Butte has the dubious distinction of being at the upper end of the largest complex of federal Superfund sites in the U.S. This Superfund complex extends from Butte and Anaconda 120 miles down the Clark Fork River to Missoula.
The word “Superfund” is tossed around a lot by local and state officials working in the Clark Fork Basin, but, to the average citizen of western Montana, the term might not mean very much. Nevertheless, Superfund is changing the landscape of western Montana, from the Berkeley Pit to the Anaconda Smelter all the way downstream to the former Milltown Dam.
In simple terms, Superfund refers to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980. This federal law, passed in the wake of environmental disasters like Love Canal, was designed to clean up abandoned hazardous waste sites that may endanger public health or the environment.
The law authorizes the Environmental Protection Agency (EPA) to identify parties responsible for contamination of sites and compel the parties to clean up the sites. Where responsible parties cannot be found, EPA is authorized to clean up sites itself using federal funding.
The Superfund cleanup process is very complex. It involves the steps taken to assess sites, place them on the National Priorities List, and establish and implement appropriate cleanup plans. This is the long-term cleanup process. EPA also has the authority to remove hazardous wastes where immediate action needs to be taken; to enforce against potentially responsible parties; to ensure community involvement; to involve states; and ensure long-term protection.
According to the EPA, as of August 5, 2013 there are 1,320 sites listed on the National Priority List, an additional 365 have been delisted, and 54 new sites have been proposed. There are currently 17 National Priority List sites in Montana, and two Superfund sites that are not part of the National Priority List.
An operable unit is a subsection of a larger EPA Federal Superfund site. There are four Operable Units (OUs) in the Butte mining district.
The Butte Mine Flooding Operable Unit, which includes the Berkeley Pit, the hydraulically-connected underground mine workings associated with the historic East Camp and West Camp tunnel systems, associated bedrock, and alluvial aquifers. The area covers approximately 23 square miles.
Butte Priority Soils is a five square mile area that includes the town of Walkerville, along with the part of the Butte Hill that is north of Silver Bow Creek, west of the Berkeley Pit, and east of Big Butte. It also includes a section of land extending south from Silver Bow Creek to Timber Butte. This Operable Unit includes residential yards, mine dumps, contaminated railroad beds, and stormwater drainages on the Butte Hill and in Walkerville.
Silver Bow Creek/Streamside Tailings Operable Unit, which follows Silver Bow Creek from just below the historic Colorado Tailings deposit in Butte and 25 miles downstream to the Warm Springs Ponds. The area includes Silver Bow Creek itself, as well as the adjacent mining wastes deposited along the creek bank and nearby floodplain, and railroad embankments adjacent to the stream that contain mining wastes.
West Side Soils Operable Unit includes lands that fall outside of the Butte Priority Soils OU. There are approximately 1,500 mine waste dumps located north and west of Butte. The dumps have not been sampled. A schedule for investigating this OU and selecting a remedy has not yet been set.
There are numerous additional operable units in the greater Clark Fork River Superfund site, which stretches from Butte and 120 miles downstream to the Milltown Dam near Missoula.