In 1922, the seven U.S. states in the Colorado River Basin established a compact to distribute the resources of the river. A border between the Upper and Lower basins was defined at Lees Ferry, Ariz. The Upper Basin (Wyoming, Colorado, Utah and New Mexico) was allocated 9.25 billion cubic meters a year, and the Lower Basin (Arizona, California and Nevada) was allotted 10.45 billion cubic meters. Mexico was allowed an unspecified amount, which in 1944 was defined as 1.85 billion cubic meters a year. The Upper and Lower basins — managed as separate organizations under the supervision of the U.S. Bureau of Reclamation — divided their allocated water among the states in their jurisdictions. Irrigation along the river started expanding in the second half of the 19th century, and agriculture still consumes more water from the Colorado than any other sector.
Large-scale manipulation of the river began in the early 20th century, and now there are more than 20 major dams along the Colorado River, along with reservoirs such as Lake Powell and Lake Mead, and large canals that bring water to areas of the Imperial and Coachella valleys in southern California for irrigation and municipal supplies. Numerous disputes arose, especially in the Lower Basin, regarding the proper division of the water resources. Over-allocation of the river's waters 90 years ago combined with increasing populations and economic growth in the river basin have created circumstances in which conservation efforts — no matter how organized — could be too little to overcome the projected water deficit that the Colorado River Basin will face in the next 20 years.
