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| Anaconda Copper Superfund cleanup | |
|---|---|
| Name | Anaconda Copper Superfund cleanup |
| Location | Butte, Montana; Anaconda, Montana; Silver Bow County, Montana |
| Coordinates | 46°00′N 112°32′W |
| Designation | Superfund site |
| Responsible agency | United States Environmental Protection Agency, Montana Department of Environmental Quality, Atlantic Richfield Company |
| Contaminants | arsenic, lead, cadmium, copper, zinc, sulfuric acid |
| Cleanup start | 1980s |
| Status | ongoing |
Anaconda Copper Superfund cleanup is the multi-decade environmental remediation of mining and smelting wastes associated with the Anaconda Copper Mining Company and successor operations in southwest Montana centered on Butte, Montana and Anaconda, Montana. The project responded to extensive releases of metals and acidic process wastes from the 19th and 20th centuries that contaminated soils, stream sediments, groundwater, and floodplains across the Upper Clark Fork River watershed. Remediation has involved federal litigation, coordinated action by the United States Environmental Protection Agency (EPA), state agencies, tribal governments, and corporate defendants including the Anaconda Copper Mining Company successors and Atlantic Richfield Company (ARCO).
The origins trace to the 1860s and the Comstock Lode-era expansion of copper mining at the Butte District, the development of the Washoe Smelter era technologies, and the consolidation under the Anaconda Copper Mining Company in the late 19th century. Large-scale underground and open-pit mining, along with smelting operations, generated sulfide-rich tailings, slag, and acid drainage that were deposited in the Silver Bow Creek floodplain and downstream to the Clark Fork River and Flint Creek (Montana). Events such as floods and dam failures exacerbated mobilization of mine wastes, paralleling contamination narratives seen at sites like Kennecott Copper Corporation operations in Alaska and the Bingham Canyon Mine in Utah. Industrial expansion during both World Wars increased throughput and waste volumes, while mergers and acquisitions involving the Anaconda Copper Mining Company and ARCO changed corporate responsibility dynamics.
In 1983, portions of the watershed, including the Upper Clark Fork River, were proposed for cleanup under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The EPA listed the area as a National Priorities List site, designating the Butte Mine Flooding, Butte Priority Soils Operable Unit, and the Upper Clark Fork operable units. The site encompassed mining districts, smelter complexes, tailings impoundments, contaminated floodplains, and municipal lands across Silver Bow County, Deer Lodge County, and downstream reaches toward Missoula, Montana. The scale was comparable in legal and technical complexity to other large contaminated watersheds such as the Tar Creek Superfund Site and the Hudson River PCBs project.
Contaminants including arsenic, lead, cadmium, copper, and zinc posed acute and chronic risks to residents of Butte, Anaconda, and rural communities along Silver Bow Creek and the Clark Fork River. Human health concerns mirrored findings at other mining-impacted areas like La Oroya and Mount Isa, with elevated blood lead levels in children, soil ingestion pathways, and exposure to airborne dust from tailings. Wildlife impacts affected trout populations important to Montana Fish, Wildlife and Parks management and Federal trust responsibilities recognized by tribes including the Confederated Salish and Kootenai Tribes. Aquatic and riparian ecosystems exhibited reduced biodiversity, sediment toxicity, and altered geomorphology reminiscent of documented effects at Yellowstone River tributaries affected by mining.
Remediation used a suite of engineered and ecological approaches: excavation and consolidation of contaminated soils, capping of tailings impoundments, streambank stabilization, floodplain regrading, phytostabilization, and groundwater treatment systems. Major projects included the removal and consolidation at the Butte Priority Soils Operable Unit, repository construction at the Butte Mine Flooding sites, and channel restoration along Silver Bow Creek. Techniques drew on precedents from the Animas River response and sediment remediation methods developed at Bunker Hill Mine and Smelting Complex. Adaptive management incorporated sediment transport modeling, surface water monitoring, and vegetation reestablishment using native species recommended by United States Fish and Wildlife Service and Natural Resources Conservation Service protocols.
The cleanup unfolded within a complex legal matrix involving CERCLA liability allocations, Natural Resource Damage Assessment (NRDA) claims under the National Oceanic and Atmospheric Administration and United States Department of the Interior authorities, and state enforcement by the Montana Department of Environmental Quality. Litigation implicated defendants including ARCO, leading to settlements and consent decrees with the United States Department of Justice and the EPA that funded remedial actions and stipulated long-term obligations. Federal funding mechanisms, Superfund trust provisions, and precedent-setting court decisions influenced arrangements comparable to settlements reached at the Libby Asbestos Superfund site and Kerr-McGee liability cases.
Local governments such as the City and County of Butte-Silver Bow, civic organizations, and tribal entities participated in stakeholder advisory groups, public comment periods, and technical review committees. Community health studies engaged partners like the Centers for Disease Control and Prevention and the Agency for Toxic Substances and Disease Registry to assess exposure, while nonprofits and advocacy groups echoed concerns similar to activism at Hanford Site and Love Canal. Economic transition initiatives addressed job loss from mine closures by coordinating with Montana Department of Commerce programs and federal workforce initiatives. Public meetings, information repositories, and Environmental Justice dialogues sought to reconcile differing perspectives on remediation pace, repository siting, and land reuse.
Long-term monitoring includes surface water and groundwater quality programs, sediment and biota sampling coordinated by the EPA, state agencies, and tribal partners, and maintenance of engineered caps and repositories. Restoration goals emphasize reestablishing self-sustaining riparian corridors, restoring sport fisheries valued by Montana Fish, Wildlife and Parks, and supporting recreational economies in Butte and Anaconda. While progress has reduced acute exposure risks and stabilized many contaminated sites, ongoing institutional controls, stewardship plans, and periodic reviews under CERCLA ensure continued oversight. The project remains a case study in large-scale Superfund remediation, intersecting with legal, ecological, public health, and socioeconomic dimensions addressed in remediation literature and federal policy analyses.
Category:Superfund sites in Montana Category:Butte, Montana Category:Mining in Montana