Officials at the Environmental Protection Agency (EPA) knew of the potential for a poisonous water “blow-out” at an abandoned mine in Colorado at least a year before the major spill earlier this month.
The revelation came in dozens of pages of documents that the EPA released late Friday night, related to the Gold King Mine near Silverton, Colo.
“Conditions may exist that could result in a blow-out of the blockages and cause a release of large volumes of contaminated mine waters and sediment from inside the mine,” the EPA’s Denver-based Region 8 wrote in the report.
A communication in May 2015 by Environmental Restoration also warned of the blowout risk. It called for the construction of a pond to catch the wastewater, but the pond did not get built.
The reports are likely to play a major role in the various investigations that have been launched into the incident. Lawmakers are conducting examinations, in addition to EPA’s Office of Inspector General, the Interior Department and other bodies.
The EPA is under fire locally and nationally over the Aug. 5 spill, in which about 3 million gallons of fluid containing heavy metals, like mercury and lead, spilled into a tributary of the Animas River, turning it bright orange and closing it and other rivers for more than a week.
The House Committee on Science, Space, and Technology announced last week that in September it would conduct the first hearing regarding the spill, after Congress returns from its summer recess.
The EPA has also weathered criticism for a perceived lack of transparency and urgency in its response.
The documents released Friday night came only after prodding from multiple media outlets. The department took the unusual step of posting them publicly on its website instead of routing them through public records requests.