Shoreline (East Bay Regional Park 

District).

• Rio Vista--proposed public education and recreation facility at former military property recently transferred to 

City of Rio Vista.

• New Research Facility proposed by CALFED Science Consortium at former military property recently transferred 

to City of Rio Vista.

• Delta Protection Commission study of Delta recreation

• California Bay-Delta Authority, various investigations for implementation of the Bay-Delta Plan

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capacity of the Delta pumping plants (to improve water supply 

reliability statewide); assuring adequate water levels for agricultural diverters; and improving levee system integrity. 

The Delta Improvements Package is a framework for moving 

forward in several of these areas simultaneously while making 

considerations beyond what is required by the ROD. For example, although the CALFED ROD did not require that Delta water 

quality improvements occur before increasing the pumping 

capacity of Delta pumping plants, DWR and USBR are working 

with Delta interests to improve salinity levels in the south Delta 

while proceeding with studies for the SDIP, which is included as 

a part of the overall Delta Improvements Package. 

The following is a summary of major programs and actions 

that are critical to achieving desired benefits for the Delta 

region. In addition to listing major project milestones established for Stage 1 (years 1 through 7) of the CALFED Bay-Delta 

Program, other Delta initiatives, including recreation efforts, 

are also included. 

Water Supply Reliability

Many of the proposed future water supply activities in the 

Delta are included as part of the Delta Improvements Package, while others are being considered independently as 

described below.

Delta Improvements Package

The Delta Improvements Package (DIP) could eventually include 

several components related to water supply reliability: 

• South Delta Improvements Project/8,500 cfs – Under the 

SDIP, permitted pumping at Banks Pumping Plant would 

be increased to 8,500 cfs. To mitigate the affects of the 

higher pumping rate, interim actions would be taken to 

maintain water levels for South Delta agriculture, protect 

water quality, prevent fish entrainment, and comply with 

environmental obligations. More permanent mitigation 

measures would include the construction of permanent 

operable barriers, development of a comprehensive San 

Joaquin River Salinity Management Plan, construction of 

water quality projects for Old River and Rock Slough, 

complying with Natural Community Conservation Planning Act7 (NCCPA) and ESA requirements, and developing a long-term Environmental Water Account.

• SWP/CVP Integration Plan – Excess capacity at Banks 

Pumping Plant, part of the SWP, could be used to convey 

up to 50,000 acre-feet of Level 2 CVP refuge water in 

return for using up to 37,000 acre-feet of CVP water to 

meet SWP in-basin water quality and flow requirements. 

These quantities could be raised if pumping at Banks is 

allowed to reach 8,500 cfs.

• SWP/CVP Intertie – SWP and CVP operations could be 

more closely linked through the construction of an intertie 

between the California Aqueduct and the Delta-Mendota 

Canal just south of the Delta. This intertie would provide 

enhanced flexibility between the two systems, and create 

additional conveyance capacity for the CVP.

In-Delta Storage Project

DWR and USBR are also investigating the In-Delta Storage 

Project as part of the Bay-Delta Program. The Project would 

include two storage islands (Webb Tract and Bacon Island) and 

two habitat islands (Holland Tract and Bouldin Island), and could 

provide for about 217,000 acre-feet of new storage for a wide 

variety of potential uses, including exports and Delta outflow. 

A State feasibility study for the project was completed in January 

2004, and a final EIR/EIS is anticipated in December 2005. 

Initial estimates from the feasibility study showed an equivalent 

annual cost for the project of $60 million, with annual water 

supply benefits between $23 and 26 million and another $2 million in annual recreation, flood damage reduction and avoided 

levee maintenance benefits. Evaluations on how In-Delta Storage 

would impact organic carbon and salinity levels in the Delta 

are ongoing, and will be important in determining the overall 

feasibility of the project.

Los Vaqueros Reservoir Expansion

Contra Costa Water District (CCWD) owns and operates Los 

Vaqueros Reservoir, a 100,000 acre-foot, offstream reservoir 

that, while located outside of the Legal Delta, diverts water 

from the Delta. Planning studies are underway to evaluate 

expansion of this reservoir’s capacity up to a maximum of 

500,000 acre-feet through the construction of a new, larger 

dam. Depending on how the reservoir would be operated, a 

portion of the storage at Los Vaqueros could be used by the 

Environmental Water Account. CCWD customers voted in 

March 2004 to continue planning studies for the project, and 

final feasibility studies and environmental documentation are 

scheduled for completion by the winter of 2007.

7 California Department of Fish and Game Code.

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Water Quality

Projects designed to improve Delta water quality are prominently included within the Delta Improvements Package, as 

well as in other initiatives. A few of the most important water 

quality efforts that can currently be identifi ed as important to

the future of the Delta are listed below.

Delta Improvements Package

A large number of water quality projects have been included 

in the Delta Improvements Package, some of which were 

included in the CALFED ROD and others that were more 

recently conceived.

• South Delta Improvements Package/Permanent Operable 

Barriers – Permanent operable barriers would be required 

before full implementation of 8,500 cfs pumping capacity 

at SWP Banks Pumping Plant. One of the primary reasons 

for the barriers would be to improve water circulation and 

water levels within the south Delta.

• San Joaquin River Salinity Management Plan – To comply 

with the salinity requirements in SWRCB Water Right 

Decision 1641, DWR and USBR are developing a comprehensive plan, in cooperation with SWRCB and the Central 

Valley Regional Water Quality Control Board. The proposed San Joaquin River Salinity Management Plan would 

address agricultural drainage issues, salt load reduction 

from Salt and Mud Sloughs, recirculation of Delta exports 

into the San Joaquin River, voluntary water transfers for 

Figure 12-6 In - Delta Storage Project 

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quality benefits, and real-time water quality monitoring.

• Vernalis Flow Objectives – Water Right Decision 1641 also 

included flow requirements at Vernalis on the lower San 

Joaquin River, which have also been addressed in the Delta 

Improvements Package. The USBR and DWR, along with 

the CALFED agencies in the Water Operations Management Team, would work together to meet flow requirements 

that protect fish and wildlife dependent on San Joaquin 

River flows.

• Old River and Rock Slough Water Quality Improvement 

Projects – Before any permanent operable barriers are 

used, agricultural drains on the Veale and Byron Tracts 

would be relocated. In addition, efforts would be made 

to reduce seepage into the Contra Costa Canal to protect 

the quality of the District’s water supply. 

• San Joaquin River Dissolved Oxygen – DWR and USBR, 

in coordination with other CALFED agencies and local 

participants, would develop a comprehensive strategy to 

alleviate dissolved oxygen problems in the Stockton Deep 

Water Channel. These improvements could go beyond 

water project obligations, and would be coordinated 

with SWRCB and Central Valley Regional Water Quality 

Control Board.

• Franks Tract – Salinity levels at the major export pumps 

in the Delta may be significantly reduced through water 

quality actions at Franks Tract (Box 12-4). Reconfiguration 

of levees and modification of water circulation are possible 

alternatives for the Franks Tract project.

• Delta Cross Channel Program – Building on completed 

studies of the Delta Cross Channel, USBR and other 

agencies would continue, under the Delta Improvements 

Package, to develop methods for improving central and 

south Delta water quality while encouraging fish passage 

around the channel.

• Relocation of CCWD Water Intake – If the Delta water quality improvements from the above measures do not provide 

acceptable continuous improvements in water quality, the 

State and federal agencies will evaluate alternatives to move 

the Contra Costa Canal intake to the lower part of Victoria 

Island. This project would require appropriate environmental 

review, as well as agreement on cost sharing requirements. 

CCWD is conducting studies to evaluate this location as an 

alternative point of diversion.

• Through-Delta Facility – As identified in the CALFED ROD, 

a screened diversion facility on the Sacramento River 

could be used to move 4,000 cfs of water through the 

Delta to the Mokelumne River to enhance water quality. 

The Through-Delta Facility (TDF) could also have water 

supply and environmental benefits, although Delta salinity 

impacts could be difficult to predict due to the complex flow 

regime of the Delta. Overall impacts on water quality in the 

Delta will be dependent on other projects and operational 

strategies, such as how the Delta Cross Channel would be 

managed in conjunction with the TDF.

Box 12-4 Franks Tract Description

Once a reclaimed tidal marsh, Franks Tract was flooded in 1938 following a levee breach, and has since become 

a focus of water supply and water quality initiatives in the Delta. Franks Tract is used for recreation purposes, and 

also plays an important role in Delta water circulation. Saline water from ocean tides tends to become “stuck” within 

the tract, creating water quality problems for the export pumps and the Delta as a whole. The proliferation of egeria 

densa, an invasive species known commonly as Brazilian waterweed, is also a problem in Franks Tract.

In response to these and other issues, DWR and the Bay-Delta Authority are conducting studies to see if levee modifications, salinity tidal gates, and other measures could be used not only to solve current problems, but to create additional 

benefits for the Delta. Recreation interests and state agencies have also identified potential sites for islands in the tract, 

which could be used for recreation and ecosystem habitat while providing erosion protection for the southern levees. 

The addition of trenches in certain segments could also enhance boating opportunities while limiting the spread of 

egeria densa, which requires shallow water for optimum growth. 

The CALFED Science Program and DWR’s Franks Tract Project are leading the way in developing alternatives to improve 

conditions in Franks Tract while providing new benefits for the Delta. CALFED efforts in the tract are ongoing, and a 

DWR-led feasibility study is now underway, with full implementation expected by 2011.

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Delta Region Water Quality Management Plan

This plan is being developed by Solana County Water Agency, 

CCWD, and the City of Stockton, all three of which are interested 

in new water supply diversions from the Delta. In addition to evaluating the potential for additional Delta water intake structures, 

these entities are also investigating water treatment technologies 

and source water protection actions as part of management plan. 

DWR MWQI Program 

The Municipal Water Quality Investigations (MWQI) Program 

under DWR investigates water quality issues for State Water 

Contractors and other Delta water users. Issues that MWQI 

intends to pursue in the near future are greater use of realtime data in modeling and O&M applications, expanded 

investigations into organic carbon loading from wetlands, 

and greater coordination with the CALFED Bay-Delta Public 

Advisory Committee’s Drinking Water Subcommittee.

CALFED Storage Projects

Investigations are currently underway to determine if CALFED 

storage projects could be used to enhance water quality conditions in the Delta by releasing water of the appropriate temperature and quantity at the beneficial times, or used in lieu of 

surface diversions to maintain the quality of Delta inflows. New 

reservoirs could also have negative water quality impacts, however, such as additional organic carbon input, and the overall 

affect will have to be considered for each project.

Ecosystem Restoration

Ecosystem restoration efforts will continue to be critical in the 

future for the Delta. Many of the efforts listed here will also 

benefit as better scientific information is obtained to develop 

specific, quantitative habitat objectives for ecosystem restoration. The population objectives that are being developed for 

listed species of anadromous fish (via processes under the 

Endangered Species Act) will also be of use towards measuring the success of restoration efforts.

Delta Improvements Package

The Delta Improvements Package includes several programs 

with ecosystem restoration components. While this list is still 

under development, a preliminary outline is included here.

 • OCAP ESA Consultation – DWR and USBR have prepared 

 a Biological Assessment for the Operations Criteria and 

 Plan (OCAP), which provides a detailed explanation 

 and analysis of the criteria and procedures used to 

 coordinate operations of the SWP and CVP. USFWS and 

 NOAA Fisheries will later respond with Biological Opinions 

 based on the OCAP Biological Assessment, and DWR 

 and USBR will continue to work with the federal agencies 

 and the California Department of Fish and Game to 

develop future policies for integrated CVP/SWP operations. 

• SDIP ESA Consultation – DWR and USBR are also 

 working on an Action Specific Implementation Plan 

 (ASIP) for species covered under the CALFED ROD 

 Multi-species Conservation Strategy (MSCS). USFWS 

 and NOAA Fisheries will review the SDIP Preliminary 

 Biological Opinions and the ASIP to determine if SDIP 

 consultation should be reinitiated, and DFG will review 

 the ASIP to consider if it should receive Natural Community 

 Conservation Plan (NCCP) authorization. 

• Update of CALFED ROD Programmatic Regulatory 

 Commitments – The CALFED ROD required that USFWS, 

 NOAA Fisheries, and DFG review and approve the 

 programmatic regulatory commitments established in the 

 ROD by September 30, 2004. A Notice of Determination 

 for the Environmental Water Account EIS/EIR was 

 signed in 2004, the Record of Decision was signed, 

 and the Notice of Determination was issued in October 

 2004. Implementation of the EWA through 2007 has 

 been authorized, and the EWA Operating Principles 

 have been extended to December 31, 2007. The State 

 and federal agencies that are signatories to the CALFED 

 Multi Species Conservation Strategy (“Conservation 

 Agreement”) have also agreed to extend these regulatory 

 commitments to December 31, 2007 to support protection 

 and recovery of the covered species. 

• Environmental Water Account – Work will continue on 

 determining if and how a long-term Environmental 

 Water Account (EWA) could be established beyond 

 the short-term EWA set up for the CALFED Stage 1 period. 

 DWR, USBR, USFWS, NOAA Fisheries, and DFG are the 

 lead agencies working to develop a long-term EWA 

 which will protect Delta fisheries while providing water 

 supply reliability benefits to SWP and CVP exporters. 

• Delta Regional Ecosystem Restoration Implementation 

 Plan – The Delta Regional Ecosystem Restoration 

 Implementation Plan (DRERIP) is a long-term regional 

 planning effort under the CALFED ERP to help examine 

 the Program’s actions, targets, and milestones for the 

 Delta. The DRERIP process includes agency review and 

 public input, and will be the primary forum for revising 

 ERP targets. DRERIP is currently being prepared by the 

 Department of Fish and Game in cooperation with 

 the Bay-Delta Authority, USFWS, NOAA Fisheries, other 

 CALFED agencies, academic institutions, science advisors, 

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 and stakeholder scientists. Through DRERIP, the ERP 

 expects to refine and prioritize actions, evaluate the 

 scientific foundation for actions and milestones, and use 

 adaptive management feedback. The Bay-Delta Public 

 Advisory Committee’s Ecosystem Subcommittee provides 

 public input for DRERIP activities, and additional oppor- 

 tunities for future public participation in the Program 

 will continue in the future. 

 • Focused Study on South Delta Hydrodynamics and Fish 

 – As a science-related action, DWR, USBR, USGS,DFG 

 and USFWS will study fish movement, distribution, 

and entrainment in the south Delta to better understand the 

 impacts of the Delta export pumps and barrier operations. 

• South Delta Fish Facilities – The fish facilities for both the 

 SWP and CVP will be evaluated by USBR and DWR, and 

 recommendations for modifying operations to better 

 manage changing environmental conditions will be 

 developed. Alternative facilities and intake locations will 

 be included as options, and special consideration will 

 be made for future SWP pumping operations.

Delta Region Farmland Preservation and Private Lands 

Stewardship Program

The DPC has partnered with the American Farmland Trust to 

prepare an inventory of Delta agriculture resources and their 

economic value. This inventory will help identify and preserve 

the best farmland in the DPC jurisdiction and the five Delta 

counties, while developing “wildlife friendly” practices on as 

much of the agricultural land as possible. The resulting DPC 

plan could help in the implementation of the CALFED ecosystem restoration goal of protecting and enhancing 45,000-

75,000 acres of wildlife friendly agriculture in the Delta.

Other CALFED ERP Projects

While DRERIP represents ERP’s focus for long-term regional 

ecosystem restoration planning, there are many other activities 

that the Program intends to carry forward into the future. The 

CALFED Programmatic EIS/EIR identified six strategic goals 

for the 30-year planning horizon of the Bay-Delta Program, 

which include issues such as endangered species recovery, 

invasive species, ecological processes, harvested species, 

habitats, and water and sediment quality. The CALFED ERP 

has developed multiple objectives for each of these goals, 

which include developing strategies for high priority topics, 

conducting a long-term program of milestone assessment for 

ecosystem-related CALFED programs, and identification of 

funding allocations to support a unified CALFED-wide restoration and recovery process.

Levee System Integrity

The future of levee management in the Delta is currently evolving, and several recent developments may play a role in future 

levee implementation activities. Key issues that will have a strong 

influence on future levee work can be grouped into three main 

categories: oversight, funding, and ecosystem integration.

Oversight

In recent history, levee maintenance and construction in the Delta 

has primarily been the responsibility of reclamation districts 

and, to a lesser extent, the U.S. Army Corps of Engineers. In 

the extreme northern part of the Delta near Sacramento, the 

Sacramento Flood Control Agency (SAFCA) was created in 

1989 to manage levies in the Sacramento region as a joint 

powers agency, and it now has management responsibilities in the Delta as well. The Department of Water Resources 

has provided financing, planning, engineering, research and 

monitoring capabilities to assist local groups (reclamation districts), and the California Department of Fish and Game and 

Bay-Delta Authority have also played important management 

and oversight roles.

In the future, the form and magnitude of responsibility shouldered by the participating levee agencies could be modified. 

Recently proposed State legislation (AB 1983) could increase 

the responsibilities of the Reclamation Board, which monitors 

reclamation districts and collects their tax revenues. The CALFED 

Record of Decision (ROD) envisioned a larger federal role 

through the Army Corps in levee maintenance and improvements 

than has yet materialized, and the Corps has been discussing 

ways to play a greater role with other participating agencies. A 

recent court decision regarding the liability of the State in the 

event of levee failures is another driving force that could lead 

DWR and other agencies to reexamine how levee responsibilities 

and oversight are assigned within the Delta.

Funding 

As already mentioned, the CALFED ROD recommended greater 

levels of federal participation, including financial participation, 

than has actually occurred. The majority of funding for Delta 

levees work over the last decade has come from State and local 

sources, with only a small amount of federal contributions. The 

federal government has historically identified flood protection as 

a national goal eligible for federal financing, and Delta interests 

could attempt to obtain more Congressional appropriations for 

future levee projects. Congress approved recent CALFED Legislation to authorize additional federal funds for levee programs, 

but very little of those funds have actually been appropriated 

by the federal budget process.

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Following the CALFED principle of “beneficiary pays”, the 

sources for levee funding could also be modified to draw more 

contributions from those receiving benefits from Delta levees. 

Because of the location of the Delta levees and the important role 

they play in protecting the drinking water supply for the majority of Californians, some have argued that a greater portion 

of levee costs should be assigned to consumers of Delta water 

exports. The Bay-Delta Authority is currently conducting studies to attempt to quantify ranges of benefits associated with all 

CALFED Program Elements, including the Levee System Integrity 

Program. Potential alternative revenue sources identified by a 

draft Bay-Delta Authority “Finance Options” report include 

recreational boating fees and a state-administered water user 

fee assessed on CVP and SWP water users, with the possible 

inclusion of non-project water users as well.

Ecosystem Integration

The degree in which levee programs include ecosystem restoration activities could also be changed in the future. The same 

legislation that would increase the role of the Reclamation 

Board in levee improvement work (AB 1983) would also allow 

the Board to directly finance habitat restoration work, instead 

of having to partner with other state agencies as is currently 

required. While the legislation could potentially streamline 

required restoration work and allow levee maintenance and 

enlargement to move forward more quickly, it can also be 

argued that ecosystem responsibilities should be limited to 

agencies such as the Department of Fish and Game so that 

Reclamation Districts can focus on preventing and fighting 

floods. Delta levee initiatives in the future will have to consider 

what level ecosystem management should be involved in levee 

efforts, and what groups and agencies should participate in 

ecosystem activities.

The North Delta Flood Control and Ecosystem Restoration Project is an example of how the Department of Water Resources 

is addressing levee and ecosystem restoration issues in the 

North Delta. Also known as the North Delta Improvements 

Project (NDIP), the Project is considering several “wildlifefriendly” modifications to levees in the North Delta, including 

setback levees. A draft EIR/EIS for the Project is currently being 

developed, and alternatives have already been identified that 

include a number of levee-related initiatives.

Recreation

Recreation-related activities in the Delta will continue to be 

important in the future, and several new initiatives are being 

planned to better characterize current recreational resources 

while developing a vision for future Delta recreation activities. 

One major effort is the Delta Recreation Master Plan. In 2003, 

DPC received funding for preparation of phase one of the Delta 

Recreation Master Plan, which has now been completed and 

addresses water-based recreation needs The second phase 

of this plan will evaluate land-based recreation needs in the 

Delta, as soon as funding for the study is secured. The Master 

Plan intends to draw from existing Delta recreation studies and 

documents, use public outreach and stakeholder involvement, 

and include new GIS mapping technologies to produce a Deltawide recreation plan.

Other Activities

Many other potential actions that could be taken by the 

California Bay-Delta Authority and others in the upstream 

Sacramento River and San Joaquin River hydrologic regions 

can benefit the Delta, especially with respect to water quality 

and flood flows. These actions may include improvements for 

conveyance, storage, levee stability, water quality, water use 

efficiency, and watersheds. A few of these additional initiatives are listed here.

• WUE Agricultural and Urban Water Use Measurement 

- One of the Bay-Delta Program’s Water Use Efficiency 

projects being developed throughout California is the 

Agricultural and Urban Water Use Measurement initiative. 

This program to produce consistent, complete, and compatible water measurement practices statewide is critical 

for monitoring and managing diversions and instream 

flows within Delta, and in other parts of the state as well. 

Considerable stakeholder input has been obtained for the 

WUE measurement efforts, and assistance from the State 

legislature will also be required for the project to be fully 

implemented.

• Lower Sacramento River Regional Flood Control Project 

- The Sacramento Area Flood Control Agency (SAFCA) is 

currently considering a project to expand the Yolo Bypass 

and use the Sacramento Deep Water Channel to convey 

floodwaters for the protection of urban areas. This project 

could potentially be integrated with CALFED activities, 

which have to date included studies on the modification of 

the Yolo Bypass to enhance fisheries, easement acquisitions, 

and modeling efforts led by the California Reclamation 

Board. Local governments, particularly the City of Rio Vista, 

would need to be included in planning and implementation 

to address downstream flooding concerns.

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California Water Plan Update 2005

The above projects will provide incremental improvements in 

water supply, water quality, levees, and ecosystem, but will not 

totally achieve the desired goals for the Delta in themselves. To 

achieve the desired cumulative benefits, integration and linkage of these projects is essential. Coordination of the CALFED 

Program, its implementing agencies, local and regional stakeholders, and the Delta Protection Commission with adequate 

funding will help the region to continue to serve society’s 

demand for farm products, fishing, recreation, and water—all 

while protecting the Delta’s ecosystem and water quality. 

Selected References

• 2002 California 305(b) Report on Water Quality, State Water Resources Control Board.

• 2003 Annual Report, California Bay-Delta Authority. 

• Bay-Delta Authority Website calwater.ca.gov/

• California’s Groundwater. Bulletin 118 03 (Draft), Update 

2003, California Department of Water Resources.

• Delta Atlas, California Department of Water Resources, 

July 1995.

• Delta Primer, a field guide to the California Delta, Jane Wolff, William Stout Publishers, San Francisco, 2003.

• Delta Protection Commission Web site www.delta.

ca.gov/ 

• DRAFT California Bay Delta Program Ecosystem Restoration Program & Drinking Water Quality Program: Water 

Quality Issues, California Bay-Delta Authority, Draft July 

2003.

• DRAFT Finance Options Report, California Bay-Delta 

Authority, Draft May 2004.

• DRAFT Memorandum of Understanding Regarding CALFED Bay Delta Program Activities in the Delta (Including Attachment A: Summary of Status of Activities Under 

Consideration), California Bay-Delta Authority, Draft May 

21, 2004.

• Layperson’s Guide to the Delta, Water Education Foundation, 2000.

• Nonpoint Source Program Strategy and Implementation 

Plan, 1998-2013, State Water Resources Control Board, 

California Coastal Commission, January 2000.

• Strategic Plan, State Water Resources Control Board, 

Regional Water Quality Control Boards, November 15, 

2001.

• Water Quality Control Plan, Regional Water Quality 

Control Board.

• Watershed Management Initiative Chapter, Regional Water Quality Control Board.

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Chapter 13 Mountain Counties Area 13 i

California Water Plan Update 2005

Chapter 13 Mountain Counties Area 

Contents

Chapter 13 Mountain Counties Area ......................................................................................................................13-1

Setting .............................. 13-1

Climate ............................. 13-1

Population ........................ 13-1

Land Use .......................... 13-1

Water Supply and Use ....... 13-1

State of the Region ............ 13-5

 Challenges ................... 13-5

 Accomplishments .......... 13-6

Relationship to Other Regions .............................................................................................................................13-7

Looking to the Future ......... 13-7

Regional Planning ............. 13-7

Water Portfolios for Water Years 1998, 2000, and 2001 .....................................................................................13-8

Selected References ......... 13-10

Boxes

Box 13-1 Regulation of Ditch Water .......................................................................................................................13-2

Box 13-2 1997 Flood Damage to Canals ................................................................................................................13-5

Box 13-3 1996 Sierra Nevada Ecosystem Study ......................................................................................................13-6

Box 13-4 South Sutter Water District’s Canal Improvement Plan ................................................................................13-8

Figures

Figure 13-1 Mountain Counties area (map) .............................................................................................................13-ii

Figure 13-2 Mountain Counties water balance for water years 1998, 2000, 2001 (2 bar charts) ...............................13-3

Figure 13-3 Mountain Counties - illustrated water flow diagram .............................................................................13-15

Figure 13-4 Mountain Counties - schematic flow diagram ......................................................................................13-16

Tables

Table 13-1 Mountain Counties water balance summary ...........................................................................................13-9

Table 13-2 Mountain Counties water use and distribution of dedicated supplies .......................................................13-11

Table 13-3 Mountain Counties water portfolios ......................................................................................................13-14

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California Water Plan Update 2005

LASSEN

PLUMAS

BUTTE

SIERRA

NEVADA

PLACER

YUBA

EL DORADO

ALPINE

TUOLUMNE

CALAVERAS

AMADOR

MARIPOSA

MADERA

FRESNO

Flow in TAF

1998

3,116

2000

4,611

2001

2,411

Lake Oroville

Flow in TAF

1998

4,191

2000

2,619

2001

1,357

Folsom Lake

Flow in TAF

1998

1,268

2000

741

2001

380

Camanche Reservoir

Mokelumne Aqueduct

Flow in TAF

1998

10

2000

9

2001

7

North Lahontan Region

Little Truckee

Flow in TAF

1998

0

2000

1

2001

2

North Lahontan Region

Echo Lake Conduit

Flow in TAF

1998

764

2000

1,212

2001

735

Millerton Lake

Friant-Kern Canal (CVP)

Flow in TAF

1998

5,429

2000

3,181

2001

1,598

New Melones Reservoir

New Don Pedro Lake

Hetch Hetchy Aqueduct

Flow in TAF

1998

2,215

2000

1,184

2001

895

Hensley Lake

Eastman Lake

Mariposa Reservoir

Owens Reservoir 

Bear Reservoir

Lake McClure

Figure13-1 Mountain Counties Area

The Mountain Counties area includes the foothills and mountains on the western slopes of the Sierra Nevada, extending from Lassen County 

on the north to Fresno County on the south. Arrows indicate annual flows entering and leaving the region for water years 1998, 2000, 

and 2001. 

Some Statistics

 Area -15,758 square miles (9.9% of State)

 Average annual precipitation - 42.7 inches

 Year 2000 population - 541,710

 2030 population projection - 840,025

 Total reservoir storage capacity -18,185 TAF

 2000 irrigated crop area - 93,600 acres

.

.

.

.

.

.

Some Statistics

 Area -15,758 square miles (9.9% of State)

 Average annual precipitation - 42.7 inches

 Year 2000 population - 541,710

 2030 population projection - 840,025

 Total reservoir storage capacity -18,185 TAF

 2000 irrigated crop area - 93,600 acres

.

.

.

.

.

.

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Chapter 13 Mountain Counties Area 13 1

California Water Plan Update 2005

Chapter 13 Mountain Counties Area

the same five-year period was about 7 percent. Although 

total population in the area is low, the area’s rate of growth 

is projected to continue to out pace that of the state as a 

whole. The projected population increase between 2000 and 

2030 is about 55 percent for this foothill and mountain area, 

while the state’s growth is projected at about 41 percent.

Land Use

The economies of these mountain and foothill areas have 

historically been tied to the land. Tourism, ranching, timber 

harvesting, limited mining, and agriculture, primarily in the 

lower elevations, continue as an economic base for many communities. A limiting factor for the area’s population growth is the 

relatively small amount of land in private ownership. The federal 

government is the dominant landowner in the area, with most 

of the higher elevation lands being under the management of 

the U.S. Forest Service or National Park Service.

Much of the state’s developed water supply originates in 

this upland area, including several CVP and SWP reservoirs. Although the region has abundant surface water 

supplies, most of it is unavailable locally because of prior 

water rights appropriations for downstream or out-of-basin 

users. Local use of water originating within this region is 

less than 3 percent of the total statewide consumption. 

Water Supply and Use

Locally developed surface water supplies account for almost 70 

percent of the public consumptive water supply for this region. 

Water is either diverted directly from the area’s streams and 

lakes or from local storage reservoirs and conveyance facilities. 

Many of the residents in the unincorporated areas are dependent on small, independent municipal water systems, and a 

few areas still use untreated water diverted directly from rawwater ditch delivery systems (see Box 13-1). In addition, many 

Setting

The Mountain Counties Area of California includes the foothills 

and mountains of the western slope of the Sierra Nevada and a 

portion of the Cascade Range. The area extends from the southern 

tip of Lassen County to the northern part of Fresno County (Figure 

13-1) and covers the eastern portions of the Sacramento River and 

San Joaquin River hydrologic regions. The foothill and mountain 

areas of these two hydrologic regions are grouped together for 

the purpose of presenting their common characteristics. 

The area generally includes all or portions of Shasta, Lassen, 

Plumas, Butte, Sierra, Yuba, Nevada, Placer, El Dorado, Amador, 

Alpine, Calaveras, Tuolumne, Mariposa, Madera, and Fresno 

counties. Elevations vary from around 100 feet near the edge of 

the valley floor to more than 10,000 feet at locations along the 

Sierra Nevada and Cascade Range crest line. The major rivers in 

the area include the Feather, Yuba, Bear, Rubicon, and American 

rivers in the Sacramento River region; and the Cosumnes, Mokelumne, Calaveras, Stanislaus, Tuolumne, Merced, Chowchilla, 

Fresno, and San Joaquin rivers in the San Joaquin River region. 

Climate

The climate is closely tied to the topography and varies widely 

throughout the area; mean annual precipitation ranges from 

more than 80 inches at Strawberry Valley, east of Lake Oroville, 

to less than 12 inches at Fresno County. Much of the precipitation 

falls as snow in the higher elevations in the winter. Water managers throughout the area rely on this natural storage as snow in 

the winter months and capture or divert spring snowmelt runoff.

Population

The 2000 population of the area was about 541,710, less 

than 2 percent of the state’s total population. However, the 

effects of urbanization are beginning to affect some of the 

foothill areas. Population growth in the area from 1990 to 

1995 was almost 10 percent. The state’s growth rate during 

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13 2 Volume 3 Regional Reports

individual water users throughout the area have developed 

their own supplies, typically groundwater for domestic use 

and small surface storage or in limited cases, groundwater for 

agricultural use. Figure 13-2 provides a graphical presentation of all of the water supply sources that are used to meet 

the developed water uses within this hydrologic subarea for 

1998, 2000, and 2001.

Mining operations, especially hydraulic mining, from the Gold 

Rush Era marked the beginning of much of the water supply 

development to the foothill and mountain areas. Many of those 

early mining water systems were later taken over by other 

water users. Pacific Gas & Electric Co. and other hydropower 

utilities subsequently developed an extensive hydroelectric 

power and consumptive water use delivery system throughBox 13-1 Regulation of Ditch Water

Regulation of Ditch Water – Water users in the foothills who obtain their water from ditches are no longer able to use 

that water for domestic purposes. New rules promulgated by the California Department of Health Services and the 

U.S. Environmental Protection Agency prohibit residential customers from cooking, drinking or brushing teeth with 

ditch water, including water processed by home treatment systems. In order to meet these requirements, several water 

districts are requiring customers to receive 5 gallons of bottled drinking water per month. This quantity meets the state’s 

minimum estimate of what a normal household would use in a month. 

The Mountain Counties Area had less than 2 percent of the state’s total population in the 2000 Census. However, the effects of urbanization are beginning 

to affect some of the foothills like those east of Sacramento. (DWR photo)

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California Water Plan Update 2005

Dedicated Water Supplies

Figure 13-2 Mountain Counties water balance for water years 1998, 2000, 2001

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

1998 2000 2001

Thousand Acre-Feet

Wild & Scenic

R.

Instream Flow

Irrigated

Agriculture

Urban

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

1998 2000 2001

Thousand Acre-Feet

Reuse &

Recycle

Ground Water

Federal

Projects

Local Projects

Applied Water Uses

Three years show a marked change in the amount and relative proportions of water delivered to Mountain Counties region urban and 

agricultural sectors and water dedicated to the environment (applied water, top chart), where the water came from, and how much water 

was reused among sectors (dedicated water supplies, bottom chart).

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13 4 Volume 3 Regional Reports

out the Sierra Nevada, often incorporating some of the old 

mining ditches. Most of the early water conveyance facilities 

were later transferred to local water agencies for consumptive 

water deliveries. Some of these water agencies still use the 

ditch systems as a primary means of water delivery to both 

their water treatment plants and to the individual water users 

along the route to the treatment plants. Many of these old and 

unimproved conveyance systems, including ditches, flumes, 

and pipes have been in use for more than 100 years. 

While logging and mining operations have decreased, recreation and tourism have increased in the Mountain Counties 

region which produces different effects on water use and 

quality. Second homes and vacation rentals are a growing 

trend in many of the foothill and mountain areas. This type 

of residential usage means that, although there is no permanent population associated with these homes, water use can 

be high on most weekends during the popular summer and 

winter vacation periods. For example, Groveland Community 

Services District, near Yosemite National Park in southern 

Tuolumne County, estimates that the service area population 

more than doubles during peak vacation periods. Tourism 

water use, which is most significant in the central Sierra, tends 

to inflate the area’s per capita water use because the volume 

of water consumed is greater than the permanent residential 

population would indicate.

Most of the area’s irrigated acres are found in the foothills 

and mountains of the Sacramento River Region. The dominant 

crop is pasture, which constitutes about 70 percent of the 

total irrigated acreage. Other crops with significant acreage include alfalfa, grain, wine grapes, apples and other 

deciduous fruit, and olives. Projections indicate almost no 

change in future irrigated acreage, with a slight change in 

crop mix. Significant amounts of unirrigated lands are also 

used as rangeland for livestock.

Environmental water use in the region consists of instream 

flow requirements and Wild and Scenic River designations. 

Instream flow requirements within the area are found on the 

Stanislaus River, below Goodwin Dam, and the Tuolumne 

River, below La Grange Dam. The controlling instream minimum flow requirements for the remainder of the area’s major 

rivers are located on the valley floor, which is downstream and 

outside of the Mountain Counties region. In addition, there 

are many smaller reservoirs in the area that do have instream 

flow requirements, which are met by the project operators. 

However, only the largest instream flow requirements for the 

major rivers have been counted as the instream demands for 

this water use tabulation. Documented Wild and Scenic River 

designations in this region include portions of the Feather River 

(north fork), Yuba River, American River, Tuolumne River and 

Merced River. Figure 13-2 presents a bar chart that summarizes all of the dedicated and developed urban, agricultural, 

and environmental water uses within the Mountain Counties 

region for 1998, 2000, and 2001.

Groundwater constitutes less than 10 percent of region’s water 

supply and is generally used as a supply for single family 

homes. Groundwater availability is often limited to fractured 

rock and small alluvial deposits immediately adjacent to the 

area’s many streams. In the rural areas, many individual 

residences are wholly dependent upon groundwater for 

domestic use. In addition, many homes are not connected to 

a municipal water system and are typically dependent upon 

individual wells, which are often unreliable during drought 

periods. A limited number of farmers have developed wells 

with enough production to irrigate their lands in all but the 

driest of years. In general, groundwater is an inadequate 

and unreliable supply for large scale usage in this region, 

due to the limitations of the fractured granite formations that 

constitute much of the Sierra Nevada foothills and the western 

slopes of the mountains. 

In addition to locally supplied surface water, some water is 

provided by storage facilities of the federal Central Valley Project, other federal water facilities, locally developed imports, 

and reclaimed wastewater. In the American River basin, the 

Foresthill Public Utility District has a water supply contract for 

CVP water. Calaveras County Water District and Union Public 

Utility District receive water from New Hogan Reservoir, which 

is operated by the U.S. Army Corps of Engineers. Irrigated 

pasture in Sierra County receives a small amount of water 

imported from the Little Truckee River in the North Lahontan 

Hydrologic Region. In addition, PG&E imports water from 

Echo Lake near Lake Tahoe in the North Lahontan Hydrologic 

Region as part of a hydropower diversion into the American 

River basin. Reclaimed wastewater is used to a limited extent 

to irrigate golf courses and meet other landscaping and agricultural needs throughout the region.

The water use and water supply graphs in Figure 13-2 summarize the detailed regional water accounting contained in 

the water portfolio tables at the end of this regional description. As shown on the map in Figure 13-1, most of the area’s 

surface water either flows to or is diverted to other regions 

outside of the Mountain Counties area.

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California Water Plan Update 2005

State of the Region

Challenges 

By virtue of their location in the upstream watersheds, domestic 

water users in the Mountain Counties generally benefit from 

higher quality surface water than most other areas of the 

state. Many water supplies originate from pristine foothill or 

mountain sources, which are largely unaffected by agricultural 

or urban pollution. Unfortunately, this higher quality surface 

water is often degraded as it flows downstream or is diverted 

through the numerous canals and delivery systems (see Box 

13-2). Water drainage from abandoned mines, including Penn 

Mine in the Mokelumne River watershed, contributes metals 

and other water quality problems downstream. Mercury was 

imported into this region as part of the gold mining activities 

of past eras, and it remains in some water supplies as a water 

quality issue. Erosion from natural flooding, logging and land 

development, and areas devastated from forest fires, introduces 

sedimentation and nutrients to waterways, as well as causing 

elevated stream temperatures due to the reduction of riparian 

shade canopy. This is a concern to both domestic water treatment operations and to spawning and migration of salmonids, 

particularly below the major dams on the Stanislaus, Tuolumne, 

and Merced rivers. The conversion of agricultural land to 

residential use, and undeveloped land to both agricultural and 

residential use, could present new and different water quality 

problems in the future.

The biggest water issue facing users in the area is the need to 

improve the water supply reliability of the various water delivery 

systems throughout the area. The population of some areas is 

increasing rapidly because people are migrating to the foothills 

from the metropolitan areas. Despite rapid population growth, 

the customer base for many of the water districts is still relatively 

small and widely dispersed. This smaller base, coupled with 

previous development of the less costly reservoir sites, as well 

as the mountainous topography, makes water system improvements expensive and makes interconnections between systems 

impractical. Also, a limited array of options are available to 

meet current and projected needs, due to the local water users’ 

limited ability to pay the costs of improvements and the lack 

of groundwater aquifers to facilitate groundwater banking 

and conjunctive use strategies. Some local officials directly 

responsible for water delivery within the Mountain Counties 

Area are evaluating the potential use of California’s “Area of 

Origin and Watershed Protection” water laws as a method for 

meeting projected growth within their respective areas as well as 

improving water supply reliability to existing users. These legal 

statutes provide for the reservation of water supplies for counties 

in which the water originates when a state water right filing is 

assigned for use elsewhere, as well as setting aside water for 

future development in the area. Typically, however, the upland 

areas have not had the population and financial base to contract 

with SWP or CVP for a water supply, nor has the SWP or CVP 

had adequate supplies of unallocated water to meet the needs 

of most Mountain Counties communities. 

Historically many small water systems in the foothills and mountains of California have relied on surface water or local springs 

with minimal or no water treatment. Some small rural water 

systems have also relied upon water from open ditch systems, 

sometimes in use for over 100 years, that were intended primarily for agriculture or hydropower purposes and used only 

incidentally for domestic water. However, with a greater recognition of the health risk posed by pathogens in drinking water 

sources, these systems must now maintain reliable filtration and 

disinfection facilities and in most cases required improvements 

are being made. In addition, low housing densities in this region 

result in a large number of isolated, small water systems, which 

individually do not have the technical or financial capacity to 

upgrade their treatment facilities and infrastructure, and cannot 

consolidate to take financial advantage of a larger water utility 

customer base. When such treatment upgrades are infeasible, 

water purveyors are instead requiring customers to use bottled 

water for drinking purposes. 

Another common problem for the older open ditch delivery 

systems within the Mountain Counties region is the tendency to 

have significant conveyance seepages and evaporation, as well 

as sanitary hazards associated with open water systems. Repairs 

and replacement of some open ditch systems have sometimes 

been opposed by various groups and landowners who argue 

Box 13-2 1997 Flood Damage to Canals

After the 1997 floods, a landslide destroyed a 30-foot section of Georgetown’s canal, which supplies water to 9,000 

customers in six towns in rural El Dorado County. Nearby, El Dorado Irrigation District also lost use of it flume from 

the forebay on the American River due to a separate landslide. 

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California Water Plan Update 2005

13 6 Volume 3 Regional Reports

against the reduction of the aesthetics of the flowing canal, and 

of vegetation and wildlife sustained by leakage and percolation. 

Many other water users in this region are on private wells, which 

are unregulated statewide and, thus, have never been assessed 

for potential water quality contamination.

Most areas within the Mountain Counties region are very 

concerned with forest fires and the damage they cause to the 

watersheds and the wooden infrastructure associated with the 

ditch systems. Every year, numerous forest fires occur in the 

Sierra Nevada which expose the watersheds to soil erosion. 

Sediment loads from erosion can obstruct water flow in open 

ditches, reduce reservoir capacity, add nutrient loading, diminish water quality and cause excessive algae growth. Fires have 

damaged components of the ditch systems including diversion 

structures and flume sections. As a result some small communities 

have been left without water for extended periods of time. 

Water supply managers in the area are concerned about federal 

and State designations of Wild and Scenic streams (see Box 13-

3). When a river or stream is designated as Wild and Scenic, 

the accompanying regulations can sometimes preclude water 

resources development. Environmental interests are concerned 

about preserving the few undeveloped streams or sections of 

streams remaining in the area. Federal statutes prohibit federal 

agencies from constructing, authorizing, or funding water 

resources projects that would have a direct and adverse effect on 

the values for which the river was designated. The state wild and 

scenic law prohibits construction of any dam, reservoir, diversion, or other water impoundment in specific regions. However in 

some situations where a diversion is needed to supply domestic 

water to residents of an area through which the wild and scenic 

river flows, such diversions may sometimes be authorized. 

Like surface water, groundwater in this region is generally of 

good quality, but it may be contaminated by naturally occurring radon, uranium, or sulfide mineral deposits containing 

heavy metals. In particular, radon contamination is associated with granite, such as the granite batholith of the Sierra 

Nevada. Meeting State secondary standards for both iron and 

magnesium can also be difficult for some groundwater sources. 

Also, because of the lack of community wastewater systems, 

individual septic tanks are prevalent for rural residential 

development in this region. The failure of septic tank systems 

can create sewage flows that have the potential to adversely 

affecting nearby wells and groundwater quality. 

Accomplishments

In 1997, Sacramento area interests released the Draft Recommendations for the Water Forum Agreement. This group is 

pursuing two objectives: (1) provide a reliable water supply for 

the region through 2030 and (2) reserve the fishery, wildlife 

recreation, and aesthetic values of the Lower American River. 

The proposed draft solution includes an integrated package of 

seven actions. Generally, foothill water interests would increase 

their diversions from the American River in average and wet 

years and decrease those diversions in drier and driest years. 

Placer County Water Agency would be providing excess water 

from non-American River sources to many of the participating 

water agencies during drier water years to help make up the 

decreased American River diversions in those years. PCWA’s 

participation in many of these specific agreements is dependent 

upon State Water Resources Control Board approval for changes 

to conditions of its existing water rights.

Box 13-3 1996 Sierra Nevada Ecosystem Study

In 1996, the University of California released its “Sierra Nevada Ecosystem Study,” as a part of a project by the same 

name. The report is the result of a three year congressionally mandated study of the entire Sierra Nevada, with a primary emphasis on gathering and analyzing data to assist Congress and other decision-makers in future management 

of the mountain range. The project goal is to maintain the health and sustainability of the ecosystem while providing 

resources to meet human needs. The study states that, “excluding the hard-to-quantify public good value of flood 

control and reservoir-based recreation, the hydroelectric generating, irrigation and urban use values of water are far 

greater than the combined value of all other commodities produced in the Sierra Nevada.” The report estimates the 

value of water at 60 percent of all commodities produced in the foothills and mountains of the Sierra Nevada. This 

commodity-based view of water leads to some of the study’s related conclusions that, “increased concern about the 

ecological impacts of diversions as well as the social decisions about who should bear the financial burdens of plans 

to reduce, or at least stop the growth of, these impacts requires a greater understanding of how diversions, economic 

benefits, and ecological impacts are linked.”

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Chapter 13 Mountain Counties Area 13 7

California Water Plan Update 2005

Relationship to Other Regions

Much of the state’s developed water supply originates from 

the Sierra Nevada in the upland portions of this region. Many 

surface storage and diversion facilities capture and export 

water, including several CVP and SWP reservoirs, and local 

facilities operated by Yuba County Water Agency, East Bay 

Municipal Utility District, the city of San Francisco, Modesto 

and Turlock Irrigation districts, and Merced Irrigation District. 

The map in Figure 13-1 provides information about the volume 

of water exports from the Mountain Counties region for years 

1998, 2000 and 2001. 

Looking to the Future

Urban and agricultural water users in most of the Mountain 

Counties region have limited water supply options to meet 

future needs, because of the mountainous topography, lack of 

significant groundwater aquifers, limited financial resources 

for water development, and the fact that most water originating in the area was previously allocated to downstream users 

and exports through the water rights process. However, most 

water agencies are actively pursuing a wide variety of supply 

augmentation and demand reduction actions to secure water 

for future needs. For example, El Dorado Irrigation District is 

considering feasibility studies for development of a 31,000 

acre-feet Alder Reservoir, which would provide drought storage, enhanced environmental flows, and hydropower generation benefits. In addition to its ongoing water conservation and 

water recycling programs, the district is planning on lining a 

2.5-mile ditch system to save an estimated 1,300 acre-feet 

that is currently lost through seepage.

At the southern end of the Mountain Counties region in the 

Upper San Joaquin River basin, the California Bay-Delta 

Authority is conducting feasibility studies for development of 

additional surface storage in the upper watershed. Several 

alternative sites will be evaluated including one called Temperance Flat. If it is determined to be feasible, such storage could 

help to contribute to restoration and improvement of water 

flows and quality in the lower San Joaquin River, and would 

facilitate conjunctive water management and water exchanges 

among downstream water agencies. 

Throughout California there are more than 100 existing 

hydroelectric projects that hold Federal Energy Regulatory 

Commission (FERC) licenses which will be up for federal 

license renewal within the next ten years. A large number of 

these projects are located on river systems within the Mountain 

Counties region. As part of the FERC license renewal process, 

the project owners must conduct studies to evaluate the future 

use, impacts and alternatives for each hydroelectric project. 

For local water agencies this process will provide key opportunities to develop and improve integrated resource planning, 

so that the proposed reoperation and federal re-licensing of 

hydroelectric projects can also consider improved benefits to 

local water supplies, instream flows, and recreation uses. 

Regional Planning

The Mountain Counties Water Resources Association assists 

water agencies and local governments in coordinating water 

resource matters important to the region. The association also 

interfaces with applicable state officials and departments on 

water resource matters. Some agencies are looking for new 

supplies from expansion of existing storage, re-operation of 

existing hydroelectric storage, or construction of new storage. For example, Lyons Reservoir, in the Tuolumne Utilities 

District is a 5,800 acre-foot joint use facility, supplying both 

hydroelectric power and consumptive water storage. TUD 

is considering the expansion of Lyons Reservoir to 50,000 

acre-feet. While large quantities of groundwater are not 

generally available in the Sierra-Cascade Mountain Area, 

a number of local agencies are implementing groundwater 

management strategies to help ensure the reliability of local 

groundwater supplies. 

Some counties and water districts meet regularly to discuss 

regional water issues. One example is the Mokelumne River 

Forum. The Forum consists of thirteen entities that have an 

interest in the Mokelumne Watershed and have signed an 

MOU to have DWR facilitate regional collaboration to help 

resolve the complex water supply issues.

Several local agencies and governments are developing 

recycled water projects. A few examples are:

• El Dorado Irrigation District is investigating construction 

of up to 5,000 acre-feet of seasonal storage to more 

efficiently use recycled water in the district. The storage 

would allow for meeting recycled water demands, without 

supplemental water or shortages through 2025.

• The city of Auburn is developing a proposal to sell up to 

5,000 acre-feet of recycled water to agricultural users 

by 2020. The water is expected to be delivered near 

Lincoln, on the valley floor. This option is included in the 

Sacramento River Region management plan. 

• The city of Angels Camp in Calaveras County is developing plans to expand its reclaimed water deliveries by 300 

acre-feet to agricultural, environmental, and landscape 

users by 2020. 

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California Water Plan Update 2005

13 8 Volume 3 Regional Reports

• Two other projects in Calaveras County will deliver 470 

acre-feet for landscape irrigation. 

• Groveland Community Services District, in southern 

Tuolumne County anticipates 425 acre-feet being made 

available to agricultural customers by 2020. 

• The Sierra Conservation Center in Tuolumne County is 

planning a project to deliver almost 300 acre-feet for 

agriculture and landscape irrigation by 2020. 

Urban growth, with an average of 1,800 new homes each 

year in the city of Lincoln, has created a need for new drinking water in an area that has been served agricultural water 

since 1926. An association consisting of the Nevada Irrigation 

District, Placer County Water Agency, and the city of Lincoln, 

is investigating how to accommodate this change in water 

use in order to eliminate the need to find additional water 

supplies or to continue groundwater pumping to meet the 

domestic water needs.

In February 2000, South Sutter Water District, Camp Far West 

Irrigation District, and the California Department of Water 

Resources entered an agreement to meet the State Water 

Resource Control Board’s water quality objectives -- Phase 8 of 

the Water Quality Control Plan for the San Francisco/Sacramento-San Joaquin Delta Estuary. In exchange for up to 4,400 

acre-feet of water from Camp Far West Reservoir in each dry 

and critical year, DWR agreed to assume all responsibility for 

all Bear River water rights holders’ obligations under Phase 8. In 

addition, South Sutter Water District is implementing its Conveyance Canal Improvement Plan to increase the system conveyance 

capacity (see Box 13-4). The additional water for conveyance 

will be obtained from increases in diversion of stored water and 

water that is spilled from Camp Far West Reservoir. 

Water Portfolios for Water 

Years 1998, 2000, and 2001

The following tables and graphs present actual information 

about the water supplies and uses for the Mountain Counties 

hydrologic region. Water year 1998 was a wet year for this 

region, with annual precipitation at 154 percent of normal, 

while the statewide annual precipitation was 171 percent of 

average. Year 2000 represents nearly normal hydrologic 

conditions with annual precipitation at 107 percent of average for the Mountain Counties region, and 2001 reflected 

dryer water year conditions with annual precipitation at 

65 percent of average. For comparison, statewide average 

precipitation in year 2001 was 72 percent of normal. Table 

13-1 provides more detailed information about the total water 

supplies available to this region for these three specific years 

from precipitation, imports and groundwater, and also summarizes the uses of all of the water supplies. 

A more detailed tabulation of the portion of the total available water that is dedicated to urban, agricultural and environmental purposes is presented in Table 13-2. Table 13-3 

also provides detailed information about the sources of the 

developed water supplies, which are primarily from surface 

water systems and include a large percentage of water imports 

from other regions. These developed water use and supplies 

for the three years are also presented graphically in Figures 

13-2. The three Water Portfolio tables included in Table 13-3 

and companion Water Portfolio flow diagrams (Figures 13-3 

and 13-4) provided more detailed information about how the 

available water supplies are distributed and used throughout 

this region.

Box 13-4 South Sutter Water District’s Canal Improvement Plan

 • Increase the flexibility, timing, and reliability of surface water supplies. 

• Replenish groundwater supplies for extraction in drier years. 

• Recharge the groundwater basin to reduce the effect of declining groundwater levels. 

• Provide the ability to meet additional water needs (including Bay Delta Authority environmental objectives) 

 outside of SSWD. 

• Replace older conveyance structures with advanced control technology. 

• Enhance SSWD’s conjunctive water management activities. 

• Reduce the need for cropping changes during drier water years. 

• Increase power generation and decrease power use for pumping. 

• Increase water use efficiency by installing state-of-the-art water control and measurement structures.

EE-RM-PET-100 C0MMENT 01A
Chapter 13 Mountain Counties Area 13 9

California Water Plan Update 2005

Water Entering the Region 

Precipitation 55,206 38,412 23,445

 Inflow from Oregon/Mexico 0 0 0

 Inflow from Colorado River 0 0 0

 Imports from Other Regions 10 10 9

Total 55,216 38,422 23,454

Water Leaving the Region 

Consumptive Use of Applied Water * 237 279 264

 (Ag, M&I, Wetlands) 

 Outflow to Oregon/Nevada/Mexico 0 0 0

 Exports to Other Regions 19,983 13,548 7,376

 Statutory Required Outflow to Salt Sink 1,227 1,090 654

 Additional Outflow to Salt Sink 81 174 180

 Evaporation, Evapotranspiration of Native 

 Vegetation, Groundwater Subsurface Outflows, 31,274 24,153 17,781

 Natural and Incidental Runoff, Ag Effective 

 Precipitation & Other Outflows 

Total 52,802 39,244 26,255

Storage Changes in the Region

 [+] Water added to storage

 [-] Water removed from storage 

 Change in Surface Reservoir Storage 2,420 -802 -2,721

 Change in Groundwater Storage ** -6 -20 -80

Total 2,414 -822 -2,801

Applied Water * (compare with Consumptive Use) 402 472 452

*Footnote for applied water

Consumptive use is the amount of applied water used and no longer available as a source of supply. Applied water is 

 greater than consumptive use because it includes consumptive use, reuse, and outflows. 

**Footnote for change in Groundwater Storage

Change in Groundwater Storage is based upon best available information. Basins in the north part of the 

state (North Coast, San Francisco, Sacramento River and North Lahontan regions and parts of Central 

 Coast and San Joaquin River regions) have been modeled – spring 1997 to spring 1998 for the 1998 

 water year and spring 1999 to spring 2000 for the 2000 water year. All other regions and year 2001 were 

 calculated using the following equation: 

GW change in storage =

 intentional recharge + deep percolation of applied water + conveyance deep percolation - withdrawals

This equation does not include the unknown factors such as natural recharge and subsurface inflow and outflow.

 Water Year (Percent of Normal Precipitation) 

1998 (154%) 2000 (107%) 2001 (65%)

Table 13-1 Mountain Counties Water Balance Summary - TAF

Water Entering the Region – Water Leaving the Region = Storage Changes in Region

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California Water Plan Update 2005

13 10 Volume 3 Regional Reports

Selected References

• 2002 California 305(b) Report on Water Quality, State 

Water Resources Control Board

• California’s Groundwater Bulletin 118-03, Update 2003, 

California Department of Water Resources

• Nonpoint Source Program Strategy and Implementation 

Plan, 1998-2013, State Water Resources Control Board, 

California Coastal Commission, January 2000

• Strategic Plan, State Water Resources Control Board, 

Regional Water Quality Control Boards, November 15, 

2001

• Water Needs Assessment, Mountain Counties Water 

Resources Association, March 1999.

• Water Quality Control Plan, Regional Water Quality 

Control Board

• Watershed Management Initiative Chapter, Regional 

Water Quality Control Board

EE-RM-PET-100 C0MMENT 01A
Chapter 13 Mountain Counties Area 13 11

California Water Plan Update 2005

 Applied Net Depletion Applied Net Depletion Applied Net Depletion

Water Use Water Use Water Use Water Use Water Use Water Use

1998 2000 2001

WATER USE

DEDICATED WATER SUPPLIES

Table 13-2 Mountain Counties of California Water Use and Distribution of Dedicated Supplies (TAF)

Urban

Large Landscape 11.2 11.0 11.4 

Commercial 11.8 12.1 12.2 

Industrial 14.6 14.6 14.8 

Energy Production 0.0 0.0 0.0

Residential - Interior 40.4 40.3 41.4 

Residential - Exterior 63.6 63.5 66.1 

Evapotranspiration of Applied Water 59.7 59.7 55.4 55.4 57.1 57.1

E&ET and Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Outflow 59.2 59.2 64.6 64.6 66.8 66.8

Conveyance Applied Water 19.9 15.7 18.9 

Conveyance Evaporation & ETAW 10.1 10.1 8.1 8.1 9.7 9.7

Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Outflow 9.8 9.8 7.6 7.6 9.2 9.2

GW Recharge Applied Water 0.0 0.0 0.0

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Urban Use 161.5 138.8 138.8 157.2 135.7 135.7 164.8 142.8 142.8

 Agriculture

On-Farm Applied Water 260.2 330.6 306.5 

Evapotranspiration of Applied Water 177.1 177.1 223.9 223.9 206.5 206.5

E&ET and Deep Perc to Salt Sink 6.0 6.0 7.8 7.8 6.0 6.0

Outflow 63.4 8.4 80.8 80.8 82.6 82.6

Conveyance Applied Water 49.1 59.6 58.1 

Conveyance Evaporation & ETAW 10.6 10.6 22.8 22.8 22.7 22.7

Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Outflow 26.3 3.7 21.3 21.3 21.5 21.5

GW Recharge Applied Water 0.0 0.0 0.0

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Agricultural Use 309.3 283.4 205.8 390.2 356.6 356.6 364.6 339.3 339.3

 Environmental

Instream

 Applied Water 1,569.5 1,563.0 1,450.6 

 Outflow 313.0 313.0 326.5 326.5 340.9 340.9

Wild & Scenic

 Applied Water 6,381.6 4,098.7 1,968.8 

 Outflow 914.1 914.1 763.0 763.0 313.3 313.3

Required Delta Outflow

 Applied Water 0.0 0.0 0.0

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Managed Wetlands

 Habitat Applied Water 0.0 0.0 0.0

 Evapotranspiration of Applied Water 0.0 0.0 0.0 0.0 0.0 0.0

 E&ET and Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Applied Water 0.0 0.0 0.0

 Conveyance Evaporation & ETAW 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Total Managed Wetlands Use 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 Total Environmental Use 7,951.1 1,227.1 1,227.1 5,661.7 1,089.5 1,089.5 3,419.4 654.2 654.2

 TOTAL USE AND OUTFLOW 8,421.9 1,649.3 1,571.7 6,209.1 1,581.8 1,581.8 3,948.8 1,136.3 1,136.3

 

Surface Water

 Local Deliveries 1,582.1 1,582.1 1,506.3 1,514.9 1,514.9 1,514.9 1,064.4 1,064.4 1,064.4

 Local Imported Deliveries 9.7 9.7 9.2 10.4 10.4 10.4 8.5 8.5 8.5

 Colorado River Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 CVP Base and Project Deliveries 25.7 25.7 24.5 26.3 26.3 26.3 18.4 18.4 18.4

 Other Federal Deliveries 1.6 1.6 1.5 1.1 1.1 1.1 1.6 1.6 1.6

 SWP Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 Required Environmental Instream Flow 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Groundwater

 Net Withdrawal 29.0 29.0 29.0 27.9 27.9 27.9 42.2 42.2 42.2

 Deep Percolation of Surface and GW 37.3 38.4 36.7 

Reuse/Recycle

 Reuse Surface Water 6,735.3 4,588.9 2,775.8 

 Recycled Water 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2

 TOTAL SUPPLIES 8,421.9 1,649.3 1,571.7 6,209.1 1,581.8 1,581.8 3,948.8 1,136.3 1,136.3

Balance = Use - Supplies 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 

EE-RM-PET-100 C0MMENT 01A
Chapter 13 Mountain Counties Area 13 13

California Water Plan Update 2005

Water Portfolios

Mountain Counties Area

EE-RM-PET-100 C0MMENT 01A
California Water Plan Update 2005

13 14 Volume 3 Regional Reports

Table 13-3 Mountain Counties water portfolios (TAF)

 ID Mountain Counties Mountain Counties Mountain Counties

Number: Flow Diagram Component (see legend) 1998 2000 2001

 1 Colorado River Deliveries - - -

 2 Total Desalination - - -

 3 Water from Refineries - - -

 4a Inflow From Oregon - - -

 b Inflow From Mexico - - -

 5 Precipitation 55,205.7 38,412.2 23,444.5

 6a Runoff - Natural N/A N/A N/A

 b Runoff - Incidental N/A N/A N/A

 7 Total Groundwater Natural Recharge N/A N/A N/A

 8 Groundwater Subsurface Inflow 

 9 Local Deliveries 1,582.1 1,514.9 1,064.4

 10 Local Imports 9.7 10.4 8.5

 11a Central Valley Project :: Base Deliveries - - -

 b Central Valley Project :: Project Deliveries 25.7 26.3 18.4

 12 Other Federal Deliveries 1.6 1.1 1.6

 13 State Water Project Deliveries - - -

 14a Water Transfers - Regional - - -

 b Water Transfers - Imported - - -

 15a Releases for Delta Outflow - CVP 

 b Releases for Delta Outflow - SWP 

 c Instream Flow Applied Water 1,569.5 1,563.0 1,450.6

 16 Environmental Water Account Releases - - -

 17a Conveyance Return Flows to Developed Supply - Urban - - -

 b Conveyance Return Flows to Developed Supply - Ag 22.6 - -

 c Conveyance Return Flows to Developed Supply - Managed Wetlands - - -

 18a Conveyance Seepage - Urban - - -

 b Conveyance Seepage - Ag 3.6 4.7 3.7

 c Conveyance Seepage - Managed Wetlands - - -

 19a Recycled Water - Agriculture 1.2 1.2 1.2

 b Recycled Water - Urban - - -

 c Recycled Water - Groundwater - - -

 20a Return Flow to Developed Supply - Ag 55.0 - -

 b Return Flow to Developed Supply - Wetlands - - -

 c Return Flow to Developed Supply - Urban - - -

 21a Deep Percolation of Applied Water - Ag 6.0 6.1 4.5

 b Deep Percolation of Applied Water - Wetlands - - -

 c Deep Percolation of Applied Water - Urban 22.7 21.5 22.0

 22a Reuse of Return Flows within Region - Ag 7.7 12.0 6.9

 b Reuse of Return Flows within Region - Wetlands, Instream, W&S 6,724.0 4,572.2 2,765.2

 24a Return Flow for Delta Outflow - Ag - - -

 b Return Flow for Delta Outflow - Wetlands, Instream, W&S 1,227.1 1,089.5 654.2

 c Return Flow for Delta Outflow - Urban Wastewater - - -

 25 Direct Diversions N/A N/A N/A

 26 Surface Water in Storage - Beg of Yr 11,595.4 12,504.6 11,702.6

 27 Groundwater Extractions - Banked - - -

 28 Groundwater Extractions - Adjudicated - - -

 29 Groundwater Extractions - Unadjudicated 66.3 66.3 78.9

 23 Groundwater Subsurface Outflow - - -

 30 Surface Water Storage - End of Yr 14,015.1 11,702.6 8,982.1

 31 Groundwater Recharge-Contract Banking - - -

 32 Groundwater Recharge-Adjudicated Basins - - -

 33 Groundwater Recharge-Unadjudicated Basins - - -

 34a Evaporation and Evapotranspiration from Native Vegetation N/A N/A N/A

 b Evaporation and Evapotranspiration from Unirrigated Ag N/A N/A N/A

 35a Evaporation from Lakes 92.4 92.4 92.4

 b Evaporation from Reservoirs 630.2 630.2 630.2

 36 Ag Effective Precipitation on Irrigated Lands 82.3 57.8 77

 37 Agricultural Water Use 260.2 330.6 306.5

 38 Managed Wetlands Water Use - - -

 39a Urban Residential Use - Single Family - Interior 29.1 28.8 29.7

 b Urban Residential Use - Single Family - Exterior 59.3 58.8 61.4

 c Urban Residential Use - Multi-family - Interior 11.3 11.5 11.7

 d Urban Residential Use - Multi-family - Exterior 4.3 4.7 4.7

 40 Urban Commercial Use 11.8 12.1 12.2

 41 Urban Industrial Use 14.6 14.6 14.8

 42 Urban Large Landscape 11.2 11.0 11.4

 43 Urban Energy Production - - -

 44 Instream Flow 313 326.5 340.9

 45 Required Delta Outflow - - -

 46 Wild and Scenic Rivers 914.1 763 313.3

 47a Evapotranspiration of Applied Water - Ag 177.1 223.9 206.5

 b Evapotranspiration of Applied Water - Managed Wetlands - - -

 c Evapotranspiration of Applied Water - Urban 59.7 55.4 57.1

 48 Evaporation and Evapotranspiration from Urban Wastewater - - -

 49 Return Flows Evaporation and Evapotranspiration - Ag 6 7.8 6

 50 Urban Waste Water Produced 45.6 53.2 54.9

 51a Conveyance Evaporation and Evapotranspiration - Urban 10.1 8.1 9.7

 b Conveyance Evaporation and Evapotranspiration - Ag 10.6 22.8 22.7

 c Conveyance Evaporation and Evapotranspiration - Managed Wetlands - - -

 d Conveyance Outflow to Mexico - 0 0

 52a Return Flows to Salt Sink - Ag 12.1 102.1 104.1

 b Return Flows to Salt Sink - Urban 69 72.2 76

 c Return Flows to Salt Sink - Wetlands 0 0 0

 53 Remaining Natural Runoff - Flows to Salt Sink 0 0 0

 54a Outflow to Nevada - - -

 b Outflow to Oregon - - -

 c Outflow to Mexico - - -

 55 Regional Imports 49.7 39.8 31.9

 56 Regional Exports 2153.1 2476.7 1561.2

 59 Groundwater Net Change in Storage -5.5 -20.1 -79.5

 60 Surface Water Net Change in Storage 2,419.7 -802.0 -2,720.5

 61 Surface Water Total Available Storage 18,185.0 18,185.0 18,185.0

 

 Inflows Outflows Green number signifies included in summary boxes

EE-RM-PET-100 C0MMENT 01A
Figure 13-3 Mountain Counties area - illustrated water flow diagram

INFLOWS

SUMMARY

OUTFLOWS

8

15a,b

21

27

31

45

48

51

5

6

46

14 16

33

28

29

32

39- 43

59

50

18

9

51

34

47b

38

35

51

26

30

60

61

11

12

13

15c

54

56

7

1

4

55

10 44

36

47a

49

51

37

17

20

47c

22

25 24

31

23

2

3

52

53

19

In this illustration of Table 13-3, key components of the flow diagram are shown as characteristic elements of the hydrologic cycle. Circled numbers correspond to the identification number of flow diagram components in the table; its color indicates whether the component is water input, output, 

or summary.

52

Volume 3 Regional Reports Chapter 13 Mountain Counties Area 13 15

California Water Plan Update 2005

EE-RM-PET-100 C0MMENT 01A
SUMMARY

OUTFLOWS

INFLOWS

Figure 13-4 Mountain Counties area - schematic flow diagram

In schematic of Table 13-3, key components of the flow diagram are shown as boxes and connectors in a flow chart. Circled numbers correspond to the identification number of flow diagram components in the table; box color indicates if the component is a water input, output, or summary. 

Blank boxes are flow diagram components not relevant to the region. 

1

2

5

4

3

55

6

13

11

19

12

10

9

7

20

21

45

29

26

30

35

39 to 43

37

38

53

54

46

14

34 36

28

52

16

24

17

18

25

47

50

49

48

27

31

32

33

23

8

15C

15A

15B

56

44

16

51

22

WILD & SCENIC RIVERS NET 

USE:

RUNOFF:

NATURAL: INCIDENTAL: PRECIPITATION: TOTAL STREAM 

FLOW: 

AG EFFECTIVE 

PRECIPITATION ON 

IRRIGATED LANDS: 

LOCAL IMPORTED 

DELIVERIES:

LOCAL

DELIVERIES:

CVP PROJECT 

DELIVERIES:

OTHER FEDERAL 

DELIVERIES:

WATER DEPOSITS: 

SURFACE WATER: 

GROUNDWATER: 

RECYL & DESAL:

TRANSFERS:

TOTAL GROUNDWATER NATURAL RECHARGE: 

GROUNDWATER CHANGE IN STORAGE: 

BANKED:

ADJUDICATED: 

UNADJUDICATED: 

GW EXTRACTIONS:

CONTRACT BANKS:

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

EVAPOTRANSPIRATION 

OF APPLIED WATER: 

AG:

WETLANDS:

URBAN:

WATER USE (APPLIED): 

AGRICULTURAL: 

WETLANDS:

URBAN:

RECYCLED WATER: 

AG: URBAN:

GW: 

URBAN

WASTEWATER 

PRODUCED:

INCIDENTAL E & ET 

AG RETURN FLOWS: 

AG & WETLANDS 

RETURN FLOWS:

RETURN FLOWS TO SALT 

SINKS:

AG: WETLANDS:

URBAN:

REMAINING NATURAL 

RUNOFF

FLOW TO SALT SINKS: 

DEEP PERC OF APPLIED 

WATER: 

AG: WETLANDS:

URBAN:

RETURN FLOW TO 

DEVELOPED

SUPPLY: 

AG:

WETLANDS:

URBAN:

EVAP FROM: 

LAKES:

RESERVOIRS:

E & ET FROM:

NATIVE VEGETATION: 

UNIRRIGATED AG: 

RELEASES FOR 

INSTREAM USE: 

CONVEYANCE E&ET, 

RETURN FLOWS, & 

SEEPAGE:

URBAN: AG:

WETLANDS:

CONVEYANCE E & ET: 

URBAN: AG:

WETLANDS:

CONVEYANCE RETURN 

FLOWS:

URBAN: AG:

WETLANDS:

CONVEYANCE SEEPAGE: 

URBAN: AG:

WETLANDS:

RETURN FLOW FOR 

DELTA OUTFLOW: 

AG:

WETLANDS:

URBAN : 

EVAPORATION AND EVAPOTRANSPIRATION OF APPLIED WATER, 

PRECIPITATION AND CONVEYANCE: 

GW RECHARGE:

CONTRACT BANKING:

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

TO E & ET: 

SUBSURFACE GW 

INFLOW: 

SUBSURFACE 

GROUNDWATER 

OUTFLOW: 

OTHER REGIONAL 

TRANSFER OUT: 

REGIONAL

TRANSFER IN: 

INSTREAM NET USE:

SURFACE WATER IN 

STORAGE: 

 Beg of Yr: 

End of Yr: 

DIRECT 

DIVERSIONS:

Service Area

Return 

Flow within

Return of

Required Instream 

Flows

Return of

Required Wild & 

Scenic Flows

13 16 Chapter 13 Mountain Counties Area Volume 3 Regional Reports

California Water Plan Update 2005

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Glossary

A

acre-foot (af) – The volume of water that would cover one acre to a depth of one foot; equal to 43,560 cubic feet or 325,851 gallons. 

adjudication –The act of judging or deciding by law. In the context of an adjudicated groundwater basin, landowners or other 

parties have turned to the courts to settle disputes over how much groundwater can be extracted by each party to the decision. 

 

agricultural discharge standards – State and federal water quality regulations regarding discharge of water used for 

agricultural production to streams, rivers, groundwater aquifers, or evaporation ponds. Context: Scenario Factor.

agricultural lands stewardship – Conserving natural resources and protecting the environment by compensating owners of 

private farms and ranches for implementing stewardship practices. Context: Resource Management Strategy.

agriculture water reliability (average) – A measure of a water system’s ability to sustain the social, environmental, and 

economic agricultural systems that it serves during a year of average precipitation

agricultural water use efficiency – The ratio of applied water to the amount of water required to sustain agricultural productivity. 

Efficiency is increased through the application of less water to achieve the same beneficial productivity or by achieving 

more productivity while applying the same amount of water. Context: Scenario Factor, Resource Management Strategy.

allocation of long-term contractual imports – Interregional allocation of water for periods of time more than one year 

through mechanisms such as the State and federal water projects. Context: Scenario Factor.

alluvial – Of or pertaining to or composed of alluvium.

alluvium – A general term for clay, silt, sand, gravel, or similar unconsolidated detrital material, deposited during comparatively 

recent geologic time by a stream or other body of running water, as a sorted or semi-sorted sediment in the bed of the 

stream or on its floodplain or delta, as a cone or fan at the base of a mountain slope.

anthropogenic – Of human origin or resulting from human activity.

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. 

applied water reduction – A decrease in the amount of water needed to meet the demand for beneficial use; can be a supply 

for both new (real) water and reused water. Context: Resource Management Strategy. See also new water.

appropriative right – The right to use water that is diverted or extracted by a nonriparian or nonoverlying party for nonriparian 

or nonoverlying beneficial uses. In California, surface water appropriative rights are subject to a statutory permitting process 

while groundwater appropriation is not.

aquifer – A body of rock or sediment that is sufficiently porous and permeable to store, transmit, and yield significant (i.e. 

economic) quantities of groundwater to wells and springs.

aquifer remediation – See groundwater remediation/aquifer remediation

aquitard – A confining bed or formation composed of rock or sediment that retards but does not prevent the flow of water to 

or from an adjacent aquifer. It does not readily yield water to wells or springs, but stores groundwater.

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2G

artesian aquifer – A body of rock or sediment containing groundwater that is under greater than hydrostatic pressure; that is, 

a confined aquifer. When an artesian aquifer is penetrated by a well, the water level will rise above the top of the aquifer. 

artesian pressure – Hydrostatic pressure of artesian water, often expressed in terms of pounds per square inch; or the height, 

in feet above the land surface, of a column of water that would be supported by the pressure.

artificial recharge – The (intentional) addition of water to a groundwater reservoir by human activity, such as putting surface 

water into dug or constructed spreading basins or injecting water through wells.

available groundwater storage capacity – The volume of a groundwater basin that is unsaturated and capable of storing 

groundwater.

available soil water – The amount of water held in the soil that can be extracted by a crop; often expressed in inches per 

foot of soil depth. It is the amount of water released between in situ field capacity and the permanent wilting point.

average annual cost of implementing option – Annualized total monetary cost of option required for “turn key” implementation 

including environmental and third party impact mitigation, storage, conveyance, energy, capitalized operations and maintenance, 

administrative, planning, legal and engineering costs. Context: Evaluation Criteria; Planning Concept/Consideration.

average annual runoff – The average value of total annual runoff volume calculated for a selected period of record, at a 

specified location, such as a dam or stream gage.

average year water demand – Demand for water under average hydrologic conditions for a specific level of development. 

B

basin irrigation – Irrigation by flooding areas of level land surrounded by dikes. Used interchangeably with level border 

irrigation, but usually refers to smaller areas.

basin management objectives (BMOs) – See management objectives

beneficial use – Use of water either directly by people or for their overall benefit. There are 24 categories of beneficial uses 

identified by the State Water Resources Control Board.

border irrigation – Irrigation by flooding strips of land, rectangular in shape and cross leveled, bordered by dikes. Water is 

applied at a rate sufficient to move it down the strip in a uniform sheet. Border strips having no downfield slope are referred 

to as level border systems. Border systems constructed on terraced lands are commonly referred to as benched borders.

C

catastrophic vulnerability – The probability and magnitude of potential negative economic, public health, and environmental 

impacts associated with water management actions. Context: Scenario Factor, Evaluation Criteria..

Central Valley Project deliveries – The volume of water imported to a given area through the Central Valley Project. Context: 

Scenario Factor.

check irrigation – Modification of a border strip with small earth ridges or restrictions (checks) constructed or inserted at 

intervals to retain water as it flows down the strip.

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CIMIS – California Irrigation Management Information System- A network of automated weather stations that are owned and 

operated cooperatively between the DWR and local agencies. The stations are installed in most of the agricultural and 

urban areas in the State and provide farm and large landscape irrigation managers and researchers with “real-time” 

weather data to estimate crop and landscape ET rates and make irrigation management decisions.

climate change – Changes in average annual temperature and precipitation and their monthly patterns in 2050 compared 

to today. 

Colorado River supply – The volume of water California has the right to import from the Colorado River. California’s allocation 

is 4.4 million acre-feet per year plus 50% of any declared surplus. Context: Scenario Factor. 

commercial activity mix – The mix of high- and low-water using commercial activity. Note that commercial activity is broken 

into two factors: total commercial activity and commercial activity mix. The latter factor allows designation of the type of 

commercial activity that is occurring. See also total commercial activity. Context: Scenario Factor. 

community water system – A public water system that serves at least 15 service connections used by yearlong residents or 

regularly serves at least 25 yearlong residents. See also public water system.

consumed fraction – the portion of agricultural applied irrigation water that satisfies evapotranspiration.

conveyance – Provides for the movement of water and includes the use of natural and constructed facilities including open 

channels, pipelines, diversions, fish screens distribution systems and pump lifts.

conveyance facilities – Canals, pipelines, pump lifts, ditches, etc. used to move water from one area to another. Context: 

Study Plan Building Block, Resource Management Strategy.

confined aquifer – An aquifer that is bounded above and below by formations of distinctly lower permeability than that of 

the aquifer itself. An aquifer containing confined groundwater. See also artesian aquifer.

conjunctive management and groundwater storage – Coordinated operation of surface water storage and use, ground 

water storage and use, and conveyance facilities. Context: Resource Management Strategy.

conjunctive use – Application of surface and groundwater to meet the demand for a beneficial use. Coordinated and planned 

management of both surface and groundwater resources in order to maximize the efficient use of the resource; that is, the 

planned and managed operation of a groundwater basin and a surface water storage system combined through a coordinated 

conveyance infrastructure. Water is stored in the groundwater basin for later and planned use by intentionally recharging 

the basin during years of above-average surface water supply.

conservation tillage – A tillage practice that leaves plant residues on the soil surface for erosion control and moisture conservation 

consumptive use – A quantity of applied water that is not available for immediate or economical reuse. It includes water that 

evaporates, transpires, or is incorporated into products, plant tissue, or animal tissue. Consumptively used water is removed 

from available supplies without return to a water resource system (uses such as manufacturing, agriculture, landscaping, 

 food preparation, and in the case of Colorado River water, water that is not returned to the river.) 

contaminant – Any substance or property preventing the use or reducing the usability of the water for ordinary purposes such 

as drinking, preparing food, bathing washing, recreation, and cooling. Any solute or cause of change in physical properties 

that renders water unfit for a given use. (Generally considered synonymous with pollutant.)

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cost recovery – Designates who (marginal or existing users) pays the marginal and existing water costs. Also specifies cir 

cumstances where other revenue sources are used to recover costs. Costs can include capital, O&M, financing, environmental 

compliance (documentation, permitting and mitigation), etc. Context: Scenario Factor

cost of reliability enhancement – The total cost required to add an increment of reliability. Context: Evaluation Criteria.

cost of unreliability – The sum of the forgone long-term value and short-term costs incurred to the users. Context: Evaluation Criteria 

critical conditions of overdraft – A groundwater basin in which continuation of present practices would probably result in 

significant adverse overdraft-related environmental, social, or economic impacts. The definition was created after an extensive 

public input process during the development of the Bulletin 118-80 report.

cover crop – Close growing crop, that provides soil protection, seeding protection, and soil improvement between periods of 

normal crop production, or between trees in orchards and vines in vineyards. When plowed under and incorporated into 

the soil, cover crops may be referred to as green manure crops.

crop coefficient – A numerical factor (normally identified as Kp or Kc) that relates the evapotranspiration (ET) of the individual 

crop (ETc) to reference evaporation or some other index.

crop idling – The temporary or permanent fallowing of land previously under irrigation that results in a reduction in stresses 

to a water system (e.g., alternate land use must result in a reduction in water use and/or enhancement of water quality, 

etc.). Context: Scenario Factor.

crop rotation – A system of farming in which a succession of different crops are planted on the same land area, as opposed 

to growing the same crop time after time (monoculture).

crop unit water use –The volume of irrigation water used per unit area of land, commonly expressed in acre feet per acre. 

As used in scenario evaluation, a change in unit water use can be a function of evapotranspiration rates and cultural practices, 

but NOT use efficiency. Agricultural use efficiency is captured under its own distinct factor. Context: Scenario Factor.

D

deep percolation – Percolation of water through the ground and beyond the lower limit of the root zone of plants into groundwater 

deep percolation of surface and groundwater – Water that is applied for agricultural, urban, and managed wetlands in 

excess of the net use requirements. Water either is applied for groundwater recharge or percolates naturally to the water 

table. This does not include reuse, evaporation, evapotranspiration of applied water, or flows/percolation to a salt sink. 

Context: Water Portfolio

depletion – Water consumed through evapotranspiration, flows to salt sinks or is otherwise no longer available as a source supply. 

desalination – Water treatment process for the removal of salt from water for beneficial use. Source water can be brackish 

(low salinity) or seawater. Context: Study Plan Building Block.

dewvaporation (Atmospheric Pressure Desalination) – Desalination through humidification and subsequent dehumidification 

(collection of evaporated water). Context: Resource Management strategy.

distribution system – System of ditches or conduits and their controls that conveys water from the supply canal to the farm 

points of delivery

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California Water Plan Update 2005

domestic well – A water well used to supply water for the domestic needs of an individual residence or systems of four or 

fewer service connections.

drinking water standards – State and federal regulations regarding water delivered by water purveyors that is used as a 

potable supply. Context: Scenario Factor.

drinking water system – see public water system

drinking water treatment and distribution – Treatment is the physical, biological and chemical processes that make water 

suitable for potable use. Distribution includes storage, pumping, and pipe systems to protect and deliver the treated water 

to customers. Context: Study Plan Building Block.

drip irrigation – A method of micro irrigation wherein water is applied to the soil surface as drops or small streams through 

emitters. Discharge rates are generally less than 8 L/h (2 gal/h) for a single-outlet emitters and 12 L/h (3 gal/h) per meter 

for line-source emitters.

drought preparedness– The magnitude and probability of economic, social or environmental consequences that would occur 

as a result of a sustained drought under a given study plan. Evaluation criteria measure the “drought tolerance” of study 

plans. Context: Water Management Objective

drought condition – Hydrologic conditions during a defined period, greater than one dry year, when precipitation and runoff 

are much less than average.

drought year supply – The average annual supply of a water development system during a defined drought period.

duty of water – The total volume of irrigation water required to mature a particular type of crop. It includes consumptive use, 

evaporation, and seepage as well as the water returned to streams by percolation and surface water.

E

earthquake vulnerability – see seismic vulnerability

economic incentives – Financial assistance and pricing policies intended to influence water management including, for 

example, amount of use, time of use wastewater volume, and source of supply. Context: Resource Management Strategy.

ecosystem restoration – The activity of improving the condition of natural landscapes and biotic communities. Context: Study 

Plan Building Block.

effective precipitation – That portion of precipitation that supplies crop evapotranspiration. It includes precipitation stored 

in the soil before and during the growing season

effective porosity – The volume of voids or open spaces in alluvium and rocks that is interconnected and can transmit fluids. 

 

effective rooting depth – The depth from which soil moisture is extracted; it is determined by the crop rooting characteristics 

and soil depth limitations.

electrical conductivity (EC) – The measure of the ability of water to conduct an electrical current, the magnitude of which 

depends on the dissolved mineral content of the water.

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6G

energy availability – The energy consumption to facilitate water management-related actions such as desalting, pump-storage, 

groundwater extraction, conveyance or treatment. This criterion pertains to the economic feasibility of a proposed water 

management action in terms of O&M costs. Context: Evaluation Criteria.

energy costs – Refers to the cost of energy use related to producing, conveying and applying water. It also refers to the cost 

of energy use for processes and inputs not directly related to water, but which can affect the demand for water (e.g., the 

cost of nitrogen fertilizer, tractor manufacturing, etc.). Context: Scenario Factor.

energy production – Both instantaneous capacity (megawatt) and energy produced (kilowatt hours). Context: Evaluation Criteria. 

environmental justice – The fair treatment of people of all races, cultures, and incomes with respect to the development, 

adoption, implementation, and enforcement of environmental laws, regulations, and policies. (Section 65040.12. (c) 

Government code)

environmental water (flow based) – The amount of water dedicated to instream fishery uses, Wild and Scenic rivers, BayDelta outflow and aquatic habitat. 

environmental water (land based) – The amount of water used for fresh-water managed wetlands and native vegetation. 

environmental water quality – Water quality in terms of ecosystem health, recreation, salinity intrusion, usability per sector, 

treatment costs, etc. Aquatic species and water bodies are vulnerable to changes to water quality. 

ETo (Reference Evapotranspiration) – The evapotranspiration rate from an extended surface of 3 to 6 inch (8–15 cm) tall 

green grass cover of uniform height, actively growing, completely shading the ground, and not short on water (the 

reference ET reported by CIMIS).

evaluation criteria – The technical information that will be used to compare the favorability of different response packages 

of resource management strategies against future scenarios in California Water Plan Update 2010. They are designed to 

identify and measure potential effects on water supply, the environment, energy use or production, recreational opportunities, 

groundwater overdraft, and many more.

evaporation – The physical process by which a liquid or solid is transformed to a gaseous state.

evaporative demand – The collective influence of all climatic factors on the rate of evaporation of water.

evapotranspiration (ET) – The quantity of water transpired by plants, retained in plant tissues, and evaporated from plant 

tissues and surrounding soil surfaces 

evapotranspiration of applied water (ETAW) – The portion of ET satisfied by applied irrigation water.

F

flood irrigation – Method of irrigation where water is applied to the soil surface without flow controls, such as furrows, 

borders, or corrugations

floodplain management – Actions designed to reduce risks to life, property, and the environment due to flooding. Actions 

can include watershed management, infrastructure construction and operation, variations in land use practices, floodway 

designations, etc. Context: Study Plan Building Block.

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Glossary 7G

California Water Plan Update 2005

flood risk – The magnitude and probability of consequences that would occur as a result of flood-induced infrastructure 

damage under a given study plan. Context: Evaluation Criteria.

flow diagram – Diagram that characterizes a region’s hydrologic cycle by documenting sources of water such as precipitation 

and inflows and tracks the water as it flows (through many different uses) to its ultimate destinations.

flow diagram table – An itemized listing of all the categories contained in the Flow Diagram including more detailed information, 

organized by “inputs” and “withdrawals.”

full cost – (1) all monetary costs associated with project planning, implementation, financing, or impact mitigation plus any 

recurring costs required to sustain benefits; PLUS (2) all nonmonetary costs that are incurred either at implementation 

or on a recurring basis such as unmitigable environmental or cultural impacts, public trust, environmental justice, or other 

nonmarket-based societal values. (Coincides with CEQA/NEPA study and other permitting requirements.) Context: Planning 

Concept/Consideration.

furrow irrigation – Method of surface irrigation where the water is supplied to small ditches or furrows for guiding across 

the field.

G

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. It excludes soil moisture, which refers to water held by capillary action in the upper unsaturated zones 

of soil or rock. 

groundwater basin – An alluvial aquifer or a stacked series of alluvial aquifers with reasonably well-defined boundaries in 

a lateral direction and having a definable bottom.

groundwater budget – A numerical accounting, the groundwater equation, of the recharge, discharge and changes in storage 

of an aquifer, part of an aquifer, or a system of aquifers.

groundwater in storage – The quantity of water in the zone of saturation.

groundwater management – The planned and coordinated management of a groundwater basin or portion of a groundwater 

basin with a goal of long-term sustainability of the resource.

groundwater management plan – A comprehensive written document developed for the purpose of groundwater management 

and adopted by an agency having appropriate legal or statutory authority.

groundwater mining – The process, deliberate or inadvertent, of extracting groundwater from a source at a rate in excess 

of the replenishment rate such that the groundwater level declines persistently, threatening exhaustion of the supply or at 

least a decline of pumping levels to uneconomic depths.

groundwater monitoring network – A series of monitoring wells at appropriate locations and depths to effectively cover 

the area of interest. Scale and density of monitoring wells is dependent on the size and complexity of the area of interest, 

and the objective of monitoring.

groundwater overdraft – The condition of a groundwater basin in which the amount of water withdrawn by pumping exceeds 

the amount of water that recharges the basin over a period of years during which water supply conditions approximate 

average conditions.

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8G

groundwater quality – See water quality

groundwater recharge facility – A structure that serves to conduct surface water into the ground for the purpose of replenishing 

groundwater. The facility may consist of dug or constructed spreading basins, pits, ditches, furrows, streambed modifications, 

or injection wells.

groundwater recharge – The natural or intentional infiltration of surface water into the zone of saturation.

groundwater remediation/aquifer remediation – Groundwater Remediation involves extracting contaminated groundwater 

from an aquifer, treating it, and then either putting it back in the aquifer or using it for agricultural or municipal purposes. 

Aquifer Remediation is usually accomplished by treating groundwater while it is still in the aquifer, using in-situ methods 

involving biological, physical, or chemical treatment or electrokinetics. Context: Study Plan Building Block, Resource 

Management Strategy.

groundwater source area – An area where groundwater may be found in economically retrievable quantities outside of 

normally defined groundwater basins, generally referring to areas of fractured bedrock in foothill and mountainous terrain 

where groundwater development is based on successful well penetration through interconnecting fracture systems. Well 

yields are generally lower in fractured bedrock than wells within groundwater basins.

groundwater storage capacity – Volume of void space that can be occupied by water in a given volume of a formation, 

aquifer, or groundwater basin.

groundwater subbasin – A subdivision of a groundwater basin created by dividing the basin using geologic and hydrologic 

conditions or institutional boundaries.

groundwater table – The upper surface of the zone of saturation in an unconfined aquifer.

groundwater quality – Water quality can affect supply integrity. Many pollutants are hydrophilic and not easily filtered by 

soil. Treated groundwater can be added to water supply. Context: Evaluation Criteria.

H

hazardous waste – Waste that poses a present or potential danger to human beings or other organisms because it is toxic, 

flammable, radioactive, explosive, or has some other property that produces substantial risk to life.

hydraulic barrier – A barrier created by injecting fresh water to control seawater intrusion in an aquifer, or created by water 

injection to control migration of contaminants in an aquifer.

hydraulic conductivity – A measure of the capacity for a rock or soil to transmit water; generally has the units of feet/day 

or cm/sec.

hydrograph – A graph that shows some property of groundwater or surface water as a function of time at a given point.

hydrology – A science related to the occurrence and distribution of natural water on the earth including the annual volume 

and the monthly timing of runoff. 

hydrologic cycle – The circulation of water from the ocean through the atmosphere to the land and ultimately back to the ocean. 

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Glossary 9G

California Water Plan Update 2005

hydrologic region – A study area consisting of multiple planning subareas. California is divided into 10 hydrologic regions. 

hydrostratigraphy – A geologic framework consisting of a body of rock having considerable lateral extent and composing 

a reasonably distinct hydrologic system.

hyporheic zone – The region of saturated sediments beneath and beside the active channel and that contain some proportion of 

surface water that was part of the flow in the surface channel and went back underground and can mix with groundwater. 

I

in-lieu recharge – The practice of providing surplus surface water to historic groundwater users, thereby leaving groundwater 

in storage for later use. 

industrial activity mix – The mix of high and low water using industrial activity. Note that Industrial Activity is broken into 

two factors: Total Industrial Activity and Industrial Activity Mix. The latter factor allows designation of the type of industry 

that is occurring. This is necessary to account for the large variation in water demands by industry type. See also total 

industrial activity. Context: Scenario Factor.

infiltration – The flow of water downward from the land surface into and through the upper soil layers.

infiltration capacity – The maximum rate at which infiltration can occur under specific conditions of soil moisture.

infrastructure – the underlying foundation or basic framework of a system

integrated regional water management – A comprehensive, systems approach for determining the appropriate mix of 

demand and supply management options that provide long-term, reliable water supply at lowest reasonable cost and with 

highest possible benefits to customers, economic development, environmental quality, and other social objectives.

intercropping – The simultaneous planting of two or more crops in the same field. The practice is used to help control pest 

populations that can occur on monoculture crops, sometimes called “polycropping” or “plant stratification.”

interregional import projects – Movement of water between regions through mechanisms such as the State and federal 

water projects. Context: Scenario Factor.

irrecoverable water – the amount of applied water that is not available for supply or reuse, including discharge to saline 

sinks, evaporation, and evapotranspiration. See recoverable water

irrigation efficiency (IE) – The efficiency of water application and use, calculated by dividing a portion of applied water 

that is beneficially used by the total applied water, expressed as a percentage The two main beneficial uses are crop water 

use (evapotranspiration, ETc) and leaching to maintain a salt balance. 

irrigation water requirements – The quantity of water exclusive of precipitation that is required from various uses.

J

joint powers agreement (JPA) – An agreement entered into by two or more public agencies that allows them to jointly exercise 

any power common to the contracting parties. The JPA is defined in Ch. 5 (commencing with Section 6500) of Division 7 

of Title 1 of the California Government Code.

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10G

L

land subsidence – The lowering of the natural land surface due to groundwater (or oil and gas) extraction.

leaching requirements – The fraction of water entering the soil that must pass through the root zone in order to prevent soil 

salinity from exceeding a specific value.

leaching efficiency – The ratio of the average salt concentration in drainage water to an average salt concentration in the 

soil water of the root zone when near field capacity.

leaky confining layer – A low-permeability layer that can transmit water at sufficient rates to furnish some recharge from an 

adjacent aquifer to a well.

lithologic log – A record of the lithology of the soils, sediments and/or rock encountered in a borehole from the surface to 

the bottom.

lithology – The description of rocks, especially in hand specimen and in outcrop, on the basis of such characteristics as color, 

mineralogic composition, and grain size.

M

management objectives – Objectives that set forth the priorities and measurable criteria of water management. Examples 

include improve water quality, augment water supplies, improve use efficiency, etc. 

matching water quality to use – a resource management strategy that recognizes not all water uses require the same quality 

water. High quality water sources can be used for drinking and industrial purposes that benefit from higher quality water, 

and lesser quality water can be desirable for some uses, such as riparian streams with plant materials benefiting fish. 

Context: Resource Management Strategy.

maximum contaminant level (MCL) – The highest drinking water contaminant concentration allowed under federal and 

State Safe Drinking Water Act regulations.

microirrigation – The frequent application of small quantities of water as drops, tiny streams, or miniature spray through 

emitters or applicators placed along a water delivery line. Microirrigation encompasses a number of methods or concepts 

such as bubbler, drip, trickle, mist, or spray.

multicropping – The practice of consecutively producing two crops (double cropping) or more of either like or unlike com 

modities on the same land within the same year. An example of double cropping might be to harvest a wheat crop by early 

summer and then plant corn or beans on that acreage for harvest in the fall. Suitable climates and reliable water supplies 

are important factors with this practice. 

N

naturally occurring conservation – The amount of background conservation occurring independent of the BMP and EWMP 

programs (e.g., plumbing codes, etc.). Context: Scenario Factor.

natural recharge – Natural replenishment of an aquifer generally from snowmelt and runoff; through seepage from the surface. 

net groundwater withdrawal - groundwater extraction in excess of percolation into a groundwater basin. Context: Water Portfolio 

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net water use (demand) – the amount of water needed in a water service area to meet all requirements or demands. It is 

the sum of several components including evapotranspiration of applied water in an area, the irrecoverable water from the 

distribution system, and the outflow leaving the service area; does not include reuse of water within a service area.

new water – Water that is legally and empirically available for a beneficial use; can be developed through many strategies 

such as capturing surplus water, desalination of ocean water and reductions in depletions. (Same meaning as real water) 

Context: Planning Concept/Consideration.

nonpoint source – Pollution discharged over a wide land area, not from one specific location. These are forms of diffuse 

pollution caused by sediment, nutrients, etc., carried to lakes and streams by surface runoff. See also point source

O

operational flexibility – The temporal or spatial operational efficiency of existing and proposed infrastructure to maximize 

benefits. Context: Evaluation Criteria.

operational yield – An optimal amount of groundwater that should be withdrawn from an aquifer system or a groundwater 

basin each year. It is a dynamic quantity that must be determined from a set of alternative groundwater management decisions 

subject to goals, objectives, and constraints of the management plan.

ordinance – A law set forth by a governmental authority.

other interregional import deliveries – This factor is intended to capture the interregional movement of water for “projects” 

such as Russian River, Trinity River Exports or Putah South Canal. Note that the project name must be specified in the study 

plan narrative. Context: Scenario Factor.

overdraft – See groundwater overdraft

overlying right – Property owners above a common aquifer possess a mutual right to the reasonable and beneficial use of a 

groundwater resource on land overlying the aquifer from which the water is taken. Overlying rights are correlative (related 

to each other) and overlying users of a common water source must share the resource on a pro rata basis in times of shortage. 

A proper overlying use takes precedence over all non-overlying uses.

P

pelagic fish – fish that spawn in open water, often near the surface. Many river-dwelling anadromous fishes, such as shad 

are also pelagic spawners

perched groundwater – Groundwater supported by a zone of material of low permeability located above an underlying main 

body of groundwater.

percolation – Process in which water moves through a porous material, usually surface water migrating through soil toward 

a groundwater aquifer.

perennial yield – The maximum quantity of water that can be annually withdrawn from a groundwater basin over a long period 

of time (during which water supply conditions approximate average conditions) without developing an overdraft condition. 

permeability – The capability of soil or other geologic formations to transmit water.

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pesticide – Any of a class of chemicals used for killing insects, weeds, or other undesirable entities. Most commonly associated 

with agricultural activities, but has significant domestic use in California.

point source – A specific site from which wastewater or polluted water is discharged into a water body. See also nonpoint source 

pollution (of water) – The alteration of the physical, chemical, or biological properties of water by the introduction of any 

substance into water that adversely affects any beneficial use of water.

pollution prevention – Improving water quality for all beneficial uses by protecting water at its source, reducing the need and 

cost for other water management actions and treatment. Context: Resource Management Strategy.

population density – The average number of people per square mile for a planning area. Context: Scenario Factor.

population distribution – The geographic location within California of the population projection. Context: Scenario Factor.

population projection – The 2030 forecast of population made by the California Department of Finance or other agencies. 

Context: Scenario Factor.

porosity – The ratio of the voids or open spaces in alluvium and rocks to the total volume of the alluvium or rock mass.

possible contaminating activity (PCA) – Human activities that are actual or potential origins of contamination for a drinking 

water source. PCAs include sources of both microbiological and chemical contaminants that could have an adverse effect 

upon human health.

precipitation enhancement – The action of artificially stimulating clouds “cloud seeding” to produce more rainfall/snowfall 

than would naturally occur. Context: Resource Management Strategy.

prescriptive right – Rights obtained through the open and notorious adverse use of another’s water rights. By definition, 

adverse use is not use of a surplus, but the use of non surplus water to the direct detriment of the original rights holder.

public trust doctrine–A legal doctrine recognizing public rights in the beds, banks, and waters of navigable waterways, and 

the State’s power and duty to exercise continued supervision over them as trustee for the benefit of the people. 

public water system – A system for the provision of water for human consumption through pipes or other constructed 

conveyances that has 15 or more service connections or regularly serves at least 25 individuals daily at least 60 days out 

of the year.

pueblo right – A water right possessed by a municipality which, as a successor of a Spanish or Mexican pueblo, entitled to 

the beneficial use of all needed, naturally occurring surface and groundwater of the original pueblo watershed Pueblo rights 

are paramount to all other claims.

R

rate structure – Designates the rate basis for cost recovery (e.g., flat, uniform, tiered, etc.). Block/Tiered rates are assumed 

to provide cost signals to consumers. Costs can include capital, O&M, financing, environmental compliance (documentation, 

permitting and mitigation), etc. Context: Scenario Factor.

real water – See new water. Context: Planning Concept/Consideration.

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recharge – Water added to an aquifer or the process of adding water to an aquifer. Groundwater recharge occurs either 

naturally as the net gain from precipitation or artificially as the result of human influence. See also artificial recharge.

recharge area protection – The action of keeping recharge areas from being paved over or otherwise developed and guarding 

the recharge areas so they don’t become contaminated Context: Resource Management Strategy.

recharge basin – A surface facility constructed to infiltrate surface water into a groundwater basin.

recoverable water – the amount of applied water that is available for supply or reuse; including surface runoff to non-saline 

bodies of water and deep percolation that becomes groundwater. 

See irrecoverable water

recreation – Water-dependent recreation activities that are consumptive (e.g., parks), flat-water (e.g., boating), or flow-based 

(e.g., whitewater rafting). Context: Scenario Factor.

recreation (reservoir-based) – Flat water recreation, such as boating and skiing, in the form of future storage facilities as 

well as operation of existing surfaces storage facilities. Context: 

recreation sport-fish populations – Populations of fish species that support recreational fishing. 

recreation (watercourse-based) – Activities that are dependent on instream flows such as whitewater rafting. Context: 

recycled water – Treated municipal, industrial, or agricultural wastewater to produce water that can be reused. Context: 

Resource Management Strategy

regional self-sufficiency – The degree to which a study plan involves implementation of regional water management options. 

Context: Evaluation Criteria.

reliability planning – Water reliability management planning is done by comparing the costs of taking actions to maintain or 

increase reliability to the costs of accepting less reliability. On this basis, accepting of the costs of adverse effects of less 

than 100 percent reliability could be a legitimate planning decision. Providing full water supply to meet 100 percent of 

projected future water demand is not the planning goal, rather, the goal is to find the justified level of reliability. Context: 

Planning Concept/Consideration.

resource management strategy – A project, program, or policy that helps federal, State or local agencies manage water 

and related resources. Resource Management Strategies can reduce water demand, improve operational flexibility, increase 

water supply, improve water quality, or practice resource stewardship.

response packages – Additional sets of resource management strategies to be tested against future scenario conditions for 

performance comparison. This analysis will take place in California Water Plan Update 2010. Comparing the performance 

of different response packages will provide useful information to decision-makers and water managers as they choose 

actions to achieve a desirable future water condition.

return-flow system – A system of pipelines or ditches to collect and convey surface or subsurface runoff from an irrigated 

field for reuse.

reused agricultural water – Water that is used by more than one grower and is, therefore, not available for reallocation 

should one grower become increasingly efficient (i.e., applied water reductions minus real water equal zero). Context: 

Planning Concept/Consideration.

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riparian right – A right to use surface water, such right derived from the fact that the land in question abuts the banks of streams. 

root zone – The portion of the soil profile through which plant roots readily penetrate to obtain water and plant nutrients, 

expressed in inches or feet of depth.

runoff – The volume of surface flow from an area.

S

safe yield – The maximum quantity of water that can be continuously withdrawn from a groundwater basin without adverse effect 

 

saline soil – A nonalkali soil containing soluble salts in such quantities that they interfere with the growth of most plants.

saline intrusion – The movement of salt water into a body of fresh water. It can occur in either surface water or groundwater bodies. 

salinity – Generally, the concentration of mineral salts dissolved in water. Salinity may be expressed in terms of a concentration 

or as electrical conductivity. When describing salinity influenced by seawater, salinity often refers to the concentration of 

chlorides in the water.

saturated zone – The zone in which all interconnected openings are filled with water, usually underlying the unsaturated zone. 

scenarios – Sets of plausible future conditions based on different assumptions of factors such as population size, density, and 

distribution, per capita income, commercial and industrial activity, and crop area and water use. In California Water Plan 

Update 2005, the three scenarios for 2030 are strictly narrative and are “no action” (i.e., they do not reflect any additional 

resource management strategies in the form of response packages beyond those currently planned, such as new water 

efficiency programs).

seasonal vs. permanent crop mix – Shifts in crop type between seasonal and permanent. This factor depicts the diminished 

ability to reduce water use during times of increased water scarcity (due to shifting from seasonal to permanent crops). In 

other words, shortage losses increase when shifting from season to permanent. Context: Scenario Factor. 

seawater intrusion barrier – A system designed to retard, cease or repel the advancement of seawater intrusion into potable 

groundwater supplies along coastal portions of California. The system may be a series of specifically placed injection wells 

where water is injected to form a hydraulic barrier. 

secondary porosity – Voids in a rock formed after the rock has been deposited; not formed with the genesis of the rock, but 

later due to other processes. Fractures in granite and caverns in limestone are examples of secondary openings.

seepage – The gradual movement of water into, through, or from a porous medium. Also, the infiltration of water into the soil 

from canals, ditches, laterals, watercourse, reservoir, storage facilities, or other body of water, or from a field.

semi-confined aquifer – A semi-confined aquifer or leaky confined aquifer is an aquifer that has aquitards either above or 

below that allow water to leak into or out of the aquifer depending on the direction of the hydraulic gradient.

service area – The geographic area served by a water agency.

soil moisture – The water in soils. Usually expressed as a percentage of the dry weight of the soil. Can also be expressed 

on a wet weight or a volume basis.

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soil texture – Soil texture refers to the percentage of sand, silt, and clay particles in a soil. Sand, silt, and clay particles are 

defined by their size. Soil texture has important effects on soil properties. Water-holding capacity, drainage class, consistence, 

and chemical properties are just a few examples of properties that are affected by soil texture.

specific retention – The ratio of the volume of water a rock or sediment will retain against the pull of gravity to the total volume 

of the rock or sediment. 

specific yield – the ratio of the volume of water a rock or soil will yield by gravity drainage to the total volume of the rock 

or soil. 

spring – a location where groundwater flows naturally to the land surface or a surface water body.

sprinkler irrigation – Method of irrigation in which the water is sprayed, or sprinkled, through the air to the ground surface. 

stakeholder – individuals or groups who can affect or be affected by an organization’s activities. or: Individuals or groups with 

an interest or “stake” in what happens as a result of any decision or action. Stakeholders do not necessarily use the products 

or receive the services of a program.

State Water Project deliveries – The volume of water imported to a given study area from the State Water Project. Context: 

Scenario Factor.

statewide water management systems – These include physical facilities (more than 1,200 State, federal, and local reservoirs, 

as well as canals, treatment plants, and levees), which make up the backbone of water management in California, and 

statewide water management programs, which include water-quality standards, monitoring programs, economic incentives, 

water pricing policies, and statewide water-efficiency programs such as appliance standards, labeling, and education.

strategic plan – The long-term goals of an organization or program and an outline of how they will be achieved (e.g., adopting 

specific strategies, approaches, and methodologies). 

stratigraphy – The science of rocks. It is concerned with the original succession and age relations of rock strata and their form, 

distribution, lithologic composition, fossil content, geophysical and geochemical properties—all characters and attributes 

of rocks as strata—and their interpretation in terms of environment and mode of origin and geologic history.

stress irrigation – Management of irrigation water to apply less than enough water to satisfy the soil water deficiency in the 

entire root zone. (Preferred term is limited irrigation.)

subirrigation – Application of irrigation water below the ground surface by raising the water table to within or near the root zone. 

subsurface drip irrigation – Application of water below the soil surface through emitters, with discharge rates generally in 

the same range as drip irrigation. This method of water application is different from and not to be confused with subirrigation 

where the root zone is irrigated by water table control.

surface irrigation – Irrigation in which the soil surface is used as the conduit, as in furrow and border irrigation, and as 

opposed to sprinkler, drip, and subirrigation. 

surface storage facilities – The volume and yield of usable reservoir storage in a given area. Context: Resource Management Strategy. 

surge irrigation – A surface irrigation technique wherein flow is applied to furrows (or less commonly, borders) intermittently 

during a single irrigation set.

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subsidence – See land subsidence

subterranean stream – Subterranean streams “flowing through known and definite channels” are regulated by California’s 

surface water rights system.

surface supply – Water supply obtained from streams, lakes, and reservoirs.

surplus water – Water that is not being used directly or indirectly to benefit the environmental, agricultural or urban use sectors. 

Context: Planning Concept/Consideration.

sustainability – A specific resource that avoids complete depletion over a specified time horizon. The continued feasibility of 

a specified economic activity over a specified time horizon, usually influenced by management and policy actions t Context: 

Economic Activity.

system reoperation – Changing existing water system operation and management procedures or priorities to either meet 

competing beneficial uses or derive more total benefits from the water system by operating more efficiently. Context: Resource 

Management Strategy.

T

third party impacts – The occurrence of incidental economic impacts to parties not directly related to (impact-causing) water 

management actions. For example, agricultural land retirement can impact local tax revenues and/or labor conditions, etc. 

Context: Evaluation Criteria.

total capital cost – Total monetary cost of option required for “turn key” implementation including environmental and third 

party impact mitigation, storage, conveyance, energy, capitalized O&M, administrative, planning, legal and engineering 

costs. Context: Planning Concept/Consideration.

total commercial activity – The amount of commercial activity (e.g., employment, productivity, commercial land use, etc) that 

occurs in a given study area. This factor is a driver of (and indicator for) commercial water use and includes institutional 

water use (government offices, schools, etc.) as well. See also commercial activity mix. Context: Scenario Factor.

total industrial activity – The total amount of industrial activity (e.g., employment, productivity, industrial land use, etc) that 

occurs in a given study area. This factor is a driver of (and indicator for) industrial water use. Context: Scenario Factor.

total irrigated crop area – The total area of irrigated crops (by type) planted in a planning area during a given year. This 

number includes multiple cropping. Context: Scenario Factor.

total population – The statewide total population projection regardless of geographical distribution. Context: Scenario Factor. 

transpiration – An essential physiological process in which plant tissues give off water vapor to the atmosphere. 

U

unconfined aquifer – An aquifer which is not bounded on top by an aquitard. The upper surface of an unconfined aquifer 

is the water table.

underground stream – Body of water flowing as a definite current in a distinct channel below the surface of the ground, 

usually in an area characterized by joints or fissures. Application of the term to ordinary aquifers is incorrect.

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unit applied water – The quantity of water applied to a specific crop per unit area (sometimes expressed in inches of depth). 

unsaturated zone – The zone below the land surface in which pore space contains both water and air.

urban land use management – Planning for the housing and economic development needs of the growing population while 

providing for the efficient use of water and other resources.

urban runoff management – A broad series of activities to manage both storm water and dry weather runoff.

Urban Water Management Planning Act – Sections 10610 through 10657 of the California Water Code. The Act requires 

urban water suppliers to prepare urban water management plans which describe and evaluate sources of water supplies, 

efficient uses of water, demand management measures, implementation strategies and schedules, and other relevant 

information and programs within their water service areas. Urban water suppliers (CWC Section 10617) are either publicly 

or privately owned and provide water for municipal purposes, either directly or indirectly, to more than 3,000 customers 

or supply more than 3,000 acre-feet of water annually.

[urban] water reliability (average) – A measure of a system’s ability to sustain the social, environmental and economic 

systems that it serves during a year of average participation. Context: Evaluation Criteria.

[urban] water reliability (dry) – A measure of a system’s ability to sustain the social, environmental and economic systems 

that it serves during a dry year. Context: Evaluation Criteria.

[urban] water reliability (wet) – A measure of a system’s ability to sustain the social, environmental and economic systems 

that it serves during a wet year. Context: Evaluation Criteria.

urban water use efficiency – Methods or technologies resulting in the same beneficial residential, commercial, industrial, 

and institutional uses with less water or increased beneficial uses from existing water quantities. Context: Scenario Factor, 

Resource Management Strategy.

usable storage capacity – The quantity of groundwater of acceptable quality that can be economically withdrawn from storage. 

V

volatile organic compound (VOC) – A manmade organic compound that readily vaporizes in the atmosphere. These com 

pounds are often highly mobile in the groundwater system and are generally associated with industrial activities.

W

water bag transport/storage technology – Water diverted in areas that have unallocated fresh water supplies, storing the 

water in large inflatable bladders, and towing to an alternate coastal region. Context: Resource Management Strategy.

water balance – An analysis of the total developed/dedicated supplies, uses, and operational characteristics for a region.

water demand – The desired quantity of water that would be used if the water is available and a number of other factors 

such as price do not change. Demand is not static. 

water demand elasticity – The desire to use water is based on a number of factors such as the intended use for the water, 

the price of water, and the cost of alternative ways to meet the intended use.

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water portfolio – A picture of the water supply and use for a given year statewide or by region, subject to availability of data; 

includes the flow diagram, flow diagram table, water balances, and summary table.

water quality – Description of the chemical, physical, and biological characteristics of water, usually in regard to its suitability 

for a particular purpose or use. 

water reliability (dry) – A measure of a system’s ability to sustain the social, environmental, and economic systems that it 

serves during a dry year.

water reliability (wet) – A measure of a system’s ability to sustain the social, environmental, and economic systems which it 

serves during a wet year.

water supply exports – The amount of water that a region transfers to another to meet needs. Context: Regional Reports.

water supply imports – The amount of water that needs to be brought in from other regions to meet needs. Context: Regional Reports. 

water table – See groundwater table

water transfers – 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. A more general definition is that water transfers are a voluntary change in the way 

water is usually distributed among water users in response to water scarcity. Context: Scenario Factor, Resource 

Management Strategy.

water year – A continuous 12-month period for which hydrologic records are compiled and summarized. Different agencies 

may use different calendar periods for their water years.

watershed – The land area from which water drains into a stream, river, or reservoir.

watershed management – The process of evaluating, planning, managing, restoring, and organizing land and other resource 

use within an area that has a single common drainage point. Context: Resource Management strategy.

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Quantity To Convert from Metric Unit To Customary Unit Multiply Metric Unit To Convert to Metric 

 By Unit Multiply

 Customary Unit By

millimeters (mm) inches (in) 0.03937 25.4

Length centimeters (cm) for snow depth inches (in) 0.3937 2.54

meters (m) feet (ft) 3.2808 0.3048

kilometers (km) miles (mi) 0.62139 1.6093

Area square millimeters (mm2) square inches (in2) 0.00155 645.16

square meters (m2) square feet (ft2) 10.764 0.092903

hectares (ha) acres (ac) 2.4710 0.40469

square kilometers (km2) square miles (mi2) 0.3861 2.590

Volume liters (L) gallons (gal) 0.26417 3.7854

megaliters (ML) million gallons (10*) 0.26417 3.7854

cubic meters (m3) cubic feet (ft3) 35.315 0.028317

cubic meters (m3) cubic yards (yd3) 1.308 0.76455

cubic dekameters (dam3) acre-feet (ac-ft) 0.8107 1.2335

Flow cubic meters per second (m3/s) cubic feet per second (ft3/s) 35.315 0.028317

liters per minute (L/mn) gallons per minute (gal/mn) 0.26417 3.7854

liters per day (L/day) gallons per day (gal/day) 0.26417 3.7854

megaliters per day (ML/day) million gallons per day (mgd) 0.26417 3.7854

cubic dekameters per day (dam3/day) acre-feet per day (ac-ft/day) 0.8107 1.2335

Mass kilograms (kg) pounds (lbs) 2.2046 0.45359

megagrams (Mg) tons (short, 2,000 lb.) 1.1023 0.90718

Velocity meters per second (m/s) feet per second (ft/s) 3.2808 0.3048

Power kilowatts (kW) horsepower (hp) 1.3405 0.746

Pressure kilopascals (kPa) pounds per square inch (psi) 0.14505 6.8948

kilopascals (kPa) feet head of water 0.32456 2.989

Specific liters per minute per meter drawdown gallons per minute per foot 0.08052 12.419

capacity drawdown

Concentration milligrams per liter (mg/L) parts per million (ppm) 1.0 1.0

Electrical microsiemens per centimeter (μS/cm) micromhos per centimeter 1.0 1.0

conductivity (μmhos/cm)

Temperature degrees Celsius (°C) degrees Fahrenheit (°F) (1.8X°C)+32 0.56(°F-32)

Metric Conversion Factors

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Chapter 1 Introduction 1 I

California Water Plan Update 2005

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Volume 3 Strategic Plan

California Water Plan Update 2005

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