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 through the desert Lower Colorado River Valley (LCRV), where its character changes significantly from fast-flowing whitewater to a low gradient braided stream with a wide floodplain. Here, the Colorado River ranges in width from and from in depth. It becomes a losing stream, with a gradual reduction in volume both due to evaporation in the hot desert climate and massive diversions for irrigation, urban areas, industry and thermo-electric power generation. The average flow rate of at Davis Dam diminishes to just at the Mexican border. At Needles, California the Colorado is crossed by Interstate 40; shortly downstream it passes the