The Colorado River
The Colorado River is the dominant river in the Southwest. Fed by snowmelt in the Rocky Mountains of Wyoming and Colorado, the river flows some 1,400 miles across seven states and Mexico. Entering Arizona from the north, it winds through the Grand Canyon, which it carved over some 5 million years. Turning south, the river forms Arizona's western border with Nevada, California and Mexico before crossing into northern Mexico, where it empties into the Sea of Cortez (Gulf of C alifornia).
Along the way, the Colorado River drains a quarter of a million square miles, nearly half of which are in Arizona. Annual flows into Arizona at Lees Ferry average 11.4 million acre-feet (1 a-f=326,000 gals.), but have ranged from as little as 4.4 to as much as 20.4 million a-f. Arizona's allocated share is 2.8 million a-f.
The river is regulated by several major dams, which form large reservoirs, including Lake Mead behind Hoover Dam and Lake Powell behind Glen Canyon Dam. These dams store water, provide flood protection, generate power and provide recreation. One out of 10 Americans and three out of four Arizonans receive water or power from the Colorado River. The 1.8 million acres of farmland that it irrigates, including 560,000 acres in Arizona, produce 15 percent of the nation's crops.
The Colorado River is large, but not large enough to meet the growing demands for its resources. This over-allocated lifeline is the source of disputes between states, between the United States and Mexico, between cities and farms, and between power users and environmentalists.
Issues Summary