<P> The SWP system begins with reservoirs on upper tributaries of the Feather River . Oroville Dam creates the largest SWP reservoir . At 770 feet (230 m) above the riverbed, the dam is the tallest in the United States . The reservoir covers 15,000 acres (61 km) and holds 3,500,000 acre feet (4.3 km). Water travels from Lake Oroville to the Sacramento River . At Harvey O. Banks Delta Pumping Plant, which pulls SWP water into the Bethany Reservoir, around 2,200,000 acre feet (2.7 km) are extracted from the Delta each year . Water that flows to the south end of the San Joaquin Valley must be pumped over the Tehachapi Mountains . Because of this, the SWP is California's largest energy consumer, and even though the hydroelectric plants of the SWP generate 5,900 GWh per year, that is only a fraction of the energy needed to lift water over the Tehachapis . Below the Tehachapis the California Aqueduct splits, with the west branch storing water in Castaic and Pyramid Lake, and the east branch storing water in the Silverwood Lake reservoir . </P> <P> The CVP's original purpose was to tame seasonal flooding and to direct water to the south to irrigate 3 million acres (12,000 km) of farmland . The CVP is operated by the United States Bureau of Reclamation . As one of the largest water systems in the world it stores over 7,000,000 acre feet (8.6 km) of water, or 17 percent of the state's developed water . The CVP dams and diverts five major rivers: the Trinity, the Sacramento, the American, the Stanislaus, and the San Joaquin . Friant Dam, on the San Joaquin, was completed in 1944, forming Millerton Lake . This was one of 20 reservoirs in the CVP . Shasta Dam, the largest CVP storage facility, was completed in 1945 . At Sacramento, American River water stored by Folsom Dam is added . 2,500,000 acre feet (3.1 km) are annually pumped from the Delta into the Delta - Mendota Canal . New Melones Dam on the Stanislaus River was finished in 1979, and the reservoir was filled in 1982 . </P> <P> The CVP has generated some controversy about environmental damage, prices charged to farmers, and lax enforcement of farm size limitations . Bureau of Reclamation water was supposed to be used for farms limited to 160 acres (see Homestead Act). Under Spanish and Mexican land grants, however, there were only a few land owners, all of whom owned large tracts of land . A 1982 reform increased CVP area limits to 960 acres (3.9 km). In 1992, the Central Valley Project Improvement Act made fish and wildlife protection and restoration an authorized purpose of the CVP on an equal footing with other authorized purposes . 800,000 acre feet (0.99 km) of annual runoff were dedicated to environmental usage, which generated intense controversy . </P> <P> The Colorado River is the source of 4,400,000 acre feet (5.4 km) per year for California . Six other states along the river's watershed (Wyoming, Nevada, Utah, Colorado, New Mexico, and Arizona) and Mexico, share allocated portions of river water . The Metropolitan Water District of Southern California, or MWD, holds priority water rights on the Colorado . It sells water to 95 percent of the South Coast region . Lake Mead, formed by Hoover Dam, is the primary reservoir in the Colorado River basin . The Colorado River Aqueduct begins 155 miles (249 km) downstream from Hoover Dam, and can carry 1,200,000 acre feet (1.5 km) annually . </P>

Where does most of the world gets its water from