BIG RIVER MINE TAILINGS/ST. JOE MINERALS CORP.

As of June 2026, the Big River Mine Tailings Superfund site is considered 'Current Human Exposure Not Under Control' because lead-contaminated yard soils and sediment remain unaddressed. Contaminated soil and sediments pose a direct contact and ingestion threat to young children and pregnant women. The planned activities to address this pathway were a series of removal actions to stabilize waste piles, replace highly contaminated surface soil in residential yards and child high use areas, and complete two remedial actions to address remaining yard soils (OU 1) and watershed sediments (OU 2). A total of 7,539 yards have been sampled. Of those 5,499 had one or more areas > 400 parts per million lead. Over 3,000 properties have been remediated where high levels of lead were found in residential properties or where children with elevated blood lead were identified. Six of the seven mine waste piles are stabilized. Surface water, sediment, and various forms of biota contain elevated concentrations of lead throughout the mining area. Fish in Big River have shown elevated concentrations of lead. Fish advisories have been in place at the site since 1981. EPA has worked with the St. Francois County Watershed Group, a group of local concerned citizens and other federal and state agencies, to help educate the community on the effects of lead contaminated soil, sediment, and surface water. Additionally, EPA completed an Environmental Evaluations Cost Analyses in 2025 to address lead-contaminated floodplain soil, surface water, and sediment in the Big River watershed from Leadwood to the confluence with the Meramec River. The planned activity to address the pathway for OU 1 is the continuation of ongoing remediation of lead contaminated soils. Additionally, the planned activities to address the pathway for OU 2 will be determined based on the results of the Non Time Critical Removal Action for OU 2. Human Exposure is expected to be under control by March 2057.