• In this Aug. 14, 2015 file photo, water flows through a series of sediment retention ponds built to reduce heavy metal and chemical contaminants from the Gold King Mine wastewater accident, in the spillway about a quarter mile downstream from the mine outside Silverton, Colo. Federal and state regulators underestimated the potential for a toxic blowout from the Colorado mine, despite warnings more than a year earlier that a large-volume spill of wastewater was possible, an internal government investigation released Wednesday, Aug. 26, 2015 found. The massive spill occurred on Aug. 5 when a government cleanup crew doing excavation work triggered the release of an estimated 3 million gallons of sludge that fouled hundreds of miles of rivers in Colorado, New Mexico and Utah.  (AP Photo/Brennan Linsley, File)

    Investigation: EPA, state missed potential for mine blowout

    BILLINGS, Mont. (AP) — Members of a federal cleanup crew were initially trapped and unable to warn downstream communities that they had accidentally unleashed toxic waste water from a Colorado gold mine, according to government documents released Thursday.