Tribes hold many reserved rights to resources on lands and waters under state and federal jurisdiction, through treaties and equivalent agreements with the U.S. government. The U.S. Constitution defines treaties as the supreme law of the land. OW is pursuing a change to its water quality standards regulations to codify the path to compliance with existing legal obligations to ensure that water quality standards do not impair tribal reserved rights and give clear and sustainable direction as to the scope of states’ obligations. This will help EPA ensure protection of resources reserved to tribes in treaties and equivalent agreements when establishing, revising, and reviewing water quality standards.