Newly released internal Environmental Protection Agency documents reveal that agency officials knew of the potential for a catastrophic "blowout" at the abandoned Gold King Mine in Colorado long before a government cleanup team triggered a spill earlier this month, reported the Associated Press.

The documents include a June 2014 work order from the contractor Environmental Restoration warning EPA managers that conditions at the mine "could result in a blowout" and release "large volumes" of wastewater laced with toxic metals, posing a danger "to human health and the environment."

"This condition has likely caused impounding of water behind the collapse," the report says, according to AP. "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."

EPA released the documents after weeks of prodding from the AP and other news organizations.

During an Aug. 5 inspection of the Gold King Mine near Silverton, Colo., an agency cleanup team using heavy equipment to enter the mine accidentally unleashed 3 million gallons of contaminated wastewater that eventually ran into rivers in Colorado, Utah and New Mexico, as previously reported by HNGN.

The contractor warned the EPA in a May 2015 action plan about a possible blowout for a second time, the documents show. Despite the multiple warnings, the EPA only appeared to have a cursory plan to deal with such a spill, AP noted.

At least three investigations are being conducted into how exactly the EPA triggered the blowout.