Lake Havasu is a large reservoir formed by Parker Dam on the Colorado River, on the border between San Bernardino County, California, and Mohave County, Arizona. Lake Havasu City sits on the Arizonan side of the lake with its Californian counterpart of Havasu Lake directly across the lake. The reservoir has an available capacity of 619,400 acre-feet (0.7640 km3). 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. Prior to the dam construction, the area was home to the Mojave people. The lake was named after the Mojave word for blue. In the early 19th century, it was frequented by beaver trappers. Spaniards also began to mine the areas along the river.