NorthWestern Energy, the state’s largest public utility, is asking regulators to allow it to temporarily tap a credit for customers to help pay for an additional $18 million associated with buying more of the Colstrip plant.

On Jan. 1, 2026, the monopoly utility will control 55% of the coal-fired electricity generation plant at Colstrip following a couple of recent acquisitions from Avista Corp and Puget Sound Energy .

In a motion pending with the Montana Public Service Commission, NorthWestern argues the newly acquired 222 megawatts from Avista will ensure reliable power for customers, but the acquisition comes with $18 million in operations and maintenance costs.

“These costs are not currently reflected in customer rates and represent a significant financial obligation for NorthWe

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