Some environmental groups are asking the federal government to pressure Minnesota to set stricter limits on air pollution to protect the Boundary Waters and Voyageurs National Park.
Minnesota, and most other states, are in a long process to figure out how to reduce haze in national parks and wilderness areas.
Four environmental groups say Minnesota's plan -- so far -- will not do enough.
They're asking the Department of the Interior to press the Minnesota Pollution Control Agency to require power plants, especially Xcel Energy's Sherco plant in Becker, to install better pollution controls.
The Department of the Interior manages national parks.
The MPCA will respond to comments on its plan, and hopes to have it ready for approval by the federal Environmental Protection Agency by the end of this year.