BILLINGS, Mont. (AP) — Federal regulators have approved a new measure meant to help turn Montana's Big Sky Country into Clear Sky Country by forcing industrial plants to cut pollutants that make hazy skies over national parks and wilderness areas.

The Environmental Protection Agency rule, signed Wednesday, has been widely criticized by industry representatives, conservationists and even other federal agencies.

The goal is to restore visibility to natural conditions in national parks and wilderness areas from Idaho to North Dakota by 2064. To get there, the agency detailed $85 million in upgrades needed within five years at the Colstrip coal power plant in southeastern Montana, the Ash Grove cement plant near Montana City and the Holcim cement plant near Three Forks.

Including operating expenses over the next 20 years, the total costs to the three plants would top $270 million.

The upgrades would reduce industrial emissions of sulfur dioxide and nitrogen oxides. The two pollutants react with the atmosphere and cause the air to appear hazy above some of the nation's prized public lands, including Yellowstone, Glacier and Theodore Roosevelt national parks.

In the western U.S., haze is blamed for reducing visibility by half versus natural conditions.

But conservationists complain the upgrades being required in Montana don't do nearly enough. They point out that it would take hundreds of years for some sites to reach the EPA goal.

"EPA is forfeiting an enormous opportunity here," said Jeremy Nichols with WildEarth Guardians. "The real benchmark is, are we doing everything reasonable to achieve clean air? EPA didn't achieve that goal."

The EPA said more expensive pollution control upgrades were not justified.

"You have incremental levels of improvement but you also have incremental costs associated with that," said Carl Daly, director of the EPA's regional air program.

The agency said achieving natural visibility by 2064 was not a realistic goal. Instead, the EPA said its plan was reasonable in that it will take between 135 years and 427 years to restore visibility to its natural conditions in the parks and wilderness areas analyzed.

Northeast Montana's Medicine Lake Wilderness would take the longest — 437 years. Among other notable locales, Yellowstone National Park would take 161 years and Glacier National Park 268 years.

Yet industry representatives said the EPA dramatically underestimated the costs of compliance, while overestimating the actual improvements those upgrades will produce.

Colstrip operator PPL Montana said installing the pollution control equipment required under the federal rule would cost it $190 million. That's more than double the EPA's $83 million estimate.

Colstrip is the second largest coal-fired power plant west of the Mississippi River, burning more than 10 million tons of coal a year to generate about 2,200 megawatts of electricity.

"These are huge investments," said PPL Montana spokesman David Hoffman. "I don't think it will actually accomplish anything that is perceptible to the human eye. And that's what this rule Is about."

Daly said that while air quality improvements from upgrades made at any single plant might not be visible, the cumulative effects would be a "significant improvement."

An estimated 6,500 tons of nitrogen oxides and 8,600 tons of sulfur dioxide will be reduced annually as a result of the plan, EPA spokesman Matthew Allen said in a statement.

Many other states have been devising their own haze-reduction plans, but Montana chose to let the federal government take the lead. Some states and utilities elsewhere have been pushing back. As with PPL, they cite costs and say the five-year timeline for compliance is too short.

The EPA's action in Montana comes after WildEarth Guardians and others sued the agency to follow through on preliminary haze rules adopted in 1999.

Any legal challenge to Wednesday's rule would have to be filed with the U.S. Court of Appeals within 60 days of its publication in the Federal Register. Montana retains the option of coming up with its own rule subject to final EPA approval, Daly said.


Volz reported from Helena.