EPA Superfund site
SILVER BOW CREEK/BUTTE AREA
Human exposure is NOT currently under control
Data limitations: Proximity to a Superfund site boundary does not mean your property is contaminated. EPA site boundaries show the area designated for cleanup, not the full extent of contamination. Groundwater plumes can extend beyond site boundaries. This tool shows publicly available EPA federal data. It is not affiliated with or endorsed by EPA, and is not a substitute for a professional environmental assessment.
About this site's exposure pathways
As of August 2026, the Silver Bow Creek/Butte Area Superfund Site (Site) is considered "Current Human Exposure Not Under Control." This large Site includes approximately 26 miles of stream and streamside habitat, the urban centers of Butte and Walkerville, rural areas outside of Butte, the Berkeley Pit and the underground mine workings of the historic Butte Mining District, and the treatment settling lagoons at the Warm Springs Ponds. The main contaminants of concern are heavy metals and arsenic.
The remedial design and remedial action work under the consent decree for the Butte Priority Soils Operable Unit 8 is progressing to address this high priority area. EPA issued an updated approach to residential lead (Pb) sites, specifically Updated Residential Lead Directive for CERCLA Sites and RCRA Hazardous Waste Cleanup Program Facilities (2025 Lead Directive) on October 16, 2025. The 2025 Lead Directive lowered the recommended regional screening level for lead-contaminated soil to 200 mg/kg and a removal management level of 600 parts per million for residential soil-lead sites. Additionally, the 2025 Lead Directive identified a lower target blood lead level of 5 ug/dl to be applied when developing a new preliminary remediation goal. Based on the 2025 Lead Directive, the EPA evaluated the potential presence and extent of soils that may present current and future-potential exposure risk to sensitive populations and is progressing a Record of Decision Amendment to finalize a new action level to address additional residential lead contamination at the Site.
EPA completed the Remedial Investigation for the West Side Soils Operable Unit 13 and is currently drafting the Feasibility Study Report. EPA will develop a Record of Decision (planned date is March 2028) to address risks to human health and the environment posed by that remaining contamination.
Human exposure is expected to be under control once the completion of the remedial action activities at Warm Springs Ponds Operable Units have been completed; this date is expected to be 12/31/2043. EPA will update this date as necessary based on the implementation of the 2025 Lead Directive and the number of residential properties that are expected to require remediation under the implementation of the Butte Priority Soils Operable Unit 8 remedial action. EPA has an extensive community outreach program which includes providing the community with information on how to reduce exposures to potentially contaminated sources.