naturally flooded had the levee system not been in place. Central Valley Project During the Great Depression in the 1930s, the first concrete proposals for a statewide water engineering project emerged, but when the state government could not sell the necessary bonds to fund the project, the federal government took over. The Central Valley Project, one of the largest irrigation projects in the world, was constructed by the U.S. Bureau of Reclamation beginning in 1935. Ultimately, the system would distribute 7 million acre feet (8.6 km3) to irrigate 3 million acres (1.2 million ha) of land in the Sacramento and San Joaquin Valleys. Construction of Shasta Dam, the principal water storage facility in the Sacramento River system, started in 1938 and was completed in 1945. Controlling runoff from the upper of the Sacramento River watershed, Shasta greatly reduces flood peaks on the middle and lower parts of the Sacramento River. Flood waters are stored for irrigation in dry years as well as navigation and electricity generation. In the following decades, more huge reservoirs – capable of storing a combined of water – were constructed on the Sacramento's main tributaries, enabling the regulation of water for irrigation and hydroelectric power. Starting in the late 1950s, two major canals were extended to irrigate the western side of the Sacramento Valley – the Tehama-Colusa and Corning Canals. Starting at the Red Bluff Diversion Dam on the Sacramento, the canals are and long respectively, and divert a total of over of water to irrigate some . State Water Project In 1960, construction began on the State Water Project, whose primary purpose was to deliver water to Los Angeles and the San Francisco Bay Area. Oroville Dam – the tallest dam in the U.S. – was built on the Sacramento's largest tributary, the Feather River. A series of channels were enlarged in the Delta to facilitate water flow from the Sacramento to the Banks Pumping Plant and the California Aqueduct, which can carry as much as 4.2 million acre feet (5 km3) of water each year. From its origin at the Delta the canal runs southwards through the west side of the San Joaquin Valley, providing irrigation water to farmlands along its length, and lifted almost over the Tehachapi Mountains via four large pumping stations. The project irrigates of land in the San Joaquin Valley and serves 22 million people in Central and Southern California.