The Boundary Waters Canoe Area and Voyageurs National Park are considered pristine wilderness areas, but they often have dirty air -- pollution from many sources, including power plants and taconite mines.
On a clear day in the Boundary Waters a visitor can see 120 miles. But on one of every five days in any given year, there are so many pollutants in the air that visibility is reduced to just 33 miles. It's part of a floating mix that also falls into area rivers and lakes.
Today the Minnesota Pollution Control Agency takes another step in a long-running effort to clean up the air over some of Minnesota's most cherished places. The MPCA's Citizens' Board will consider a state plan to reduce air pollution that it must present to the federal Environmental Protection Agency.
The Regional Haze Rule is part of a nationwide attempt to return clear skies to the largest national parks and wilderness areas, including the Grand Canyon, Lake Superior's Isle Royale, and other treasures. The plan also aims to rid the air of pollutants that contribute to heart attacks, asthma, and other health problems.
Environmental Protection Agency officials have indicated they likely will approve it. But the National Park Service and the U.S. Forest Service, the agencies responsible for the national parks and wilderness areas, have criticized the state's plan and say it doesn't cut pollution enough.
Congress mandated the project in 1977, and gave states nearly a century to meet the goal. The big question is whether interested parties, among them industry and environmental groups, can settle on a means of doing it.
The first steps mandated by the federal government are to reduce emissions from older coal-fired power plants and taconite plants that have largely fallen through the cracks of other pollution-control programs.
Minnesota's plan has not changed much since it was first outlined in 2008. For power plants, the state embraces the federal EPA's argument that a different rule, designed to cut back on air pollution that crosses state boundaries, will address the issue.
For the taconite industry, state officials say processing plants can meet the requirements by fine-tuning existing scrubbers and operating their furnaces as efficiently as possible.
"Getting to the ultimate goals is a long process," said Catherine Neuschler, the MPCA's Regional Haze plan coordinator. "It's something we're going to be doing multiple plans for between now and 2064."
Neuschler has been working on the Regional Haze Rule since she started at the Minnesota Pollution Control Agency in 2006. She reminds people that the state is still in the early stages of a big project.
Five power plants in Minnesota fall under the Regional Haze Rule, but the biggest by far is Xcel Energy's Sherco plant near Becker.
Frank Prager, Xcel's vice president of environmental policy and energy, said Sherco has already embarked on a big clean-up program, addressing two major pollutants that cause haze, nitrogen oxides and sulfur dioxide. He said the plant has reduced its nitrogen oxide emissions by 45 percent and its sulfur dioxide emissions by 50 percent - for $50 million.
MPCA officials say that's good enough to meet interim goals set for 2018.
But environmental groups say it doesn't make sense to take limited measures.
Mark Wenzler, director of clean air and climate programs for the National Parks Conservation Association, said a technology called selective catalytic reduction could capture 90 percent of nitrogen oxides. The process uses a catalyst to convert nitrogen into harmless diatomic nitrogen and water.
"Companies don't want to install that technology because it costs more," he said. But if they are serious about reducing nitrogen oxide emissions and haze pollution, he said, "that's the best way to do it."
MPCA officials say selective catalytic reduction would not be cost-effective at the Sherco plant, and might not achieve as much reduction as environmental groups think.
Environmental groups also criticize the state's plan for taconite plants. An earlier version would have required taconite producers to try out some new technologies to evaluate how well they would work.
U.S. Steel's Minntac plant has been testing a burner is designed to minimize nitrogen oxide emissions.
But state pollution control officials recently decided to rely on a new and separate federal rule that also requires reductions of nitrogen oxide and sulfur dioxide.
Neuschler said because the state is unwilling to mandate certain technologies, the federal EPA might decide to oversee the taconite industry on nitrogen oxide.
"We're interested in letting them figure out what control technologies make sense to do that, rather than dictating a specific control technology," she said.
But Neuschler said burners that use less nitrogen oxide have great potential.
Kevin Reuther, legal director for the Minnesota Center for Environmental Advocacy, said trying out new technologies is a key part of the Regional Haze Rule, and the state is sidestepping it.
"They really just took a pass [and] said, 'we're okay with the level of pollutants that the taconite industry is currently emitting,' " he said.
Officials at U.S. Steel, which operates two big taconite plants, declined to comment for this story.
Cliffs Natural Resources operates three plants. Its officials said in a statement that they are concerned about the state's proposed limits and about the company's ability to meet the limits with available technology.
The federal government is under a court-ordered consent decree to accept or reject state plans this year. The decree stems from a lawsuit filed by the National Parks Conservation Association pushing the EPA to act.
Meanwhile, industry groups are challenging the cross-state rule that both EPA and Minnesota want to use to address power plant pollution in national parks.