Public Notice: Seventh Five-Year Review of Anaconda Co. Smelter Superfund Site Complete

Summary

The U.S. Environmental Protection Agency (EPA) Region 8 has completed the Seventh Five-Year Review(pdf) for the Anaconda Co. Smelter Superfund Site in Anaconda-Deer Lodge County, Montana. Five-Year Reviews are required by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as Superfund, when hazardous substances remain on-site above levels that permit unrestricted use and unlimited exposure. Five-Year Reviews provide an opportunity to evaluate the site remedy to determine whether it remains protective of human health and the environment.

The FYR found that the remedies implemented to date address smelter waste, contaminated soil, and dust in all five operable units (OUs) addressed in the FYR (Mill Creek, Community Soils, Flue Dust, Old Works, and ARWWS) are effective in eliminating direct exposure and minimizing the migration of contaminants to groundwater and downgradient surface water.

Remedial actions such as removal, excavation, treatment and capping of smelter waste, soil and dust, and various controls continue at the following OUs: Community Soils, Old Works, and ARWWS.

Attic dust abatement in the Community Soils OU is expected to continue until 2045. Yard remediation in the OU is anticipated to be complete in the next three years. While the “last call” for yard cleanups occurred in late 2024, provisions remain for certain homes and properties—such as those where residents have an elevated blood-lead level or where a homeowner bought the property post-December 2024—to receive cleanup into the future.

Additional factors, such as the recently changed reference value for arsenic toxicity, will be evaluated to determine their effects, if any, on remedy protectiveness. This evaluation will take approximately three years to complete.

This Five-Year Review Report was signed September 25, 2025.

Site project information and the Five-Year Review are available to the public at web repositories. To view cleanup documents, please visit EPA’s Site Profile page.