State PUC Denies Northwestern Energy Rate Increase, Approves New Power Plant

PSC Denies $43 Million in Northwestern Energy Rate Case, Approves New Power Plant

MONTANA CUSTOMERS TO BENEFIT

19 November 2025

HELENA, Montana — The Montana Public Service Commission (PSC) announced its final decision today in NorthWestern Energy’s 2024 electric and natural gas rate case, concluding a 16-month process marked by rigorous analysis, extensive public participation, and a firm commitment to transparency and fairness.

Because NorthWestern self-implemented significantly higher rates in May 2025 based on its original request, customers can expect a reduction in the rates they are currently paying once the PSC’s final, lower rates take effect. Customers will also receive refunds with interest for any overcharges collected during the self-implementation period.

A central outcome of the case is the Commission’s decision to approve $246 million in additional rate base related to the Yellowstone County Generating Station—a reduction of approximately $43 million from NorthWestern's $289 million request. This $43 million reduction represents substantial savings for Montanans and reflects the PSC’s careful evaluation of every component of the company’s proposal. The Commission determined that significant portions of the original request were not supported by sufficient data, documentation, or technical justification.

“The Commission’s responsibility is to strike the right balance—ensuring utilities remain capable of delivering safe and reliable service while protecting customers from paying more than what is just and reasonable,” Commission President Jeffrey Welborn said. “This decision, and the $43 million in savings for customers, demonstrates the value of a thorough public process and the dedication of our staff.”

The Commission’s decision also approves the Yellowstone County Generating Station, authorizing a new power plant that will provide critical capacity during Montana’s coldest winter days. This resource approval—combined with the $43 million in customer savings—demonstrates the PSC’s balanced approach to ensuring both reliability and affordability for Montana’s energy consumers.

This decision was reached through a rigorous evidentiary process involving consumer advocates, tribal nations, large industrial customers, environmental organizations, academic institutions, and low-income service providers. In response to concerns raised early in the proceeding, the Commission implemented increased procedural safeguards that required written testimony for all settlements and ensured all parties had the opportunity to ask questions and provide counter-evidence. These measures improved transparency and fairness throughout the case.

PSC staff played an essential role throughout the 16-month review, conducting detailed technical analysis, identifying unsupported cost components, and evaluating the reasonableness of each element of NorthWestern’s request. Their work, combined with testimony and cross-examination from intervenors, was instrumental in identifying the $43 million in costs that the Commission ultimately found unjustified.

The PSC will now oversee the implementation of the approved rates and ensure that all required customer refunds are issued promptly and accurately.

The Commission regulates private investor-owned natural gas, electric, telephone, water, and sewer companies, certain motor carriers, and oversees natural gas pipeline safety and intrastate railroad safety. The Commission works to ensure that Montanans receive safe and reliable service from regulated public utilities while paying reasonable rates. For more information, visit psc.mt.gov or contact the Commission at 1-800-646-6150.  Follow the Commission at x.com/MT_PSC or visit facebook.com/MontanaPSC.

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