State regulators Thursday directed Cotter Corp. to treat water from its nonoperating uranium mine in Jefferson County to keep contamination from reaching Ralston Reservoir, a drinking-water supply for Denver Water and the city of Arvada.
The state Division of Reclamation Mining and Safety rejected the protection plan Cotter submitted last month and instructed the Denver-based company to submit a water-treatment plan within two weeks, the agency said in a news release.
The mine closed in 2000, and Cotter dismantled its treatment plant in 2002, according to the agency. Drinking water remains safe, Denver Water and Arvada authorities said, because uranium has been removed by water-treatment plants.
The latest water-quality tests showed that Ralston Creek below the mine carried as much as 390 parts per billion of uranium, 13 times higher than the safety standard.
Cotter had proposed a man-made wetland and a chemical filter to capture uranium leaking from the mine. The Denver Post
