Colorado River too much of the lower basin allotment; in 1944 a compromise was reached in which Arizona would get a firm allocation of , but only if California's allocation was prioritized during drought years. These and nine other decisions, compacts, federal acts and agreements made between 1922 and 1973 form what is now known as the Law of the River. On September 30, 1935, the United States Bureau of Reclamation (USBR) completed Hoover Dam in the Black Canyon of the Colorado River. Behind the dam rose Lake Mead, the largest artificial lake in the U.S., capable of holding more than two
Course of the Colorado River Topock Marsh in Topock Gorge and widens into Lake Havasu, formed by Parker Dam. Lake Havasu provides recreation as well as the home of the retired U.K. London Bridge in Lake Havasu City, Arizona, now the New London Bridge. Near Parker Dam are the first two major diversions of the lower Colorado: the Colorado River Aqueduct, which travels west to Los Angeles and San Diego, California; and the Central Arizona Project, which sends water east towards Phoenix and Tucson, Arizona. The intermittent Bill Williams River joins the Colorado from the east in Lake Havasu, just above Parker Dam. The river