Clayton Silver Mine

—> Project Photos

Clayton Silver Mine is located on private land about 1.5 miles north of Clayton in central Idaho.

This mine was one of the largest producers of silver and lead in the Bayhorse Mining District of Custer County, Idaho. The mine and milling facility operated between 1935 and 1985 and produced about 6.7 million ounces of silver and 83.5 million pounds of lead. The mine also produced a small amount of gold and copper and a substantial amount of zinc during its 50-year operational period. The mine closed in 1986 due to low silver prices and the high cost of dewatering the mine after the 1983 Borah Peak earthquake.

The tailings pile associated with the mine was 15 acres in size and in direct contact with Kinnikinic Creek. This resulted in erosion of the tailings into the creek and deposition downstream, eventually reaching the Salmon River. The tailings consisted of extremely fine flotation tailings bearing elevated levels of arsenic, cadmium, copper, lead, and zinc. Kinnikinic Creek is habitat for Bull Trout and the Salmon River is habitat for Chinook Salmon; both fish are listed species. On windy days, airborne particulates (likely to carry arsenic, lead and zinc) from the tailings posed an inhalation hazard to humans.

In 1994, the Agency for Toxic Substances and Disease Registry (ATSDR) provided a health consultation which indicated that human health problems could be associated with the site, based on metals concentrations in soils in the town of Clayton. A voluntary cleanup was conducted by local residents in 1994 to remove soil contaminated with mill concentrates in the area of the town’s outdoor basketball court, which had previously served as a pad to hold mill concentrates for shipping. Approximately 80 truckloads of material were removed and hauled up to the mill-site tailings pile. In 1995, the Idaho Bureau of Environmental Health and Safety completed an arsenic and lead study of Clayton residents, which showed blood lead and arsenic in urine and hair samples all within normal ranges.

The goal of this project was to reduce wind and water erosion of the tailings along Kinnikinic Creek. The tailings were stabilized on-site due to sheer volume (which were far too immense to consider complete removal). The clean-up plan included shaping and armoring the tailings with a cover of 8 inches of coarse, inert bedrock; shifting about 800 feet of the road away from the creek to accommodate floodplain development; moving the stream channel 10-12 feet east of the tailings pile; and constructing the stream channel to emulate the natural stream-channel characteristics above the mine site. The channel was designed to accommodate flooding at high flows, and avoid further erosion of tailings. Native riparian plantings of willow, birch, alder, cottonwood and aspen revegetated the area to its natural landscape.

For additional information regarding this project, contact the area specialist or call the BLM Challis Field Office at (208) 879-6200.

Facts

 Location

• 1.5 miles north of Clayton in central Idaho
• Mine located on private land; however, most of Kinnikinic Creek above and below mine on public land

History

• Operated 1935-1985
• Produced about 6.7 million ounces of silver and 83.5 million pounds of lead
• Produced a substantial amount of zinc and a small amount of gold and copper

Impacts

• Tailings contaminated with elevated levels of arsenic, cadmium, copper, lead and zinc

Risks

• Water quality affecting Kinnikinic Creek and Salmon River
• Airborne particulates posing inhalation hazard to humans

Actions

• Stabilize tailings
• Shift road away from Kinnikinic Creek for floodplain
• Shift Kinnikinic Creek stream channel away from tailings
• Revegetate area with native riparian plantings of willow, birch, alder, cottonwood and aspen to natural landscape

Challis Field Office  |  1151 Blue Mountain Road |  Challis, ID 83226
208-879-6200  |  Fax: 208-879-6219 |  Office hours: 7:45am - 4:30pm, M-F