NorthWestern Energy customers will see lower utility bills and receive refunds with interest after the Montana Public Service Commission finalized a sweeping decision in the company’s 2024 electric and natural gas rate case, rejecting $43 million of the utility’s proposed costs while approving construction of a new Yellowstone County power plant.
The decision caps a 16-month regulatory process marked by extensive public participation, technical scrutiny, and heightened transparency requirements. NorthWestern had self-implemented higher rates in May 2025 based on its original request. Because the PSC ultimately approved lower rates, customers will now receive refunds for any overcharges collected during that period.
A central outcome of the ruling is the Commission’s decision to approve $246 million in rate base for the Yellowstone County Generating Station—approximately $43 million less than NorthWestern’s $289 million request. Commissioners determined that large portions of the company’s proposal lacked adequate data, documentation, or technical justification. The PSC did, however, allow the company to recover $18 million related to lawsuits brought against the project by a liberal environmental group, concluding those legal costs were reasonably incurred during delays.
Commission President Jeffrey Welborn said the ruling demonstrates the PSC’s dual mandate to ensure grid reliability while protecting Montanans from unjustified rate increases.
The PSC also approved the Yellowstone County Generating Station itself, calling the new facility a critical resource for meeting electricity demand during Montana’s coldest winter days. Regulators framed the combined outcome—greenlighting a key reliability project while cutting unsupported costs—as evidence of a balanced approach.
The case featured broad participation from consumer advocates, tribal nations, industrial customers, environmental groups, academic institutions, and low-income service providers. Responding to early concerns, commissioners imposed additional procedural safeguards requiring written testimony for all settlements and ensuring each party had the chance to submit counter-evidence.
PSC staff played a central role in reviewing the utility’s filings, conducting detailed analysis that ultimately identified the $43 million in costs deemed unjustified. Their work, along with cross-examination from intervenors, shaped the final outcome.
With the ruling finalized, the PSC will oversee implementation of the new rates and ensure all customer refunds are issued promptly and accurately.