DENVER—State regulators have rejected a plan by Cotter Corp. to clean up contamination from a closed uranium mine that has flowed into a creek that feeds a Denver-area reservoir.
The Colorado Division of Reclamation Mining and Safety said Thursday it doesn’t believe the plan would prevent uranium from contaminating Ralston Reservoir, which supplies some of the Denver area’s drinking water.
Loretta Pineda, the agency’s director said Cotter has been directed to resume treating the water and submit a new plan within two weeks.
“Protecting the public and drinking water supplies is our top priority,” Pineda said. “We have concluded that Cotter’s plan will not accomplish the goal of protecting Ralston Reservoir.”
State officials said they would begin enforcement proceedings against the company.
Denver-based Cotter didn’t return a call for comment after business hours Thursday.
The contamination is coming from the Schwartzwalder mine northeast of Golden, which operated from 1953 until May 2000. High concentrations of uranium have been found in Ralston Creek, which feeds the reservoir.
Recent water-quality tests showed that uranium levels in Ralston Creek below the mine were 13 times higher than the public health standard.
Water managers are pressuring regulators to force Cotter to clean up the contamination, but say drinking water in the reservoir is still safe.
Cotter’s plan rejected by the state included water monitoring and creation of a wetland to trap the uranium.
