MONTANA ENVIRONMENTAL INFORMATION CENTER and SIERRA CLUB, Plaintiffs, Appellees, and Cross-Appellants, v. MONTANA DEPARTMENT OF ENVIRONMENTAL QUALITY and NORTHWESTERN CORPORATION, Defendants, Appellants, and Cross-Appellees, and STATE OF MONTANA, by and through the OFFICE OF THE ATTORNEY GENERAL, Intervenor/Defendant

MONTANA ENVIRONMENTAL INFORMATION CENTER and SIERRA CLUB, Plaintiffs, Appellees, and Cross-Appellants, v. MONTANA DEPARTMENT OF ENVIRONMENTAL QUALITY and NORTHWESTERN CORPORATION, Defendants, Appellants, and Cross-Appellees, and STATE OF MONTANA, by and through the OFFICE OF THE ATTORNEY GENERAL, Intervenor/Defendant. Oral Argument is set for Wednesday, May 15, 2024, at 9:30 a.m. in courtroom of the Montana Supreme Court, Joseph P. Mazurek Justice Building, Helena, Montana. Recording of Argument: https://youtu.be/WTRjcmhC2UA The Montana Environmental Information Center and Sierra Club (Environmental Groups) challenged a permit issued by the Montana Department of Environmental Quality to allow Northwestern Corporation to construct a new power plant. The Environmental Groups alleged that DEQ failed to evaluate the environmental consequences of the power plant as required by the Montana Environmental Policy Act (MEPA). The District Court determined that DEQ had complied with MEPA on some issues, but had failed to take a “hard look” at lighting and greenhouse gas emissions and corresponding impacts to the climate in Montana. The court did not reach the Environmental Groups’ argument that a provision of MEPA that prohibits state agencies from reviewing potential climate impacts beyond Montana is unconstitutional. The court remanded the environmental assessment to DEQ for further analysis and vacated the air quality permit that DEQ had issued. On appeal, Northwestern argues the court erred because DEQ was not required to analyze the effect of greenhouse gas emissions, and DEQ sufficiently analyzed the lighting issue. Northwestern further maintains that recent amendments to MEPA has mooted the greenhouse gas issue. Northwestern and DEQ both argue it was improper for the court to vacate the permit. The Environmental Groups argue that the court should have concluded that DEQ also failed to adequately evaluate noise impacts and to evaluate greenhouse gas emissions in general. They argue that if amendments to MEPA no longer allow evaluation of greenhouse gas emissions, then those amendments are unconstitutional.