The Iron Mountain Site is part of the larger Flat Creek/Iron Mountain & Mill (IMM) federal Superfund site that was added to the U.S. Environmental Protection Agency’s (EPA) National Priorities List in 2009. Under the Montana Settlement Agreement, in consultation with the United States Forest Service (USFS), the Montana Department of Environmental Quality (MDEQ) is the Lead Agency for the Iron Mountain Site. Cleanup of the property owned by the Montana Environmental Custodial Trust (Custodial Trust) will be coordinated with the EPA-led Superfund cleanup process at the Flat Creek/IMM NPL site. The U.S. Department of the Interior (USDOI) will address natural resource damages utilizing trust funds.
After decades of silver, gold, lead, copper, and zinc mining, the now-abandoned mining district includes tunnels, tailings, a discharging adit, and mill remnants. Evidence of Iron Mountain mine tailings have been found along the Flat Creek River and downstream as far as its confluence with the Clark Fork River.