The proposed $700 million natural gas power plant in Superior will be air cooled instead of water cooled after Wisconsin regulators last year raised concerns over the potential for the plant to deplete nearby wells.

The changes were announced in a short letter filed to the Wisconsin Public Service Commission on Monday by Justin Chasco, a lawyer representing Minnesota Power and Dairyland Power. Together, the companies are looking to build the 625-megawatt Nemadji Trail Energy Center between Enbridge Energy's Superior Terminal and the Nemadji River in Superior.

"This proposed change is expected to address concerns regarding site stability and will eliminate the need for high-capacity wells," Chasco wrote. "The applicants intend to provide more detailed information in the second half of April 2020."

Last year, a Wisconsin Department of Natural Resources hydrologist wrote "it appears that the operation of the proposed (Nemadji) wells is likely to deplete groundwater from the sand and gravel seam beneath the Nemadji River site,” and that the agency, with the data available at that time, could not determine the project “would not have a significant detrimental effect on the quantity” of the groundwater.

At the time, Minnesota Power said that if the plant couldn't use groundwater, it could tie into the city of Superior’s water system or pull from Lake Superior.

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But Julie Pierce, vice president of strategy and planning at Minnesota Power, told the News Tribune on Monday that won't be necessary if they change to the air-cooled method as it would eliminate the need for much of the plant's water consumption, and the company will no longer pursue a high-capacity well permit from the WDNR.

"What we heard in terms of outreach with our stakeholders is that any consumption of water was a concern," Pierce said. "And so as we looked at those other options, we wanted to think outside the box and think if there were ways that we could do this without consuming and so that's what led us down this air-cooled option."

Minnesota Power has maintained that it needs "renewable-enabling" sources of power like natural gas to balance the grid when solar and wind power are affected by weather, but opponents of the project argue the companies should be moving away from burning fossil fuels, namely coal, to produce energy, not transitioning to a different fossil fuel like natural gas.

In an emailed statement, Katie Nekola, general counsel of Clean Wisconsin, one of the groups suing to stop the plant, said this change requires a public review.

“If they are changing the design of the plant, that should go through a public review process," Nekola said. "Air cooling was not part of the application and the impacts of that should be thoroughly analyzed.”

Pierce said the Wisconsin Public Service Commission will review the proposed changes and could seek additional information from the companies if it needs it.

The commission approved the natural gas plant in January. Environmental groups then sued over that decision in February. The Minnesota Supreme Court is also set to review a lower court's ruling that said the Minnesota Public Utilities Commission was wrong to approve the plant in 2018 because they did not consider the plant's environmental impact.