Chapter III. Environmental setting

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This chapter describes the environmental setting of the proposed project. The environmental setting is defined as the physical conditions which exist within the area which will be affected either directly or indirectly by the proposed project. (Public Resources Code section 15360). The purpose of the Environmental Setting chapter is to provide a baseline of the existing environmental conditions by which to determine the environmental impacts of the proposed action. The environmental setting for this project was described in Chapter IV of the ER (SWRCB 1995). The discussion here details the upstream areas and updates the discussion in Chapter IV of the ER.
Due to the significant interdependence of water supplies and uses in California, implemeting the objectives for the Bay/Delta Estuary is relevant not only to the Estuary itself but also to a large portion of the State. The effects of the SWRCB's water right decision may be seen in the areas that are the source of the water for the Bay/Delta Estuary, as well as the service areas where water from the Central Valley is exported to. The source areas include the Trinity River Basin, Sacramento River Basin, San Joaquin River Basin, the Sacramento-San Joaquin Delta, and Suisun Marsh. The export areas include the San Francisco Bay Region, Tulare Lake Basin, Central Coast Region, and Southern California. The project area is shown in Figure III-1.
The discussion of the environmental setting is organized essentially by the major hydrologic regions as defined in DWR Bulletin 160-93, The California Water Plan Update (DWR 1994). The Trinity River Basin is part of the North Coast Region, however, it is unlikely that any effects of the SWRCB decision will be seen in the North Coast Region outside of the Trinity River Basin. The project area in Southern California includes the South Coast Region, as well as the Antelope Valley and Mojave areas of the South Lahontan Region and the Coachella area of the Colorado River Region. These areas were combined to represent the SWP Southern California service area.
The factors used to describe the existing environmental conditions in the affected areas include: geography and climate, population, land use and economy, water supply (including hydrology and water quality), water use, vegetation, fish, wildlife, and recreation. The source of much of the information on geography and climate, population, land use and economy, water supply, and water use is DWR Bulletin 160-93. Much of the information on hydrology, water quality, vegetation, fish, and wildlife is taken from the State Water Project Supplemental Water Purchase Program, Draft Program Environmental Impact Report (DWR 1996). The discussion of surface water development draws from Bulletin 160-93 (DWR 1994) and the Central Valley Project Improvement Act, Draft Programmatic Environmental Impact Statement, Technical Appendix, Volume 2, Surface Water Supplies and Facilities Operations (USBR 1997a). Information on recreation in the Sacramento River, San Joaquin River, and Tulare Lake regions comes from the Central Valley Project Improvement Act, Draft

Programmatic Environmental Impact Statement, Technical Appendix, Volume 4, Recreation

(USBR 1997b). The discussion of aquatic resources is based in large part on the Recovery Plan for the Sacramento/San Joaquin Delta Native Fishes (USFWS 1996).

This chapter begins with an overview of the Central Valley, including the development of surface water supplies, and the aquatic resources and recreational opportunities found therein. The Central Valley overview includes a discussion of the physical components of the Central Valley Project (CVP), State Water Project (SWP), and local water supply projects. Detailed descriptions of several anadromous fish and other special-status species found in the Bay/Delta Estuary and tributary streams are also presented in the overview.
The Central Valley basin of California (Figure III-2) is comprised of the 450-mile long Central Valley and the surrounding upland and mountain areas which drain into it. The basin encompasses about 60,000 square miles and makes up about 40 percent of California. The basin is entirely surrounded by mountains except for a narrow gap on the western edge at the Carquinez Strait.
Stream flow in the Central Valley is chiefly derived from runoff from the Cascade and Sierra Nevada mountains, with minor amounts from the Coast Ranges. Precipitation totals vary annually with about four-fifths of the total occurring between the last of October and the first of April. Snow storage in the high Sierra delays the runoff from that area until the snow melts in April, May, and June. Normally, half of the annual runoff occurs in these months.
The Central Valley basin is divided into the Sacramento Valley on the north and the San Joaquin Valley on the south. The Sacramento Valley is part of the Sacramento River Basin. The San Joaquin Valley spans two sub basins: the San Joaquin River Basin and the Tulare Lake Basin. These two basins are distinct drainage areas separated by a low divide formed by coalescing alluvial fans. The divide lies between the San Joaquin River to the north and Kings River to the south. Because the rivers and streams in the Tulare Lake Basin do not normally contribute runoff to the Delta, the environmental setting of the Tulare Lake Basin will be discussed as a separate region. The area in the center of the Central Valley where the Sacramento and San Joaquin valleys merge coincides with a break in the coastal mountains which border the basin on the west side. Here the Sacramento and San Joaquin rivers converge in the Bay/Delta Estuary, flow through Suisun Bay and Carquinez Strait into San Francisco Bay, and out the Golden Gate to the Pacific Ocean.
Water is used in the Central Valley basin primarily for growing crops. Water is used to a lesser extent to meet urban, industrial, and instream needs, and for other uses. Surface water supply projects have been developed by local irrigation districts, municipal utility districts, county agencies, private companies or corporations, and State and federal agencies. Flood control, water storage, and diversion works exist on all major streams in the basin, altering the natural flow patterns. These projects also produce hydroelectric power, enhance recreation

opportunities, and serve other purposes. The major surface water supply developments will be discussed in the following sections.
Ground water is also used extensively in the Central Valley. The regional aquifer system beneath the Central Valley is contained in semi-consolidated to unconsolidated marine and continental deposits. Fresh water in these deposits extends to about 1,100 feet below land surface in the Sacramento Valley and to about 1,500 feet below land surface in the San Joaquin Valley. The storage capacity of the Central Valley regional aquifer system has been estimated by DWR to be 64 million acre feet and the perennial yield to be 5.7 million acre-feet. Overdraft conditions exist throughout much of the aquifer system in the San Joaquin Valley. In the Sacramento Valley, overdraft conditions are limited to a few localized areas.
1. Surface Water Development
This section discusses the development of the surface water supplies of the Central Valley. The major developments include the CVP, other federal projects, the SWP, and several local projects.
a. Central Valley Project. The CVP is a water supply, flood control and power generation project owned and operated by the USBR. It is the largest water storage and delivery system in California. Extending from the Cascade Range to the Kern River, the CVP consists of 18 federal reservoirs, plus four additional reservoirs jointly owned with the SWP. It also includes eight hydroelectric plants, two pumping plants, two pump-generating plants, and about 500 miles of major canals and aqueducts. The project stores and controls waters of the Sacramento, Trinity, American, San Joaquin, and Stanislaus river basins. The major features of the CVP are shown in Figure III-3.
The CVP has three main storage facilities in northern California. The principal facility is Shasta Dam and the 4.5 MAF Lake Shasta on the Sacramento River near Redding. Water from the Trinity River, which drains to the Pacific Ocean, is imported into the Central Valley through tunnels connecting to the Sacramento River north of Redding. Clair Engle Lake is the largest storage facility in the Trinity River Division. Folsom Dam is located on the American River about 30 river miles upstream from its confluence with the Sacramento River. These main reservoirs of the CVP have a total storage capacity of about 8 MAF. The major storage facilities south of the Delta include New Melones Reservoir on the Stanislaus River, Millerton Lake on the San Joaquin River, and San Luis Reservoir. San Luis Reservoir is a pumped-storage reservoir on the west side of the San Joaquin Valley shared with the SWP. The storage facilities south of the Delta provide an additional 4 MAF storage capacity for the CVP.
A number of conveyance and pumping facilities are used to distribute water throughout the CVP service area. The major conveyance facilities of the CVP include the Corning and Tehama-Colusa canals which divert water from the Sacramento River to serve the west side of the Sacramento Valley, the Contra Costa and Delta-Mendota canals which divert water from the Delta, the San Luis Canal which carries water along the west side of the San Joaquin

Valley, and the Madera and Friant-Kern canals which divert water from the San Joaquin River and distribute it along the east side of the San Joaquin Valley and Tulare Lake Basin. Tracy Pumping Plant pumps most of the water that the CVP exports from the Delta.

The CVP supplies water to over 250 long-term water contractors whose contracts total 9.3 MAF per year. Of the 9.3 MAF, 6.2 MAF is project water, including 1.4 MAF of Friant Division Class 2 supply in wet years, and 3.1 MAF is water right settlement water. Water right settlement water is diverted by water right holders whose diversions were in existence before the project was constructed. The diversions are made in accordance with agreements between the CVP and the water right holders. Average-year deliveries by the CVP have been around 7 MAF. Figure III-4 shows the CVP contractors' service areas. Figure III-5 shows CVP deliveries for the period 1960-1996.
About 90 percent of the CVP water has gone to agricultural uses in the recent past; this includes water delivered to prior right holders. CVP water is used to irrigate some 19,000 farms covering 3 million acres. Currently, increasing quantities of water are being served to municipal customers. Urban areas receiving CVP water supply include Redding, Sacramento, Folsom, Tracy, most of Santa Clara County, northeastern Contra Costa County, and Fresno.
Water stored in CVP northern reservoirs is gradually released down the Sacramento River, where it helps meet contract commitments along the river and quality and flow requirements in the Delta. The remainder is exported via the Contra Costa Canal and the Delta-Mendota Canal. Excess water during the winter is conveyed to off-stream storage in San Luis Reservoir on the west side of the San Joaquin Valley for subsequent delivery to the San Luis and San Felipe units.
Many of the CVP contractors in the Sacramento Valley held prior rights to the waters of the Sacramento River. Since construction of the CVP altered the natural flows upon which water right holders had relied, contracts were negotiated to serve the users stored water to supplement the river flows available under their water rights. CVP contractors with prior water rights on the Sacramento River (called settlement contractors) receive their supply from natural flow and storage regulated at Shasta Dam. Table III-1 shows base entitlement, project entitlement, and average deliveries from the main stem of the Sacramento River for some of the largest CVP contractors in the Sacramento Valley. The Tehama-Colusa and Corning canals serve an area on the west side of the Sacramento Valley. Table III-2 shows project entitlement and average deliveries for CVP contractors served by the Tehama-Colusa and Corning canals.
Settlement contractors on the San Joaquin River (called exchange contractors) receive Delta water via the Delta-Mendota Canal. A portion of the water exported from the Delta via the Delta-Mendota Canal is placed back into the San Joaquin River at Mendota Pool to serve, by exchange, water users who have long-standing historical rights to use of San Joaquin River flow. This exchange enabled the CVP to build Friant Dam on the San Joaquin River, northeast of Fresno, and divert a major portion of the flow from the river at that point. Most of the

Figure III-5

Central Valley Project Deliveries, 1960 to 1996

(Million of acre-feet)

Table III-1. CVP Sacramento River Settlement Contractors


Total Project






Glen Colusa I.D.

154.8 R




Sutter Mutual Water Co.

32.4 L




Anderson Cottonwood I.D.

240.5 L




Reclamation District #108

43.1 R




Natomas Central Mutual Water Co.

2.15 L




Reclamation District #1004

85.3 L




Princeton-Codora-Glen I.D.

112.3 R




Provident I.D.

124.2 R




Conaway Conservancy

12.0 R




Olive Percy Davis Trust

77.8 R




Meridian Farms Water Co.

71.1 R




River Garden Farms Co.

3405 R




Pleasant Grove-Verona MWC

19.6 L




Colusa Drain MWC





City of Redding

246.0 L




Total, Fifteen Major Contractors


Total, 124 Other Settlement Contractors


Majors as % of Grand Total


Table III- 2. CVP Deliveries to Tehama-Colusa Canal Contractors

Total Project





Orland-Artois Water District



Colusa County Water District



Kanawha Water District



Westside Water District



Corning Water District



Glide Water District



Dunnigan Water District



Westside Water Dist. (from Colusa Co.)



Thomes Creek Water District



Proberta Water District



Davis Water District



La Grande Water District



4-M Water District (from Colusa Co.)



Holthouse Water District (from Colusa Co.)



Cortina Water District (from Colusa Co.)



Colusa Co. Water Dist (from Colusa Co.)



La Grande Water Dist. (from Colusa Co.)



Glenn Valley Water District



Kirkwood Water District



Myers-Marsh MWC (from Colusa Co.)





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