aiver of their sovereign immunity.ImplicationsAlthough the Supreme Court declined to hear the case, litigation involving tribal water rights and water rights more generally will likely continue to increase. As water becomes more scarce and disputes over the resource increase, courts will continue to ensure that the rights of all interested parties, including tribes, are recognized and, to the extent possible, protected. Following the Ninth Circuit’s decision, parties seeking to challenge agency actions that implicate tribal water rights must involve the tribes in discussion and negotiation and ensure that all parties with established water rights can be joined in any litigation so that an adjudicating court can grant appropriate relief.Alaska v. U.S. & Michael Regan, No. 22-0157 (Mining and Mineral Rights)Case SummaryIn February 2023, EPA blocked a proposed copper and gold mine, the Pebble Mine, and similar extraction projects within approximately 300 square miles in Southwest Alaska. 88 Fed. Reg. 7441 (Feb. 3, 2023). In July 2023, the State of Alaskaaskedthe U.S. Supreme Court to reverse EPA’s decision and allow Pebble Mine and similar projects to proceed. EPA issued its decision under CWA Section 404(c), allowing the agency to bar certain waters of the United States from being used as disposal sites for the discharge of dredged or fill material for the construction and routine operation of the proposed mine. Alaska’s complaint argues that EPA’s veto overrides state authority, which violatesAlaska’s Statehood Act and effectively creates a new federal preserve.The United States argued that this case does not fall within the narrow class of disputes warranting the Court’s original jurisdiction and that Alaska’s claims do not rise to the “seriousness and dignity” the Court has required to exercise its jurisdiction. The United States contended that there is nothing distinctly sovereign in Alaska’s claims and that the State has other, fully adequate, federal forums available to challenge the agency’s