Parker Dam is a concrete arch-gravity dam that crosses the Colorado River  downstream of Hoover Dam. Built between 1934 and 1938 by the Bureau of Reclamation, it is high, of which are below the riverbed, making it "the deepest dam in the world". The dam's primary functions are to create a reservoir, and to generate hydroelectric power. The reservoir behind the dam is called Lake Havasu and can store or over 210 billion US gallons. The dam straddles the state border at the narrows the river passes through between the Whipple Mountains of California and the Buckskin Mountains of Arizona.