Parker Dam is a concrete arch-gravity dam that crosses the Colorado River 155 miles (249 km) downstream of Hoover Dam. Built between 1934 and 1938 by the Bureau of Reclamation, it is 320 feet (98 m) high, 235 feet (72 m) 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 dam straddles the border between California and Arizona. The reservoir behind the dam is called Lake Havasu.