BILLINGS, Mont. (AP) — Montana's Public Service Commission has acknowledged a potential $300 million risk for NorthWestern Energy customers if the Colstrip power plant closes early, but decided to keep questions about the coal-fired plant's future out of the utility's rate case.

The PSC previously approved NorthWestern's $6.5 million rate increase request and met Monday to close the case.

The utility owns 30% of one of the four coal-fired plant's units, and it is planning for the Colstrip plant to continue running until 2043.

The Billings Gazette reports that four other Colstrip owners plan to stop investing money in the plant beginning in 2025.

The risk of an early closure is that up to $300 million of Colstrip debt could end up on NorthWestern customers' bills for the next two decades if the utility doesn't address it.

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Information from: The Billings Gazette, http://www.billingsgazette.com