A Colorado gold mine that spilled more than 3 million gallons of wastewater into western rivers was among nearly a dozen sites added Wednesday to the Environmental Protection Agency’s Superfund National Priorities List.

The designation of the inactive Gold King Mine in the Bonita Peak Mining District paves the way for a multimillion-dollar cleanup if Congress approves the Superfund listing. The other locations added to the Superfund list or proposed for addition include a custom cleaners site in Memphis, a plastic-manufacturing site in Hoosick Falls, N.Y., a lumber site in Quincy, Fla., and a site with contaminated groundwater in Dorado, Puerto Rico.

“Listing the Bonita Peak Mining District on the National Priorities List is an important step that enables 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,” EPA Regional Administrator Shaun McGrath said in a statement. “We look forward to continuing our efforts with the state of Colorado, the Bureau of Land Management, the U.S. Forest Service, tribal governments and our community partners to address the impacts of acid mine drainage on the Animas River.”

Within a day of the wastewater spill in August 2015, the Animas between the communities of Silverton and Durango turned a sickly yellow. The accident was blamed on workers who damaged a plug that held the water back. The spill flooded a holding pond and sent water fouled with lead, arsenic, zinc, iron, cadmium and other toxins into tributaries to the Animas River.

In the days that followed, the contamination spread to rivers in New Mexico and Utah. “Listing the Bonita Peak Mining District is critical to addressing historic mining impacts in San Juan County and our downstream communities,” Martha Rudolph, director of environmental programs for the Colorado Department of Public Health and Environment, said in a statement. “We are committed to working closely with our federal and state partners to achieve an effective cleanup, while ensuring that all our affected communities have a voice in the process as this moves forward.”

The EPA proposed listing the district in April. According to a report in the Denver Post, it consists of three dozen dormant mines, seven tunnels, four mine dumps and two study areas — sites along Mineral Creek, Cement Creek and the Upper Animas that flow into the main Animas. The area has been mined since the start of the Civil War.

Congress established the Superfund program in 1980 to reduce threats to human health and ecological systems from massive and toxic sites.

According to Thaddeus Lightfoot, who practices environmental law, the designation is important for several reasons. It clears a path for funding that would allow an investigation into the extent of damage caused by the mining district and the start of the actual cleanup. In doing so, it also would end a long debate in the area over whether the federal government should orchestrate a cleanup.

The decision “is the latest step in addressing the disastrous damage caused over one year ago at the Gold King Mine,” Lightfoot said. But the listing doesn’t resolve pending litigation by the state of New Mexico and the Navajo Nation, which alleges that EPA negligence “caused extensive damage to the Animas and San Juan Rivers,” according to Lightfoot.

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