Today, the Colorado River and its tributaries supply vast quantities of water to cities and farms in seven western states. Without that water, growth in the sprawling metropolitan areas of Los Angeles, San Diego, Las Vegas, Phoenix, and Denver would have been frustrated long ago.[1] The development and apportionment of the river's water, which occurred over the first half of the twentieth century, is a story of conflict and cooperation, politics and water law, and the struggle by a variety of participants to assess and satisfy their water needs far into the future.

River View

Colorado River

Copyright Gary Ladd

Although the Colorado River was first viewed by Europeans in the sixteenth century, it was only lightly used as a water supply before 1900. There were no major cities on the river and little agriculture. With the river flowing virtually unimpeded, steamboats plied its channel from the Gulf of California almost two hundred miles upstream.[2] That changed in 1901 when river water was diverted just above the Mexican border and sent by gravity sixty miles to the fertile soil of the Imperial Valley in California. The United States Bureau of Reclamation was created the next year with the purpose of developing western water supplies, particularly on the Colorado River.[3] It was clear that without regulation and an enforceable apportionment of water rights, exploitation of the river would soon become a chaotic free-for-all.

Basin Graphic

Colorado River Basin

Image: U. S. Bureau of Reclamation

The Colorado River Basin lies within the States of Colorado, Utah, Wyoming, New Mexico, Nevada, Arizona, and California. Because it is an interstate system, apportionment of the river and its tributaries among the states was the responsibility of the federal government. In 1921, President Harding assigned his Secretary of Commerce, Herbert Hoover, to meet with representatives of the seven states to agree on an equitable division of the water.[4] The upper basin states, where most of the system's water originated as mountain snowfall, were afraid that expanding use of the river in the lower basin would thwart later development in the upper basin.[5] The lower basin states worried that the upper basin might someday prevent water from flowing downstream. In short, the parties were motivated to discuss an agreement.

Over the next twenty five years, through a series of laws, contracts, court decisions, and treaties, the water of the Colorado River was divided among the seven states and Mexico, with each state determining how its apportionment would be used. The process was not always smooth but, despite occasional disputes, it resulted in an allocation that remains in place today. This is the story of how it happened, with two postscripts, the first describing current challenges posed by rising water demands, and the other describing interests that may in the future compel reallocation of the river's water.

Click on the following links:

Getting Started
The Colorado River Compact and Boulder Canyon Project Act


Contracting for Water Deliveries in the Lower Basin


Mexico Gets A Share
The Mexican Water Treaty


Division of the Upper Basin Apportionment
The Upper Colorado River Compact


Postscript One
Confronting a Dwindling Supply


Postscript Two
Revising the Water Allocations?





[1] Marc Reisner, Cadillac Desert: The American West and Its Disappearing Water (New York: Viking Penguin, 1986), 125-126.

[2]Richard E. Lingenfelter, Steamboats on the Colorado River: 1852-1916 (Tucson: University of Arizona Press, 1978).

[3]H. Stuart Burness and James P. Quirk, "Water Law, Water Transfers, and Economic Efficiency: The Colorado River," Journal of Law and Economics 23, no. 1 (1980) 112.

[4]Norris Hundley, Jr., Water and the West (Berkeley: University of California Press, 1975) 130.

[5]Burness and Quirk, "Water Law, Water Transfers, and Economic Efficiency," 112.