The Status of Tribal Water Rights in the Colorado River Basin

There are 30 federally recognized tribes in the Colorado River Basin. Twenty two of these tribes have recognized rights to use 3.2 million-acre feet (maf) of Colorado River system water annually, or approximately 22 to 26 percent of the Basin’s average annual water supply. In addition, 12 of the tribes have unresolved water rights claims, which will likely increase the overall volume of tribal water rights in the Basin. Under the Upper Colorado River Basin Compact and the U.S. Supreme Court’s decree in Arizona v. California, all tribal water uses are counted against the apportionments made to the states. Tribes’ rights are generally senior to state law-based water rights.