Colorado River System
Framework of Compacts, Treaties and Federal Water Laws

Colorado River Compact – Signed in 1922, this compact was ratified by California, Colorado, Nevada, New Mexico, Utah and Wyoming by 1929 and approved by Congress in the Boulder Canyon Project Act of 1929. Although Arizona did not ratify the compact until 1944, the President of the United States proclaimed it effective in 1929. The compact apportions the use of waters of the Colorado River system to the Upper and Lower basins. Parts of Arizona, Colorado, New Mexico, Utah and Wyoming constitute the Upper Basin. The Lower Basin includes parts of Arizona, California, Nevada, New Mexico and Utah. The compact provides that each state, through the state official charged with water rights administration, together with certain agencies of the federal government, shall cooperate to promote the systematic determination and coordination of the facts as to flow, appropriation, and consumptive use of water in the Colorado River Basin; ascertain and publish the annual flow of the Colorado River at Lee Ferry, the point of division between the Upper and Lower basins; and perform such other duties as may be assigned by mutual consent of the signatory states.

Boulder Canyon Project Act – This act in 1929 ratified the 1922 Colorado River Compact; authorized the construction of Hoover Dam and related irrigation facilities in the Lower Basin; allocated among the states of Arizona, California and Nevada the use of 7.5 million acre-feet per year of water from the lower Colorado River mainstream; and authorized and directed the Secretary of the Interior to function as the sole contracting authority for Colorado River water use in the Lower Basin.

Mexican Water Treaty – This treaty in 1944 committed 1.5 million acre-feet of the Colorado River’s annual flow to Mexico.

Upper Colorado River Basin Compact – This compact, signed in 1948 by Arizona, Colorado, New Mexico, Utah and Wyoming, was ratified by Congress in 1949. The compact apportions the use of waters of the Upper Basin among the signatory states, and created the Upper Colorado River Commission to administer its provisions. The commission consists of representatives of the United States and each compact state except Arizona, and has an office and staff in Salt Lake City, Utah. Annual reports of the commission document activities of the commission and streamflow, storage and water development conditions in the Upper Basin. Copies of the annual reports are available for inspection at the commission office in Salt Lake City and the Interstate Stream Commission office in Santa Fe.

Colorado River Storage Project Act – This act in 1956 provided a comprehensive Upper Basin water resource development plan and authorized the construction of Glen Canyon, Flaming Gorge, Navajo and Curecanti dams for river regulation and power production. The act also authorized several projects for irrigation and other uses as participating projects of the Colorado River Storage Project, including the Hammond Irrigation Project.

Act of June 13, 1962 (Public Law 87-483) – This act authorized the Secretary of the Interior to construct, operate and maintain the Navajo Indian Irrigation Project and the initial stage of the San Juan-Chama Project as participating projects of the Colorado River Storage Project.

Decree in Arizona v. California – The US Supreme Court in 1964 issued a decree in this case that resolved disputes over the apportionments of water from the Colorado River mainstream for uses in Arizona, California and Nevada, defined present perfected rights, and apportioned the use of water from the Gila River stream system between New Mexico and Arizona. The Court in 2006 issued a consolidated decree in this case to incorporate amendments made over time to the 1964 decree.

Colorado River Basin Projects Act – This act in 1968 authorized construction of a number of water development projects in both the Upper and Lower basins, including the Animas-La Plata Project and a New Mexico unit of the Central Arizona Project. This act also ratified the Animas-La Plata Project Compact to provide equal priority for project uses in Colorado and New Mexico, and made the priority of the Central Arizona Project water supply subordinate to California’s Colorado River apportionment in times of shortage. This act also directed the Secretary of the Interior to prepare, in consultation with the Colorado River Basin states, long-range operating criteria for the Colorado River reservoir system and to submit regular reports to Congress on consumptive uses from the Colorado River system.

Jicarilla Apache Tribe Water Rights Settlement Act of 1992 – This act authorized a settlement of the water right claims of the Jicarilla Apache Nation to waters of the San Juan and Rio Chama basins.

Colorado Ute Settlements Act Amendments of 2000 – This act authorized amendments to previous water rights settlements of two Indian tribes in the San Juan River Basin in Colorado, and authorized construction of a downscaled version of the Animas-La Plata Project to develop water for municipal, industrial and domestic uses in Colorado and New Mexico, including uses by the San Juan Water Commission, the Navajo Nation and the La Plata Conservancy District in New Mexico.

Arizona Water Settlements Act – This act in 2004 provided for the settlement of water right claims of Indian tribes in Arizona, resolved disputes regarding allocations of water from the Central Arizona Project, resolved litigation regarding water rights on the Gila River system, and set forth limitations for development of a New Mexico unit of the Central Arizona Project first authorized by the Colorado River Basin Projects Act.

Northwestern New Mexico Rural Water Projects Act – This act in 2009 approved the settlement of water right claims of the Navajo Nation in the San Juan River Basin in New Mexico, and authorized construction of the Navajo-Gallup Water Supply Project to provide water for municipal and domestic uses of the Navajo Nation and others in New Mexico and Arizona.