Under the consent decree, the EPA has to propose a plan by Feb. 27 and finalize it by August 2015.
The EPA first must decide whether the National Park Service was right when it certified that the haze problem at the parks was "reasonably attributable" to the plant's emissions, Reuther said. If so, then the EPA would determine what kind of pollution control technology is required, he said. Adding it could require an expensive investment by Xcel, which would have just five years to install it.
"This is a major step toward clean air in Boundary Waters, Voyageurs and Isle Royale," Stephanie Kodish, director of the Clean Air Program at the National Parks Conservation Association, said in a statement.
The EPA must publish the proposed consent decree in the Federal Register and hold at least a 30-day public comment period before the settlement goes to a federal judge for approval.