Basin Mining Area

Location

Contaminants of concern

• ALUMINUM
• ANTIMONY
• ARSENIC
• CADMIUM
• COPPER
• IRON
• LEAD
• MANGANESE
• MERCURY
• SELENIUM

Contaminated media

• Leachate
• Surface Water
• Soil
• Solid Waste
• Groundwater
• Sediment

Cleanup timeline

1. Initial Assessment Completed — Not Yet Achieved
2. Proposed to the National Priorities List — 07/22/1999
3. Finalized on the National Priorities List — 10/22/1999
4. Remedial Investigation Started — 09/28/1999
5. Remedy Selected — 03/30/2001
6. Remedial Action Started — 06/24/2002
7. Construction Completed — Not Yet Achieved
8. Deleted from National Priorities List — Not Yet Achieved
9. Most Recent Five-Year Review — 09/28/2023
10. Achieved Sitewide Ready for Anticipated Reuse — Not Yet Achieved

EPA references

• EPA facility record →
• EPA Superfund profile →

Understanding this Superfund site

Basin Mining Area is a federal Superfund site in Montana. The Superfund program, created by Congress in 1980, addresses sites where hazardous substances have been released or threaten release into the environment. EPA scores potential sites using the Hazard Ranking System; those that score high enough are placed on the National Priorities List.

Current status: Cleanup underway. Active cleanup is underway, meaning EPA has approved a remediation plan and work is in progress. Cleanup timelines vary widely — some sites take decades depending on contamination depth, groundwater involvement, and funding availability.

EPA has identified 10 contaminants of concern at this site, including aluminum, antimony, arsenic. Contamination has been detected in leachate, surface water, soil, solid waste, groundwater, sediment.

If you live near this site and have health concerns, your state health department can provide site-specific guidance. EPA maintains a community involvement program for most NPL sites, and site documents — including the Record of Decision, five-year reviews, and public health assessments — are typically available through EPA's Superfund site profile.