Over a century of copper smelting left the Anaconda Co. Smelter site in Anaconda, Montana heavily contaminated with arsenic, lead, cadmium, copper, beryllium, iron, and zinc. EPA added the site to its National Priorities List in 1983. Contamination affects soil, groundwater, surface water, air, and buildings across multiple areas, including the Old Works, East Anaconda, Mill Creek, and Community Soils zones. Arsenic and lead are the most widespread contaminants, found in nearly every affected medium.
Atlantic Richfield Company, which bought the smelter in 1977, funds and carries out cleanup under a Consent Decree with EPA oversight. Work completed to date includes cleanup of more than 1,600 residential and commercial properties, removal of over 3 million cubic yards of waste, capping and revegetating more than 5,000 acres of former smelter facilities, building nearly 1,000 acres of new wetlands, and restoring 30,000 feet of stream for fish habitat. All domestic wells have been tested and remediated, with ongoing sampling and treatment. The site is divided into multiple operable units, and several have been partially deleted from the National Priorities List, including units covering beryllium removal, flue dust, and Mill Creek.
EPA's Seventh Five-Year Review, completed in September 2025, found that remedies in place across five operational units are working to eliminate direct exposure to smelter waste and limit contaminant movement into groundwater and surface water. Even so, human exposure is not currently under control sitewide, meaning an unsafe level of contamination has been detected and people could reasonably be exposed. Groundwater migration is under control, with no unacceptable discharge to surface water. Physical construction is not yet complete for the entire site. Attic dust abatement is expected to continue until 2045, and yard remediation is anticipated to be done within three years. EPA updated its lead directive in October 2025, changing blood lead levels of concern and soil screening levels, and the site team is evaluating what that means for ongoing work. EPA is also spending roughly three years evaluating how a changed reference value for arsenic toxicity affects the remedy's protective capacity.
Residents can get involved through the Anaconda-Deer Lodge County Superfund Program, which provides public information and maintains a document repository at 186 Landfill Road in Anaconda. EPA also maintains site records at its Superfund Records Center in Helena, open weekdays from 8:00 a.m. to 4:30 p.m. A free blood lead level monitoring program is available at the Community Hospital of Anaconda. EPA recommends annual lead testing for children under 7 and suggests keeping yard cover intact, washing hands after soil contact, and keeping dust levels low. Residents can sign up for news and updates about the site through the county Superfund program.
