The development and exploitation of mineral resources in the western United States was important to both our economic development and our history. With continued population growth and economic development in this region, the impacts of our mining legacy are proving to be equally important to citizens in our modern society. By one estimate, 500,000 abandoned mine sites are scattered across the western landscape, largely on public land (state and federal), affecting 16,000 miles of streams. Federal land management agencies such as the U.S. Department of Agriculture Forest Service and U.S. Department of Interior Bureau of Land Management are able to use their authorities under the Comprehensive Environmental Response, Compensation, and Liability Act to respond to the release of hazardous substances from these abandoned mines. Although human health is a primary consideration in prioritizing site response, environmental issues such as the impact on terrestrial species, water quality, or aquatic species also may influence site response priorities. Challenges faced in reducing or preventing further release of hazardous substances at historic mines sites include limited available funds, difficult access, changing public land uses, and increasing populations in nearby areas.