The ACM Smelter and Refinery operated for 80 years along the Missouri River in Cascade County, Montana, near the community of Black Eagle. Starting in 1893, the facility smelted and refined copper, zinc, arsenic, and cadmium. Millions of tons of slag and tailings were dumped into the Missouri River before 1915, and smokestacks released lead, arsenic, and other metals that settled into nearby residential yards. Contamination has been found more than 30 miles downstream. The plant closed in 1980, and EPA added the site to the Superfund National Priority List (NPL) in 2011.
Contaminants found at the site include antimony, arsenic, cadmium, chromium, cobalt, copper, iron, lead, manganese, mercury, nickel, selenium, silver, and zinc. These have been detected in soil, groundwater, and surface water. People can be exposed by ingesting, touching, or inhaling these materials. As of the latest assessment, human exposure is not under control, groundwater contamination has not been stabilized, and cleanup construction is not complete.
The site is divided into three operable units (OUs). OU1 covers community soils and received a Record of Decision in August 2021. Cleanup methods include excavation of contaminated soil, replacement with clean topsoil, engineered caps, and institutional controls. Yard cleanup began in May 2024 under a 2023 agreement with Atlantic Richfield, the company that owned the facility when it closed. As of May 2025, crews completed cleanup at 159 properties and finished sampling at 105 more. A 2007-2008 EPA study found about 45 percent of sampled yards had elevated lead, arsenic, or both. Atlantic Richfield's estimated cost for the community cleanup is 3.9 million dollars. Work is expected to continue through at least the 2026 field season. OU2, covering the smelter facility itself, is under investigation. OU3, covering the Missouri River, has no decision document yet. Cleanup of the railroad corridor is under negotiation with BNSF Railway.
EPA also removed about 1,200 cubic yards of contaminated soil from the Moose Lodge property, which was later developed for residential housing. A recycling facility and golf course currently operate on parts of the site. As of December 2024, three on-site businesses employed 48 people and generated an estimated 2.6 million dollars in annual sales.
Community members can get involved through the Black Eagle Civic Club's Superfund technical committee, which meets monthly at the Black Eagle Community Center. The committee received a Technical Assistance Grant from EPA and hired a technical advisor to help residents understand site documents. Site records are available at the Black Eagle Community Center at 2332 Smelter Avenue, or at the EPA Superfund Records Center in Helena, Montana, reachable at 406-457-5046 or toll-free at 866-457-2690.
