Ten Mile Creek Tailings Ponds, Colorado

Covering a wide area on the Continental Divide, the Climax Mine is at the headwaters of a few river drainages. However, most of the mine’s wastes have been placed in one of them, the Ten Mile Creek drainage, which flows directly into the Dillon Reservoir, Denver’s largest drinking water reservoir, ten miles downstream from the last of the mine’s tailings dams. More than half a billion tons of tailings have been impounded in basins constructed along the drainage of the creek, creating new land masses of waste material that cover around six square miles. State Highway 91 has been moved five times over the years to make room for new tailing ponds. The acidic mining waste water is treated with lime to help precipitate-out heavy metals, before the water flows out the end of the last impoundment dam into the creek. Interceptor canals also catch water on slopes before it drains into the tailings ponds, diverting it downstream around the tailings impoundments.