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Southern Nevada Water Authority

Colorado River

Colorado River

The Colorado River winds 1,450 miles
and empties into the Gulf of California
in Mexico.

Southern Nevada gets nearly 90 percent of its water supply from the Colorado River, which begins as snow melt in the Rocky Mountains. The snow melt travels through a series of tributaries into the river, which winds its way south for 1,450 miles and empties into the Gulf of California in Mexico.

Sharing the River

Seven western states and Mexico share the river, which serves more than 25 million people. The river is divided into two major districts: the Upper Basin and the Lower Basin, and it is governed by a series of compacts, laws and court decisions collectively known as the Law of the River.


Nevada receives 300,000 acre-feet per year (AFY) of Colorado River water under the Law of the River compacts. An acre-foot is equivalent to 325,851 gallons of water.

When the allocation was assigned, Nevada’s negotiators viewed 300,000 acre-feet as more than reasonable for the sparsely populated Southern Nevada. The state instead focused on hydro-electricity and secured one-third of the electricity generated by Hoover Dam.

Colorado River Apportionment
Allocation Million Acre-Feet Per Year (MAFY)
Upper Basin  
Colorado 3.9 MAFY
Utah 1.7 MAFY
Wyoming 1 MAFY
New Mexico 0.85 MAFY
Lower Basin  
Arizona 2.85 MAFY
California 4.4 MAFY
Nevada 0.3 MAFY
Additional Allocations  
Mexico 1.5 MAFY


16.5 MAFY

Unused Apportionment

As part of its 1992 Colorado River contract, the SNWA has a right to the unused apportionment of other Nevada Colorado River contract holders. The SNWA anticipates some of this water will be available for use in the planning horizon, and plans to utilize this water if and when it is available.

SNWA may also choose to leave a portion of Nevada's unused allocation in Lake Mead to help alleviate the impacts of drought conditions and avoid critical Lake Mead elevations.

Hoover Dam

The 1922 Colorado River Compact provided the legislative stimulus to harness the Colorado River. Congress authorized the building of Hoover Dam in 1928, and construction began in 1931. Completed on March 1, 1936, the dam was the first step toward controlling the rampaging river.



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