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Lower Colorado River Water Delivery Contracts
Questions and Answers

Where and how is Colorado River Water used in the Lower Basin?

Where the water is used:

The Colorado River Compact of 1922 apportioned 7.5 million acre-feet of river water annually to the Upper Basin and 7.5 million acre-feet annually to the Lower Basin. The Lower Basin’s 7.5 million acre-feet was further apportioned by the Boulder Canyon Project Act to the Lower Division States as follows: 4.4 million acre-feet to California, 2.8 million acre-feet to Arizona, and 300,000 acre-feet to Nevada. Later, the Mexican Water Treaty of 1944 recognized the United States’ obligation to annually deliver 1.5 million acre-feet of Colorado River water to Mexico. (One acre-foot is equal to approximately 326,000 gallons)

The primary Colorado River water users in each Lower Basin state are:


Metropolitan Water District of Southern California
Imperial Irrigation District
Coachella Valley Water District
Palo Verde Irrigation District
Bard Water District


Central Arizona Water Conservation District
Yuma County Water Users’ Association
Wellton Mohawk Irrigation and Drainage District
Yuma Mesa Division of the Gila Project (Three Districts):
     1. Yuma Irrigation District
     2. Yuma Mesa Irrigation and Drainage District
     3. North Gila Valley Irrigation District
Unit B Irrigation and Drainage District
City of Bullhead City
City of Yuma
Lake Havasu City
Mohave Valley Irrigation and Drainage District
Cibola Valley Irrigation and Drainage District


Southern Nevada Water Authority

Native American Tribes:

Fort Mojave Indian Tribe (California, Arizona and Nevada)
Colorado River Indian Tribes (California and Arizona)
Chemehuevi Indian Tribe (California)
Cocopah Indian Tribe (Arizona)
Quechan Indian Tribe (California)

For a complete listing of water users, visit the Lower Colorado River Water Entitlements web page.

How the water is used:

In Arizona and California, Colorado River water is used for irrigation and domestic uses. In Nevada, the water is only used for domestic purposes.

The use of Colorado River water in the Lower Basin is governed by the Boulder Canyon Project Act. Section 5 of the Act refers to the contract requirement for Colorado River water; therefore, the contracts with the Secretary of Interior are referred to as “section 5 contracts.”

In these section 5 contracts, “irrigation use” means the use of mainstream water for the commercial production of agricultural crops or livestock, including use of water for other purposes related to agricultural activities on tracts of arable land greater than 5 acres. “Domestic use” means the use of water for household, stock, municipal, mining, industrial, and other similar purposes, but excludes the release of water solely for generation of hydroelectric power.

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Updated: March 2005