Industry and environmental groups — incongruously — both celebrated the same major victory Thursday after an administrative law judge threw out a proposed state rule to protect wild rice in Minnesota.

The proposed rule, which has sparked fierce political fights and multiple lawsuits since the state began writing it in 2010, was designed to regulate sulfate, a mineral salt that damages wild rice; it is produced by taconite mines, wastewater treatment plants and other industries. While the state's rule is specific to wild rice, sulfate also plays a part in converting mercury into a form that is taken up by fish, creating significant health risks for pregnant women and children.

The proposal, written by the Minnesota Pollution Control Agency (MPCA), was bitterly opposed by Minnesota's Indian tribes, environmental groups, industry and wastewater treatment operators. But they had different reasons.

Environmentalists and the tribes said the state's existing sulfate standard of 10 parts per million, which has been in place since the 1970s, protects wild rice if it is enforced. With few exceptions, however, the state has never done so.

Industry representatives said the state's new rule would be prohibitively expensive and unworkable: The highly complicated plan would use a chemical formula to set sulfate limits on discharges upstream of each of 1,300 individual lakes or rivers where wild rice grows.

On Thursday, LauraSue Schlatter, the administrative law judge charged with deciding whether the rule is reasonable, agreed with both arguments. She reimposed the MPCA's original standard of 10 parts per million, saying that the state's decision to repeal it was a violation of the federal Clean Water Act. She also concluded that while the formula approach had scientific validity, the state could not effectively implement it without first conducting years of study on the 1,300 wild rice waters. It was unconstitutionally "void for vagueness," she said.

Officials from the Minnesota Pollution Control Agency and some industry groups declined to comment.

Environmentalists generally welcomed the decision.

"It has been a long and difficult road," said Paula Maccabee, an attorney for WaterLegacy, an environmental group that has fought the proposed rule since the beginning. "For the first time in a long time, it feels as if the rule of law matters."

Kelsey Johnson, president of the Iron Mining Association of Minnesota, also said the ruling was huge relief. If established, the new rule might eventually have forced taconite mine operators to spend billions of dollars on reverse osmosis water treatment plants, the only known process for removing sulfates, she said.

'Our voices were heard'

During multiple public hearings over the last year, mining industry executives said the rule could force many mines out of business. Larry Sutherland, head of U.S. Steel's operations in Minnesota, said at an October hearing before Schlatter that its Keetac mine would have to spend $200 million to control sulfates.

"That cost is supposedly to protect the rice that, by the way, is flourishing downstream where we have discharged for 50 years," he said.

"We believe our voices were heard," Johnson said. The judge "understood that this is dire situation for a lot of communities."

Johnson said taconite and other industry officials do not believe the state needs a sulfate standard, and that there are other ways to restore wild rice.

But tribal members and officials also argued that the proposed rule would have meant the destruction of what's left of wild rice in the United States, a fundamental part of their diet and spiritual lives. It once grew across the eastern part of the nation, but now exists exclusively in some parts of the Great Lakes States, primarily Minnesota. It has been named the state grain.

The judge said the agency did too little in considering the impact of the rule on tribes.

"Implementation of the rule as proposed is a burden to the Minnesota Indian tribes, and many Native American individuals," she said. "They are compelled to continue to challenge the rule because they believe that the long-term survival of wild rice is in peril and do not believe that the Agency understands the importance of wild rice in Native American culture and life."

Contaminated muck

The state has until 2019 to come up with another sulfate rule. The MPCA commissioner can implement the agency's new rule despite Thursday's ruling, which is considered advisory, but that is considered likely to result in lawsuits against the agency. The agency can also appeal the ruling to the State Court of Appeals.

But whatever rule is adopted must also be approved by the U.S. Environmental Protection Agency, which under Administrator Scott Pruitt has become more friendly to industry.

"We look forward to working with the EPA to find a reasonable solution," Johnson said.

The state first adopted its sulfate standard in the 1970s, based on the research by a noted biologist who found that wild rice didn't grow well in waters with high sulfate levels. But it was largely ignored until the last decade, when Indian tribes and environmental groups brought it to the attention of the EPA. It has since become a contentious issue, resulting in legislative attempts to change the rule, failed lawsuits by industry, and several years of scientific study by the MPCA.

The research showed that sulfates are converted to sulfide in the muck at the bottom of lakes and rivers. That transformation varies depending on how much carbon and iron are present. But it's the sulfides that inhibit wild rice.

The state's proposed rule would have required agency researchers to examine each of the 1,300 bodies of water that have so far been identified as places where wild rice grows — or used to grow. A formula would be applied to each one to determine how much to limit sulfate discharges upstream, a process that agency officials said could take years to complete.

Josephine Marcotty • 612-673-7394