Although there are extensive resources in the state, most urban population reside in the water-scare coastal and southern region and most agricultural activities are in semi-arid lands. To accommodate the growth in population, California and the federal government, built a complex and expansive network of dams, aqueducts, and pumping facilities to harness California’s water supplies and deliver them to its cities and agricultural areas . Today, California’s water resources support over 38.3 million people , a $2.2 trillion economy , and the largest agricultural sector in the country . California’s rivers, streams, lakes, and estuaries are also home to a vast array of aquatic species and habitats, and support substantial aquatic recreation. The state’s water system has a total storage capacity of about 43 million acre-feet and includes hundreds of miles of aqueducts to deliver supplies to places of need and hundreds of thousands of wells to tap the state’s vast groundwater resources . The system is comprised of federal, state and local projects and it’s operated by federal, state, regional, and local organizations as shown in Figure 2-1. The Central Valley Project was authorized in 1935 by the federal government to increase the Central Valley’s resilience to drought and protect it from flooding. Shasta Dam was the first dam to be built as part of the CVP and was initiated in 1938. In 1979, the last dam, New Melones, was completed. The CVP system includes 18 other dams and reservoirs, 11 power plants, and 500 miles of conveyance and related facilities .
The CVP has facilities on the Trinity, Sacramento, American, Stanislaus, and San Joaquin Rivers,blueberry plant size and it serves over 250 long-term water contractors in the Central Valley, Santa Clara Valley, and the San Francisco Bay Area . The total annual contract exceeds 9 MAF . Historically, 90% of CVP deliveries serve agricultural users. In 2000, the CVP and other smaller federal projects delivered about 7.5 MAF to users. About 35% went to the Sacramento River region, 31% went to the Tulare Lake region, and 24% went to the San Joaquin region. Smaller shares went to the North Coast, San Francisco and Central Coast regions . Agricultural users served by the CVP will likely experience additional price increases . CVP contractors are currently behind on repaying the project costs. Under the original contracts, which were negotiated and signed in the late 1940s, the project was to be paid off 50 years after its construction . By 2002, however, irrigators had repaid only 11 percent of the project cost . Based on an analysis of 120 CVP irrigation contracts and a review of full cost rates, which include cost of service and interest on unpaid capital costs since1982 , water contractors will need to pay on average an additional 196 percent to be brought up to full cost rates. Combining the estimated price increases for CVP contractors with rising cost of service rates for the remainder of agricultural water users, Gleick et al 2005 projected that overall agricultural water price will increase by 68 percent statewide between 2000 and 2030. The State Water Project was the first stage of an ambitious strategy outlined in 1957 State Water Plan to improve the reliability and capacity of water delivery throughout California. The SWP captures large amounts of water behind 28 different dams in the Western Sierra Nevada. The Oroville Dam, the largest in the system with a capacity of 3.5 MAF, began construction in 1961 and was completed in 1967.
The dams control the flow of water through the Sacramento River system, in order to maximize the amount of fresh water that can be pumped out of the Bay-Delta into the California Aqueduct. The California Aqueduct then transports the supply south through the San Joaquin Valley to Southern California and the Central Coast. The transport of water is facilitated by 26 pumping and generating plants and about 660 miles of aqueducts. The last major component of the system – the Coastal Branch, which delivers supply to Santa Barbara and San Luis Obispo counties, was completed in 1997. Prior to the commencement of construction of the SWP, contracts were signed between the DWR, the managers of SWP, and urban and agricultural water districts. Since the signing of the contracts in the 1960s, the capabilities of the system have not fully developed, and the SWP regularly does not meet all of its obligations. In 1998, existing long-term SWP water supply contracts totaled about 4.1 MAF , and these contracts are scheduled to increase to about 4.2 MAF by 2020 . In the year 2000 , however, the SWP delivered only 2.9 MAF of Table A water . DWR’s State of Water Project Delivery Reliability Report confirms that without additional facilities, the SWP will consistently be unable to meet its obligations to Table-A contractors. The Department of Water Resources administers long-term water supply contracts to 29 local water agencies for water service from the State Water Project. These water supply contracts are central to the SWP construction and operation. In return for State financing, construction, operation, and maintenance of Project facilities, the agencies contractually agree to repay all associated SWP capital and operating costs. To provide a convenient reference, SWP Analysis Office has prepared consolidated contracts for several contracting agencies.
These contracts contain the amendments integrated into the language of the original contract. Listed below, under the names of the contracting agencies, are the consolidated contracts and original contracts. DWR plans to add more consolidated long-term water supply contracts as they are completed. The 29 State Water Project contractors are shown in Table 2-1.The Bay-Delta ecosystem is a major hub of the state’s water re-distribution system. In order for the large freshwater of the Sacramento River and its tributaries to be made available to users in the southern half of the state, they must flow from north through the Sacramento-San Joaquin Delta and then be pumped out of the Delta in South into the aqueducts of the State Water Project. An extensive system of levees has also developed over the years to protect agricultural and urban land holdings within the delta from water intrusion and flooding. Together, the pumping of freshwater from the south to the delta and the artificial support of the Delta’s numerous islands has dramatically altered the natural hydrology and ecosystem function of the Bay-Delta system. In response to dramatic declines in Delta ecosystem quality during the 1987-1992 drought, a Federal and State partnership was established in 1994. The purpose of the multibillion dollar restoration and management effort, now managed by the California Bay-Delta Authority is to restore ecosystems within the Delta, improve the quality and reliability of water supplies from the Delta, and stabilize the Delta’s levee systems . The challenge of this mandate is immense, particularly when considered along with potential climate change . The incongruent nature of the program’s objectives has arguably hampered its effectiveness to date,plant raspberry in container yet the effort continues and will remain a significant consideration in future California water management and planning. Prior to extensive human development, the San Francisco Bay-Delta was largely marsh, river channels, and islands, bounded in the west by the Golden Gate Strait and Pacific Ocean and in the East by the confluence of the Sacramento and San Joaquin Rivers which drain the Sierra Nevada Mountains to the Pacific Ocean. The Bay-Delta in its natural state was an enormous estuary and supported extensive habitat for fish, birds, and other terrestrial animals. Water flowing through the Delta is the main source of supply for two major California water delivery projects, the SWP and the Federal CVP. From these projects, a majority of Californian relies on water flowing through the Delta for all or part of their drinking water. In addition, approximately one third of the state’s cropland uses water flowing through the Delta . Figure 2-2 shows the Bay Delta water distribution during a typical hydrological year. The Colorado River supplies Southern California with more than 4 MAF a year of water via the Colorado River Aqueduct and the Coachella and All American Canals.
The Colorado River Compact, signed six states bordering the Colorado River in 1922, established California’s base water entitlement to be 4.4 MAF a year. In recent years, however, California has relied upon the unused allocation of upstream states, importing more than 0.8 MAF a year of additional supply some years . Due to growing water use by other states, California was forced to reach an agreement to gradually eliminate its use of surplus water. The Colorado River Quantification Settlement Agreement resolves much of the uncertainty over Colorado River allocations, but an on-going drought in the Colorado River basin still threatens future Colorado River water availability to California. The iconic Colorado River supplies water to millions of people in fast-growing cities in Colorado River’s watershed, such as Las Vegas, Mexicali, Phoenix, and St. George, Utah. Tens of millions of people outside the watershed, from Denver to Albuquerque and from Salt Lake City to Los Angeles, San Diego and Tijuana, also receive water exported from the basin to meet at least some of their residential and commercial water needs. More than half of the people receiving water from the basin live in Southern California . Figure 2-3 shows historical water supply and usage for the Colorado River Basin from 1914 to 2007. Local cities in California have also taken initiative to develop water supplies. The cities of Los Angeles, San Francisco, and several in the East Bay region have all financed and constructed infrastructure to capture, store, and transport water from sources far away from the municipalities. Specifically, the Los Angeles Aqueduct transports water over 200 miles from the Owens Valley to the Los Angeles area; the O’Shaughnessy Dam captures and stores water in the Hetch Hetchy Valley for delivery to San Francisco and surrounding cities; and the PardeeReservoir and Mokelumne Aqueducts supply the East Bay Municipal Water District service area with supplies from the western slopes of the Sierra Nevada . Groundwater is a major source of water for California’s agricultural industry and municipalities. During an average year a third of the state’s water supply comes from groundwater. Some regions are entirely dependent on groundwater, and 40-50% of Californians use some amount of groundwater . Much of the state’s groundwater resources have been developed locally by individual landowners or municipalities. Such decentralized management has led to unsustainable groundwater use in California. Estimates by DWR in 1980 suggest that use of groundwater exceeds recharge by between 1 and 2 MAF per year . Such overuse has led and will continue to lead to many serious problems including land subsidence, sea water intrusion, and degradation of groundwater quality. Groundwater is currently managed through local water agencies, local groundwater management ordinances, and court adjudication. Importantly, state and regional planning agencies have little influence or control over the management of groundwater, making it difficult to implement integrated surface and groundwater management plans. The total groundwater storage in California is estimated to be about 1.3 billion acre-feet and about 140 MAF of precipitation percolates into the state’s aquifer annually . These estimates however, do not characterize the potential water supply for the region – many other factors limit the development potential of an aquifer . Most of the state’s groundwater is located in the aquifers beneath the Central Valley, although Southern California also has considerable amount of groundwater. Groundwater is a major contributor to the state’s water supply and even more so in dry years. As shown in Figure 2-4, groundwater supplies on average 30 percent of California’s overall demand and up to 40 percent in dry years . In some areas where surface water supplies are not accessible or economically feasible, groundwater provides 100 percent of a community’s public water . During years where surface water deliveries are not available, groundwater may also provide up to100 percent of irrigation water for certain areas. About 43 percent of Californians obtain at least some of their drinking water from groundwater sources. Local municipalities and regional water agencies are increasingly turning to alternative sources of water supply. Treated urban wastewater is becoming an important source of water for agriculture, industry, landscaping, and some non-potable uses in commercial and institutional buildings. In many regions it is discharged into rivers and streams and thus used by downstream users. In some regions it is also blended with conventional sources and is injected or allowed to percolate into groundwater basins.