DELTA WATER PROJECTS SUMMARY
Modeling Description of the Sacramento-San Joaquin Delta and
Suisun Marsh Constraints on the SWP/CVP Water System
By Armin Munévar
1.0 INTRODUCTION
The Delta of the Sacramento and San Joaquin rivers is the major collection point for California’s complex water system and the focus of increased debate regarding a number of complicated water-related issues. Over 20 million people, nearly two-thirds the State’s population, depend on water from the Delta for their daily water requirements: from irrigation on agricultural lands in the San Joaquin Valley to urban and industrial uses in the Metropolitan Water District of Southern California’s (MWDSC) densely populated service area. The Delta also provides important habitat for numerous species of fish, bird, mammal, and plant and serves as a major recreation area. The protection of these varied, and often divergent, interests has made the Delta one of the most regulated watercourses in the world. State and federal agencies have imposed water quantity and quality standards to protect the general estuarine habitat, and water project operations have been modified to meet these constraints. The modeling of these system/operational constraints in a new State water resources simulation model, CalSim, is described in this report.
Description of the Delta
The Delta, which has legal boundaries established in California Water Code Section12220, comprises a 738,000 acre area generally bordered by the cities of Sacramento, Stockton, Tracy, and Pittsburg (Fig. 1). This former wetland area has been reclaimed into more than 60 islands and tracts devoted primarily to farming and protected from river waters and tides by a 1,110-mile network of levees. Oxidation, shrinkage, and erosion of the Delta peat soils have caused subsidence of many of the island lands. As a result, several tracts and islands are now well below mean sea level.
The Sacramento and San Joaquin rivers unite at the western end of the Delta near Suisun Bay. The Sacramento River contributes about 85% of the Delta inflow on average, while the San Joaquin River contributes 10 to 15%. The Mokelumne, Consumnes, and Calaveras rivers, known collectively as the "East Side streams", contribute the remainder of the Delta inflow. The rivers flow through the Delta and into Suisun Bay. From Suisun Bay water continues through the Carquinez Strait and into San Pablo and San Francisco bays, and finally out to sea through the Golden Gate.
Tidal influence and subsequent saltwater intrusion is important throughout the Delta. Historically, during dry summer months, when mountain runoff is reduced, ocean water intruded inland as far as Sacramento. During the wet winter and spring, freshwater inflows to the Delta pushed the salt water as far back as the Golden Gate. Development of Shasta, Oroville, and Folsom dams on the Sacramento River and its’ tributaries, and their companion export facilities in the Delta, have altered the seasonal fluctuations of salt water intrusion. Winter and spring inflows have typically decreased, while summer and fall inflows have increased from their historical values due to these controlling facilities. The salinity of the main channels in the Delta is now managed by controlled releases from the upstream storage reservoirs.
On average, approximately 21 MAF of water reaches the Delta annually, but varies considerably depending on the wetness of the year. During the drought year of 1977 only 5.9 MAF reached the Delta, while in the wet year of 1983 the inflow was over 70 MAF. During a normal water year, about 10% of the water reaching the Delta would be withdrawn for local use and 30% would be withdrawn for export by the SWP and CVP. Approximately 20% of the inflow would be required for salinity control, and the remaining 40% would become Delta outflow in excess of the minimum requirements.
The Delta contains a high level of diversity of wildlife and fish species that live within, or depend upon, the watercourses. Waterfowl, migratory birds, numerous game and non-game birds, furbearers, and other mammals are dependent on the estuarine environment and riparian vegetation supported by the Delta’s waters. The Delta is particularly important for waterfowl migrating via the Pacific Flyway as it serves as their major wetland habitat. The Bay-Delta Estuary supports about 90 species of fish including several anadromous species, such as chinook salmon, striped bass, sturgeon, American shad, and steelhead trout. Other fish species include Delta smelt, Sacramento splittail, Sacramento perch, catfish, largemouth bass, black bass, crappie, and bluegill. Food supplies for the fish species include phytoplankton, zooplankton, benthic invertebrates, and insects. Overall productivity at the lower food chain levels is believed to have decreased during the past 15 years.
Biological production in the Estuary may be higher in the entrapment zone where freshwater from Delta outflow mixes with salt water from the bay. The entrapment zone concentrates sediments, nutrients, phytoplankton, striped bass larvae, and other organisms needed as fish food. It is considered advantageous to have sufficient Delta outflows to maintain the entrapment zone in the upper reaches of Suisun Bay, where it can spread out over a large area, rather than constricted to the narrower Delta channels upstream of the Suisun Bay.
Numerous threatened or endangered vertebrate species are known to live within the Delta. Seven listed species are birds (bald eagle, American peregrine falcon, Swaison’s hawk, California black rail, Aleutian Canada goose, tricolored blackbird, and western yellow-billed cuckoo), two are mammals (salt marsh harvest mouse and San Joaquin kit fox), two are reptiles (giant garter snake and southwestern pond turtle), two are amphibians (California tiger salamander and California red-legged frog), and four are fish (winter-run chinook salmon, Delta smelt, Sacramento splittail, and Sacramento perch). In addition, there are five invertebrate species and twelve plant species found in the Delta that are listed as endangered or threatened.
The Suisun Marsh, while just outside of the legal Delta, is included in this report because of its’ importance in formulating many of the water quality and flow standards that directly affect water project operations. The Suisun Marsh is one of the few major marshes remaining in California and the largest remaining brackish wetland in western North America. Most of the Marsh consists of managed diked wetlands; however, numerous studies have established that tidal marshlands can have significant geomorphic and ecological values, including flood control, shoreline stabilization, sediment entrapment, water quality improvement, and food chain support for aquatic, semi-aquatic, and terrestrial plants and animals. Waterfowl are attracted to the Marsh by the water and abundance of natural food plants, which require the proper soil and water salinity. The dominant fish species found in Suisun Marsh is the striped bass, for which the Marsh is an important nursery area.
Delta Facilities
The Department of Water Resources (DWR) and U.S. Bureau of Reclamation (USBR) both have constructed various facilities within the Delta to facilitate the export, conveyance, and distribution of water for their respective projects. The State Water Project and Central Valley Project use the Sacramento River and channels in the Delta to transport water to the export pumping plants in the southern Delta. Due to the complexity of the Delta hydraulics and the wide range of water quality, flow, and operational standards, a detailed understanding of the structural facilities present in the Delta is imperative. This section attempts to summarize the major facilities in a concise manner.
State Water Project
The State Water Project collects runoff from the Feather River basin in Lake Oroville and conveys its stored water to the Banks pumping plant in the Delta using the Sacramento River channel. Water in the Delta is then exported to agricultural and municipal contractors in the San Joaquin Valley and southern California. The facilities associated with, and owned by, the State Water Project are described below.
Clifton Court Forebay (CCF)
This 31 TAF storage reservoir serves as the forebay for Banks Pumping Plant (BPP). CCF moderates the effects of the pumping on fluctuations of flow in adjacent Delta channels. The intake channel from to CCF to BPP is approximately 1 mile.
Harvey O. Banks Pumping Plant (BPP)
This is the major pumping plant for the SWP and pumps water from CCF into Bethany Reservoir at the head of the California Aqueduct (CAQ). There are a total of 11 pumps (2@375cfs, 5@1130cfs, and 4@1067cfs) with maximum pumping capacity of 10,670 cfs, but is limited to discharge channel capacity of 10,300 cfs.
California Aqueduct (CAQ)
This is the major north-south conveyance facility for the SWP. Begins at CCF, through Bethany Reservoir, and ends at the terminal reservoirs, Lake Castaic and Lake Perris. Maximum nominal capacity is 10,300 cfs between CCF and Bethany and 10,000 cfs between Bethany and O’Neil Forebay at San Luis.
John E. Skinner Fish Protective Facility
This facility intercepts fish that would otherwise be entrained into BPP pumps and CAQ and relocates captured fish elsewhere in Delta.
Barker Slough Pumping Plant (BSPP)
BSPP pumps water from Barker Slough into the North Bay Aqueduct (NBAQ). The maximum pumping capacity at Barker Slough is 228 cfs, but is limited to the pipeline capacity of 175 cfs. The intake contains fish screens.
North Bay Aqueduct (NBAQ)
NBAQ receives water from the BSPP and delivers to areas in Napa and Solano counties. The aqueduct (pipeline) design capacity is 175 cfs.
South Bay Pumping Plant (SBPP)
SBPP pumps water from Bethany Reservoir at the head of CAQ and into the South Bay Aqueduct. Maximum pumping capacity is 330 cfs, but is limited to the aqueduct channel capacity of 300 cfs.
South Bay Aqueduct (SBAQ)
The SBAQ conveys water from the SBPP to counties in the South Bay. Maximum channel capacity is 300 cfs.
Suisun Marsh Salinity Control Structure (SMSCS)
The SMSCS, consisting of 3 radial gates, spans Montezuma Slough in Suisun Marsh and has a width of 465 feet. The gates restrict the flow of salty water from Suisun Bay during flood tides and allow Sacramento River flow during ebb tides. The SMSCS helps meet water quality standards in the Marsh channels.
Central Valley Project
The Central Valley Project has major storage reservoirs on the Sacramento and American rivers, Lake Shasta and Lake Folsom, and, similar to the SWP, conveys its stored water to the Tracy pumping plant in the Delta using the Sacramento River channel. CVP water is supplied to agricultural contractors both upstream and south of the Delta. Exports south of the Delta are primarily for agriculture in the San Joaquin Valley. The facilities associated with, and owned by, the Central Valley Project are described below.
Tracy Pumping Plant (TPP)
This is the major pumping plant for the CVP and pumps water from the Old River channel into the Delta-Mendota Canal (DMC). A 2.5 mile intake channel brings water from the Old River to 6 pumps (1 @ 800 cfs, 2 @ 850 cfs, 3 @ 950 cfs) for a total pumping capacity of 5,350 cfs. However, pumping is limited to DMC channel capacity of 4,600 cfs.
Delta-Mendota Canal (DMC)
The DMC is the major south of Delta conveyance facility for the CVP. It receives water from TPP, delivers water to San Joaquin contractors, and terminates at the Mendota pool. Nominal capacity is 4,600 cfs near Tracy PP
Tracy Fish Protection Facility
This fish protection facility is similar to the SWP Skinner facility. Intercepts fish at intake screens and relocates fish by tanker to release sites away from pumps.
Delta Cross Channel (DXC)
The DXC is gated diversion on Sacramento River near Walnut Grove and Snodgrass Slough. When the gates are open, water is diverted through the natural channels of Mokelumne and San Joaquin rivers towards the pumping plants in the south Delta. It increases circulation of high quality Sacramento River water toward the pumping plants.
Contra Costa Canal
This is a CVP facility but is operated and maintained by Contra Costa WD. Water is pumped from Rock Slough in the south Delta and is conveyed by this canal to Contra Costa County. Historical pumping at PP#1 is between 50 and 250 cfs.
Other
City of Vallejo Pipeline
This pipeline pumps water from Cache Slough in north Delta, near Barker Slough and the NBAQ intake. Diversion amounts are modeled as constant for all years and only varying by month. Diversion range from 0 to 33.6 cfs.
2.0 LEGISLATIVE HISTORY
The legislative history of the water quality control plans, water rights decisions, and biological opinions concerning the Bay-Delta is reviewed briefly in this section as they affect the SWP/CVP operation. For a more complete summary of legislative action, the reader is directed to Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta Estuary, Environmental Report, Appendix 1 (May, 1995).
State Water Rights Board Decision 990 (February, 1961)
Decision 990 approved water rights for the federal Central Valley Project’s Shasta Dam, Tehama-Colusa Canal, Corning Canal, Delta-Mendota Canal, and Contra Costa Canal. It did not attach any specific water quality standards, but reserved jurisdiction to impose such requirements in the future.
SWRB Decision 1275 (May, 1967)
Decision 1275 approved water rights required for the operation of the State Water Project. Adopted agricultural water quality standards to protect water rights in the Delta. D-1275 also determined that water was not available to the SWP for diversion from the Feather River or the Delta in July, August, and September.
SWRCB Resolution 68-17 (1968)
Secretary of Interior requested supplemental water quality objectives for chloride and TDS concentrations to protect municipal, industrial, agricultural, and fishery uses in the Delta. He approved the State water quality objectives, even though they failed to satisfy the federal recommendations regarding the spawning of striped bass and uses in the western Delta.
SWRCB Decision 1379 (July, 1971)
Required SWP and CVP to meet standards for non-consumptive fish and wildlife uses in addition to agricultural, municipal, and industrial consumptive uses in accordance with Resolution 68-17. Decision was stayed by court action by SWP and CVP contractors and no court ruled on this decision until it was superseded by D-1485.
SWRCB Resolution 73-16 (April 1973)
Implemented State "Water Quality Control Plan Supplementing State Water Quality Control Policies for the Sacramento-San Joaquin Delta". Clarified conditional approval previously received by federal government.
SWRCB Decision 1485 and 1978 Delta Plan (August 1978)
Decision 1485 and the 1978 Delta Plan revised existing standards for flow and salinity in Delta channels and required USBR and DWR to meet standards by either reducing pumping or releasing more water upstream or both. Plan was committed for ten years.
SWRCB Draft 1998 Delta Plan (November, 1998)
Draft water quality control plan met with intense opposition and was withdrawn in January 1989. SWRCB decided thereafter to bifurcate the process. It first prepared a draft water quality control plan that did not include flow and export objectives. The plan was to be followed with a water rights decision that would contain flow and export requirements and allocate responsibility to meet all standards.
SWRCB 1991 Bay-Delta Plan (May 1991)
Bay-Delta Plan adopted with objectives for salinity, dissolved oxygen, and temperature. Litigation ensued. Submitted to USEPA for approval. September 1991, USEPA approved all salinity objectives for agricultural, municipal, and industrial beneficial uses, and dissolved oxygen objective for fish and wildlife beneficial uses. However, the USEPA disapproved all other fish and wildlife objectives because of failure to protect estuarine habitat and other beneficial uses.
SWRCB Draft Water Right Decision 1630 (December 1992)
At Governor Wilson’s behest, a hearing process was begun to develop interim protections to stop decline of fish and wildlife resources in the Bay-Delta Estuary. D-1630 proposed interim water right terms and conditions to protect the Estuary. In April 1993, Governor requested SWRCB cease its work on D-1630 and work on long-term protections. The reasons for the change were the issuance of protections for the winter-run chinook salmon by NMFS, the upcoming protections for Delta smelt by USFWS, and the end of the drought which benefited the fisheries. These protections were adopted under the authority of the Endangered Species Act (ESA).