The Flat Creek Iron Mountain Mine and Mill site sits in Superior, Montana. Mining ran there from 1909 to 1930 and again from 1947 to 1953, producing silver, gold, lead, copper, and zinc. Those operations left behind heavy metals and metalloids in soil and groundwater. A 2000 forest fire and debris flow spread mine tailings into Flat Creek, which prompted EPA to investigate. The agency added the site to the National Priorities List in September 2009.
The confirmed contaminants of concern in residential soils are antimony, arsenic, and lead. The site also contains cadmium, copper, manganese, and zinc in soil and groundwater. Young children and pregnant women face the greatest risk from ingesting contaminated soil or water. Human exposure at the site is not under control, meaning unsafe contamination levels have been detected and people could reasonably be exposed.
Cleanup is divided into three operable units covering sitewide issues, residential soils, and the mine watershed. Soil removal in residential areas took place in 2002, 2010, 2011, and 2013, with the most recent residential soil removal running from July 2013 to September 2014. A new remedial investigation and feasibility study for residential soils began in September 2024. The mine watershed study started in September 2010 and remains ongoing. A 2018 five-year review found the remedy for the town is functioning as intended, and the most recent five-year review was completed in August 2023. Construction has not been completed across the site. Mineral County runs a Soil Excavation Permit program requiring permits for anyone displacing soil in Superior, and maintains a geographic information system database to track cleanup activities. In October 2025, EPA released an updated lead directive and is evaluating its impacts on this site.
Community members can get involved through the Superior Technical Assistance Committee, known as STAC. STAC has six community representatives and a technical advisor. It meets monthly and receives funding through EPA's Technical Assistance Grant program. The Montana Environmental Trust Group, a nonprofit created to clean up sites formerly owned by the American Smelter and Refinery Company, manages lands in Superior acquired through a 2009 bankruptcy settlement. Mineral County also holds extensive records on sampled and cleaned-up properties. For direct questions, residents can contact EPA's Remedial Project Manager.
