The Clayton Silver Mine operated as a mine and milling facility from 1935 through 1986. Metals of interest were silver, lead and zinc. Milled tailings were deposited in what is now a 16 acre tailings pile (light brown in color on photo). The tailings contain elevated concentrations of arsenic, lead and other metals. Kinnikinic Creek runs along the toe of the tailings pile for approximately 1,300 feet and empties into the Salmon River 1.5 miles downstream from the site. Tailings pile fines were eroding into Kinnikinic Creek and being carried downstream to the Salmon River, where they could have an adverse impact on aquatic species, including endangered Chinook salmon. Also, people visiting the site could be exposed to metals from wind blown dust that is carried off of the tailings pile.
The Environmental Protection Agency (EPA) initially took CERCLA removal action at the site in 1999, to remove and dispose of hazardous floatation and assay lab chemicals that were left at the site when it was abandoned. In 2000, EPA conducted a geotechnical study of the tailings pile to evaluate groundwater hydrology and tailings pile slope stability. In the summer of 2001, EPA conducted a site stabilization action to cover the tailings pile with a minimum of 8 inches of native rock and soil, and isolate Kinnikinic Creek from contact with the toe of the tailings pile. This action will mitigate the continued migration of tailings pile fines via wind erosion and down Kinnikinic Creek to the Salmon River.
