In 1919, Colonel Robert Bradford Marshall of the United States Geological Survey proposed an unprecedented system of dams, canals, and pumps to move Delta-bound water from California's wet north and snowy Sierra Nevada mountains to its arid south and cities. This blueprint shaped California's two landmark water plans that still guide the state. During the Great Depression, California persuaded the federal government to build parts of its 1930 State Water Plan as the Central Valley Project. In 1960, California voters narrowly approved construction of elements of the 1957 California Water Plan, today's State Water Project. Together, these projects supply water to 22 million Californians, irrigate nearly four million acres of farmland, and provide hydroelectricity, flood control, and recreation. California's water development has also been controversial and complicated, with limited supply, rising demand, legal disputes, and environmental concerns, especially in the Delta, making the state's water future more challenging than Marshall could have imagined.