Many tribes hold 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 ensure that water quality standards do not impair tribal reserved rights by giving clear direction to states for developing water quality standards where tribes hold reserved rights. This will help EPA ensure protection of resources reserved to tribes in treaties and equivalent agreements when establishing, revising, and reviewing water quality standards.