This week, the U.S. Environmental Protection Agency (EPA) added three mining-related sites to the National Priorities List (NPL) of Superfund sites. These include the Bonita Peak Mining District (BPMD) site in San Juan County, Colorado; the Argonaut mine, Amador County, California; and the Anaconda Aluminum Co.’s Columbia Falls Reduction Plant site, also known as the Columbia Falls Aluminum Co. (CFAC) site, in Columbia Falls, Montana.

The law establishing the Superfund program, the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), requires the EPA to update the NPL at least annually and clean up hazardous waste sites. The designation comes a little more than a year after the EPA released 3 million gallons of water from the Gold King mine into the Animas River fouling rivers and lakes from Colorado to Nevada. The Gold King mine is one of several abandoned mines in the Bonita Peak district.

“Listing [it] on the [NPL] is an important step that enables the EPA to secure the necessary resources to investigate and address contamination concerns of San Juan and La Plata counties, as well as other downstream communities in New Mexico, Utah, and the Navajo Nation,” said Shaun McGrath, EPA’s regional administrator.

The lawsuits stemming from this mishap are just now coming to a head. The state of New Mexico, however, is suing the state of Colorado, claiming it approved the plans that led to this situation.

The Bonita Peak Mining District site consists of historic and ongoing releases from mining operations in three drainages, which converge into the Animas River near Silverton, Colorado. Water quality in the BPMD has been impaired by acid mine drainage for decades. Since 1998, the state of Colorado has designated portions of the Animas River downstream from Cement Creek as impaired for heavy metals, including lead, iron and aluminum. The EPA has waste quantity data on 32 of Bonita Peak’s 48 sources. These 32 sources have waste rock and water discharging out of adits at a combined rate of 5.4 million gallons per day. Cadmium, copper, manganese and zinc are the known contaminants associated with these discharges.

The CFAC site is located outside Columbia Falls near the south entrance of Glacier National Park. The CFAC plant operated between 1955 and 2009 and created significant quantities of spent potliner material, a federally listed hazardous waste, as a byproduct of the aluminum smelting process. A remedial investigation of the CFAC site is under way and is being completed by CFAC and its contractors.

“Now that Argonaut mine is on the Superfund list, the EPA can begin full-scale efforts to clean up contaminated soil throughout the site,” said Alexis Strauss, EPA’s acting regional administrator for the Pacific Southwest. “As we have been working with the community since 2013, this is an important step to address the mine’s toxic legacy.”

The Argonaut gold mine operated from the 1850s to 1942, placing tailings on the northwest side of Jackson, California. Most of the contaminated soil is contained in a 65-acre area to the west of Highway 49.