The Montana Department of Environmental Quality (DEQ) has determined that the environmental assessment for the Yellowstone County Generation Station at Laurel is adequate, following a lawsuit by environmental groups that claimed it was not done properly. DEQ released the final supplemental environmental assessment(EA) that was delayed by the suit. Construction of the facility is complete, and it is operating.

The supplemental EA is the result of litigation in which environmental plaintiffs alleged that DEQ’s initial EA for the project, which was issued on August 23, 2021, was inadequate under the Montana Environmental Policy Act (MEPA). In particular, before a Montana State District Court, environmental plaintiffs argued DEQ inadequately addressed pipeline, water quality, light, noise impacts, as well as the cumulative impacts of sulfur dioxide (“SO2”) and greenhouse gas emissions. The District Court found that DEQ had adequately addressed all impacts in its initial EA, except for DEQ’s evaluation of light and greenhouse gas emission impacts.  

On appeal, the Montana Supreme Court affirmed the District Court’s findings and returned these issues to DEQ to address in this supplemental EA. The Montana Supreme Court, additionally, found that the District Court had not made the necessary findings to vacate the permit under MEPA, which is why the project is able to operate while this supplemental EA was being prepared. Within the EA, DEQ responded to court findings regarding lighting and greenhouse gases and presented their potential impacts.

DEQ prepared the draft supplemental EA in compliance with MEPA to analyze potential impacts of the proposal. The draft supplemental EA was posted for public comment, and all comments are addressed in the final supplemental EA. The final supplemental EA materials can be accessed through DEQ’s website.