An internal government investigation has found that federal and state regulators underestimated the potential for a blowout from a Colorado mine. The disclosure was contained in documents released yesterday by the U.S. Environmental Protection Agency. Investigators concluded that EPA and state regulators underestimated how much water pressure had built up inside the inactive mine before a government cleanup crew triggered the release. The EPA previously offered only partial information on events leading up to the spill. The August 5th spill involved 3 million gallons of waste from the idle Gold King Mine near Silverton, unleashing a torrent of toxic water that fouled rivers in three states. The Associated Press reported Saturday that EPA managers knew that a large spill was a possibility yet had drafted only a cursory response plan for responding to a spill. An opinion piece that was published a week before the spill predicted that it would occur, that the EPA knew that it would occur, and that the event would be used to secure Superfund status, a designation many feel will hurt the local economy.