On June 22, 2023, the U.S. Supreme Court issued its opinion in Arizona v. Navajo Nation, No. 21-1484, limiting the federal government’s obligation to affirmatively secure water for federally recognized Indian tribes. The Supreme Court held that the 1868 treaty establishing the Navajo Reservation (the “Treaty”) “did not require the United States to take affirmative steps to secure water for the [Navajo Nation].” Among other things, the Court closed the door on the Navajo Nation’s ability to secure an affirmative accounting of its reserved water rights through a lawsuit directly against the federal government.
The water rights at issue in the case are “reserved water rights,” also referred to as “Winters rights.” These are rights implicitly reserved by Congress, at the time of a federal reservation of land, to accomplish the primary purposes of that reservation. See Winters v. United States, 207 U.S. 564, 576–77 (1908). Winters rights are often some of the most—if not the most—senior water rights on a particular water system, so in times of shortage, the holders of Winters rights often have priority over junior water users whose use might be curtailed. The scope of Winters rights (e.g., the instantaneous and annual volumes of water reserved) often remains unresolved absent a general stream adjudication that resolves all claims to water rights on a particular water system.