Large-scale open-pit mining in British Columbia is threatening the health of the Stikine River and downstream communities in Alaska. The Stikine River is a transboundary river that flows from British Columbia, Canada, to Alaska in the United States. The upper watershed of the Stikine is part of what is known as the Sacred Headwaters, an origin zone for four major river systems. Several proposed large-scale mining projects in B.C. threaten water quality and critical salmon spawning habitat in the Stikine River. The U.S. State Department must work with Canada to prevent toxic mining waste from entering the waters of the United States.