Conservationists in California are active in the fields of flood control, prevention of soil erosion, forest conservation, preservation of the state’s scenic areas and wildlife resources, and reduction of air pollution. Federal agencies that maintain conservation programs in California include the Natural Resources Conservation Service, the Forest Service, the Bureau of Land Management, the Water and Power Resources Service, the National Park Service, the Fish and Wildlife Service, and the Army Corps of Engineers. The resources agency of California is responsible for state conservation programs. Also active are such private groups as the Save-the-Redwoods League, Sierra Club, and California Conservation Council.
Numerous conservationists in California consider urban encroachment on farmland and scenic rural areas to be a major problem, especially around the rapidly growing cities of the south. Efforts are being made to avoid haphazard development by regional planning. Air pollution, an essentially urban problem, is particularly serious in the Los Angeles area, the San Francisco Bay area, and the Central Valley.
One of California’s greatest problems is to provide adequate water to meet the needs of its rapidly expanding population. There is an abundant water supply in sparsely settled northern California, but the demand is greatest in the more densely populated and much drier sections of central and southern California. In addition, water flow in the rivers is often irregular, and flooding may occur in the winter and spring. The redistribution and regulation of the water supply is the major objective of the state’s water projects.
The federal Central Valley Project, sponsored by the United States Bureau of Reclamation in the 1930s, is an extensive system of dams, reservoirs, and irrigation canals that supplies water to the Central Valley for irrigation and urban use. The aims of the project also include flood control and the generation of hydroelectric power. The main units include the Shasta, Friant, Trinity, and San Luis dams and their reservoirs, and the Delta-Mendota and Friant-Kern canals.
The California State Water Project seeks to alleviate water shortages in the Central Valley and also in southern California. Key units include the Feather River Project and the huge Oroville Dam in northern California, the California Aqueduct, and Lake Perris in Riverside County, the southern terminus of the nearly 1,000-km (600-mi) long system.
San Francisco receives much of its water supply from the Tuolumne River in the Sierra Nevada, by way of Hetch Hetchy Aqueduct. A large part of the water supply of Los Angeles is carried by aqueduct from the distant Owens River, the Mono Lake area, and the eastern Sierra Nevada watershed. The Los Angeles Aqueduct system, run by the city’s Department of Water and Power, is the only gravity-flow water redistribution system in the state. Water carried by the aqueduct flows downhill from the Mono Basin, at an elevation of 1,945 m (6,380 ft), southward to the Los Angeles Basin, at near sea level. All other major projects use pumps to lift water over elevated terrain. Another project bringing water to southern California is the Colorado River Aqueduct, which taps the Colorado River.
The All-American Canal carries irrigation water from Imperial Dam on the Colorado to the Imperial Valley. Water from the Colorado, of major importance to southern California, is available in amounts limited by agreements with Arizona and other states in the Colorado River basin.
Heavy use of groundwater, from wells, in coastal areas of southern California has lowered the water table. As a result, salt water from the ocean has seeped into the water table and is a threat to local water supplies. However, the ocean is also a possible source of fresh water. Small desalination plants have been built in Santa Barbara, on Santa Catalina Island, and elsewhere. The cost to consumers of desalinated water, however, is many times that of water supplied by freshwater redistribution projects. Moreover, with desalination plants using large amounts of electricity to operate and traditional sources of energy dwindling in supply, desalination is unlikely to become a viable solution to California’s water problems. "USA" © Emmanuel BUCHOT, Encarta, Wikipedia
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