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
Bridge Canyon Dam reservoir stretching more than upstream, including along the border of Grand Canyon National Park. The dam would serve mainly for hydropower production in conjunction with several others further upstream including Marble Canyon Dam, on the Colorado, Green and other rivers. Due to its enormous potential for environmental destruction and the dwindling flows of the Colorado River, the project stalled in 1968 after years of public opposition. However, the location is considered one of the best remaining sites for a large dam in the western United States. Bridge Canyon Dam was first seriously considered in the mid-20th century as part of