California Water Plan Update 2005

6 14 Volume 3 Regional Reports

established as an alternative to SWRCB Phase 8 litigation 

proceedings designed to determine the responsibility of meeting 

water quality standards in the Delta. This agreement allows the 

parties to collaborate in the development and implementation 

of a variety of water management projects that will increase 

the availability of Sacramento Valley water. The agreement 

provides that increased supplies will be used first to fully meet 

the in basin needs, but would also be made available to help 

meet the requirements of the 1995 Water Quality Control Plan, 

provide other environmental benefits, and potentially meet 

additional export needs. 

The key to this program is to keep it focused on integrated 

regional planning. SVWMP hydrologists and engineers are 

involved in more than 50 projects into both short- and longterm work plans for the region. These projects are designed to 

protect Northern California surface water rights and groundwater basins through the implementation of groundwater 

planning and monitoring that provides for unmet demands 

in the Sacramento Valley before exporting water to other 

regions. They include system improvement and water-use 

efficiency measures, conjunctive management, and surface 

water reoperation projects that include groundwater protection 

elements. The SVWMP is based on local control. This program 

is undergoing an environmental review and will seek public 

funds, including Proposition 50, to help implement many of 

these projects.

In addition to the Sacramento Valley Water Management 

Program, several other entities are working to improve water 

supply reliability and quality in the region and throughout 

the state. For example, the Redding Area Water Council is 

considering local water transfers, conjunctive use of groundwater, groundwater management, and additional surface 

water developments to increase supplies. 

The Regional Water Authority is a joint powers authority that 

represents the interests of nearly 20 water providers around 

Sacramento. The organization’s mission is to help its members 

protect and enhance the reliability, availability, affordability 

and quality of water in this area of the region. RWA and its 

members have successfully implemented the American River 

Basin Conjunctive Use Program and a region-wide water efficiency program in furtherance of the goals and objectives of 

the historic Water Forum Agreement.

The Sacramento Water Forum has developed a Water Forum 

Agreement containing two, equal objectives: 1) provide reliable 

and safe water for the region’s economic health and planned 

development through 2030; and 2) preserve the fishery, wildlife, 

recreational 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 and driest years to help make up 

the decreased American River diversions in those years.

The Sacramento Valley Water Quality Coalition (SVWQC) was 

formed in 2002 to enhance and improve water quality in the 

Sacramento River watershed (Sacramento River Basin, Region 

5a), while sustaining the economic viability of agriculture, functional values of managed wetlands and sources of safe drinking 

water. This group is comprised of more than 200 agricultural 

and wetlands interests that have joined with local governments 

throughout the region to improve water quality for Northern 

California farms, cities and the environment.

In response to the Central Valley Regional Water Quality Control 

Board’s recent decisions to revise agricultural water discharge 

waivers, the SVWQC developed and submitted its Regional 

Plan for Action to both the SWRCB and the Regional Water 

Quality Control Board in June 2003. This plan was submitted 

as the SVWQC’s General Report with its Notice of Intent (NOI) 

to meet the newly adopted water quality regulations. On Feb. 

10, 2004, the Regional Board issued a Notice of Applicability 

(NOA) to the SVWQC verifying the NOI. As the next step to 

implement this SVWQC Plan and to meet the Regional Board’s 

regulations, two documents were prepared and submitted on 

April 1, 2004, a Watershed Evaluation Report (WER) and 

a Monitoring and Reporting Program Plan (MRP). When 

approved by the RWQCB, these documents are intended to 

become the foundation for a rational, phased water quality 

management program. 

Changes in Water 

Demands for 2030 Scenarios

To illustrate the general magnitude of future changes in urban, 

agricultural, and environmental water demands, DWR prepared 

preliminary estimates of average-year water demands for each 

of the three example 2030 scenarios. As described in Chapter 

3 of Volume 1, these three future scenarios are identified as 

Current Trends, Less Resource Intensive, and More Resource 

Intensive. The Volume 4 Reference Guide includes a description 

of the methods and assumptions used to produce these estimates 

in “Analytical-based Scenario Water Demand Estimation.”

EE-RM-PET-100 C0MMENT 01A
Chapter 6 Sacramento River Hydrologic Region 6 15

California Water Plan Update 2005

Scenario demand estimates were made individually for the 

urban, agricultural, and environmental sectors for each of 

the 10 California hydrologic regions. DWR staff assigned 

a unique set of input values for each scenario to reflect the 

qualitative narrative descriptions and scenario factors in Table 

4-1 of Volume 1.

As previously stated, these projections are preliminary estimates of plausible future demands, which were developed 

without consideration of water supplies and delivery capabilities. The complex modeling necessary to complete a full 

analysis of the three described scenarios will be undertaken 

in the next CWP process.

Regional Planning and Coordination

Regional coordination of water resource issues and planning 

in the Sacramento River region is just beginning and will 

initially focus on fostering regional cooperation and helping 

regional interests develop programs that are mutually beneficial to the various stakeholders. Efforts will be made to assist 

the stakeholders by increasing communication between groups 

in the region and between the region and CBDA programs. 

CBDA staff and associated federal, State and local agencies 

will work closely with Sacramento Valley stakeholders, including those mentioned in preceding paragraphs as well as local 

elected officials, water district elected officials and staff, public 

agencies, watershed groups, environmental activists and other 

interested members of the public. The goal will be to assist 

regional efforts in the development of regional planning. This 

strategy will allow local stakeholders to have a voice in activities 

supported by CBDA through funding in the region. It will also 

outline how the region will coordinate these activities with other 

regions throughout the Bay-Delta solution area. 

Several northern California counties have also sought and 

obtained grant funding through the AB 303 program, and 

formed working partnerships to help them develop regional 

groundwater monitoring. AB 303 provides up to $250,000 

per project for groundwater monitoring activities, including 

the drilling of monitoring wells. Both Butte and Tehama County 

have completed an inventory/analysis of their water resources 

to assist them in future water planning. Lake County recently 

applied for funding under AB 303 to do the same. Butte, 

Glenn, Plumas, Sutter, Shasta, Tehama and Sacramento counties have all moved forward with the development of integrated 

groundwater management plans. Glenn, Tehama and Butte 

counties have obtained funding to increase their groundwater 

monitoring activities through AB 303 grant funding. Several 

other entities, such as Anderson-Cottonwood Irrigation District, 

Deer Creek Irrigation District, Glenn-Colusa Irrigation District, 

Western Canal Water District and Maxwell Irrigation District 

have all augmented their groundwater monitoring activities 

in the region as well. Other counties, some non-profit groups, 

and Resource Conservation Districts (RCDs) in the region 

have also received funding for major ecosystem restoration 

and conservation programs through the CBDA program. 

Water Portfolios for Water 

Years 1998, 2000, and 2001

Tables 6-3 and 6-4 present actual information about the water 

supplies and uses for the Sacramento River Hydrologic Region. 

Water year 1998 was wet for this region, with annual precipitation at 168 percent of normal, while the statewide annual precipitation was 171 percent of average. 2000 represents nearly 

normal hydrologic conditions with annual precipitation at 105 

percent of average for the Sacramento River region, and 2001 

reflected dryer water year conditions with annual precipitation 

at 67 percent of average. For comparison, statewide average 

precipitation in 2001 was 72 percent of normal. Table 6-3 

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. Water portfolio information 

is included in Table 6-4 and companion water portfolio flow 

diagram figures 6-5 and 6-6 provided more detailed information about how the available water supplies are distributed and 

used throughout this region.

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 6-4. Because much of the Sacramento River region is devoted to agricultural activities, a large 

component of the developed water is supplied to agricultural 

purposes. Dedicated environmental water use is also a large 

component of the developed water supply, primarily because the 

required Sacramento – San Joaquin Delta outflow is accounted 

for in this region. Table 6-4 also provides detailed information 

about the sources of the developed water supplies, which are 

primarily from surface water systems of the Sacramento River 

and its tributaries. The use of available groundwater supplies 

is also a significant resource to this region.

Selected References

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

Water Resources Control Board 

Bulletin 118 (Draft), California’s Groundwater, Update 

2003, Department of Water Resources 

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

6 16 Volume 3 Regional Reports 

California Department of Fish and Game (CDFG). 2001. 

Spring-run 

Chinook salmon annual report for the Fish and Game Commission. 

Hanak, Ellen 2003, Who Should be Allowed to Sell Water in 

California? Third-Party Issues and the Water Market, Public 

Policy Institute of California 

Kelley, Robert 1998 Battling the Inland Sea, University of 

California Press, Berkeley 

Nonpoint Source Program Strategy and Implementation Plan, 

1998-2013, State Water Resources Control Board, California 

Coastal Commission, January 2000 

Smith, F. 1980. A short review of the status of riparian forests 

in California. Pages 1-2 in: A. Sands (Editor). Riparian 

Forests in California. University of California Press, Berkeley, CA. 

Strategic Plan, State Water Resources Control Board, Regional 

Water Quality Control Boards, November 15, 2001 

USDA Forest Service Web site at 

www.fs.fed.us/recreation/map/state_list.shtml#California 

Water Quality Control Plan, RegionalWater Quality Control Board

Watershed Management Initiative Chapter, Regional 

EE-RM-PET-100 C0MMENT 01A
Chapter 6 Sacramento River Hydrologic Region 6 17

California Water Plan Update 2005

Water Portfolios

Sacramento River Hydrologic Region

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Chapter 6 Sacramento River Hydrologic Region 6 18

California Water Plan Update 2005

Table 6-4 Sacramento River region water portfolio (TAF) 

 ID Sacramento River Sacramento River Sacramento River

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 89,500.1 57,105.9 35,894.8

 6a Runoff - Natural 

 b Runoff - Incidental 

 7 Total Groundwater Natural Recharge 

 8 Groundwater Subsurface Inflow N/A

 9 Local Deliveries 13,939.5 12,204.8 8,843.0

 10 Local Imports 9.7 10.4 8.5

 11a Central Valley Project :: Base Deliveries 1,572.3 1,912.9 2,002.0

 b Central Valley Project :: Project Deliveries 418.4 553.8 495.3

 12 Other Federal Deliveries 198.0 228.3 239.5

 13 State Water Project Deliveries 14.9 14.9 19.6

 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 3,699.6 3,759.8 3,747.5

 16 Environmental Water Account Releases 0 264 242

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

 b Conveyance Return Flows to Developed Supply - Ag 60.0 44.5 45.4

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

 18a Conveyance Seepage - Urban - - -

 b Conveyance Seepage - Ag 208.1 273.3 271.8

 c Conveyance Seepage - Managed Wetlands 23.8 24.5 13.4

 19a Recycled Water - Agriculture - - -

 b Recycled Water - Urban - - -

 c Recycled Water - Groundwater - - -

 20a Return Flow to Developed Supply - Ag 996.7 1,211.2 955.2

 b Return Flow to Developed Supply - Wetlands 4.0 4.2 4.4

 c Return Flow to Developed Supply - Urban 2.6 2.6 2.6

 21a Deep Percolation of Applied Water - Ag 179.3 299.8 320.3

 b Deep Percolation of Applied Water - Wetlands 8.3 11.6 12.3

 c Deep Percolation of Applied Water - Urban 80.0 91.6 91.4

 22a Reuse of Return Flows within Region - Ag 367.6 569.2 446.1

 b Reuse of Return Flows within Region - Wetlands, Instream, W&S 4,964.2 4,442.0 3,752.8

 24a Return Flow for Delta Outflow - Ag - - 227.9

 b Return Flow for Delta Outflow - Wetlands, Instream, W&S 1,564.2 1,413.2 965.0

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

 25 Direct Diversions 

 26 Surface Water in Storage - Beg of Yr 9,727.2 11,603.3 10,502.6

 27 Groundwater Extractions - Banked - - -

 28 Groundwater Extractions - Adjudicated - - -

 29 Groundwater Extractions - Unadjudicated 1,854.7 2,815.2 2,926.9

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

 30 Surface Water Storage - End of Yr 12,479.2 10,502.6 8,090.8

 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 320.7 331.5 326.1

 b Evaporation from Reservoirs 700.7 798.5 728.9

 36 Ag Effective Precipitation on Irrigated Lands 1358 1057.5 1056.6

 37 Agricultural Water Use 5,841.2 7,927.1 7,781.7

 38 Managed Wetlands Water Use 398.3 429.5 445.7

 39a Urban Residential Use - Single Family - Interior 120.0 136.1 139.8

 b Urban Residential Use - Single Family - Exterior 224.3 267.9 273.0

 c Urban Residential Use - Multi-family - Interior 71.5 87.2 89.4

 d Urban Residential Use - Multi-family - Exterior 19.5 23.8 24.3

 40 Urban Commercial Use 113.1 140.4 137.5

 41 Urban Industrial Use 77.3 84.2 84.5

 42 Urban Large Landscape 91.8 111.2 120.1

 43 Urban Energy Production - 0.3 0.1

 44 Instream Flow 586.3 600.2 614.1

 45 Required Delta Outflow 9505 7231.6 4486.2

 46 Wild and Scenic Rivers 947.7 782.8 320.5

 47a Evapotranspiration of Applied Water - Ag 3677.9 4983.2 4908.4

 b Evapotranspiration of Applied Water - Managed Wetlands 127.5 169.7 162.9

 c Evapotranspiration of Applied Water - Urban 313.2 378.8 384.4

 48 Evaporation and Evapotranspiration from Urban Wastewater 0.2 0.1 0.2

 49 Return Flows Evaporation and Evapotranspiration - Ag 122 173.4 174.2

 50 Urban Waste Water Produced 253 299.7 312.6

 51a Conveyance Evaporation and Evapotranspiration - Urban 4.9 4.3 4.3

 b Conveyance Evaporation and Evapotranspiration - Ag 40.6 61.5 59.9

 c Conveyance Evaporation and Evapotranspiration - Managed Wetlands 11.7 16.3 15.5

 d Conveyance Outflow to Mexico 

 52a Return Flows to Salt Sink - Ag 637 869.5 931.5

 b Return Flows to Salt Sink - Urban 314.3 370.4 381.2

 c Return Flows to Salt Sink - Wetlands 179.24 164.1 169.3

 53 Remaining Natural Runoff - Flows to Salt Sink 33,981.9 10,924.2 2,457.9

 54a Outflow to Nevada - - -

 b Outflow to Oregon - - -

 c Outflow to Mexico - - -

 55 Regional Imports 901.1 1,150.3 700.4

 56 Regional Exports 5193.6 6250.8 4657.1

 59 Groundwater Net Change in Storage 739.9 -150.8 -1,147.6

 60 Surface Water Net Change in Storage 2,752.0 -1,100.7 -2,411.8

 61 Surface Water Total Available Storage 16,145.6 16,145.6 16,145.6

 

 Inflows Outflows Green number signifies included in summary boxes

EE-RM-PET-100 C0MMENT 01A
Figure 6-5 Sacramento 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 6-4, 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 6 Sacramento River Region 6 19

California Water Plan Update 2005

EE-RM-PET-100 C0MMENT 01A
SUMMARY

OUTFLOWS

INFLOWS

Figure 6-6 Sacramento River region - schematic flow diagram 

In schematic of Table 6-4, 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:

CVP BASE 

DELIVERIES: CVP 

PROJECT

DELIVERIES:

OTHER FEDERAL 

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:

REQUIRED DELTA OUTFLOW: 

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:

ENVIRONMENTAL 

WATER ACCOUNT 

RELEASES:

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:

ENVIRONMENTAL WATER 

ACCOUNT RELEASES: 

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

6 20 Chapter 6 Sacramento River Region Volume 3 Regional Reports

California Water Plan Update 2005

EE-RM-PET-100 C0MMENT 01A
Chapter 7 San Joaquin River Hydrologic Region 

Volume 3 

EE-RM-PET-100 C0MMENT 01A
Chapter 7 San Joaquin River Hydrologic Region 7 i

California Water Plan Update 2005

Chapter 7 San Joaquin River Hydrologic Region

Contents

Chapter 7 San Joaquin River Hydrologic Region ........................................................................................................7-1

Setting ................................ 7-1

Climate ............................... 7-1

Population .......................... 7-1

Land Use ............................ 7-2

Water Supply and Use ......... 7-5

State of the Region .............. 7-8

 Challenges ...................... 7-8

 Accomplishments .......... 7-10

Relationship with Other Regions .........................................................................................................................7-11

Looking to the Future ......... 7-12

Regional Planning ............. 7-12

Water Portfolios for Water Years 1998, 2000, and 2001 .....................................................................................7-12

 Water Year 1998 .......... 7-12

 Water Year 2000 .......... 7-13

 Water Year 2001 .......... 7-14

Selected References ........... 7-14

Figures

Figure 7-1 San Joaquin River Hydrologic Region (map) .............................................................................................7-ii

Figure 7-2 San Joaquin River Hydrologic Region population ......................................................................................7-3

Figure 7-3 San Joaquin River region water balance for water years 1998, 2000, 2001 (2 bar charts) ..........................7-6

Figure 7-4 San Joaquin River region - illustrated water flow diagram ........................................................................7-17

Figure 7-5 San Joaquin River region - schematic flow diagram .................................................................................7-18

Tables

Table 7-1 San Joaquin River Hydrologic Region water balance summary .....................................................................7-4

Table 7-2 San Joaquin River Hydrologic Region water use and distribution of dedicated supplies ..................................7-7

Table 7-3 San Joaquin River region water portfolios ................................................................................................7-16

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Volume 3 Regional Reports

California Water Plan Update 2005

Some Statistics

 Area -15,214 square miles (9.6% of State)

 Average annual precipitation - 26.3 inches

 Year 2000 population - 1,751,010

 2030 population projection - 3,385,885

 Total reservoir storage capacity -11,477 TAF

 2000 irrigated crop area - 2,050,400 acres

.

.

.

.

.

.

Flow in TAF

1998

83

2000

113

2001

152

Central Coast Region

San Felipe Unit (CVP)

Flow in TAF

1998

40

2000

30

2001

23

Sacramento River Region

Sly Park

Flow in TAF

1998

764

2000

1,212

2001

735

Tulare Lake Region

Friant-Kern Canal (CVP)

Flow in TAF

1998

915

2000

0

2001

0

San Joaquin River Region

Kings River

Flow in TAF

1998

 8,491

2000

2,846

2001

1,732

San Joaquin River Region

Flow in TAF

1998

597

2000

629

2001

625

San Francisco Bay Region

Contra Costa Canal

Mokelumne Aqueduct

Hetch Hetchy Aqueduct

South Bay Aqueduct

Flow in TAF

1998

5,119

2000

6,174

2001

4,572

Sacramento River Region

Delta Mendota Canal (CVP)

Folsom South Canal

California Aqueduct (SWP)

Flow in TAF

1998

2,952

2000

4,414

2001

2,961

Tulare Lake Region

California Aqueduct (SWP)

San Luis Unit (CVP)

Delta-Mendota Pool

ALPINE

MARIPOSA

MERCED

MADERA

FRESNO

CALAVERAS

SAN

JOAQUIN

CONTRA

COSTA

TUOLUMNE

STANISLAUS

AMADOR

Figure 7-1 San Joaquin River Hydrologic Region

The San Joaquin River Hydrologic Region includes all of the San Joaquin River drainage area extending from Madera County in the south to the 

Delta in the north. Arrows indicate annual flows entering and leaving the region for water years 1998, 2000, and 2001. 

EE-RM-PET-100 C0MMENT 01A
Chapter 7 San Joaquin River Hydrologic Region 7 1

California Water Plan Update 2005

Chapter 7 San Joaquin River Hydrologic Region

Climate

Because the San Joaquin Valley is isolated by mountains 

from the marine effects of coastal California, the maximum 

average daily temperature in the valley reaches a high of 

101 degrees during late July. Daily temperatures during the 

warmest months usually range between 76 and 115 degrees. 

The northern part of this hydrologic region does benefit from 

Delta breezes during the hot summer periods, which are winds 

produced by the strong temperature difference between the 

hot valley regions and the cooler coastal climate of the San 

Francisco Bay area. Winter temperatures in the valley floor 

regions are usually mild, but during infrequent cold spells 

minimum readings occasionally drop below freezing. Heavy 

frost occurs in most fall and winter seasons, typically between 

the end of November and early March. 

The San Joaquin River hydrologic region experiences a 

wide range of precipitation, which varies from low rainfall 

amounts on the valley floor to extensive amounts of snow 

in the higher elevations of the Sierra Nevada. The climate 

of much of the upland area on the west side of the valley 

floor resembles that of the Sierra Nevada foothills on the 

east side. The average annual precipitation of several Sierra 

Nevada stations is about 35 inches. Snowmelt runoff from 

the mountains is the major contributor to local water supplies 

for the eastern San Joaquin Valley. The climate of the valley 

is characterized by long, hot summers and mild winters. 

Average annual precipitation ranges from about 22 inches 

near the Stockton area in the north to about 11 inches in the 

southern portion of the region and further decreases to about 

6.5 inches near the dry southwestern corner of the region. 

Population

The population of the San Joaquin River region in year 2000 

was about 1.7 million, which was about 5 percent of the state’s 

total population. Although there are 15 counties partially or 

entirely in the San Joaquin River region, most of the populaSetting

The San Joaquin River hydrologic region is in the heart of 

California and includes the northern portion of the San 

Joaquin Valley. It is bordered on the east by the Sierra 

Nevada and on the west by the coastal mountains of the 

Diablo Range. It extends from the southern boundaries of 

the Sacramento – San Joaquin Delta to include all of the 

San Joaquin River drainage area to the northern edge 

of the San Joaquin River in Madera. Roughly half of the 

Sacramento – San Joaquin Delta is within this hydrologic 

region, encompassing those portions of the Delta in Contra 

Costa, Alameda, and San Joaquin counties. The region 

extends south from just below the northeastern corner of 

Sacramento County and east to include the southern third 

of El Dorado County, almost all of Amador County, all of 

Calaveras, Mariposa, Madera, Merced, Stanislaus, and 

Tuolumne counties, and the western slope of Alpine County. 

The San Joaquin River Basin is hydrologically separated from 

the Tulare Lake Basin by a low, broad ridge that extends 

across the San Joaquin Valley between the San Joaquin 

and Kings rivers. A map and table of statistics describing 

the region are presented in Figure 7-1.

The San Joaquin River is roughly 300 miles long, which 

makes it one of the state’s longest rivers. It has an average 

unimpaired runoff of about 1.8 million acre-feet per year, 

and its eight major tributaries drain about 32,000 square 

miles of watershed lands. The headwaters of the San Joaquin 

River begin near the 14,000 foot elevation of the crest of 

the Sierra Nevada. The river runs down the western slope 

of the Sierra, and then flows northwest to the Delta where 

it meets the Sacramento River. The two rivers converge in 

the 1,153-square-mile Sacramento-San Joaquin Delta—a 

maze of channels and islands—which also receives freshwater inflow from the Cosumnes, Mokelumne and Calaveras 

rivers and other smaller streams. Historically, more than 40 

percent of the state’s annual run-off flowed to the Delta via 

the Sacramento, San Joaquin and Mokelumne rivers.

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tion and agricultural land use occurs within five counties: San 

Joaquin, Stanislaus, Merced, Contra Costa, and Madera. Of 

these, the county with the largest year 2000 population was 

San Joaquin County with 567,600 people. Stockton, its largest city, had 243,771 people. Stanislaus County, population 

567,600, was the second largest county in the region, and its 

largest city is Modesto with a population of 188,856. The county 

of Merced is the next largest with a population of 210,200; 

the city of Merced had a population of 63,800. For counties 

that are only partially within this hydrologic region, Contra 

Costa County had 145,775 residents, and Madera County 

had a year 2000 population of 127,400. Figure 7-2 provides 

a graphical depiction of the San Joaquin River region’s total 

actual population from years 1960 through year 2000, with 

projections to year 2030.

California experienced a statewide population increase of 

almost 14 percent from 1990 to 2000, and the growth rates 

in San Joaquin valley cities and counties are projected to 

exceed that trend. According to California Department of 

Finance projections, growth rates for the above five counties will range between 18 and 32 percent over the next 

10 years. The highest rate of urbanization will occur in the 

northern portion of the region. For San Joaquin County, the 

projected population will increase to 747,100 by 2010 and 

to 1,229,000 by 2030. Similarly, the projected population 

for Stanislaus County will increase to 559,100 by 2010, 

and to 744,600 by 2030. The rapid rates of growth and 

urbanization in these regions will generate significant land 

and water uses challenges for the entire San Joaquin Valley. 

Land Use

The valley portion of the San Joaquin River region consists 

primarily of highly productive farmland and the rapidly 

growing urban areas of Stockton, Tracy, Modesto, Manteca, 

and Merced. Agriculture is the major economic and land use 

activity in the San Joaquin River region. The San Joaquin 

The valley portion of the San Joaquin River region consists primarily of highly productive farmland and the rapidly growing urban areas of Stockton, Tracy, 

Modesto, Manteca, and Merced. The river runs down the western slope of the Sierra, and then flows northwest to the Delta. (DWR photo)

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Valley is recognized as one of the most important agricultural 

regions in California, with roughly 2 million acres of irrigated 

cropland and an annual agricultural output valued at more 

than $ 4.9 billion. The region has a high diversity of irrigated 

crops with about 34 percent as permanent orchard and vineyard crops and 29 percent as grains, hay, and pasture. Some 

of the other major crops include cotton, corn, tomatoes, and 

a variety of other fi eld and truck crops. In addition to agriculture, other important industries in the region include food 

processing, chemical production, lumber and wood products, 

glass, textiles, paper, machinery, fabricated metal products, 

and various other commodities. About 1.95 million acres or 

21 percent of the region’s total land area were devoted to 

irrigated agriculture in year 2000.

While the valley fl oor areas of the San Joaquin River region 

are primarily privately owned agricultural land, much of the 

Sierra Nevada is national forest. The government-owned 

public lands include the El Dorado, Stanislaus, and Sierra 

national forests and Yosemite National Park. Public lands 

amount to about one-third of the San Joaquin River region’s 

total land area. The national forest and park lands encompass 

more than 2.9 million acres; State parks and recreational 

areas and other State property account for about 80,000 

acres; and U.S. Bureau of Land Management and military 

properties occupy over 200,000 and 5,100 acres, respectively. The valley portion of the region constitutes about 3.5 

million acres, the eastern foothills and mountains total about 

5.8 million acres, and the western coastal mountains comprise 

about 900,000 acres.

Restoration of Central Valley wetlands habitat is critical to the 

preservation of many species of fi sh and wildlife in the San 

Joaquin River ecosystem. Beginning in the 1990s, agencies 

began to make progress in efforts to set aside and restore 

acreage for wetland habitat. In 1990, the San Joaquin River 

Management Program was formed to restore the river system, 

which led to completion of the San Joaquin River Management 

Plan in 1995. This plan identifi ed nearly 80 consensus-based 

actions intended to benefi t the San Joaquin River system, 

which are organized into the categories of projects, feasibility studies, and riparian habitat acquisitions. Many federal 

and State agencies now have active roles in the funding and 

implementation of wetlands habitat restoration programs, 

including the U.S. Fish and Wild Service, the California BayDelta Authority and the California Department of Fish and 

Game. One of the larger projects along the San Joaquin River 

is the restoration of 775 acres of native riparian habitat on the 

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

3,500,000

4,000,000

1960 1970 1980 1990 2000 2010 2020 2030

Figure 7-2 San Joaquin River Hydrologic Region population

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

for the San Joaquin River region.

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Water Entering the Region 

Precipitation 35,535 23,209 16,120

 Inflow from Oregon/Mexico 0 0 0

 Inflow from Colorado River 0 0 0

 Imports from Other Regions 6,034 6,174 4,572

Total 41,569 29,383 20,692

Water Leaving the Region 

Consumptive Use of Applied Water * 3,705 4,762 4,983

 (Ag, M&I, Wetlands) 

 Outflow to Oregon/Nevada/Mexico 0 0 0

 Exports to Other Regions*** 4,436 6,398 4,496

 Statutory Required Outflow to Salt Sink 0 0 0

 Additional Outflow to Salt Sink 176 196 218

 Evaporation, Evapotranspiration of Native 

 Vegetation, Groundwater Subsurface Outflows, 31,448 18,055 13,690

 Natural and Incidental Runoff, Ag Effective 

 Precipitation & Other Outflows 

Total 39,765 29,412 23,387

Storage Changes in the Region

[+] Water added to storage

 [-] Water removed from storage 

 Change in Surface Reservoir Storage 2,248 67 -1,435

 Change in Groundwater Storage ** -444 -96 -1,260

Total 1,804 -29 -2,695

 Applied Water * (compare with Consumptive Use) 6,035 7,584 7,817

*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 (174%) 2000 (113%) 2001 (79%)

Table 7-1 San Joaquin River Hydrologic Region water balance summary - TAF

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

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West Unit of the San Joaquin River National Wildlife Refuge, 

west of Modesto. About 158,000 native trees, shrubs, and 

vines will be planted to accommodate the habitat needs of 

threatened and endangered species.

The San Joaquin Valley serves as a breeding and resting 

stop along the Pacific Flyway for many species of waterfowl. 

Public wildlife refuges in the San Joaquin River region include 

the San Luis National Wildlife Refuge, which encompasses 

26,340 acres; the San Joaquin River National Wildlife 

Refuge with 2,875 acres; Merced National Wildlife Refuge 

with 8,280 acres; Los Banos Wildlife Area with 5,586 acres; 

Volta Wildlife Area with 2,891 acres; the North Grasslands 

Wildlife Area with 7,069 acres; the White Slough Wildlife 

Area with 969 acres; and the Isenberg Sandhill Crane 

Reserve at 361 acres. Toward the northern end of this region, 

the Cosumnes River Preserve is managed by the Nature 

Conservancy and has become the largest refuge area in the 

region at 36,300 acres. Additionally, there are many private duck clubs in the region that maintain wetland habitat. 

Water Supply and Use

The primary sources of surface water in the San Joaquin 

River region are the rivers that drain the western slope of the 

Sierra Nevada. These include the San Joaquin River and its 

major tributaries, the Merced, Tuolumne, Stanislaus, Calaveras, 

Mokelumne, and Cosumnes rivers. Most of these rivers drain 

large areas of high-elevation watersheds that supply snowmelt 

runoff during the late spring and early summer. Other tributaries to the San Joaquin River include the Chowchilla and Fresno 

rivers, which originate in the Sierra Nevada foothills where most 

of the runoff results directly from rainfall. 

The water balance table for the San Joaquin River hydrologic 

region (Table 7-1) summarizes all of the water supplies, uses, 

and outflows for years 1998, 2000, and 2001 and is supplemented by the detailed regional water accounting information 

in Table 7-2. As shown in Table 7-1, changes in groundwater 

storage are balanced with the available surface water each 

year to meet the regions needs. In wet years like 1998 excess 

surface water supply is added into groundwater storage, while 

in a drier year like 2001 the amount of groundwater pumped 

to meet water needs results in a net reduction of groundwater 

in storage. Table 7-3 (in large format at the end of this chapter) 

provides more specific information about the developed or 

dedicated component of water supplies for agricultural, urban 

and environmental purposes, as assembled from actual data 

for 1998, 2000 and 2001.

In 2000, an average water year, about 44 percent of the San 

Joaquin River region’s developed water supply came from local 

surface sources, 23 percent was from imported surface supplies, 

and groundwater provided about 33 percent of the water supply. 

About 26 percent of the developed supply, excluding surface 

water and groundwater reuse, was used for dedicated natural 

flows to meet instream flow requirements. Figure 7-3 and Table 

7-2 summarize all of the developed urban, agricultural and 

dedicated environmental water uses in this region for years 1998, 

2000 and 2001. 

Many surface water supply systems in the Sierra Nevada streams 

and rivers follow a similar pattern of use. Often a series of small 

reservoirs in the mountain valleys will gathers and store snowmelt 

runoff. This water is used to generate electricity as it is released 

downstream. Some diversions occur for consumptive use in local 

communities, but most flows are recaptured in larger reservoirs 

in the foothills and along the eastern edge of the valley. Most 

of these larger reservoirs were built primarily for flood control. 

However, many of them also store water for urban and agricultural purposes, and make downstream releases for fish and 

environmental needs. Irrigation canals and municipal pipelines 

divert much of the water from these reservoirs. Many of the 

small communities in the Sierra Nevada foothills receive most of 

their water from local surface supplies. The extensive network of 

canals and ditches constructed in the 1850s for hydraulic mining 

forms the basis of many of the conveyance systems. In addition 

to surface water, many of these foothill and mountain communities pump groundwater from hard rock wells and old mines to 

augment their supplies, especially during droughts. Groundwater 

supplies in the foothills are limited, but this is the primary source of 

water for individual residents who are not connected to municipal 

water systems.

On the valley floor, many agricultural and municipal users 

receive their water supply from large irrigation districts, such as 

the Modesto, Merced, Oakdale, South San Joaquin and Turlock 

Irrigation Districts. Most of this region’s imported surface water 

supplies are delivered by the federal Central Valley Project, 

which average about 1.9 million acre-feet per year. In addition, 

Oak Flat Water District receives about 4,500 acre-feet per year 

from the State Water Project.

Most of the surface water in the upper San Joaquin River is 

stored and diverted at Friant Dam, and is then conveyed north 

through the Madera Canal and south through the Friant-Kern 

Canal. Average annual diversions from the San Joaquin River 

through the Friant-Kern and Madera Canals total about 1.5 

million acre-feet per year. Releases from Friant Dam to the San 

Joaquin River are generally limited to those required to satisfy 

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Figure 7-3 San Joaquin River region water balance for water years 1998, 2000, 2001

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

1998 2000 2001

Thousand Acre-Feet

Wild & Scenic

R.

Instream Flow

Managed

Wetlands

Irrigated

Agriculture

Urban

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

1998 2000 2001

Thousand Acre-Feet

Reuse &

Recycle

Ground Water

State Project

Federal

Projects

Local Projects

Dedicated Water Supplies

Applied Water Uses

Three years show a marked change in the amount and relative proportions of water delivered to San Joaquin 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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 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 7-2 San Joaquin River Hydrologic Region water use and distribution of dedicated supplies (TAF)

DEDICATED WATER SUPPLIES

Urban

Large Landscape 30.2 32.9 35.5 

Commercial 34.5 37.6 39.6 

Industrial 86.3 89.4 90.1 

Energy Production 0.0 0.0 0.0

Residential - Interior 176.2 191.5 199.7 

Residential - Exterior 214.0 231.3 243.7 

Evapotranspiration of Applied Water 191.0 191.0 206.6 206.6 218.4 218.4

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

Outflow 142.3 142.3 150.0 150.0 160.8 160.8

Conveyance Applied Water 19.2 17.5 20.5 

Conveyance Evaporation & ETAW 12.6 12.6 12.0 12.0 13.6 13.6

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

Conveyance Outflow 6.6 6.6 5.5 5.5 6.9 6.9

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 560.4 352.5 352.5 600.2 374.1 374.1 629.1 399.7 399.7

Agriculture

On-Farm Applied Water 4,823.5 6,215.8 6,533.0 

Evapotranspiration of Applied Water 3,408.1 3,408.1 4,406.0 4,406.0 4,627.8 4,627.8

E&ET and Deep Perc to Salt Sink 74.4 74.4 11.6 11.6 14.3 14.3

Outflow 1,183.4 4.0 954.1 5.0 980.8 12.4

Conveyance Applied Water 379.0 461.5 449.1 

Conveyance Evaporation & ETAW 207.7 207.7 248.8 248.8 245.3 245.3

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

Conveyance Outflow 22.9 22.9 35.4 35.4 37.9 37.9

GW Recharge Applied Water 255.5 340.5 260.9 

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Agricultural Use 5,458.0 4,896.5 3,717.1 7,017.8 5,655.9 4,706.8 7,243.0 5,906.1 4,937.7

 Environmental

Instream

 Applied Water 1,528.9 2,098.5 1,424.4 

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Wild & Scenic

 Applied Water 3,661.1 2,093.8 1,091.0 

 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 414.5 444.8 414.7 

 Evapotranspiration of Applied Water 105.9 105.9 149.7 149.7 136.6 136.6

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

 Outflow 134.2 1.6 128.3 1.6 135.7 1.5

 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 414.5 240.1 107.5 444.8 278.0 151.3 414.7 272.3 138.1

 Total Environmental Use 5,604.5 240.1 107.5 4,637.1 278.0 151.3 2,930.1 272.3 138.1

 TOTAL USE AND OUTFLOW 11,622.9 5,489.1 4,177.1 12,255.1 6,308.0 5,232.2 10,802.2 6,578.1 5,475.5

 

Surface Water

 Local Deliveries 3,229.8 3,229.8 2,321.5 3,540.7 3,540.7 2,837.2 3,548.5 3,548.5 2,812.5

 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 1,367.0 1,367.0 982.6 1,803.5 1,803.5 1,445.2 1,666.5 1,666.5 1,320.9

 Other Federal Deliveries 64.3 64.3 46.2 65.8 65.8 52.7 97.6 97.6 77.4

 SWP Deliveries 4.3 4.3 3.1 4.6 4.6 3.7 3.5 3.5 2.8

 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 821.8 821.8 821.8 891.5 891.5 891.5 1,260.1 1,260.1 1,260.1

 Deep Percolation of Surface and GW 943.8 1,754.8 1,708.5 

Reuse/Recycle

 Reuse Surface Water 5,190.0 4,192.3 2,515.6 

 Recycled Water 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9 1.9

 TOTAL SUPPLIES 11,622.9 5,489.1 4,177.1 12,255.1 6,308.0 5,232.2 10,802.2 6,578.1 5,475.5

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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downstream water rights, above Gravelly Ford, and for flood 

control. In the vicinity of Gravelly Ford, a high amount of subsurface percolation into the groundwater basin occurs because 

the river bed is primarily sand and gravel. As a result of the 

operation of Friant Dam, there are seldom any surface flows in 

the middle reaches of the San Joaquin River until it is joined by 

the Merced River and other major downstream tributaries Agricultural and municipal return flows into the river also contribute 

to the surface flow of the lower San Joaquin River. 

The tributaries of the San Joaquin River provide the region with 

high-quality water that constitutes most of the surface water supplies for local uses. Much of this water is regulated by reservoirs 

and used on the east side of the San Joaquin Valley. Significant 

amounts of water are also diverted west across the valley to 

the San Francisco Bay Area via the Mokelumne Aqueduct, 

which supplies some for the urban water demands of East Bay 

Municipal Utility District, and the Hetch Hetchy Aqueduct, which 

supplies urban water to San Francisco and several other Bay 

Area cities. The average annual water diversions from the Mokelumne and Tuolumne rivers for export from the basin include 

245,000 acre-feet through the Mokelumne Aqueduct and 

267,000 acre-feet through the Hetch-Hetchy Aqueduct. Major 

dams on the tributary streams include Pardee and Camanche 

dams on the Mokelumne River, New Melones, Donnells, and 

Beardsley dams on the Stanislaus River, O’Shaunessy and New 

Don Pedro dams on the Tuolumne River, and Exchequer Dam 

on the Merced River.

In 2000, an average water year, agriculture accounted for about 

57 percent of the San Joaquin River region’s total developed 

water use, while urban water use was about 5 percent and 

environmental water use for dedicated purposes was 38 percent. 

Regional average urban per capita water use was about 304 

gpcd. Imported water supplies to this region from the Central 

Valley Project, the State Water Project, and other federal deliveries, amounted to 1,874,000 acre feet. Environmental demands, 

including for refuges, instream requirements, and wild and scenic 

flows, totaled 4,637,100 acre feet (see Figure 7-3 and Table 7-2)

State of the Region

Challenges

Historically, the surface water originating from Sierra Nevada 

rivers has proven to be a dependable supply of high quality 

water, but it meets only half of the region’s total water requirements. Imported surface water and groundwater-pumping 

make up the difference. Because the region relies on imported 

surface water from other regions, there is growing concern 

over the long-term availability of external supplies. Additionally, proposals to restore fisheries on the San Joaquin River 

through larger releases of water from Friant Dam have resulted 

in growing concerns over the long-term stability of the existing 

surface water supplies. 

One of the major challenges facing the San Joaquin River 

hydrologic region is restoring the ecosystem along the San 

Joaquin River below Friant Dam while maintaining water supply 

reliability for other purposes. The river’s historic salmon populations upstream of the Merced River were eradicated after the 

river water was diverted with the construction of Friant Dam 

in the 1940s. In August 2004, a federal judge ruled that the 

U.S. Bureau of Reclamation violated California State Fish and 

Game Code 5937 by not providing enough water downstream 

to sustain fish populations. Efforts to restore some surface flows 

to the San Joaquin River would help restore the ecosystem and 

improve the reliability and quality of water available to downstream farmers in the Delta. The litigation of these issues is not 

resolved, and the development of acceptable solutions will be 

challenging because of the potential to adversely impact water 

supplies to the Friant Water Users Authority.

Another major challenge is maintaining the integrity of the 

Sacramento – San Joaquin Delta levee system. More than 1,000 

miles of levees protect Delta islands, and these lands are commonly 10 to 15 feet below sea level. The potential failure of a 

levee could occur as the result of major earthquakes or floods, or 

because of gradual deterioration and inadequate maintenance. 

Composed largely of peat soils, many islands are vulnerable to 

seepage and subsidence, which contributes to settlement and 

the risk of levee failure. Protection and restoration of the Delta 

levees is one of the key objectives of the CALFED Bay-Delta 

program as discussed in Chapter 12 of this volume.

Groundwater pumping is a major source of water supply for 

the San Joaquin River region, and it continues to increase in 

response to the growing urban and agricultural demands. Over 

the long-term, groundwater extraction cannot continue to meet 

all of the current and projected water demands without causing negative impacts on the groundwater basins. The primary 

impact is groundwater overdraft, a condition where the average 

long-term amount of water pumped out of the basin exceeds 

the amount of water recharged or naturally replenished into 

the groundwater basin. A serious consequence of long-term 

groundwater overdraft is land subsidence and compaction of the 

aquifer, with a resulting drop in the natural land surface. Land 

subsidence results in a reduction of aquifer storage space and 

may damage public facilities such as canals, utilities, pipelines, 

and roads. Pumping depressions from wells have caused poor 

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California Water Plan Update 2005

quality water from the Delta to migrate underground toward 

eastern San Joaquin County. Several municipal wells in western 

Stockton have been abandoned because of the resulting decline 

in groundwater quality. Several existing and proposed measures 

can help counteract potentially serious overdraft conditions in 

some areas of the region, such as groundwater spreading basins 

and recharge programs. In some situations, the over-irrigation 

of crops with extra surface water in wet years and seepage from 

unlined canal systems can aid in groundwater recharge. 

The major water quality problems of the San Joaquin River region 

are a result of many factors, including depleted freshwater flows, 

municipal and industrial wastewater discharges, salt loads from 

agricultural drainage and runoff, and other pollutants associated 

with long-term agricultural irrigation and production, including 

nutrients, selenium, boron, and organophosphate pesticides. The 

entire Central Valley, which includes the San Joaquin River, as 

well as the Sacramento River and Tulare Lake basins, has 40 

water bodies that are impaired due to agriculture, including 

800 miles of waterways, and 40,000 acres in the Delta. In its 

most recent triennial review of its basin plan, the Central Valley 

Regional Water Quality Control Board identified high priority 

problems as salinity and boron discharges to the San Joaquin 

River, low dissolved oxygen problems in the lower San Joaquin 

River, control of organophosphorous pesticides, and the need 

for stronger policies to protect Delta drinking water quality.

High salinity is a problem in the San Joaquin River basin because 

of the greatly altered flows of the river, most of which is diverted 

from its natural course at Friant Dam. In addition, imported irrigation water from State and federal projects annually transport 

more than a half million tons of salts into the west side of the 

San Joaquin River region. Water released from New Melones 

Reservoir on the Stanislaus River is used to help meet the salinity and dissolved oxygen requirements at Vernalis on the lower 

San Joaquin River. Agricultural drainage and discharges from 

managed wetlands are already regulated in the 370,000 acre 

Grasslands watershed, which contributes high levels of salts, 

selenium, boron, and nutrients to Mud and Salt Sloughs. These 

sloughs are some of the primary contributors of selenium to the 

San Joaquin River. Dairies, stockyards, and poultry ranches 

are also a concern in the region because they generate waste 

products including pathogens, nutrients, salts, and emerging 

contaminants that enter the waterways. Some dairies and 

other agricultural operations are already subject to regulatory 

review. Water releases from managed wetlands, part of State 

and federal wildlife refuge system, also can discharge salts and 

nutrients. The erosion of westside streams is the primary source 

of organochlorine pesticides in the San Joaquin River. 

Migrating and spawning salmonids face high temperatures in 

the Stanislaus, Tuolumne, and Merced rivers downstream from 

dams during certain times of the year, depending on hydrologic 

and water supply conditions. Contamination of fish is also a 

concern in these three rivers as well as the main stem of the San 

Joaquin River. For example, the Central Valley Regional Water 

Quality Control Board cites one study of a 43-mile reach of the 

San Joaquin River (between the confluences with the Merced 

and the Stanislaus rivers) to be toxic to fish about half the time. 

In the lower San Joaquin River, low dissolved oxygen levels in 

the Stockton Deepwater Ship Channel are attributable to warm 

temperatures, low flows, nutrients, and channel configuration. 

This portion of the river with low dissolved oxygen is potentially 

a barrier to fall-run Chinook salmon migrating upstream to the 

Merced, Tuolumne, and Stanislaus rivers to spawn.

Groundwater quality throughout the region is generally adequate for most urban and agricultural uses. However there are 

roughly 1,000 square miles overlying groundwater along the 

western edge of the valley floor that is contaminated with high 

salinity from naturally occurring marine sediments of the Coast 

Range. The salinity of groundwater in the region can increase 

as a result of agricultural practices in which the evapotranspiration of crops and wetlands leaves behind the majority of salts 

contained in the imported water. In addition, high water-table 

conditions underlying marginal lands along the west side of 

the San Joaquin River region contribute to subsurface drainage problems. In order to maintain a salt balance in the root 

zone, much of this salt is leached into the groundwater. For 

aesthetic purposes, such as taste, Department of Health Services 

regulations recommend that drinking water contain less than 

500 mg/L of salinity as measured by total dissolved solids. For 

agricultural uses, water with a salinity of less than 450 mg/L 

total dissolved solids is generally considered acceptable. While 

the above Department of Health Services recommendation is 

adopted by reference into the Regional Water Quality Control 

Board’s basin plan to protect domestic use of groundwater, the 

basin plan contains no numerical salinity objectives for protection of agricultural beneficial uses.

Nitrates that are generated from the disposal of human and 

animal waste products or from the inefficient application of 

fertilizer and irrigation water have contaminated 200 square 

miles of groundwater in the region and do threaten some 

domestic water supplies. Pesticides have contaminated 500 

square miles of groundwater basins, primarily in agricultural 

areas on the east side of the San Joaquin Valley, where soil 

permeability is higher and the depth to groundwater is more 

shallow. The entire Central Valley is home to about 500,000 

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7 10 Volume 3 Regional Reports

single-family residential septic systems, each with leach fields 

that discharge to the groundwater. The most notable agricultural contaminant detected in groundwater samples from this 

region is dibromochloropropane, DBCP, which is a banned 

nematocide that has been found mostly along the State Route 

99 highway corridor. There are also roughly 200 square miles 

of groundwater basins that are contaminated by naturally 

occurring selenium. 

As of January 1, 2003, the passage of Senate Bill 390 ended 

the previously used conditional waivers for waste discharge 

requirements for 23 types of waste discharges, including irrigated agriculture and logging. A previously submitted petition 

from three environmental groups had requested that these waivers be rescinded because of concerns about pesticides in discharges. Unlike the federal Clean Water Act, which specifically 

exempts agricultural discharges from regulation, California’s 

Porter-Cologne Water Quality Control Act allows a waiver 

from regulation only if it does not conflict with the public interest. The Central Valley Regional Water Quality Control Board 

granted such a waiver to irrigated lands in 1982, exempting the 

agricultural discharges using the waste discharge requirements 

process. That waiver did have conditions imposed, but because 

of a lack of staff resources, the regional board did not monitor or 

review compliance. Senate Bill 390 still allows the continuation 

of waivers, but only when specifically renewed by the regional 

board and when subject to a five-year review. 

In relation to other regions of the State, water discharges from 

irrigated lands have their greatest impact to water quality in the 

Central Valley, which covers 40 percent of California’s land area 

and contains 7-million irrigated acres and more than 25,000 

individual agricultural dischargers. As an interim measure in 

July 2003, the Central Valley regional board adopted two types 

of conditional waivers for such discharges into surface water, 

one for “coalition groups” and the other for individuals. These 

waivers applied to surface runoff or tailwater, excess water 

diverted but not used, subsurface drainage to lower the water 

table for growing, and storm water runoff. Additional commodity-specific and low-threat waivers are also under consideration. 

The requirements contained in these new waivers include water 

quality monitoring and implementation of best management 

practices or management measures to control pollution. This 

new waiver program, which focuses on data collection, monitoring for toxicity, and drinking water constituents will expire on 

December 31, 2005. Subsequently, a 10-year implementation 

program is envisioned that would fully protect the state’s waters 

from quality problems associated with discharges from irrigated 

lands in order to meet water quality objectives.

Although existing agricultural land use practices affect water 

quality now, the expanding urbanization of Central Valley 

cities will generate new and different water quality problems in 

the future. In anticipation of these problems, the Central Valley 

regional board has recently started requiring many municipal 

wastewater discharge systems to construct and operate more 

costly tertiary wastewater treatment facilities.

Accomplishments

The Reclamation Board of California and the U.S. Army Corps 

of Engineers in coordination with a broad array of stakeholders, have recently developed a new Comprehensive Plan for the 

flood management system of the Sacramento and San Joaquin 

River regions. Rather than a physical plan for flood facilities and 

systems, this Comprehensive Plan recommends an approach to 

design and implement projects in the future in ways that would 

reduce damage from flooding and restore the ecosystem.

The Millerton Area Watershed Coalition is conducting a comprehensive assessment of the San Joaquin River watershed 

and will evaluate activities that need to be changed to better 

protect and care for the watershed. The information and 

recommendations from this study will be developed into an 

outreach program to promote the protection and enhancement 

of the watershed, including the economic and environmental 

well-being of the communities within it. This comprehensive 

assessment is sponsored by the CALFED Watershed Program 

and coordinated through the U.S. Bureau of Reclamation.

The San Joaquin River Group Authority was formed in the 

1990s in response to the development of the Sacramento 

– San Joaquin Bay Delta Water Quality Control Plan by 

the State Water Resources Control Board. The water quality 

control plan was adopted in 1995 and included significant 

water quality and flow standards for the lower San Joaquin 

River. The goals of the authority are to investigate fishery and 

water quality issues on the San Joaquin River and develop 

solutions that will protect the salmon fishery and improve 

water quality. To respond to water quality issues, the regional 

board is studying agricultural discharge quality controls, and 

may consider the use of agriculture waivers at a watershed 

level. Additional water quality monitoring will be necessary to 

address the various water quality problems on the Lower San 

Joaquin River. Landowners will have the choice of participating 

in water quality monitoring and improvement programs on 

a watershed level or on an individual basis. The watershed 

approach can be used to identify and address “hot spots” by 

working directly with individual landowners or encouraging 

individuals to work together to find solutions.

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The San Joaquin River Group Authority also led the development of the Vernalis Adaptive Management Plan as a 10-year 

test program designed to study methods to improve salmon 

smolt survival in the lower San Joaquin River. Starting in the 

year 2000, the Vernalis plan has coordinated the release of 

water from upstream reservoirs each spring to generate a 

calculated pulse flow down the lower river to help salmon 

smolts migrate to San Francisco Bay and the ocean. The timing 

and duration of this pulse flow is coordinated with reduced 

State Water Project and Central Valley Project Delta export 

pumping in order to improve Delta flow patterns to guide 

the salmon smolts to the ocean. The plan’s technical group 

coordinates extensively with several local and government 

agencies to oversee the successful test flow each year, which 

include real-time facility operations and monitoring, tracking 

of water flows and fish migration, and outreach and education. It is still too early in the 10-year test to determine how 

successful this program will be.

The Upper San Joaquin River Basin Storage Investigation 

evolved out of the CALFED Record of Decision of 2000. That 

decision states, “250 to 700 [thousand acre-feet] of additional 

storage in the upper San Joaquin watershed ... would be 

designed to contribute to restoration of and improve water 

quality for the San Joaquin River, and facilitate conjunctive 

water management and water exchanges that improve the 

quality of water deliveries to urban communities. Additional 

storage could come from enlargement of Millerton Lake at 

Friant Dam or a functionally equivalent storage program in 

the region.” Surface storage options in the San Joaquin River 

region that may be considered as part of the CALFED program 

include of the investigation of (1) raising Friant Dam, (2) 

Fine Gold Creek Dam, and (3) Temperance Flat Dam, which 

includes three alternative sites. Additionally, Yokohl Valley 

Reservoir near Visalia in the Tulare Lake region could also be 

considered as part of these planning studies.

The Farmington Groundwater Recharge and Seasonal Habitat 

Program is a regional effort to recharge the underground 

aquifer in the Eastern San Joaquin County Basin. The basin 

aquifer is threatened by the eastward movement of saltwater 

from the Delta, which could eventually contaminate municipal 

wells in Stockton and limit the ability of farmers to grow crops, 

except for some salt-tolerant, low-value varieties. By periodically spreading an average of 35,000 acre feet of surplus 

water per year using the flooded-field method, the program 

is intended to reduce groundwater overdraft and establish a 

barrier to prevent saline water intrusion. The $33.5 million 

program is a partnership between Stockton East Water District and the U.S. Army Corps of Engineers. The program will 

initially seek to secure flooding rights on about 25 agricultural 

parcels totaling 1,200 acres. The initial 35,000 acre-foot 

per year objective was based on the Farming Groundwater 

Recharge and Seasonal Habitat Study, which was completed in 

2001. Stockton East Water District was the lead local sponsor 

of the feasibility study with the U.S. Army Corps of Engineers. 

Other study participants included Central San Joaquin Water 

Conservation District, North San Joaquin Water Conservation 

District, City of Stockton, San Joaquin County, and California 

Water Service Company. 

Through the South San Joaquin County Surface Water Supply 

Project, the cities of Tracy, Manteca, Lathrop, and Escalon have 

joined with the South San Joaquin Irrigation District to plan 

for a water treatment plant on the Stanislaus River. The project 

will use water that the irrigation district has conserved from 

improvements in irrigation practices and water efficiencies. 

Water will be taken from Woodward Reservoir, treated to 

drinking standards, and conveyed to the cities. A 40-mile long 

transmission pipeline would also be built from the treatment 

plant to deliver water to each of the participant cities. The $150 

million project is expected to begin deliveries around May 

2005. The project is scheduled to deliver 30,000 acre feet per 

year to the cities through 2010 and up to 44,000 acre-feet per 

year thereafter. The intent of the project is to reduce the reliance 

on groundwater and to satisfy future urban demand increases. 

Relationship with Other Regions

The San Joaquin River region is dependent on receiving surface 

water from other regions of the State to meet a portion of its 

developed agricultural and urban water uses. For many years, 

the region has received imported Central Valley Project water 

from the Sacramento-San Joaquin Delta via the Delta Mendota 

Canal and from the project’s Friant Dam on the upper San Joaquin River. This region also receives some State Water Project 

water from the California Aqueduct. The regional map in Figure 

7-1 includes arrows that summarize these regional imports and 

exports for the years 1998, 2000, and 2001.

Some surface water supplies that originate in the San Joaquin 

region are also diverted across the valley to the San Francisco Bay region via the Mokelumne Aqueduct by the East 

Bay Municipal Utility District and through the Hetch Hetchy 

Aqueduct by the City of San Francisco. The average annual 

diversions by these two projects from the Mokelumne and 

Tuolumne rivers are about 245,000 acre-feet per year through 

the Mokelumne Aqueduct and 267,000 acre-feet per year 

through the Hetch-Hetchy Aqueduct. 

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In 1998, Contra Costa Water District completed Los Vaqueros 

Reservoir, which can hold 100,000 acre-feet in storage. This 

is an offstream reservoir in the northwest corner of the San 

Joaquin hydrologic region. The reservoir stores Contra Costa 

Water District water that has been diverted from the Delta in 

the late winter and spring when water quality is good. Water 

is typically withdrawn from Los Vaqueros Reservoir in the 

summer and fall to meet demands and improve the quality of 

water delivered to the water district’s service areas. However, 

because a portion of the service area is in the San Francisco 

Bay Hydrologic Region, this water is considered to be an 

export from the San Joaquin region. Los Vaqueros Reservoir 

has only been operated for a few years, such that normal patterns of diversion and water use have not yet been established. 

Looking to the Future

The water agencies within this region have many projects 

and programs planned to address water supply problems. 

These include studies to evaluate new local surface storage 

projects and investigations for water storage development in 

conjunction with the CALFED program. Local agencies are 

further implementing groundwater conjunctive use projects 

and increasing their efforts on water use efficiency and 

water recycling programs. As the urban areas in the valley 

continue to grow and expand, the current trend of agricultural land conversion to subdivisions is likely to continue. 

As an outcome of urban expansion, urban water usage is 

expected to increase in the future, while agricultural water 

use is projected to decline slightly. The effectiveness of urban 

and agricultural water conservation and water use efficiency measures will influence these water use trends. 

Regional Planning

The San Joaquin Valley Water Coalition is a forum where 

water entities and interest groups can come together to 

discuss common issues related to water supply, quality, and 

distribution. The objective of this group is to ensure a water 

supply for the valley that is sustainable and capable of meeting the needs and concerns of all water users. The Westside 

Integrated Water Resources Plan was initiated in 2000 and is 

evaluating alternatives to increase water supplies and reduce 

demands in order to address current water supply deficits. The 

West Stanislaus Hydrologic Unit Area Project is a program 

sponsored by the U.S. Department of Agriculture and local 

growers to enhance water quality by reducing soil erosion 

into the San Joaquin River. 

There are several other programs that are focusing on ecosystem restoration for the Merced, Stanislaus, Tuolumne, and 

San Joaquin rivers. The Grassland Bypass Project on the west 

side of the valley will consolidate the conveyance of subsurface drain flows on a regional basis. A portion of the federal 

San Luis Drain will be used to convey drainage flows around 

the Grassland habitat areas into Mud Slough before being 

discharged into the San Joaquin River above its confluence 

with the Merced River. The San Joaquin River Parkway and 

Conservation Trust has goals to preserve and restore San 

Joaquin River lands that have ecological, scenic, or historic 

significance. This group also works to educate the public on 

the need for river stewardship, research issues affecting the 

river, and promote educational, recreational and agricultural 

uses consistent with the protection of the river’s resources. 

Work is continuing on several programs at the watershed 

level in the region. For example, the San Joaquin River 

Management Program is seeking solutions to the common 

problems facing the region that affect the environment, water 

quality, agriculture, and flood control in the San Joaquin 

River watershed, without the limitations imposed by political 

boundaries. Also, several public and private partnerships 

on the east side of the valley are attempting to develop a 

Comprehensive Plan for the management, protection and 

restoration of the watersheds of the San Joaquin, Merced, 

Chowchilla, and Fresno rivers. The goal of this plan is to 

attain designations as Resource Conservation and Development Areas, so that watershed projects can be coordinated in Mariposa County and eastern Madera County. 

Water Portfolios for Water 

Years 1998, 2000, and 2001

Water Year 1998

California experienced the affects of El Nino weather patterns 

from July 1997 to June 1998. The wet winter set new records 

for precipitation at many locations throughout the state. Annual 

precipitation for Fresno exceeded 180 percent of average; 

Stockton had almost 200 percent of average; and Los Banos 

recorded 248 percent of average rainfall. Watershed runoff 

was well above average as streamflow in the San Joaquin, 

Merced, Stanislaus and Tuolumne rivers reached about 165 

percent of average. More detailed information about how 

these water supplies were stored and used on a region-wide 

basis is presented in water portfolio Table 7-3, and the companion Water Portfolio flow diagram Figures 7-4 and 7-5 

(large-format graphics placed at the end of this chapter).

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California Water Plan Update 2005

Total irrigated acreage in the San Joaquin River region was 

about 2,053,700 acres in 1998. Alfalfa acreage accounted for 

11.5 percent of all irrigated crops in the region; almond and 

pistachio acreage accounted for 13.8 percent; and vineyard 

acreage was 10.9 percent of the total. Compared to year 

1995, irrigated pasture acreage declined by about 15,400 

acres. However, the acreage of corn rose by 36,800 acres, 

almonds and pistachios increased 8,600 acres, and vineyards 

increased by 29,600 acres compared to 1995 levels. These 

crop shifts indicate that growers are continuing the trend of 

converting field crops to almond and pistachio orchards and 

vineyards, in an effort to find commodities that generate better 

long-term profits.

The effects of the wet El Nino phenomenon on the San Joaquin 

River region were extensive, such that growers had little need to 

irrigate during the first four to five months of 1998. As shown 

in Table 7-3, the total 1998 agricultural on-farm applied water 

use was 4.8 million acre feet, and total agricultural water 

use was 5.5 million acre feet or 47 percent of all uses. These 

water use volumes are significantly lower than what is usually 

required in a normal year such as 2000. The regional average 

for agricultural on-farm applied water was 2.4 acre feet per 

acre. The total agricultural evapotranspiration of applied water, 

or ETAW, in 1998 amounted to 3.4 million acre feet. 

Total urban applied water use, including residential, commercial, industrial, and landscape, in the region totaled 560,400 

acre feet. The average per capita water use was about 301 

gallons per day, and the urban ETAW was 191,000 acre feet. 

Urban water use accounted for only about 5 percent of the total 

water use in the region, and the population for the region was 

1,669,890, or 4.9 percent more than 1995.

Total environmental water use for instream flows, wild and 

scenic rivers, and refuges was about 5.6 million acre-feet. This 

accounted for 48 percent of total uses. Environmental water 

includes water that is reserved for instream and wild and scenic 

river flow but can be used later as a supply by downstream 

users. Most of these requirements are for locations on the major 

rivers that drain from the Sierra Nevada to the valley floor. 

Refuge water supplies, which are diverted and applied directly 

onto wildlife refuges, totaled 414,500 acre feet, or 7 percent 

of total environmental uses.

Total water supplies needed to meet all of the above demands 

were 11.6 million acre feet, including local and imported 

Central Valley Project and State Water Project surface water, 

groundwater, and water reuse.

Water Year 2000 

The weather for the 1999-2000 water year in the San Joaquin 

River region produced normal precipitation and streamflow. 

Rainfall amounts were slightly above average for most of the 

measuring stations in the region. Annual precipitation in both 

Madera and Modesto was 120 percent of average; Stockton 

rainfall was 99 percent of average; and Los Banos had 88 

percent of normal precipitation. Ample moisture was received 

in the local watersheds, and runoff resulted in good surface 

water supplies. Watershed runoff was about average, with 

unimpaired runoff from the Tuolumne, Merced and San Joaquin 

rivers at about 103 percent of average. The unimpaired runoff 

from the Stanislaus, Mokelumne, and Cosumnes rivers was 99, 

89, and 70 percent, respectively, indicating the regional variability of surface flows from one watershed to the next. Heavy 

rainfall occurred in January and February, delaying many 

agricultural activities such as pruning, planting, spraying, and 

field preparation.

Total irrigated acreage decreased only slightly from 1998, and 

was 2,050,400 acres for year 2000. Almond and pistachio 

acreage in 2000 was 292,500 acres, which was 9,300 acres 

higher than in 1998. The acreage of sugar beets dropped 26 

percent to 18,500 acres, while the acreages of most other crops 

in the region remained about the same as in 1998.

In general, 2000 weather, water supplies, and evaporative 

demand were close to average in the San Joaquin River region. 

The total agricultural on-farm applied water was 6.2 million acre 

feet, and total agricultural water use was 7 million acre-feet or 

57 percent of all uses, about 29 percent more than 1998. The 

regional average on-farm unit applied water use was 3 acrefeet per acre. The total agricultural ETAW was about 4.4 million 

acre feet, 29 percent higher than 1998. Since both 1998 and 

2000 had similar total crop acreage, the significant increase 

in total agricultural applied water (29 percent higher) confirms 

that wet weather patterns result in significantly reductions in 

agricultural water needs.

Total urban water use for the region was 600,200 acre feet, which 

was about 7 percent higher than the total urban water use for 

1998. Average per capita water use was around 304 gallons per 

day, and total urban ETAW for the year was about 206,600 acrefeet, 8 percent higher than 1998. Urban applied water accounted 

for about 5 percent of the total water use in the region. 

Total environmental water use for instream flows, wild and 

scenic rivers, and refuges was about 4.6 million acre feet, 

17 percent less than in 1998. Although water for required 

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7 14 Volume 3 Regional Reports

instream flows was higher than in 1998, the amount of water 

dedicated to wild and scenic rivers was much lower than those 

of 1998. In 2000, total environmental water use accounted 

for 38 percent of all developed water uses. Refuge supplies 

accounted for 444,800 acre feet or 10 percent of total environmental uses.

As shown in Table 7-2, total water supplies, including local 

and imported Central Valley Project and State Water Project 

surface water, groundwater, and reuse, amounted to 12.3 million acre-feet in year 2000, which was a 5 percent increase 

from 1998.

Water Year 2001

The 2000-2001 water year started out cooler than normal with 

cumulative rainfall below average through most of January. 

Rainfall amounts were slightly less than average for the water 

year, and annual totals were 88 and 83 percent of average 

for Madera and Stockton, respectively. As the accumulated 

precipitation lagged in January, large-scale weather patterns 

changed significantly as February approached and a series of 

Pacific storms moved into the state, helping to bring precipitation totals closer to average. This cool, wet period delayed 

many agricultural activities such as pruning, planting, spraying, and ground preparation. The weather became warmer 

by late April and the balance of the growing season offered 

good growing conditions.

Irrigated crop acreage totaled 2,042,700 acres in 2001, 

representing a 7,700 acre decline from water year 1998. Irrigated pasture acreage decreased to 158,800 acres, a 28,900 

acres decrease or 15.4 percent decline from 1998; sugar beet 

acreage decreased to 7,600 acres, a 70 percent decline from 

1998. However, miscellaneous truck crop acreage increased 

10,800 acres or 16.7 percent higher than 1998, and vineyard 

acreage increased 18,800 acres or 8.4 percent. The acreage 

of almond and pistachio orchards increased by 13,000 acres 

compared to 1998 levels. 

The total agricultural on-farm applied water in 2001 was 6.5 

million acre feet, and total agricultural water use was 7.2 

million acre feet or 67 percent of all water uses, 33 percent 

more than 1998 and 3 percent more than 2000. The regional 

average on-farm unit applied water was 3.2 acre feet per 

acre. Total agricultural ETAW was estimated at 4.6 million 

acre feet. This was about 36 percent higher than 1998 and 

5 percent higher than 2000. 

Total urban applied water use in this region was 629,100 acre 

feet, which was 12 percent higher than 1998 and 5 percent more 

than in year 2000. Average per capita water use was about 307 

gallons per day, and total urban ETAW was about 218,400 acre 

feet, a 14 percent increase from 1998 and 6 percent increase 

from 2000. Total urban applied water use accounted for about 

6 percent of the total water use in the region. Population for the 

region was 1,812,710, which is an 8.6 percent increase from 

1998 levels.

Total environmental water use for instream flows, wild and 

scenic rivers, and refuges was about 2.9 million acre feet, 

48 percent less than in 1998 and 37 percent less than in 

2000. This decline in environmental water use occurs because 

instream flow requirements and wild and scenic river flows do 

change in response to the wetness or dryness of water year 

conditions. Total environmental water use was 27 percent of 

all uses in 2001, which is much less than the 48 percent share 

from year 1998. Refuge water supplies accounted for 414,700 

acre feet or 14 percent of total environmental uses.

Total water supplies needed to meet the 2001 water uses, 

including local and imported from Central Valley Project and 

State Water Project surface water, groundwater, and reuse, 

amounted to 10.8 million acre feet, which was 7 percent less 

than 1998 and 12 percent less than 2000.

Selected References

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

Resources Control Board 

California’s Groundwater Update 2003 Bulletin 118-03, 

California Department of Water Resources 

Contra Costa Water District 

Farmington Groundwater Recharge Program Web site, 

www.farmingtonprogram.org 

Programmatic Record of Decision, California Bay-Delta 

Program, August 28, 2000. 

San Joaquin River Management Program Advisory Council 

Strategic Plan, State Water Resources Control Board, Regional 

Water Quality Control Boards, November 15, 2001 

The Modesto Bee newspaper 

U.S. Bureau of Reclamation 

Water Quality Control Plan, Regional Water Quality Control Board 

Watershed Management Initiative Chapter, Regional Water 

Quality Control Board

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Chapter 7 San Joaquin River Hydrologic Region 7 15

California Water Plan Update 2005

Water Portfolios

San Joaquin River Hydrologic Region

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Table 7-3 San Joaquin River region water portfolio (TAF)

 ID San Joaquin River San Joaquin River San Joaquin River

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 35,534.7 23,208.5 16,120.2

 6a Runoff - Natural 

 b Runoff - Incidental 

 7 Total Groundwater Natural Recharge 

 8 Groundwater Subsurface Inflow -

 9 Local Deliveries 3,229.8 3,540.7 3,548.5

 10 Local Imports - - -

 11a Central Valley Project :: Base Deliveries 12.8 12.8 12.8

 b Central Valley Project :: Project Deliveries 1,354.2 1,790.7 1,653.7

 12 Other Federal Deliveries 64.3 65.8 97.6

 13 State Water Project Deliveries 4.3 4.6 3.5

 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 1,528.9 2,098.5 1,424.4

 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 - - 0.2

 c Conveyance Seepage - Managed Wetlands - - -

 19a Recycled Water - Agriculture 1.2 1.2 1.2

 b Recycled Water - Urban 0.7 0.7 0.7

 c Recycled Water - Groundwater - - -

 20a Return Flow to Developed Supply - Ag 1,179.4 949.1 968.4

 b Return Flow to Developed Supply - Wetlands 132.6 126.7 134.2

 c Return Flow to Developed Supply - Urban - - -

 21a Deep Percolation of Applied Water - Ag 157.7 844.2 910.1

 b Deep Percolation of Applied Water - Wetlands 174.3 166.5 142.3

 c Deep Percolation of Applied Water - Urban 207.9 226.3 229.5

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

 b Reuse of Return Flows within Region - Wetlands, Instream, W&S 5,190.0 4,192.3 2,515.4

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

 b Return Flow for Delta Outflow - Wetlands, Instream, W&S 1.6 1.6 1.5

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

 25 Direct Diversions 

 26 Surface Water in Storage - Beg of Yr 6,943.0 7,378.6 7,446.0

 27 Groundwater Extractions - Banked - - -

 28 Groundwater Extractions - Adjudicated - - -

 29 Groundwater Extractions - Unadjudicated 1,765.6 2,646.3 2,968.6

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

 30 Surface Water Storage - End of Yr 9,190.7 7,446.0 6,010.8

 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 77.3 89.7 82

 b Evaporation from Reservoirs 419.9 477.1 449.3

 36 Ag Effective Precipitation on Irrigated Lands 1514 870.3 820

 37 Agricultural Water Use 5,079.0 6,556.3 6,793.9

 38 Managed Wetlands Water Use 414.5 444.8 414.7

 39a Urban Residential Use - Single Family - Interior 93.5 101.4 106.1

 b Urban Residential Use - Single Family - Exterior 172.3 186.0 197.2

 c Urban Residential Use - Multi-family - Interior 82.7 90.1 93.6

 d Urban Residential Use - Multi-family - Exterior 41.7 45.3 46.5

 40 Urban Commercial Use 34.5 37.6 39.6

 41 Urban Industrial Use 86.3 89.4 90.1

 42 Urban Large Landscape 30.2 32.9 35.5

 43 Urban Energy Production - - -

 44 Instream Flow - - -

 45 Required Delta Outflow - - -

 46 Wild and Scenic Rivers - - -

 47a Evapotranspiration of Applied Water - Ag 3408.1 4406 4627.8

 b Evapotranspiration of Applied Water - Managed Wetlands 105.9 149.7 136.6

 c Evapotranspiration of Applied Water - Urban 191 206.6 218.4

 48 Evaporation and Evapotranspiration from Urban Wastewater - - -

 49 Return Flows Evaporation and Evapotranspiration - Ag 74.4 11.6 14.3

 50 Urban Waste Water Produced 117.8 123.4 131.8

 51a Conveyance Evaporation and Evapotranspiration - Urban 12.6 12 13.6

 b Conveyance Evaporation and Evapotranspiration - Ag 207.7 248.8 245.3

 c Conveyance Evaporation and Evapotranspiration - Managed Wetlands - - -

 d Conveyance Outflow to Mexico 

 52a Return Flows to Salt Sink - Ag 26.7 40.4 50.3

 b Return Flows to Salt Sink - Urban 148.9 155.5 167.7

 c Return Flows to Salt Sink - Wetlands - - -

 53 Remaining Natural Runoff - Flows to Salt Sink 0.2 - -

 54a Outflow to Nevada - - -

 b Outflow to Oregon - - -

 c Outflow to Mexico - - -

 55 Regional Imports 6,034.4 6,173.5 4,571.8

 56 Regional Exports 4435.8 6398.2 4496

 59 Groundwater Net Change in Storage -443.9 -96.1 -1,259.9

 60 Surface Water Net Change in Storage 2,247.7 67.4 -1,435.2

 61 Surface Water Total Available Storage 11,372.3 11,477.1 11,477.1

 

 Inflows Outflows Green number signifies included in summary boxes

EE-RM-PET-100 C0MMENT 01A
Figure 7-4 San Joaquin 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 7-3, 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 7 San Joaquin River Region 7 17

California Water Plan Update 2005

EE-RM-PET-100 C0MMENT 01A
SUMMARY

OUTFLOWS

INFLOWS

Figure 7-5 San Joaquin River region - schematic flow diagram

In schematic of Table 7-3, 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

RUNOFF:

NATURAL: INCIDENTAL: 

PRECIPITATION: TOTAL STREAM 

FLOW: 

AG EFFECTIVE 

PRECIPITATION ON 

IRRIGATED LANDS: 

LOCAL

DELIVERIES:

CVP BASE 

DELIVERIES: CVP 

PROJECT

DELIVERIES:

OTHER FEDERAL 

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: 

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

7 18 Chapter 7 San Joaquin River Region Volume 3 Regional Reports

California Water Plan Update 2005

EE-RM-PET-100 C0MMENT 01A
Chapter 8 Tulare Lake Hydrologic Region 

Volume 3 

EE-RM-PET-100 C0MMENT 01A
Chapter 8 Tulare Lake Hydrologic Region i8

California Water Plan Update 2005

Chapter 8 Tulare Lake Hydrologic Region

Contents

Chapter 8 Tulare Lake Hydrologic Region ..................................................................................................................8-1

Setting ................................ 8-1

Climate ............................... 8-1

Population .......................... 8-2

Land Use ............................ 8-3

Water Supply and Use ......... 8-4

Water Recycling .................. 8-6

State of the Region .............. 8-8

 Challenges .................... 8-8

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

Relationship with Other Regions .........................................................................................................................8-13

Looking to the Future ......... 8-13

Regional Planning ............. 8-13

Water Portfolios for Water Years 1998, 2000, and 2001 .....................................................................................8-15

 Water Year 1998 ......... 8-15

 Water Year 2000 ......... 8-17

 Water Year 2001 ......... 8-18

Selected References ........... 8-19

Box

Box 8-1 Ongoing Planning .... 8-14

Figures

Figure 8-1 Tulare Lake Hydrologic Region (map) ........................................................................................................8-ii

Figure 8-2 Tulare Lake Hydrologic Region population .................................................................................................8-3

Figure 8-3 Tulare Lake region water balance for water years 1998, 2000, and 2001 (2 bar charts) ..............................8-5

Figure 8-4 Tulare Lake region - illustrated water flow diagram ..................................................................................8-23

Figure 8-5 Tulare Lake region - schematic flow diagram ...........................................................................................8-24

Tables

Table 8-1 Tulare Lake Hydrologic Region water balance summary ...............................................................................8-7

Table 8-2 Percentage of acreage of each crop category by irrigation method used – Kern County ...............................8-11

Table 8-3 Tulare Lake Hydrologic Region water use and distribution of dedicated supplies ..........................................8-16

Table 8-4 Tulare Lake region water portfolios ...........................................................................................................8-22

EE-RM-PET-100 C0MMENT 01A
Volume 3 Regional Reports

California Water Plan Update 2005

Some Statistics

 Area -17,033 square miles (10.7% of State)

 Average annual precipitation - 15.2 inches

 Year 2000 population - 1,884,675

 2030 population projection - 3,121,625

 Total reservoir storage capacity -2,046 TAF

 2000 irrigated crop area - 3,219,000 acres

.

.

.

.

.

.

Flow in TAF

1998

917

2000

1,509

2001

1,065

South Lahontan Region

California Aqueduct (SWP)

Flow in TAF

1998

764

2000

1,212

2001

735

San Joaquin Region

Friant-Kern Canal (CVP)

Flow in TAF

1998

25

2000

31

2001

28

Central Coast Region

Coastal Branch

California Aqueduct (SWP)

Flow in TAF

1998

2,952

2000

4,414

2001

2,961

San Joaquin River Region

San Luis Unit (CVP)

DMC-Mendota Pool

California Aqueduct (SWP)

FRESNO

TULARE

KINGS

KERN

Figure 8-1 Tulare Lake Hydrologic Region

The Tulare Lake Hydrologic Region is in the southern end of the Central Valley and is one of the nation’s leading areas in agricultural 

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

Flow in TAF

1998

915

2000

0

2001

0

San Joaquin River Region

Kings River

EE-RM-PET-100 C0MMENT 01A
Chapter 8 Tulare Lake Hydrologic Region 18

California Water Plan Update 2005

Chapter 8 Tulare Lake Hydrologic Region

Lake and Buena Vista Lake. These lakes have been dry for many 

decades, and the waters that once fed them were long ago 

diverted for irrigation, such that the lake bottom lands are now 

heavily farmed. No significant rivers or creeks drain eastward 

from the Coast Ranges into the valley. 

Climate

Land in the region is fertile and well suited for farming. The valley 

portion of the region is hot and dry in summer with long, sunny 

days and cooler nights. Winters are wet and often blanketed 

with dense fog. Nearly all of the annual rainfall occurs in the six 

months from November to April. The valley is broad and flat, 

and is surrounded by the Diablo and Coast Ranges to the west, 

the Sierra Nevada to the east, and the Tehachapi Mountains to 

the south. The surrounding mountains result in the comparative 

isolation of the region from marine effects. Because of this and 

the comparatively cloudless summers, average maximum temperatures approach a high of 101 degrees in late July. Winter 

temperatures on the valley floor are usually mild, but during 

infrequent cold spells readings occasionally drop below freezing. Heavy frost occurs during the winter of most years, and 

the geographic orientation of the valley generates prevailing 

winds from the northwest.

The mean annual precipitation in the valley portion of this region 

ranges from about 6 to 11 inches, with the lowest amounts near 

the south and eastern ends of the region. Sixty-seven percent of 

the precipitation occurs during the months of December through 

March, and 95 percent of all precipitation falls during the October through April period. The Tulare Lake region enjoys a high 

percentage of clear sunny days during most of the year, except 

during the winter months of November, December, January, and 

February. During periods of tule fog, which can last up to two 

weeks, sunshine is reduced to a minimum. This fog frequently 

extends to a few hundred feet above the surface of the valley 

and presents the appearance of a heavy, solid cloud layer. These 

prolonged periods of fog and low temperatures are important 

to orchard production for the deciduous fruit industry.

Setting

The Tulare Lake Hydrologic Region is in the southern end of 

the San Joaquin Valley. This region includes all of Tulare and 

Kings counties and large portions of Fresno and Kern counties. Major cities include Fresno, Bakersfield, and Visalia. 

The Tulare Lake region is one of the nation’s leading areas in 

agricultural production with a wide variety of crops on about 

3 million acres. Agricultural production has been a mainstay 

of the region since the late-1800s, and gross farm production 

receipts from the region account for 35 percent of the state’s 

total agricultural economy. This region’s population is also 

growing rapidly, and population growth rates began increasing 

above historical trends in the 1980s. As property values in the 

metropolitan coastal areas have become less affordable, many 

people began relocating to more affordable areas in the San 

Joaquin Valley. This trend has accelerated in recent years, and 

the California Department of Finance reported the Tulare Lake 

regional population at 2 million in 2001. 

Native habitat in the region includes vernal pools, areas of 

valley sink scrub and saltbush, freshwater marsh, grasslands, 

arid plains, and oak savannah. The growth of agriculture in 

the Tulare Lake region has replaced much of the historic native 

grassland, woodland, and wetland. 

A map of this region with a table of statistics are presented 

in Figure 8-1. The largest river is the Kings River, which flows 

west from the Sierra Nevada near the northern border of the 

region. The California Aqueduct extends the entire length of 

the west side of the region, delivering water to State Water 

Project (SWP) and Central Valley Project (CVP) contractors in 

the region and exporting water over the Tehachapi Mountains 

to Southern California. Significant rivers in the region include 

the Kings, Kaweah, Tule and Kern rivers, which drain into the 

valley floor of this hydrologically closed region. The Kings and 

Tule rivers historically terminated at the Tulare Lake, which was 

once the largest freshwater lake in the western United States. 

The Kern River historically terminated in two small lakes, Kern 

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

28 Volume 3 Regional Reports

Population

The rate of population growth throughout the San Joaquin Valley 

is among the highest in the state, creating a strong demand for 

housing and urban infrastructure. The population in the Tulare 

Lake Region is now about 52 percent of the entire San Joaquin 

Valley population. While many communities in the region welcome the growth and income from a diversifying economy, the 

rapid urban growth is beginning to generate impacts on farming and the agricultural industry. In six years, between 1992 

and 1998, nearly 37,000 acres of farmland were converted to 

urban uses according to Department of Conservation statistics. 

Even though there is a concern about accelerated urbanization and the subsequent conversion of farmland, relatively 

few private agricultural preservation efforts exist in the San 

Joaquin Valley. The largest regional population centers are the 

Fresno/Clovis metropolitan area and the cities of Bakersfield 

and Visalia. Other smaller population centers include the cities 

of Tulare, Hanford, Porterville, and Delano.

Household incomes and housing prices in the Tulare Lake 

region are lower on an average basis, compared to other 

regions of the state. New jobs in services, industries, construction, and agriculture are generally low-skilled and 

low-wage jobs, subject to seasonal fluctuation. As a result, 

unemployment consistently exceeds the state and national 

rates by as much as 10 percent. According to an April 2004 

Public Policy Institute of California (PPIC) special survey, the 

most pressing San Joaquin Valley issues for residents of the 

South San Joaquin survey area were related to population 

growth and development. These issues included pollution, 32 

percent; healthy economy, 13 percent; population growth, 11 

percent; crime, 9 percent; and adequate water at 6 percent. 

The most notable trend of annual PPIC surveys is the increasing amount of concern about air pollution and all pollution 

in general. In 1999, pollution was cited by 9 percent of the 

survey respondents as the most important issue, 13 percent 

in 2001, 19 percent in 2002, 28 percent in 2003, and 32 

percent in 2004.

The Tulare Lake region is one of the nation’s leading areas in agricultural production with a wide variety of crops on about 3 million acres. This is an unusual 

photo of Tulare Lake, which is normally dry. (DWR photo)

EE-RM-PET-100 C0MMENT 01A
Chapter 8 Tulare Lake Hydrologic Region 38

California Water Plan Update 2005

Population density varies widely on a county-by-county basis, 

and large portions of some counties are virtually unpopulated. 

Much of the population lives in the more densely developed 

cities and towns. The population in the Tulare Lake region 

was about 1.55 million people in 1990 and reached 1.88 

million by 2000. This is more than a 20 percent growth rate 

over that 10-year period. Statewide, California experienced 

a population increase approaching 14 percent from 1990 to 

2000. Between 1998 and 2000, the population increased 

more than 3 percent, and California Department of Finance 

statistics project continued growth rates of 18 percent to 

22 percent for the region’s four counties over the next 10 

years. Figure 8-2 shows the Tulare Lake region’s population 

from 1960 through 2000, with projections to year 2030. 

Land Use

The State and federal government agencies own about 30 

percent of the land in the region, including about 1.7 million 

acres of national forest, 0.8 million acres of national parks 

and recreation areas, and 1 million acres of land managed 

by the U.S. Bureau of Land Management. The region’s foothills 

border Kings Canyon and Sequoia National Parks and the 

Sierra National Forest. Privately owned land totals about 7.4 

million acres. Irrigated agriculture accounts for more than 3 

million acres of the private land, while urban areas take up 

over 350,000 acres. Other agricultural lands and areas with 

native vegetation represent an additional 1.4 million acres in 

the region.

The climate and soils of the Tulare Lake region contribute 

signifi cantly to the tremendous agricultural production of the 

farm lands and to the diversity of crops grown. Counties in the 

Tulare Lake region represent three of the top fi ve agricultural 

counties in the state, as measured by total value of production. 

More than 250 varieties of crops and farm commodities are 

produced in the region. While cotton was the number one crop 

in many past years, grapes have recently outpaced cotton in 

terms of gross production receipts. More than 10 percent of 

the irrigated acreage in California and about 12 percent of 

the 3 million irrigated acres in the region is planted in alfalfa. 

Alfalfa acreage in the region has been rising in recent years in 

response to the needs of the expanding dairy industry. Tulare 

County, in the heart of the region, is currently the nation’s 

richest dairy county. Deciduous and citrus trees are the main 

agricultural crops in the lower foothills, and livestock grazing 

and timber harvesting occur in the higher elevation areas.

Figure 8-2 Tulare Lake Hydrologic Region population

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

3,500,000

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 the Tulare Lake region.

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

48 Volume 3 Regional Reports

The Central Valley constitutes less than 1 percent of the United 

States farmland but produces 8 percent of the total agricultural 

output. Further, while more than 12 percent of the national 

gross receipts for farming came from California’s agriculture, 

more than 4 percent of these came from the Tulare Lake region 

alone. According to the California Department of Agriculture, 

total statewide agricultural production and gross cash income 

in 1998 declined 6 percent from 1997, and statewide gross 

income in 2001 increased 1 percent from 2000. By comparison, agricultural production and cash income in the Tulare 

Lake region declined to $9.1 billion from 1997 to 1998, 

which was only a 3.7 percent decrease. Between 2000 and 

2001, the Tulare Lake regions agricultural production increased 

by 3.4 percent to $9.9 billion. 

Some of the crops and farm commodities that are produced in the 

Tulare Lake region experienced dramatic increases in export value 

in 2001. Table grapes, milk and cream, and walnuts all showed 

double-digit percentage increases in export value from 1998. 

However, most farm commodities experienced declines in export 

values between 1998 and 2001. Seven of the top 10 exported 

crops or commodities declined in value. These included almonds, 

$760 million to $686 million; cotton, $734 million to $605 million; and wine, $506 million to $491 million. These increases 

and decreases within the agricultural industry dominate the 

economy of these four counties and the region as a whole. 

Water Supply and Use

The region receives most of its surface water runoff from four 

main rivers that flow out of the Sierra Nevada, which are the 

Kings, Kaweah, Tule, and Kern rivers. The development and 

use of water from these rivers has played a major role in 

the history and economic development of the region. Major 

water conveyance facilities in the region include the California 

Aqueduct, the Friant-Kern Canal, and the Cross Valley Canal. 

Water diversions from the San Joaquin River at Friant Dam are 

also a significant supply source for all uses in the Tulare Lake 

region. The water districts in the region have developed an 

extensive network of canals, channels, and pipelines to deliver 

water supplies to customers. Water storage facilities and conveyance systems control and retain most of the surface water 

runoff from the watersheds in the region, except in extremely 

wet years when floodwaters may flow out of the region to the 

San Joaquin River. During flood years, excess water flows 

down the north fork of the Kings River toward Mendota Pool 

and on to the San Joaquin River. In the wettest years, Kings 

River floodwaters reach the normally dry Tulare Lake via the 

south fork of the river. Excess runoff from the Kaweah and Tule 

rivers might also flow into Tulare lakebed, flooding low-lying 

agricultural fields. This excess surface water is managed to the 

maximum extent for use in artificial groundwater recharge. In 

the rare event water leaves the basin, it is because the absorptive capacity of the groundwater systems in the region has been 

exceeded. Floodwater can also occasionally be diverted from 

the Kern River intertie into the California Aqueduct for use in 

other SWP service areas. Figure 8-3 graphically summarizes 

the water supplies and the developed water uses in the region 

for 1998, 2000, and 2001. 

Water stored in many Sierra Nevada reservoirs is also used 

to generate electricity as it is released downstream. Some 

diversions occur for consumptive use in local communities, 

but most flows are recaptured in larger reservoirs in the foothills and along the eastern edge of the valley. These larger 

reservoirs were built primarily for flood control, but many of 

them were also designed with additional storage capacity for 

agricultural, urban, and fishery purposes. Smaller communities 

in the Sierra foothills receive their water from smaller local 

surface supplies and groundwater. These mountain communities sometimes pump groundwater from hard rock wells 

and old mines to augment their supplies, especially during 

droughts. Groundwater is the only source available for many 

foothill and mountain residents who are not connected to a 

municipal water system.

Major statewide water projects in the Tulare Lake region 

include the SWP’s California Aqueduct, which includes a 

State/federal joint use segment known as the San Luis Canal. 

The aqueduct is along the western side of the valley, and it 

also pumps water over the Tehachapi Mountains for uses in 

Southern California. Water from the Sacramento-San Joaquin Delta is imported into the region through the California 

Aqueduct for both agricultural and urban purposes. Federal 

CVP water is also exported from the Delta through the San 

Luis Canal to agencies with federal water contracts on the west 

side of the valley, such as Westlands Water District. On the 

eastern side of the valley, the CVP’s Friant-Kern Canal runs 

south along the foothills and transports San Joaquin River 

water to agencies along the valley’s eastern side and extends 

into Kern County. 

The SWP provides an average of 1.2 million acre-feet of 

surface water annually to the region for both agricultural and 

urban purposes. The U.S. Bureau of Reclamation supplies an 

average of 2.7 million acre-feet from the CVP through the 

Mendota Pool, the San Luis Canal, and the Friant-Kern Canal, 

primarily for agricultural uses. Actual deliveries to contracEE-RM-PET-100 C0MMENT 01A
Chapter 8 Tulare Lake Hydrologic Region 58

California Water Plan Update 2005

Figure 8-3 Tulare Lake region water balance for water years 1998, 2000, 2001

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

1998 2000 2001

Thousand Acre-Feet

Wild & Scenic

R.

Managed

Wetlands

Irrigated

Agriculture

Urban

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

1998 2000 2001

Thousand Acre-Feet

Reuse &

Recycle

Ground Water

State Project

Federal

Projects

Local Projects

Dedicated Water Supplies

Applied Water Uses

Three years show a marked change in the amount and relative proportions of water delivered to Tulare Lake 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
California Water Plan Update 2005

68 Volume 3 Regional Reports

tors vary from year to year based upon a number of factors, 

including water supply conditions and reservoir storage in 

Northern California. Other factors that may influence imported 

surface water deliveries include pumping equipment malfunction, natural disasters, temporary closures for infrastructure 

development, and environmental challenges. 

Groundwater has historically been important for both urban 

and agricultural uses in the Tulare Lake region. Groundwater 

pumped from the basin’s aquifers account for about 33 percent 

of the region’s total annual water supply, and also account for 

35 percent of all groundwater use in the state. Additionally, the 

region’s groundwater supply represents about 10 percent of 

the state’s overall developed water supply for agricultural and 

urban uses. Most towns and cities along the east side of the 

valley, including Fresno, Visalia and Bakersfield, rely primarily 

on groundwater. Bakersfield occasionally obtains supplemental water from local surface water and some imported SWP 

water. Fresno, Visalia, Bakersfield, and other cities also have 

groundwater recharge programs to help ensure that groundwater will continue to be a viable water supply in the future. 

On the valley’s western side, smaller cities like Avenal, Huron, 

and Coalinga rely on imported surface water from the San 

Luis Canal to meet municipal demands. This surface water is 

of better quality than the local groundwater supplies on the 

western side, which often have poor water quality. 

In addition to the recharge programs employed by some valley 

cities, extensive groundwater recharge programs (known as 

water banks) are also operated by water districts and agencies, which have stored significant amounts of surplus water 

underground for future use and exchanges through water 

banking programs. For more than 100 years, water users 

throughout the region have used conjunctive use to maximize 

the water supply and maintain the groundwater basins. 

Table 8-1 presents a water balance summary of all water 

supplies and uses for the Tulare Lake region. Table 8-3 presents actual data for the dedicated and developed urban, 

agricultural and environmental water uses in the region for 

1998, 2000, and 2001. A comparison of regional urban, 

agricultural and environmental water uses indicates that urban 

water use is about 5 percent of total uses, agricultural water 

use averages 84 percent and environmental water use is normally about 11 percent of the developed water supplies. 

As surface water was developed and imported water became 

available, water districts were organized to fund water conveyance and delivery infrastructure to serve the area’s developing agriculture. Many different crops are grown throughout 

the region. Most of the agricultural land in the region lies in 

organized water districts. Many water districts in recent years 

have actively been changing water management practices 

and physical structures to improve the efficiency of water 

delivery and use. 

Urban water use accounts for about 5 percent of the total 

applied water in the Tulare Lake region. Until recently, many 

of the communities in the region have not used water meters, 

and customers are charged a flat rate for water use. However, 

urban communities are gradually working toward the installation of water meters as funding allows. State legislation, 

AB 514 (Kehoe), signed into law in October 2003, requires 

all California cities that receive water from the CVP to install 

and use water meters by year 2013. Some of the larger cities 

that are affected include Sacramento, Folsom and Fresno. In 

Fresno, the new law is being viewed as a solution to a longstanding problem. It is believed that AB 514 will remove the 

requirement for Fresno to obtain voter approval to amend its 

charter to permit metering of water. The U.S. Bureau of Reclamation and the federal Department of Interior have made the 

installation of water meters a requirement if Fresno plans to 

renew its CVP contract for 60,000 acre-feet of surface water 

from the Friant Division. 

The variability of industrial water use is a function of economic, climate, and technological factors. Agriculture harvest 

schedules have a large effect because significant amounts of 

water are used for processing harvested crops. Local water 

agencies supply water to most of the smaller industrial facilities in the cities. However, larger industrial and institutional 

water users both inside and outside urban areas generally 

develop their own groundwater supplies or divert from local 

surface water sources. Higher per capita water use in areas 

like Fresno and Bakersfield are generally due to their higher 

concentration of these industries. In the case of Bakersfield, 

the food processing and oil industries have historically been 

a large segment of the total industrial water use activity. 

Water Recycling

In the Tulare Lake region, discharge of recycled water is regulated through the Central Valley Regional Water Resources 

Control Board, as described in the Board’s Tulare Lake Basin 

Plan. The significant increase in population in the Tulare Lake 

region has resulted in a rising volume of recyclable water. This 

has forced municipalities to reassess collection, transmission, 

and treatment capacities of their wastewater plants to handle 

EE-RM-PET-100 C0MMENT 01A
Chapter 8 Tulare Lake Hydrologic Region 78

California Water Plan Update 2005

Water Entering the Region 

Precipitation 27,306 12,693 11,564

 Inflow from Oregon/Mexico 0 0 0

 Inflow from Colorado River 0 0 0

 Imports from Other Regions 3,716 5,627 3,696

 Total 31,022 18,320 15,260

Water Leaving the Region

Consumptive Use of Applied Water * 5,401 7,427 7,591

 (Ag, M&I, Wetlands) 

 Outflow to Oregon/Nevada/Mexico 0 0 0

 Exports to Other Regions 1,857 1,540 1,093

 Statutory Required Outflow to Salt Sink 0 0 0

 Additional Outflow to Salt Sink 457 457 458

 Evaporation, Evapotranspiration of Native 

 Vegetation, Groundwater Subsurface Outflows, 22,606 10,578 10,374

 Natural and Incidental Runoff, Ag Effective 

 Precipitation & Other Outflows 

Total 30,321 20,002 19,516

Storage Changes in the Region

[+] Water added to storage

 [-] Water removed from storage

 Change in Surface Reservoir Storage 438 -57 -141

 Change in Groundwater Storage ** 263 -1,625 -4,115

Total 701 -1,682 -4,256

 Applied Water * (compare with Consumptive Use) 8,429 10,717 10,717

*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 (207%) 2000 (93%) 2001 (85%)

Table 8-1 Tulare Lake Hydrologic Region Water Balance Summary - TAF

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

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increasing volumes. Most of the recycled water in the region 

is used for irrigation and groundwater recharge. The rest is 

evaporated. There are several cities, such as Bakersfield, that 

built recycled water delivery systems for agricultural irrigation 

use. When effluent is discharged, a discharge permit must 

be obtained as part of the EPA National Pollutant Discharge 

Elimination System (NPDES) Permitting Program. Water reuse 

in the Tulare Lake region was estimated to be over 150,000 

acre-feet in 2000. Groundwater recharge programs account 

for more than half of all recycled water use.

State of the Region

Challenges

Whenever a region looks outside of its borders for more water, 

statewide water management and integrated resource planning 

become important considerations. Depending on the package of 

options chosen, one region’s actions can affect another region’s 

supplies. Statewide planning involves assessing trends in each 

region’s water demand and quantifying the cumulative effects 

of each region’s demand and use patterns on statewide supplies. It basically parallels planning at the local and regional 

levels. By working through a statewide planning process, the 

magnitude of both intra- and inter-regional effects can be 

analyzed. However, in a number of circumstances, measures 

that would be taken to manage demand, to increase supplies, 

or to improve water service reliability are local decisions. These 

decisions must assess and compare the cost of increased water 

reliability against the economic, environmental, and social costs 

of potential shortages. 

In the short term, those areas of California that rely on the 

Sacramento-San Joaquin Delta for all or a portion of their 

surface water face an unreliable supply due to the evolving 

protections for aquatic species and water quality. At the same 

time, California’s water supply infrastructure is severely limited 

in its capacity to transfer marketed water through the Delta 

due to those same operating constraints. Until solutions to 

complex Delta problems are identified and put in place and 

demand management and supply augmentation options are 

implemented, some water-dependent regions will experience 

imported water shortfalls. Such limitations of surface water 

deliveries will continue to exacerbate groundwater overdraft 

in the Tulare Lake region because groundwater is used to 

replace much of the shortfall in surface water. In addition, 

water transfers within these areas have and will become more 

common as farmers seek to minimize water supply effects on 

their operations. In urban areas, water conservation and water 

recycling will be accelerated to help offset short-term water 

needs. Proposition 50, also known as “Water Security, Clean 

Drinking Water, Coastal and Beach Protection Act of 2002,” 

provides a mechanism for funding projects to augment systems 

and supplies, optimize delivery systems, use recycled water, 

and increase water management efficiency. 

Distinct environmental water needs exist for each of the four 

major watersheds in the Tulare Lake Hydrologic Region that 

encompass the river systems of the Kings, Kaweah, Tule and 

Kern. There has been significant activity on both the Kings and 

Kern Rivers to restore flows for habitat as well as recreation. 

Modification to outlet structures and timing of releases on the 

Kings River provide cooler water temperatures to protect the 

resident trout populations. Gravel augmentation is also carried out to provide spawning habitat. The Kern County Water 

Agency has implemented a successful and innovative program 

of delivering water supplies down the river through the City of 

Bakersfield, thus providing water for instream uses which can 

later be extracted farther downstream through the use of wells. 

Environmental water supplies on the Kaweah and Tule rivers 

are being modified due to the mitigation requirements tied to 

reservoir enlargement projects on both systems.

Groundwater pumping, a major source of supply in the Tulare 

Lake region, continues to increase in response to growing urban 

and agricultural demands. If groundwater extraction continues 

to be used to offset anticipated but unmet surface water imports, 

it will have negative consequences. One such effect of long-term 

groundwater overdraft is land subsidence, which also results in 

a reduction of aquifer storage space. This has already caused 

some damage to canals, utilities, pipelines, and roads in the 

region. In an effort to slow this condition, many water agencies 

have adopted groundwater replenishment programs by taking 

advantage of excess water supplies available in wet years, incidental deep percolation, and seepage from unlined canals.

On the region’s west side, salinity, sulfate, boron, chloride, and 

selenium limit the uses of groundwater. Salinity is the primary 

water quality factor affecting use of groundwater for irrigation 

and native habitat. Where groundwater quality is marginal to 

unusable for agriculture, farmers use good quality surface water 

to irrigate crops or blend higher quality surface water with poor 

quality groundwater to create a larger supply. The inefficiency 

of some crop irrigation systems can increase percolation of 

irrigation water into the shallow unconfined aquifers, causing 

drainage problems and degrading groundwater quality. This 

marginal to poor quality groundwater has mounded up to reach 

crop root zones in this area and is threatening the viability of 

agriculture there.

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Agricultural runoff and drainage are also the main sources of 

nitrate, pesticides, and selenium that endanger groundwater 

and surface water beneficial uses. The basin also has a relatively large concentration of dairies that contribute microbes, 

salinity, and nutrients to both surface water and groundwater. 

Nitrate has contaminated more than 400 square miles of 

groundwater in the Tulare Lake Basin. In addition, oilfield waste 

has impacted water quality. According to the Regional Water 

Quality Control Board’s basin plan, there are more than 800 

oilfield waste dischargers, of which 250 are regulated under 

waste discharge requirements.

Naturally occurring arsenic as well as pesticides and industrial 

chemicals have contaminated some groundwater supplies that 

are used for domestic water in the region. For example, the 

lone well that provides water for city of Alpaugh’s 760 residents 

(40 percent of whom are defined as living at poverty levels) 

contains unsafe levels of naturally occurring arsenic. By 2006, 

new federal and State rules will force more than 50 central San 

Joaquin Valley communities, including Hanford, Pixley, and 

Tranquility, to cut arsenic levels to one-fifth the current allowable 

levels. The contamination of 40 wells in Fresno due to high levels 

of dibromochloropropane (DBCP), trichloroethylene (TCE), and 

other organic compounds resulted in the installation of activated 

charcoal filtration systems to remove these contaminants. 

The quality of local surface water from the Kings River and 

the San Joaquin River (diverted south through the Friant-Kern 

Canal) is generally considered excellent for irrigation, municipal, and industrial uses. However the Central Valley Regional 

Water Quality Control Board has specifically identified salinity 

in the lower Kings River as a water quality priority in its 2002 

Triennial Review. On the west side of the region, the California 

Department of Water Resouces (DWR) has sought solutions 

to the flooding on the Arroyo Pasajero, which threatens the 

California Aqueduct. The aqueduct, which forms a barrier to 

arroyo floodwaters and sediment flow, is at risk of failure during 

major rainstorms in the watershed. Also, the naturally occurring asbestos in the arroyo sediments that enter the aqueduct 

during floods has raised questions of possible health risks. Both 

Panoche and Silver creeks contribute large sediment loads to 

the valley floor, and Panoche Creek also contains elevated 

levels of selenium.

For many years, portions of the Tulare Lake region have experienced significant drainage problems. The need for proper 

drainage of agricultural return flows has long been recognized 

by federal and State agencies. Planning for drainage facilities 

to serve the San Joaquin Valley began in the mid-1950s. The 

poorly drained area is concentrated along the western side of 

the San Joaquin Valley from Kern County north into the San 

Joaquin River Hydrologic Region. Although the San Joaquin 

Valley has some of the most productive agricultural lands in the 

world, much of the west side of the valley is plagued by poor 

subsurface drainage that adversely effects crop productivity. 

Between 1977 and 1991, the area affected by saline shallow groundwater on the west side doubled to about 750,000 

acres. At present, a substantial portion of the valley, about 

2.5 million acres, is threatened by saline shallow groundwater 

resulting from the lack of proper drainage.

In addition, drainage water is sometimes contaminated with 

naturally occurring, but elevated, levels of selenium, boron, 

and other toxic trace elements that threaten the water quality, 

environment, and fish and wildlife. Water planners had originally envisioned a master surface water drain to remove this 

poor quality water, but that proposal was never implemented. 

The U.S. Bureau of Reclamation has an obligation to provide 

agricultural drainage service to farm lands served by the CVP 

on the west side of the valley. To convey this sometimes contaminated drainwater more directly to the San Joaquin River 

and away from the sensitive San Luis National Wildlife Refuge 

Complex, a portion of the San Luis Drain was reopened in 

September 1996 as part of the Grassland Bypass Project. The 

San Luis Drain was modified to allow drainage through six 

miles of Mud Slough, a natural waterway that passes through 

the San Luis National Wildlife Refuge Complex and a section 

of the North Grassland Wildlife Area. 

Monitoring the quality of San Joaquin Valley agricultural 

drainage water began in 1959 as a cooperative agreement 

between the DWR and the University of California. In 1984, 

the San Joaquin Valley Drainage Program was established 

as a joint federal and State effort to investigate drainage and 

drainage-related problems and identify possible solutions. In 

September 1990 the San Joaquin Valley Drainage Program 

summarized its findings and presented a plan to manage 

drainage problems in a report titled “A Management Plan 

For Agricultural Subsurface Drainage and Related Problems 

in the Westside San Joaquin Valley.” In December 1991 

several federal and State agencies signed a memorandum of 

understanding and released an implementation strategy titled 

“The San Joaquin Valley Drainage Implementation Program.” 

The purpose of the 1991 MOU and its strategy document was 

to coordinate various programs in implementing the 1990 

recommendations.

In 1997 member agencies of the San Joaquin Valley Drainage 

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Implementation Program and the University of California initiated a plan to review and evaluate the 1990 Plan and update 

its recommendations. Eventually, the San Joaquin Valley 

Drainage Authority, which includes districts in the Grassland, 

Westlands, and Tulare subareas, was formed to develop a 

long-term solution for drainage problems in the valley, which 

could include out-of-valley disposal. Studies continue in pursuit 

of cost-effective ways to dispose of the drainage water.

In 2002 the U.S. Bureau of Reclamation released a new 

San Luis report, which declared that an “in-Valley” solution 

to the drainage problem on the valley’s west side should be 

implemented. The proposed alternative contains features that 

include a drainwater collection system, regional drainwater 

reuse facilities, selenium treatment, reverse osmosis treatment 

for the Northerly Area, and evaporation ponds for disposal 

of accumulated salts. 

Also in 2002 the Westlands Water District and the United 

States reached a settlement agreement regarding the drainage 

of lands that the federal government was legally obligated to 

provide to west side farmers. Under this agreement the federal 

government would buy the poorest drained agricultural lands 

from farmers and then remove those lands from agricultural 

production. As a result of this agreement, the number of acres 

requiring drainage service in the San Luis Unit will initially be 

reduced by retiring about 33,000 acres, part of a long-term 

plan that may eventually retire up to 200,000 acres. 

Accomplishments

Many water districts in recent years have actively been working 

to improve agricultural water delivery and use efficiencies. 

About 14 individual water districts encompassing more than 

1.3 million acres have become signatories to the Agricultural 

Water Management Council and have prepared Agricultural 

Water Management Plans. In addition, many water districts 

are working with individual growers to improve on-farm 

irrigation water management systems and efficiency. These 

activities include providing irrigation scheduling information, 

assistance in obtaining low interest loans, water trading to 

improve delivery efficiency, delivery augmentation and irrigation system evaluations.

On the western side of the San Joaquin Valley, particularly 

in Fresno and Kings counties, farmers are using more sprinkler irrigation and less flood, basin, or furrow irrigation as 

a means to reduce excess runoff. This change in water use 

methods also reduces incidental deep percolation to groundwater, which is beneficial for areas that have problems with 

high water tables. In addition, improved management of the 

remaining farm lands that use furrow and basin irrigation is 

resulting in the reduction of applied water. By 1998, less than 

half of the agricultural land in this region still used the flood 

irrigation method. 

Many farmers use sprinklers and drip irrigation, especially 

on truck crops where small applications of water early in the 

growing season are very beneficial. The amount of water 

applied during the pre-irrigation of cotton and other crops 

has been significantly lowered via increased use of sprinklers. 

Buried drip irrigation systems have been increasing in acreage, 

as the proper equipment and designs are proven successful. 

Currently, almost all new plantings and replanting of orchards 

and vineyards are installing drip or micro-sprinkler irrigation 

systems and many older plantings are being converted from 

furrow or basin systems, where conditions are favorable for 

success. As trees and vines age, their yields decrease to a 

point where returns are no longer profitable, and orchards 

are then replanted. Eventually nearly all trees and vines in the 

region are likely to be irrigated with micro-irrigation systems, 

as long as conditions are favorable to this conversion. 

DWR conducted a survey of irrigation methods being used to 

irrigate crops in Kern County in conjunction with its summer 

land use surveys performed in 1984 and 1998, as shown in 

Table 8-2. The results indicate that the adoption of micro-irrigation systems has increased dramatically in all plantings of 

truck and permanent crops over this period. This transition to 

the more efficient drip and micro-sprinkler systems has greatly 

improved agricultural water use efficiency and thus reduced 

the amount of applied water that is needed. 

In general, management of all irrigation systems, including 

non-pressurized irrigation systems, such as furrow and basin, 

has been improving. Economic factors, such as the need to 

keep overall production costs down, are a primary reason 

for increasing farm water use efficiency. These agricultural 

economic considerations include higher production costs, 

higher utility rates, and low market prices for crops sold. 

Inconsistent year to year contract deliveries from the CVP 

and SWP have also motivated farmers to improve efficiency. 

Farmers are using a wider availability of crop irrigation 

scheduling information and soil moisture monitoring programs 

to respond to these cost concerns. On-going and expanded 

public outreach and training efforts by the UC Cooperative 

Extension, irrigation districts, and other agencies has made 

helped make these improvements possible. 

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Efforts to improve water use effi ciency in the urban sector began 

earnestly during the last six-year drought, which extended from 

1987 through 1992. The California Urban Water Conservation 

Council was created in 1991 with the development and signing of the “Memorandum of Understanding Regarding Urban 

Water Conservation in California.” The CUWCC is composed 

of urban water agencies, public interest organizations, government agencies, and private entities. Together these organizations 

work to promote effi cient urban water use statewide. Many water 

and utility companies throughout the state offer fi nancial and 

technical assistance programs that specifi cally help residential 

customers with limited fi nances to implement water and energy 

effi ciency programs in their homes.

Throughout the State, Urban Water Management Plans are 

now required under the provisions of the California Urban 

Water Management Planning Act. These plans must be 

adopted and submitted to the State every fi ve years by all 

water suppliers that provide water for municipal purposes 

to more than 3,000 customers. In general, these plans must 

describe an agency’s current sources of water supply and the 

municipal demands being served, provide estimates of future 

urban demands, and describe the proposed management 

methods and water supply sources that will be developed 

to meet the future needs. Water agencies and municipalities 

in the Tulare Lake region that have submitted urban water 

management plans include West Kern Water District, North 

of the River Municipal Water District, East Niles Community 

Services District, City of Clovis, City of Dinuba, McAllister 

Ranch, Tejon-Castaic Water District, City of Wasco, Oildale 

Mutual Water Company, Vaughn Water Company, City of 

Bakersfi eld, City of Corcoran, City of Lemoore, City of Reedley, 

City of Hanford, Kern County Water Agency, and the City 

of Sanger. Nine of the above agencies now have completed 

urban water management plans.

Regarding groundwater, the Groundwater Management Act 

of 1992, AB 3030 (California Water Code Section 10750 et 

seq.) allows certain defi ned existing local agencies to develop 

groundwater management plans. Groundwater basins are 

explained and defi ned in “California’s Groundwater” (DWR 

Bulletin 118, Update 2003). Before the passage of AB 3030, the 

California Water Code had been amended by AB 255 in 1991 

which allowed local agencies overlying critically overdrafted 

groundwater basins to develop groundwater management 

plans. Six water agencies in the Tulare Lake region prepared 

groundwater management plans under AB 255 laws. Following 

AB 3030 legislation, 26 additional groundwater management 

plans have been adopted in this region. In 2002, SB 1938 

amended existing law related to groundwater management by 

local agencies. This law now requires any public agency that 

applies for State funds for the construction of groundwater projects or groundwater quality projects to prepare and implement 

a groundwater management plan that contains more specifi c 

procedures and plan components.

Cities and counties in the region are continually introducing 

new water system technology to solve problems, reduce costs, 

and improve system operations as part of efforts to maintain, 

expand, and update their municipal water systems. After 

years of violating state drinking water standards for taste and 

smell, the city of Mendota, in western Fresno County, is in the 

process of implementing major water system improvements. 

Three new wells east of the city have been constructed, each 

with the capacity to pump up to 1,500 gallons per minute. This 

new groundwater supply is transported to the city’s treatment 

facility via a 20-inch pipeline, where a new fi ltering tank has 

been added to improve the water purifi cation system.

1984 1998 1984 1998 1984 1998

 SURFACE SPRINKLER MIRCRO

GRAIN 52.1 46.1 47.9 53.9 0.0 0.0

FIELD CROPS 63.9 77.2 36.1 22.8 0.0 0.0

ALFALFA 77.2 88.3 22.8 11.7 0.0 0.0

PASTURE 76.9 81.7 23.1 18.3 0.0 0.0

TRUCK CROPS 17.4 24.9 82.6 70.5 0.0 4.6

DECIDUOUS ORCHARD 41.9 29.9 27.2 6.1 30.9 64.0

SUBTROPICAL 13.8 2.8 23.4 0.6 62.8 96.6

VINEYARD 59.2 36.1 15.7 1.8 25.2 62.1

Table 8-2 Percentage of acreage of each crop category by 

irrigation method used – Kern County

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The California Revolving Fund program disburses low interest loans to address water quality problems associated with 

discharges from wastewater and water reclamation facilities, 

as well as from nonpoint source discharges and for estuary 

enhancement. This policy was written to implement the 1987 

Amendments to the Federal Clean Water Act, which created 

the State Revolving Fund (SRF) Loan Program. In the Tulare 

Lake Region recent program participants include (1) the town 

of Alpaugh with a treatment and collection system, (2) the City 

of Fresno’s treatment plant expansion, (3) the County of Kern’s 

Rexland Acres community sewer collection and transmission 

system, and (4) the Fresno Metropolitan Flood Control District’s 

storm water quality management program.

The City of Clovis received AB 303 funding for a proposed 

project that will include (1) compiling groundwater recharge 

basin site characteristics to increase recharge capabilities, (2) 

constructing groundwater monitoring wells at recharge facilities 

to better monitor percolation and movement, and (3) creating a 

Ground Water Information System (data management system) to 

provide a comprehensive and organized data base for improved 

groundwater data accessibility and maintenance.

In Kern County, the Kern Water Bank groundwater program will 

receive Proposition 13 funding to increase the recovery capacity 

of the Kern Water Bank. The Kern County Groundwater Storage 

and Water Conveyance Infrastructure Improvement Program 

administered by the Kern County Water Agency will receive 

Proposition 13 funding to provide additional opportunities for 

Kern County facilities to capture and transport high-flow water 

supplies and may provide water for ecosystem restoration and 

the Environmental Water Account. 

Another project receiving Proposition 13 funding is the Kern 

Water Bank River Area Recharge and Recovery Project that 

would allow the Kern Water Bank Authority to provide as much 

as 50,000 acre-feet per year of additional water recovery 

capability. In years when recovery needs are less than recovery 

capacity, water could be recovered for the Environmental Water 

Account or other ecosystem restoration needs. 

The North Kern Groundwater Storage Project will take advantage of 

wet-year high flows and store them in the groundwater aquifer. This 

may reduce demands on water supplies from the Delta in dry years. 

The Westlands Water District received AB 303 funding to find 

more water, including potential conjunctive use opportunities. 

The investigation included three deep soil-boring and monitoring 

wells installed by DWR to evaluate the storage, water quality, 

and extraction potential of the groundwater aquifer. AB 303 

also paid for the installation of 35 shallow borings to evaluate the percolation potential of the uppermost soil sediments. 

The study was completed in 2002 and recommended the area 

where Arroyo Pasajero intersects with Interstate 5 as a site for 

conjunctive use groundwater application. 

Within the past several years, Broadview Water District 

announced that landowners had decided to sell the district due 

to the increasing costs of water production and the additional 

water system costs associated with the district’s drainage and 

salinity problems. In 2003 the Pajaro Valley Water Management 

Agency and Broadview Water District began negotiating the 

sale. Pajaro Valley WMA had prepared the necessary paperwork and completed the required studies, but negotiations never 

culminated in an agreement that was acceptable to both parties. 

At about this time, Westlands Water District, which shares part 

of its northern district boundary with Broadview, began negotiations with the Broadview Water District. Westlands recently 

announced that negotiations had been completed to purchase 

the Broadview Water District and that the acquisition would 

encompass all the Broadview lands and include the Broadview 

Water District’s 27,000 acre-foot CVP water service contract. 

This sales/purchase agreement is being circulated among 

Broadview landowners for their approval, and the transaction 

is expected to be completed in 2005. District staff has also met 

with Fresno County Local Agency Formation Commission to 

discuss annexing the Broadview lands into Westlands.

For several years Westlands WD has been attempting to “augment” its water supplies by selling agricultural lands that have 

severe drainage problems and then using the water entitlements 

retained from those lands to firm up the water entitlements to 

the remaining irrigated lands within the district. The impending 

purchase of Broadview Water District with its CVP water entitlement is another example of this ongoing process.

Among other regional programs, the U.S. Natural Resources 

Conservation Service has been promoting agricultural programs in western Fresno County that:

(1) reduce the amount of salts leached to ground water 

and improve shallow, saline water table conditions with 

improved irrigation water management.

(2) improve the distribution and management of livestock to 

reduce erosion using prescribed grazing, fencing, and 

improved watering facilities for livestock.

(3) reduce soil salinity in the crop root zone to improve cropland 

productivity with improved irrigation water management 

and soil salinity management.

(4) reduce the amount of airborne particulates with adjusted 

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timing of agricultural operations, vegetating turn areas, 

and avoiding tracking soil onto the county roads.

(5) reduce sheet and rill erosion on rangeland through 

improved livestock distribution and production of forage.

The Lake Kaweah Enlargement Project proposes to raise the 

Lake Kaweah spillway by 21 feet and increase the lake’s water 

storage capacity by 43,000 acre-feet to 183,000 acre-feet, or 

28 percent. Still a small lake in comparison to others in California, the enlargement project will increase flood protection 

to downstream communities on the Kaweah Delta river system, 

especially near Visalia. The dam’s spillway crest, a U-shaped 

cut, is being raised with the installation of “fuse gates.” These 

gates are like large concrete teeth that pop out like fuses if 

the lake should become so full. Once completed, farmers are 

expected to see immediate benefits because a larger lake will 

allow longer irrigation periods during the summer months. 

Additionally, the Tulare Lake bottom lands are less likely to be 

inundated with flood flows that occasionally interrupt farming 

operations. Recreational use will also be enhanced because even 

in winter, when lake levels are low, it will be large enough for 

boating. The federal government is funding more than half the 

cost of the $33 million project, the State Reclamation Board is 

providing $10.1 million, and the local agencies are providing 

the remaining $5.4 million. 

The Coordinated Resource Management and Planning (CRMP) 

groups in the Tulare Lake region include the Panoche/Silver 

Creek CRMP, the Stewards of the Arroyo Pasajero Watershed 

CRMP, and the Cantua/Salt Creek Watersheds CRMP. The 

general purpose of these groups is to promote watershed health 

throughout the western Fresno County foothills. The primary 

concerns in these watersheds are flooding, erosion, sediment 

transport, and the quality of water entering into the San Joaquin River and the California Aqueduct. Some of the water 

management strategies that have been developed to address 

these problems include streamflow and water quality monitoring 

programs, revegetation of embankments, and implementation 

of watershed best management practices. 

As part of the Kern County Water Agency’s Kern River Restoration and Water Supply Improvement Program, the Kern River 

Parkway will include a new 40-acre multipurpose recharge lake 

and recreation area with a permanent 10-acre recharge lake 

and adjoining playing field that will be surrounded by grassy 

slopes and tree-shaded seating areas. During extremely wet 

water years, these open 25-acre fields will be flooded and used 

for groundwater recharge in the spring. There will also be a new 

access route to the existing Kern River north bank equestrian 

trail from the future Jewetta Avenue extension.

Relationship with Other Regions

The Tulare Lake region receives CVP water from the San Joaquin River region via the Friant-Kern Canal and imported water 

from the Sacramento-San Joaquin Delta via the SWP California 

Aqueduct and the CVP San Luis and Delta-Mendota canals. 

The regional map in Figure 8-1 identifies the amounts of water 

imports and exports for recent years 1998, 2000, and 2001. The 

economic health of the region heavily depends on the availability 

of imported surface water to meet current and future needs.

Several water districts within the Tulare Lake region have developed groundwater storage and recovery programs that benefit 

water districts outside of the region. Groundwater overdraft 

has created sufficient dewatered storage space to store water 

for local uses and for extraction and exchange or delivery 

to other agencies. Revenues generated by these storage and 

recovery programs have helped finance additional conveyance infrastructure to move surface water to areas that were 

previously served with groundwater. This type of conjunctive 

use activity ultimately helps relieve overdraft, while providing 

additional water supplies to agencies outside of the region. 

Looking to the Future

Major water agencies and counties within the Tulare Lake 

region have been proactive for many years in all facets of 

water use and supply planning (see Box 8-1 Ongoing Planning 

Activities). The efficiency of water diversions from local rivers 

and streams is continually being optimized to meet agricultural 

and urban purposes. In addition, when it became apparent 

that the groundwater supply was not sustainable for meeting 

all future water demands, water agencies worked with the CVP 

and SWP to find ways to improve delivery capabilities.

The predominantly agricultural economy is now adapting to 

share water resources with the rapidly growing urban economy. 

New projects have been identified as necessary to better manage 

the local water supplies, as well as to adhere to more stringent water quality standards and environmental regulations. 

Regional Planning

An important component of California’s ability to meet future 

water needs involves the voluntary transfer of water from one 

user to another. In recent years, programs and proposals that 

involve water transfers have become very active in the Tulare 

Lake region and adjacent areas. Water districts have also 

made significant progress in the development and expansion of groundwater banking agreements and conjunctive 

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148 Volume 3 Regional Reports

use programs, which facilitate the storage and movement of 

water to where it is needed.

The San Joaquin Valley Water Coalition is one example 

of several regional groups that facilitate the discussion of 

common issues related to water supply, water quality, and 

water management to ensure the reliable distribution of water. 

Some of the factors that are commonly considered in these 

regional planning efforts include:

 • Population growth, impacts, and resulting water needs 

• Groundwater overdraft and associated problems 

• Preservation of prime agricultural lands 

• Reliability of water supplies in foothill and mountain 

 communities 

• Reliability of water supplies for fish, refuges, and the 

 environment 

• Potential water transfers and exchanges and their 

 effects 

• Groundwater banking programs 

• Groundwater quality issues, particularly for drinking 

 and municipal use

Several examples of recent projects that have evolved through the 

use of regional planning approaches are mentioned below.

Pond-Poso Improvement District Project Enhancements. The 

Pond-Poso Improvement District is working to improve the 

groundwater resource in north-central Kern County. The district 

recently qualified for Proposition 204 funds. A primary goal is 

to encourage local groundwater users to begin using surface 

water whenever available instead of groundwater, which will 

help to stabilize the groundwater basin. The project is being 

completed by the Semitropic Water Storage District.

Pioneer Groundwater Recharge and Recovery Project. Funding 

obtained from Proposition 204 will be used to enhance the Kern 

County Water Agency’s Pioneer Project. This project will develop 

methods to maximize recovery of recharged groundwater, to 

increase the water supply available to the program participants. 

The project has the potential to reduce dry-year demands for 

surface water from the Sacramento-San Joaquin 

Pond - Shafter - Wasco Irrigation and Water Use Efficiency. 

This effort is targeting agricultural irrigation in Kern County. 

The project’s goals are to (1) implement a Total Farm Management Program for the San Joaquin Valley portion of Kern 

County; (2) reduce PM-10 levels on 50 percent of the permanent crops harvested in the valley; (3) reduce agricultural water 

use by 15 percent over the next five years through changes 

to irrigation systems and irrigation management; (4) increase 

wildlife habitat by 30 percent over the next five years; and 

5) educate local growers about new or proven techniques in 

water, air, nutrient, and pesticide management. The PondShafter-Wasco Resource Conservation District and the Natural 

Resources Conservation Service are leading this project.

Kern County Groundwater Storage and Water Conveyance 

Infrastructure Improvement Program. Proposition 13 funding will be used to provide additional opportunities for Kern 

County to develop water supplies for local uses, increase 

opportunities for ecosystem restoration, and increase sales to 

the Environmental Water Account. Kern County Water Agency 

has received the funding to develop this program.

White Wolf Basin Groundwater Banking Project. The White 

Wolf Basin is a small, somewhat isolated, groundwater basin 

in the southeastern corner of Kern County. The Wheeler RidgeMaricopa Water Storage District is studying groundwater 

banking using this aquifer. Surface water from the California 

Aqueduct would be imported for use in groundwater storage. 

Recovered water could then be conveyed back to the aqueduct, or introduced into the district’s distribution system and 

exchanged for SWP water. Pilot wells are being drilled in order 

to better understand the geology of the groundwater basin. 

South Valley Water Management Program. The southern 

Box 8-1 Ongoing Planning Activities

• Kern County Water Agency Conjunctive Management Program 

• Water Agency Exchanges and Transfers 

• Kern County Water Agency EWA Sales 

• Optimization of Water Conveyance Systems 

• Inter-regional Water Storage, Drought Supply Agreements

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end of the San Joaquin Valley has water conveyance facilities 

that are interconnected, especially in Kern County. During wet 

years water can become available for short durations from 

any of a number of sources, including the San Joaquin River, 

Kings River, and Kern River. The Kern County Water Agency 

and several south valley water districts are evaluating possible 

ways to coordinate supplies and deliveries in order to take 

full advantage of these wet year supplies. 

Rosedale-Rio Bravo Water Storage District Banking Program. 

The Rosedale-Rio Bravo Water Storage District (RRB) is developing a groundwater banking project with a maximum storage 

of 500,000 acre-feet. Recharge basins and recovery wells are 

being constructed. Generally, RRB will store water for other 

entities in wet years by offering a 2-for-1 exchange proposal. 

In drier years this water would be returned, either by exchange 

delivery of RRB’s SWP or Kern River water, or by pumping 

from wells if there is insufficient exchange capacity.

Kern Delta Water District/Metropolitan Water District Joint 

Banking Project. Kern Delta Water District is developing a 

groundwater banking partnership with the Metropolitan Water 

District of Southern California. MWD will store water in the 

groundwater basin underlying the Kern Delta Water District in 

wet years and recover the water during drier years. The project 

is similar in concept to a separate joint Arvin-Edison/MWD 

Program. The program contemplates storing a maximum of 

250,000 acre-feet of water for MWD. 

Other long-term programs and activities that may be considered for the Tulare Lake region include:

 • Methods to increase agricultural water use efficiency 

• Methods to increase urban water use efficiency 

• Water conservation activities 

• Agricultural land retirement 

• Temporary fallowing of crop lands 

• SWP water supply augmentation concepts 

• CVP water supply augmentation proposals 

• Mid-Valley Canal as a new surface water facility 

• Demand reduction strategies 

• Short-term water transfers 

• Use of “gray water” for approved purposes 

• Water recycling proposals 

• Local conjunctive use 

• Groundwater reclamation efforts 

• Treatment and reuse of brackish agricultural drainage water 

Water Portfolios for Water Years 

1998, 2000, and 2001

Detailed information about actual water supplies and water uses 

(called “water portfolios”) for water years 1998, 2000, and 

2001 is presented in tables 8-3 and 8-4 and figures 8-4 and 8-5. 

Water Year 1998 

California weather and precipitation were significantly 

affected by an El Nino weather event during the winter of 

1997-98. The last prior El Nino period occurred in 1991-92. 

Wet El Nino storms did not begin earnestly until January 1998, 

after which storm impacts resulted in damage to a number of 

crops. Of California’s 58 counties, 42 were declared major 

disaster areas during that year.

The wet weather damaged some winter and spring crops and 

delayed the planting and development of some summer season 

crops. Consumers felt the impacts from the resulting higher 

supermarket prices for California vegetables. Producers had 

difficulty getting into their soggy fields in the spring, delaying 

normal farming practices, such as spraying, pruning, and 

tying vines. The wet weather also reduced both the quality and 

volume of many crops harvested during this year. However for 

late-developing crops such as cotton, raisins, and table grapes, 

the fall weather produced clear skies and good temperatures, 

which allowed the majority of these late-season crops to be 

harvested without weather problems.

Watershed runoff was well above normal, as unimpaired runoff 

from both the San Joaquin and Kings rivers was about 170 percent of average, the Kaweah River was 196 percent of normal, 

and the Kern River runoff was 224 percent of average.

The total amount of acreage irrigated in this region varies 

in direct relation to the amount of surface water available 

from local and imported sources in any particular year. The 

1998 total irrigated acreage was 3.2 million acres, based on 

abundant water supplies. The trends in crop acreage pointed 

towards increased acreage of higher value commodities such 

as fruits, tree nuts and vegetables; while the acreage of field 

crops was declining. Acreage planted in wine grapes was 

rapidly increasing, and the acreage planted in almond trees 

also continued to increase at a steady rate.

The dairy industry continued its growth in 1998, particularly in 

Tulare County, which is now the top milk-producing county in 

the nation. Alfalfa acreage in the Tulare Lake region exceeded 

360,000 acres in 1998, up from 279,600 acres reported in 

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 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 8-3 Tulare Lake Hydrologic Region Water Use and Distribution of Dedicated supplies (TAF)

Urban

Large Landscape 16.1 19.2 19.8 

Commercial 37.5 44.6 46.4 

Industrial 53.5 63.8 66.4 

Energy Production 0.0 0.0 0.0 

Residential - Interior 208.6 248.8 259.0 

Residential - Exterior 219.4 261.4 272.5 

Evapotranspiration of Applied Water 187.1 187.1 223.3 223.3 232.5 232.5

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 10.6 12.8 13.3 

Conveyance Evaporation & ETAW 10.6 10.6 12.8 12.8 13.3 13.3

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 0.7 2.9 0.0 

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Urban Use 546.4 197.7 197.7 653.5 236.1 236.1 677.4 245.8 245.8

 Agriculture

On-Farm Applied Water 7,006.6 9,677.3 9,933.6 

Evapotranspiration of Applied Water 5,181.0 5,181.0 7,162.0 7,162.0 7,320.4 7,320.4

E&ET and Deep Perc to Salt Sink 457.3 457.3 457.3 457.3 457.8 457.8

Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Applied Water 735.4 797.0 590.5 

Conveyance Evaporation & ETAW 415.3 415.3 472.5 472.5 380.0 380.0

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 824.8 328.3 42.6 

GW Recharge Evap + Evapotranspiration 18.0 18.0 13.0 13.0 1.4 1.4

 Total Agricultural Use 8,566.8 6,071.6 6,071.6 10,802.6 8,104.8 8,104.8 10,566.7 8,159.6 8,159.6

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 3,205.0 1,331.1 964.1 

 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 62.9 73.7 76.3 

 Evapotranspiration of Applied Water 32.7 32.7 41.4 41.4 38.3 38.3

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

 Outflow 3.1 0.0 2.5 0.0 2.5 0.5

 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 62.9 35.8 32.7 73.7 43.9 41.4 76.3 40.8 38.8

 Total Environmental Use 3,267.9 35.8 32.7 1,404.8 43.9 41.4 1,040.4 40.8 38.8

 

 TOTAL USE AND OUTFLOW 12,381.1 6,305.1 6,302.0 12,860.9 8,384.8 8,382.3 12,284.5 8,446.2 8,444.2

 

 

Surface Water

 Local Deliveries 3,621.8 3,621.8 3,620.1 2,397.0 2,397.0 2,396.1 1,698.0 1,698.0 1,697.2

 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 1,811.3 1,811.3 1,810.4 2,280.2 2,280.2 2,279.3 1,787.9 1,787.9 1,787.1

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

 SWP Deliveries 1,035.0 1,035.0 1,034.5 1,915.2 1,915.2 1,914.5 849.3 849.3 848.9

 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 -163.0 -163.0 -163.0 1,792.4 1,792.4 1,792.4 4,111.0 4,111.0 4,111.0

 Deep Percolation of Surface and GW 2,871.0 3,145.0 2,874.2 

Reuse/Recycle

 Reuse Surface Water 3,205.0 1,331.1 964.1 

 Recycled Water 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 TOTAL SUPPLIES 12,381.1 6,305.1 6,302.0 12,860.9 8,384.8 8,382.3 12,284.5 8,446.2 8,444.2

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

DEDICATED WATER SUPPLIES

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1995. Corn acreage rose even faster than alfalfa, exceeding 

257,000 acres in the region in 1998, which was driven by the 

increasing demand for cattle feed by the dairy industry.

Cotton acreage was substantially lower due primarily to the El 

Nino weather, decreasing to 655,400 acres (35 percent less 

than year 1995). Growers continued the trend of converting field 

crop land to almond/pistachio orchards in an effort to generate 

better long-term profits. The combined almond/pistachio acreage of 245,700 acres was 32 percent higher than the acreage 

reported in 1995.

The El Nino storms provided a significant amount of rainfall 

on agricultural fields, filling soil profiles, and reducing the 

early season evapotranspiration of applied water (ETAW). 

Consequently, less applied water was needed for irrigation 

compared to most normal years. Estimated total agricultural 

on-farm applied water was 7 million acre-feet for the Tulare 

Lake region; total agricultural water use was 8.6 million acre-feet 

(or 69 percent of all uses). The total agricultural ETAW in 1998 

in the region was 5.2 million acre-feet. The regional average 

unit ETAW was 1.6 acre-feet per acre. Individual crop ETAW 

amounts vary due to differences in rainfall, growing season, 

soil texture, and rooting depths.

Total urban applied water use, including residential, commercial, 

industrial, and landscape, in the region was 546,400 acre-feet. 

Urban water use accounted for only about 5 percent of the total 

applied water in this hydrologic region. The total population of 

the region in 1998 was 1,816,440. Total urban ETAW for the 

year was about 187,100 acre-feet, and the regional average 

per capita water use was about 268 gallons per day.

Total environmental demand for instream flows, wild and scenic 

rivers, and waterfowl refuges was about 3.3 million acre-feet. 

This accounted for 26 percent of total uses. This includes water 

that is reserved for instream and wild and scenic river flows but 

can later be diverted as a supply by other downstream users. 

Refuge water uses, which are supplies applied directly onto 

wildlife refuges, accounted for 62,900 acre-feet.

Total supplies, including local and imported CVP and SWP surface water, groundwater, and reuse, amounted to 12.4 million 

acre-feet, as detailed in Table 8-3.

Water Year 2000

The weather for water year 1999-2000 in the Tulare Lake 

Region was very close to the long-term average. Rainfall was 

slightly below normal in the southern areas of the region, 

where Bakersfield received 81 percent of average. Precipitation was somewhat higher than normal in the northern areas 

of this region, where Fresno received 120 percent of average. 

Watershed runoff was about 101 percent of average from 

both the San Joaquin and Kings rivers, 87 percent of average from the Kaweah River and about 70 percent of average 

from the Kern River.

Total irrigated crop acreage within the region was 3.2 million 

acres, which was virtually unchanged from 1998. However, 

the acreage of some individual crops did change significantly from 1998. The largest change in crop acreage was 

for cotton, which increased 10.7 percent to 725,300 acres 

in 2000. The combined almond and pistachio acreage of 

257,000 was 11,200 acres, or 4.6 percent higher than in 

1998. Corn acreage, primarily for silage, declined 10 percent 

during this year.

The total agricultural on-farm applied water in 2000 for the 

Tulare Lake region was 9.7 million acre-feet, a significant 38 

percent increase over 1998. This large difference illustrates 

the degree to which wet and cool conditions can alter the 

irrigation water demand and crop acreage grown. 1998 was 

a very wet and cool year (low evaporative demand), which 

reduced irrigation demand dramatically. In contrast the total 

agricultural water use for 2000 was 10.8 million acre-feet 

(84 percent of all uses) and 26 percent more than 1998. The 

regional average agricultural on-farm unit applied water was 

about 3.4 acre-feet per acre.

The total agricultural ETAW in the region was about 7.2 million 

acre-feet, or 38 percent higher than that of 1998. The regional 

average unit ETAW was 2.2 acre-feet per acre. 

The dairy industry continued its strong growth in year 2000. 

New records were set for the number of milk cows and milk 

production. In 2000, California led the nation in total milk 

production with a record 32.2 billion pounds, representing 

a 6 percent increase from the previous year. The Tulare Lake 

region was responsible for a large part of this increase in the 

number of dairies and cows.

In 2000, total urban applied water for the region was 653,500 

acre-feet, which was about 20 percent higher than the total 

applied water in 1998. Urban water use accounted for more 

than 5 percent of the total applied water in the region. Total 

population in 2000 in the Tulare Lake region climbed to 

1,884,650, an increase of 3.8 percent over the 1998 population. Average per capita water use was also much higher 

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than 1998, at 310 gallons per day. Total urban ETAW for 

the year was about 223,300 acre-feet, an increase of 19 

percent from 1998. 

Environmental demand for instream flows, wild and scenic 

rivers, and refuges for the region was about 1.4 million acrefeet in year 2000, which is 57 percent less than 1998. This 

category accounted for 11 percent of total uses. Because the 

components of environmental water use are directly tied to 

streamflows, this category of use will always decline during 

normal to drier water years. Refuge supplies, which are supplies applied directly onto wildlife refuges, accounted for 

73,700 acre-feet in 2000.

Total developed water supplies, including local and imported 

from the CVP and SWP surface water, groundwater, and 

reuse, amounted to about 12.9 million acre-feet, which is 4 

percent more than in 1998.

Water Year 2001

The 2001 water year started out cooler than normal with 

cumulative rainfall below average through most of January. 

However, large-scale weather patterns changed significantly 

as February approached and a series of Pacific storms moved 

into the state, bringing regional precipitation totals closer to 

normal. Rainfall amounts were slightly less that average for 

the water year in the region with totals in both Fresno and 

Bakersfield about 93 percent of average.

Except for a thunderstorm in April that produced significant 

high wind, hail, and rainfall, crop development was generally 

normal throughout the remainder of the growing season. Less 

than normal precipitation in local watersheds resulted in below 

normal river runoff and below normal surface water supplies. 

Runoff from the San Joaquin, Kings, and Kaweah rivers was 

about 71 percent of average for each, while runoff from the 

Kern River was 54 percent of average. 

Total irrigated agricultural acreage was 3.1 million acres, a 

decline of 9.6 percent (or 126,000 acres) from year 2000. The 

price for milk and cream commodities rose 14 percent in 2001 

and pushed Tulare County to the top agricultural producing 

position in the nation, surpassing Fresno County, which had 

held the number-one position for many years. Cotton acreage 

was 639,400 acres, which was 85,900 fewer acres than in 

2000, due primarily to the drop in price of the upland variety. 

Sugar beet acreage continued its multiyear downward spiral 

to 15,100 acres, 47 percent less acreage than in 2000. The 

transition into wine grapes over the past several years leveled 

out as the market reached a point of saturation, and prices 

began to weaken. The acreage of raisin grapes dropped 

almost 20 percent in 2001 responding to the dramatic drop 

in price over the past two years. Raisin growers had received 

more than $1,000 per ton in 1999 compared to about $525 

per ton in 2001. The almond/pistachio acreage continued 

the upward trend of previous years, increasing more than 10 

percent in 2001. 

The total agricultural on-farm applied water in 2001 for the 

Tulare Lake region was 9.9 million acre-feet, and total agricultural water use was 10.6 million acre-feet or 86 percent of all 

water uses. This amount is 23 percent more than 1998, but 2 

percent less than year 2000. This resulted in an average unit 

rate of 3.4 acre-feet per acre. The total agricultural ETAW in 

the region was 7.3 million acre-feet, about 41 percent higher 

than 1998 and 2 percent higher than 2000. 

The total urban applied water in 2001 for the region was 

677,400 acre-feet, which was 24 percent higher than 1998 

and 4 percent higher than 2000. Urban water use accounted 

for about 5.5 percent of the total applied water in the region. 

Total population in the region for 2001, was 1,921,915, 

an increase of 2 percent over the 2000 population and 5.7 

percent higher than 1998. Average per capita water use was 

about 315 gallons per day, possibly due partly to the drier 

water supply conditions. Total urban ETAW for the year was 

about 232,500 acre-feet, an increase of 24 percent from 

1998 and 4 percent from 2000.

Total environmental demand for instream flows, wild and 

scenic rivers, and refuges for the region was about 1.04 million 

acre-feet, 68 percent less than 1998 and 26 percent less than 

2000. This accounted for about 8.5 percent of total uses. This 

includes water that is reserved for instream and wild and scenic 

river flow, which is generally much lower in below normal 

water years. Refuge supplies, which are applied directly onto 

wildlife refuges, accounted for 76,300 acre-feet.

Total water supplies, including local and imported CVP and SWP 

surface water, groundwater, and reuse, amounted to 12.3 million 

acre-feet, 1 percent less than 1998 and 4 percent less than 2000. 

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Selected References

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

Water Resources Control Board 

California’s Groundwater Bulletin 118 (Draft), Update 2003, 

California Department of Water Resources 

Fresno Metropolitan Water Resources Management Plan 

Phase III Report Implementation Plan Excerpts, city of 

Fresno Planning Library Web site, 

www.fresno.gov/planning_library/default.asp

Grassland Bypass Project Contaminants Investigation - 

Sacramento Fish and Wildlife Service website: 

http://sacramento.fws.gov/ec/grassland.htm

Nonpoint Source Program Strategy and Implementation 

Plan, 1998-2013, State Water Resources Control Board, 

California Coastal Commission, January 2000 

PPIC Statewide Survey: Special Survey of the Central Valley. 

Public Policy Institute of California. Mark Baldassare. 

April 2004. 

Strategic Plan, State Water Resources Control Board, Regional 

Water Quality Control Boards, November 15, 2001 

Various articles, Fresno Bee newspaper 

Water Quality Control Plan, Regional Water Quality Control Board 

Watershed Management Initiative Chapter, Regional Water 

Quality Control Board 

Westlands Water District Web site, www.westlandswater.org 

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Water Portfolios

Tulare Lake Hydrologic Region

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228 Volume 3 Regional Reports

Table 8-4 Tulare Lake region water portfolio (TAF)

 ID Tulare Lake Tulare Lake Tulare Lake

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 27,305.9 12,692.9 11,563.6

 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 3,621.8 2,397.0 1,698.0

 10 Local Imports - - -

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

 b Central Valley Project :: Project Deliveries 1,811.3 2,280.2 1,787.9

 12 Other Federal Deliveries - - -

 13 State Water Project Deliveries 1,035.0 1,915.2 849.3

 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 - - -

 c Recycled Water - Groundwater - - -

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

 b Return Flow to Developed Supply - Wetlands 3.1 2.5 2.0

 c Return Flow to Developed Supply - Urban - - -

 21a Deep Percolation of Applied Water - Ag 1,368.1 2,058.2 2,155.2

 b Deep Percolation of Applied Water - Wetlands 27.1 29.7 34.5

 c Deep Percolation of Applied Water - Urban 348.2 414.5 431.7

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

 b Reuse of Return Flows within Region - Wetlands, Instream, W&S 3,205.0 1,331.1 964.1

 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 865.3 708.7 652.2

 27 Groundwater Extractions - Banked - - -

 28 Groundwater Extractions - Adjudicated - - -

 29 Groundwater Extractions - Unadjudicated 2,708.0 4,937.4 6,985.2

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

 30 Surface Water Storage - End of Yr 1,303.6 652.2 511.4

 31 Groundwater Recharge-Contract Banking 99.8 167.4 -3.9

 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 39.3 38.5 34.2

 b Evaporation from Reservoirs 232.9 233.8 190.6

 36 Ag Effective Precipitation on Irrigated Lands 2320.5 1121.7 729.6

 37 Agricultural Water Use 7,831.4 10,005.6 9,976.2

 38 Managed Wetlands Water Use 62.9 73.7 76.3

 39a Urban Residential Use - Single Family - Interior 101.6 121.1 126.2

 b Urban Residential Use - Single Family - Exterior 155.1 184.9 192.7

 c Urban Residential Use - Multi-family - Interior 107.0 127.7 132.8

 d Urban Residential Use - Multi-family - Exterior 64.3 76.5 79.8

 40 Urban Commercial Use 37.5 44.6 46.4

 41 Urban Industrial Use 53.5 63.8 66.4

 42 Urban Large Landscape 16.1 19.2 19.8

 43 Urban Energy Production - - -

 44 Instream Flow - - -

 45 Required Delta Outflow - - -

 46 Wild and Scenic Rivers - - -

 47a Evapotranspiration of Applied Water - Ag 5181 7162 7320.4

 b Evapotranspiration of Applied Water - Managed Wetlands 32.7 41.4 38.3

 c Evapotranspiration of Applied Water - Urban 187.1 223.3 232.5

 48 Evaporation and Evapotranspiration from Urban Wastewater - - -

 49 Return Flows Evaporation and Evapotranspiration - Ag - - -

 50 Urban Waste Water Produced - - -

 51a Conveyance Evaporation and Evapotranspiration - Urban 10.6 12.8 13.3

 b Conveyance Evaporation and Evapotranspiration - Ag 433.3 485.5 381.4

 c Conveyance Evaporation and Evapotranspiration - Managed Wetlands - - -

 d Conveyance Outflow to Mexico 

 52a Return Flows to Salt Sink - Ag 457.3 457.3 457.8

 b Return Flows to Salt Sink - Urban - - -

 c Return Flows to Salt Sink - Wetlands - - 0.5

 53 Remaining Natural Runoff - Flows to Salt Sink - - -

 54a Outflow to Nevada - - -

 b Outflow to Oregon - - -

 c Outflow to Mexico - - -

 55 Regional Imports 3,715.7 5,626.6 3,695.8

 56 Regional Exports 1856.7 1539.9 1093

 59 Groundwater Net Change in Storage 262.8 -1,625.0 -4,114.9

 60 Surface Water Net Change in Storage 438.3 -56.5 -140.8

 61 Surface Water Total Available Storage 2,046.1 2,046.1 2,046.1

 

 Inflows Outflows Green number signifies included in summary boxes 

 

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Figure 8-4 Tulare Lake 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 8-4, 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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SUMMARY

OUTFLOWS

INFLOWS

Figure 8-5 Tulare Lake region - schematic flow diagram 

In schematic of Table 8-4, 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. 

RUNOFF:

NATURAL: INCIDENTAL: 

PRECIPITATION: TOTAL STREAM 

FLOW: 

AG EFFECTIVE 

PRECIPITATION ON 

IRRIGATED LANDS: 

LOCAL

DELIVERIES:

CVP PROJECT 

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:

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: 

CONVEYANCE RETURN 

FLOWS:

URBAN: AG:

WETLANDS:

CONVEYANCE SEEPAGE: 

URBAN: AG:

WETLANDS:

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

8 24 Chapter 8 Tulare Lake Region Volume 3 Regional Reports

California Water Plan Update 2005

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Chapter 9 North Lahontan Hydrologic Region 

Volume 3 

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Chapter 9 North Lahontan Hydrologic Region 9 i

California Water Plan Update 2005

Chapter 9 North Lahontan Hydrologic Region

Contents

Chapter 9 North Lahontan Hydrologic Region ...........................................................................................................9-1

Setting ................................ 9-1

Climate ............................... 9-1

Population .......................... 9-1

Land Use ............................ 9-1

Water Supply and Use ......... 9-2

State of the Region .............. 9-5

 Challenges .................... 9-5

 Accomplishments ........... 9-6

Relationship with Other Regions ...........................................................................................................................9-7

Looking to the Future ........... 9-8

Water Portfolios for Water Years 1998, 2000, and 2001 .......................................................................................9-8

 Selected References ............. 9-8

Figures

Figure 9-1 North Lahontan Hydrologic Region (map) .................................................................................................9-ii

Figure 9-2 North Lahontan Hydrologic Region population ..........................................................................................9-3

Figure 9-3 North Lahontan region water balance for water years 1998, 2000, 2001 (2 bar charts) ..............................9-4

Figure 9-4 North Lahontan region - illustrated water flow diagram ...........................................................................9-13

Figure 9-5 North Lahontan region - schematic flow diagram ....................................................................................9-14

Tables

Table 9-1 North Lahontan Hydrologic Region water balance summary ........................................................................9-9

Table 9-2 North Lahontan Hydrologic Region water use and distribution of dedicated supplies ....................................9-10

Table 9-3 North Lahontan region water portfolios ....................................................................................................9-12

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California Water Plan Update 2005

Some Statistics

 Area - 6,122 square miles (3.9% of State)

 Average annual precipitation - 23.1 inches

 Year 2000 population - 99,035

 2030 population projection -130,800

 Total reservoir storage capacity - 1,181 TAF

 2000 irrigated crop area - 125,200 acres

.

.

.

.

.

.

NEVADA

SIERRA

PLACER

EL DORADO

ALPINE

TUOLUMNE

MODOC

LASSEN

Flow in TAF

1998

1

2000

1

2001

1

South Lahontan Region

Virginia Creek

Flow in TAF

1998

1,391

2000

754

2001

552

Outflow to Nevada

Flow in TAF

1998

0

2000

1

2001

2

Sacramento River Region

Echo Lake Conduit

Flow in TAF

1998

10

2000

9

2001

7

Sacramento River Region

Little Truckee

Flow in TAF

1998

3

2000

3

2001

3

Sacramento River Region

Pit River

Figure 9-1 North Lahontan Hydrologic Region

The North Lahontan Hydrologic Region is in the northeast corner of California, and its surface waters drain eastward toward Nevada. 

Arrows indicate annual flows entering and leaving the region for water years 1998, 2000, and 2001.

EE-RM-PET-100 C0MMENT 01A
Chapter 9 North Lahontan Hydrologic Region 9 1

California Water Plan Update 2005

Chapter 9 North Lahontan Hydrologic Region

Population

By 2000, about 99,000 people, a quarter of 1 percent of 

California’s population, lived in the North Lahontan Region. The 

largest population center is the city of Susanville, the county seat 

of Lassen County. The cities of Truckee and South Lake Tahoe 

have large permanent populations, and large transient tourist 

populations during the summer and winter holidays. 

It is estimated that the region’s population will grow to 

130,800 by 2030. Most of this growth is expected to 

occur around the existing urban communities of Susanville, Lake Tahoe, Truckee, and the adjacent Martis 

Valley area. Figure 9-2 provides a graphical depiction 

of the North Lahontan region’s total population from 

1960 through 2000, with current projections to 2030. 

Land Use

Much of the region is either national forest or lands under the 

jurisdiction of the Bureau of Land Management. Cattle-ranching is the principal agricultural activity with pasture and alfalfa 

being the dominant irrigated crops. Commercial crop production 

is very limited because of the short growing season. Although 

growing seasons vary considerably each year, the mountain 

valleys where most crops are grown are usually frost free from 

late May to mid-September or about 120 days.

Tourism and recreation are the principal economic activities in 

the Truckee-Tahoe area and the surrounding mountains. On a 

typical summer day, the number of visitors in the Tahoe basin 

often exceeds the number of full-time residents. In the Lake 

Tahoe Basin, urban growth is tightly controlled by the Tahoe 

Regional Planning Agency, which is responsible for protecting 

the sensitive environment and water quality of the basin. To 

the north, the town of Truckee and the adjacent Martis Valley 

region are experiencing more rapid urban development. 

For environmental purposes, the principal consumptive use 

of water is for the State wildlife areas around Honey Lake, 

Setting

The North Lahontan Hydrologic Region forms part of the 

western edge of the Great Basin, a large landlocked area 

that includes most of Nevada and northern Utah. The crest 

of the Sierra Nevada forms much of the western boundary of 

this region. All surface water in the region drains eastward 

toward Nevada. This hydrologic region extends about 270 

miles from the Oregon border to the southern boundary of 

the Walker River drainage in Mono County (Figure 9-1). 

The region covers 6,122 square miles, about 4 percent 

of California’s total area. The region includes portions of 

Modoc, Lassen, Sierra, Nevada, Placer, El Dorado, Alpine, 

Tuolumne, and Mono counties. The northern part of this 

region is primarily arid high desert with relatively flat valleys 

at elevations of 4,000 to 5,000 feet, bordered on the west by 

mountain peaks that reach between 7,000 and 9,000 feet. 

The central and southern portions of this region are comprised 

of the eastern slopes of the Sierra Nevada and include the 

California portion of the Lake Tahoe Basin. The major rivers of 

the region are the Truckee, Carson and Walker, which carry 

the mountain snowmelt into Nevada. The mountain crests 

up to 11,000 feet form the western boundary of the region. 

Climate

The region’s climate is characterized by dry summers with 

the exception of occasional scattered thundershowers. Winter 

precipitation ranges from less than 5 inches in the valleys of 

Eastern Modoc and Lassen counties to about 30 inches in 

the Walker Mountains to more than 60 inches in the Sierra 

Nevada in the upper reaches of the Truckee, Carson and 

Walker River basins. Most of the winter precipitation is snow, 

which generally accumulates in mountain areas above 5,000 

feet. In the valleys, winter precipitation is a mixture of rain and 

some snow, which usually melts between storms. Snowpack 

from the eastern slopes of the Sierra Nevada melts in the late 

spring and summer to become the primary source of surface 

water supplies for much of northern Nevada

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California Water Plan Update 2005

9 2 Volume 3 Regional Reports

which provide important habitat for waterfowl and several 

threatened or endangered species, including the bald eagle, 

sand hill crane, bank swallow, and peregrine falcon. 

Water Supply and Use

Unimpaired runoff of the streams and rivers averages 1.6 

million acre-feet per year, of which only about one-quarter is 

in the drier northern portion. The largest rivers in the region 

and their average regulated runoff at the Nevada state line 

are the Truckee River with 540,000 acre-feet; the Carson River, 

335,000 acre-feet; and the Walker River, 300,000 acre-feet. 

The Susan River is the only major river in the northern half of 

the region and its annual discharge at Susanville averages 

60,000 acre-feet.

The Truckee, Carson, and Walker rivers are governed in large 

part by existing federal court water rights decrees administered by court-appointed watermasters. The interstate nature 

of these rivers, combined with the long history of disputes over 

water rights, has created a complex system of river management criteria. On the Carson River for example, more than 55 

years of federal court litigation has been necessary to resolve 

water rights disputes, resulting in approval of the Alpine 

Decree, which governs operation of the river today.

Much of the supply from the Truckee, Carson, and Walker rivers 

has been reserved for use by Nevada interests under various 

historical water rights settlements, agreements, and SWRCB 

surface water rights permits. On the California side of these 

interstate basins, most locally developed water supplies are from 

groundwater or small surface water diversions, with storage 

provided by outlet dams constructed on natural lakes. Figure 

9-3 provides a graphical presentation of all of the water supply 

sources that are used to meet the developed water uses in this 

hydrologic region for 1998, 2000 and 2001. A second chart 

in this figure summarizes all of the dedicated and developed 

The central and southern portions of the North Lahontan region include the eastern slopes of the Sierra Nevada and the California portion of the Lake Tahoe 

Basin. (DWR Photo)

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Chapter 9 North Lahontan Hydrologic Region 9 3

California Water Plan Update 2005

urban, agricultural and environmental water uses within this 

region for the three years.

Lake Tahoe is the largest reservoir in the region, with the top 6 

feet of storage operated by the U.S. Bureau of Reclamation in 

conjunction with the federal watermaster to meet downstream 

water rights in Nevada. Other federal water storage facilities 

in the Truckee River basin include Stampede Reservoir, Boca 

Reservoir, and Prosser Creek Reservoir, constructed primarily 

to provide water supply for urban and agricultural water use in 

Nevada, downstream fl ood protection, protection of threatened 

and endangered species and recreation. Independence and 

Donner lakes are now operated by Truckee Meadows Water 

Authority to supply water to the Reno – Sparks region. The 

U.S. Army Corps of Engineers also completed the Martis Creek 

Dam in 1971 as additional Truckee River fl ood protection for 

the Reno-Sparks area. 

Farther south on the Walker River, both Bridgeport Reservoir 

and Topaz Lake are large reservoirs that capture the spring 

snowmelt from the Sierra Nevada, and are operated by the 

Walker River Irrigation District to provide summer irrigation 

water to Nevada farmers in that watershed.

Most urban water uses in the North Lahontan region are supplied from groundwater wells. There are 24 groundwater basins 

and two subbasins recognized in the region. Thirteen of these 

basins are shared with Nevada and one with Oregon. These 

basins cover about 1,033,240 acres (1,610 square miles) or 

about 26 percent of the entire region. Information about groundwater storage capacities is available for only six of the 26 

basins, and the combined storage for these underground basins 

is estimated at approximately 24 million acre-feet. Although the 

groundwater basins were delineated based on mapped alluvial 

fi ll, much of the groundwater produced actually comes from 

underlying fractured rock aquifers. This is particularly true in the 

volcanic areas of Modoc and Lassen counties where volcanic 

fl ows are interstratifi ed with lake sediments and alluvium. Wells 

constructed in these volcanic formations commonly produce 

large amounts of groundwater, whereas wells constructed in 

fi ne-grained lake deposits produce less. Because the thickness 

and lateral extent of the fractured hard rocks outside of the 

defi ned basin are generally not known, actual groundwater in 

storage in these areas is also unknown. 

About 5,000 acre-feet of reclaimed municipal wastewater 

are exported out of the Lake Tahoe Basin each year by the 

South Tahoe Public Utility District for recharge and agriFigure 9-2 North Lahontan Hydrologic Region population

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

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 the North Lahontan region.

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9 4 Volume 3 Regional Reports

Figure 9-3 North Lahontan region water balance for water years 1998, 2000, 2001

0

100

200

300

400

500

600

700

800

900

1,000

1998 2000 2001

Thousand Acre-Feet

Wild & Scenic

R.

Instream Flow

Managed

Wetlands

Irrigated

Agriculture

Urban

0

100

200

300

400

500

600

700

800

900

1,000

1998 2000 2001

Thousand Acre-Feet

Reuse &

Recycle

Ground Water

Local Projects

Dedicated Water Supplies

Applied Water Uses

Three years show a marked change in the amount and relative proportions of water delivered to North 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).

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Chapter 9 North Lahontan Hydrologic Region 9 5

California Water Plan Update 2005

cultural use in the Carson River watershed. Truckee Tahoe 

Sanitation Agency also treats wastewater from the north end 

of the Lake Tahoe Basin and returns about 4,000 acre-feet 

to the Martis Valley groundwater basin each year. Farther to 

the north, the Susanville Sanitary District reclaims more than 

3,000 acre-feet of wastewater each year for use on nearby 

irrigated pasturelands.

The principal consumptive uses of water for environmental 

uses in the region are those of State wildlife areas around 

Honey Lake. The Honey Lake Wildlife Area in southern Lassen 

County consists of the 4,271-acre Dakin Unit and the 3,569-

acre Fleming Unit. The two units provide important habitat 

for several threatened or endangered species, including the 

bald eagle, sand hill crane, bank swallow, and peregrine 

falcon. This wildlife area has winter-storage rights from the 

Susan River from November 1 until the last day of February. 

The HLWA also operates eight wells, each producing between 

1,260 and 2,100 gallons per minute. In an average year, the 

HLWA floods 3,000 acres by March 1 for waterfowl brood 

habitat.

In 1989, the California Department of Fish and Game purchased the 2,714-acre Willow Creek Wildlife Area in Lassen 

County to preserve existing wetlands and to increase the 

potential for waterfowl production and migration habitat. 

About 2,000 acres are wetlands and riparian habitats. The 

endangered bald eagle and sand hill crane also inhabit this 

area. In addition to the Honey Lake and Willow Creek Wildlife Areas, DFG operates the Doyle Wildlife Area, also in the 

Honey Lake Basin. This wildlife area is protected as dry land 

winter range for deer and requires less water than the Honey 

Lake or Willow Creek areas. 

River flows that have been designated as wild and 

scenic constitute a large part of the environmental water 

use within the North Lahontan region. The east fork 

of the Carson River and the west fork of the Walker 

River are listed as State-designated wild and scenic, for 

the California portions of these two interstate rivers. 

State of the Region

Challenges

Much of the northern portion of North Lahontan region is 

chronically short of water. In the Modoc and Lassen County 

areas drought is a way of life for agriculture, and seasonal 

irrigation takes place only as long as water is available. 

During dry years areas with little or no surface storage may 

only have irrigation water available for a short period early 

in the season, resulting in irrigation of limited acreage unless 

growers are able to supplement their surface water supply 

by pumping groundwater. However in the Modoc and Lassen 

County regions groundwater is also limited and some wellpumping capacities are known to diminish very rapidly during 

the first year of droughts. 

While the Truckee River Operating Agreement has the potential to settle 50 years of disputes over Truckee and Carson 

River waters, the execution and implementation of this agreement will require considerable effort in the coming years. A 

final environmental impact statement /environmental impact 

report (EIS/EIR) is being prepared by the U.S. Department of 

Interior and the California Department of Water Resources to 

evaluate the potential benefits and impacts of TROA, as well 

as alternatives to TROA. After the EIS/EIR is completed and 

certified, TROA will be signed, approved by the courts and 

implemented. The TROA contains 14 chapters with more than 

200 pages of operating criteria and conditions pertaining to 

water priorities, deliveries and operation of the water facilities in the system. 

In the Walker River basin, California and Nevada have been 

discussing interstate water allocation issues that could potentially affect future uses of the river in both states. The primary 

issue of concern is the long-term decline in the water level 

and associated water quality of Walker Lake, which is the 

river’s terminus in central Nevada. The water level at Walker 

Lake is estimated to have declined by about 140 feet from 

an historical high elevation of about 4,080 feet in 1882 to 

3,941 feet in 2003. Starting in the early 1900s much of the 

water in the Walker River was developed to provide water to 

agricultural lands in Nevada. Bridgeport Reservoir and Topaz 

Lake were built upstream to meet those needs. As the uses 

increased, the flows to Walker Lake diminished, and the lake 

has become increasing more saline, such that the lakes historic 

Lahontan cutthroat trout population is severely threatened. 

As the lake has declined, the level of salinity as measured by 

total dissolved solids (TDS) has increased to measured values 

of 13,000 ppm TDS. Significant increases in the amount of 

fresh water entering Walker Lake will be needed in order to 

maintain or restore the fishery, which would likely affect the 

water uses and supplies of all upstream parties in both states. 

Other issues that could also affect existing water users in this 

basin are the potential water rights claims of the Walker River 

Indian Reservation, which is just upstream of Walker Lake.

Water quality in the North Lahontan region is generally very 

good, but many communities face specific water quality 

EE-RM-PET-100 C0MMENT 01A