One year ago - on Aug. 5, 2015 - an EPA crew at the Gold King Mine in southwest Colorado accidentally unleashed 3 million gallons of orange water filled with mercury and arsenic.The toxic spill flowed into the Animas River, eventually running into New Mexico's San Juan River and into Lake Powell. So far, disaster response and water quality monitoring have cost the EPA about $29 million - and the problem isn't over yet.