The state's largest business group filed suit against the Minnesota Pollution Control Agency on Friday, raising the heat in an increasingly contentious fight over mining in northern Minnesota and what's good for wild rice.

The Minnesota Chamber of Commerce, which represents PolyMet Mining Corp. and other minerals companies, accused the agency of holding them to a different standard from other industries on how much sulfate they can discharge into Minnesota's wild rice waters.

High concentrations of sulfates are toxic to wild rice, and the debate about how much is too much has become a flashpoint in the broader environmental conflict over the proposed expansion of mining on the Iron Range.

"They are trying to rewrite the rule under which they are regulated," said Paula Maccabee, an attorney for Water Legacy, one of the environmental groups that has so far successfully fought to keep the standard where it is.

The chamber contends that the state's 1973 sulfates rule is outdated, was intended for commercially grown paddies, not natural stands, and should be loosened -- in addition to accusing the PCA of applying it unequally.

Mark Tomasek, supervisor of the PCA's water quality unit, said Friday he could not comment on the lawsuit. But he said it's clear from both the language of the rule and the historical record that the standard is intended to apply natural wild rice.

Tomasek also said the agency will enforce the rule whenever it finds through monitoring and data collection that an industry is out of compliance.

The state is reviewing the sulfate standard and other water quality standards as part of a scheduled review conducted every three years or so.

But the sulfate standard has not been included in the regular review in decades. Nor was it enforced on industry and other potential polluters until earlier this year, when it popped up as an issue in the proposed PolyMet copper-nickel mine near Babbitt and Hoyt Lakes.

In February the federal Environmental Protection Agency sharply criticized the government review of the $600 million copper-nickel mine -- citing as one reason the state's disregard for its own sulfate standard.

Now the state and federal governments are conducting a second environmental review of the mining project. This time the EPA insisted that the state clarify how and if the sulfate rule will be applied -- and assess how the project will affect wild rice waters.

Since then the state has told mining companies -- but not municipal wastewater treatment facilities -- that they will be expected to comply with the rule. The cost could run into the hundreds of millions of dollars, said Mike Robertson, an environmental consultant for the chamber.

That set the stage for the chamber's unusual legal action on Friday.

Robertson said the public review that's underway will take too long. "We think that establishing a higher priority for this issue will get more attention from the people that need to participate, and move in a fashion where we can address it," he said.

Environmentalists, however, said the business group is trying to avoid complying with established regulations.

"Dealing with sulfate is going to be a huge hurdle that will be impossible for PolyMet without making significant alteration in their project," said Betsy Daub, policy director for Friends of the BWCA, an advocacy group. "What do they do? They try and weaken our laws."

Along with the lawsuit, the chamber has petitioned the PCA to start a special rule-making process for wild rice alone. That will speed up the process as well, Peterson said.

"One of the immediate needs is research" to determine a scientifically based level that will protect wild rice, he said. A special rule-making process can determine "what's needed, how much it will cost, and how long it will take," he said. The timing is critical, he said, because the Legislature may have to decide whether or not to devote funds to it, he said.

However, Tomasek of the PCA said state and federal environmental agencies are already working on a research plan.

Both environmental groups and Minnesota Indian tribes, who rely on wild rice for food and cultural traditions, say the scientific basis for the rule is sound. It should remain where it is until research proves otherwise, they said.

Josephine Marcotty • 612-673-7394