The U.S. Environmental Protection Agency on Friday denied that it is obligated to order advanced pollution controls at a large, coal-burning power plant to reduce haze over national parks in Minnesota and Michigan.
The agency responded in U.S. District Court for Minnesota to a December lawsuit by six environmental groups accusing the agency of not enforcing air pollution rules on two 1970s-era generators at Xcel Energy's Sherco power plant in Becker, Minn.
The power plant -- largest in the state -- has been declared by the U.S. Interior Department to be a source of haze over Voyageurs National Park in Minnesota and Isle Royale National Park in Lake Superior. The National Parks Conservation Association and other groups sued the EPA to take action.
In its response, the EPA said it is "under no mandatory duty" to make a haze-related regulatory case against the Sherco plant and that environmental groups are engaging in "speculation" to suggest it. The EPA asked the court to dismiss the case.
Haze is caused by smokestack emissions that can travel hundreds of miles, reducing visibility. The federal Clean Air Act has long required protecting pristine natural areas from such visual pollution.
Xcel, the Minneapolis-based power company that serves 1.2 million electric customers in the state, is adding pollution controls to Sherco at a cost of $50 million. Environmental groups contend the law requires more advanced technology, called Selective Catalytic Reduction, that would cost an estimated $340 million.
The utility is not a party to the lawsuit. When asked whether Xcel would try to join the case, Frank Prager, vice president of environmental policy and services, responded by e-mail that the company will evaluate whether to intervene.
"Regardless of our legal response, we believe that our investments in emission reductions at Sherco have addressed its contribution to haze in Minnesota's national parks and wilderness areas and that the plant is in full compliance with the Clean Air Act," Prager said.
Xcel also is studying the future of the Sherco plant, including whether the older units should be replaced by units fueled by natural gas. That study will be submitted to the state Public Utilities Commission in July.
Other groups behind the lawsuit are the Minnesota Center for Environmental Advocacy, Friends of the Boundary Waters, Voyageurs National Park Association, Fresh Energy and Sierra Club.
The EPA recently issued haze-related rules for the taconite industry that will force plants in Minnesota to add expensive controls for nitrogen oxides and sulfur dioxide that cause haze over Voyageurs and the Boundary Waters Canoe Area.
David Shaffer 612-673-7090 @ShafferStrib