Lake Havasu is a large reservoir behind Parker Dam on the Colorado River, on the border between California and Arizona. Lake Havasu City sits on the lake's eastern shore. The lake has a capacity of 648,000 acre feet (799,000 dam³). The concrete arch dam was built by the United States Bureau of Reclamation between 1934 and 1938. The lake's primary purpose is to store water for pumping into two aqueducts.