Earlier last month, the Environmental Protection Agency (EPA) tried to clean up the Gold King Mine, but instead released 3 million gallons of contaminated water into the Animas River in southwest Colorado. Internal documents now show that the EPA knew of the risk of a blowout, the Associated Press reports.

The documents include a June 2014 work order for the planned cleanup of the Gold King Mine, which no one had accessed since 1995, when the entrance partially collapsed. The document notes that “This condition has likely caused impounding of water behind the collapse…In addition, other collapses within the workings may have occurred creating additional water impounding conditions.”

“Conditions may exist that could result in a blowout of the blockages and cause a release of large volumes of contaminated mine waters and sediment from inside the mine, which contain concentrated heavy metals,” the report says.

The EPA was criticized for not immediately announcing the accident to locals, which saw initial estimates jump from 1 million gallons of contaminated water to 3 million. The EPA is responsible for clearing up environmental disasters, not causing them – an irony that was not lost on a local resident who suggested the agency should call itself the “Environmental Pollution Agency.”

The contaminated water is thought to contain heavy metals, including arsenic, mercury, iron, zinc, copper and lead. The EPA is still investigating the health effects of the leak, which now stretches more than 160 kilometers (100 miles) into neighboring New Mexico. The Animas River reopened earlier last week as contamination levels have fallen back to pre-spill levels. The agency said the spill now presents little danger to locals beyond Lake Powell.  

The Associated Press reports that “A 71-page safety plan for the site included only a few lines describing what to do if there was a spill: Locate the source and stop the flow, begin containment and recovery of the spilled materials, and alert downstream drinking water systems as needed.”

It remains unclear what happened before or after the spill. Currently, there are three ongoing investigations trying to uncover what triggered the explosion and how it was dealt with. The EPA has not only been criticized by elected officials in the area, but also by the president of Navajo Nation. In response to the spill, the EPA delivered water to sustain agricultural operations and livestock. Tensions increased between the EPA and Navajo Nation when the latter accused the agency of recently delivering water in dirty oil tanks. The agency has promised to investigate the Navajo Nation’s allegations.