State Water Project
In 1960, California voters approved financing for construction of the initial features of the State Water Project (SWP). The project includes some 22 dams and reservoirs, a Delta pumping plant, a 444-mile-long aqueduct that carries water from the Delta through the San Joaquin Valley to southern California. The project begins at Oroville Dam on the Feather River and ends at Lake Perris near Riverside. At the Tehachapi Mountains, giant pumps lift the water from the California Aqueduct some 2,000 feet over the mountains and into southern California.
The SWP provides irrigation water to farms in the San Joaquin Valley, and is a major source of supply for cities in Los Angeles, Riverside, San Bernardino, San Diego, and other parts of southern California. In addition, the SWP serves cities in Napa and Solano counties through the North Bay Aqueduct, Santa Barbara and San Luis Obispo counties through the Coastal Aqueduct and communities in Alameda and Santa Clara counties through the South Bay Aqueduct. The project is operated by the California Department of Water Resources.
The Colorado River
The 1,440-mile-long Colorado River passes through parts of seven states, several Indian reservations and the Republic of Mexico. California is entitled to 4.4 million acre-feet of water annually from river. Most of that water irrigates crops in the Palo Verde, Imperial and Coachella valleys, located in the southeastern corner of the state, but the Colorado also is a vital source of water for urban southern California. Urban supplies are distributed by the Metropolitan Water District of Southern California through its Colorado River Aqueduct. MWD is a water wholesale agency that supplies water to water districts that serve 18 million customers in Los Angeles, Orange, San Diego, Riverside, San Bernardino and Ventura counties.
Groundwater
About 30 percent of California's total annual water supply comes from groundwater in normal years, and up to 60 percent in drought years. Local communities' usage may be different; many areas rely exclusively on groundwater while others use only surface water supplies. Contrary to popular opinion, groundwater does not exist in underground lakes. Groundwater fills pores (spaces) between sand, gravel, silt and clay in water-bearing formations known as aquifers.
Local Streams and Reservoirs
Many cities rely on local water projects for all or a portion of their supplies. These projects typically were built and are operated by local public water districts, county water departments, city water departments or other special districts. Nearly 600 special purpose local agencies in California provide water to their areas through local development projects and imported supplies. A number of local agencies may also operate flood control and wastewater treatment facilities in addition to providing drinking water. Local water agencies usually are formed by a vote of the community, operate as public organizations, are governed by elected directors and fund their projects through bond issues.
In some communities, water is provided by private companies. Approximately 6 million Californians are served by these investor-owned utilities, which are regulated by the California Public Utilities Commission. The PUC monitors operations and service, sets water rates, and enforces water quality standards set by state and federal regulators.
