By Tom Lutey and Holly Michels, Billings Gazette
A 2013 aerial view shows Colstrip power plant. LARRY MAYER, Billings Gazette
NorthWestern Energy will increase its share of Colstrip Power Plant in 2026 under an agreement with Spokane-based Avista Corp, the two utilities announced Monday night.
The transaction is timed with Avista’s state deadline to stop delivering coal power to its Washington customers by the end of 2025. The handoff resembles one announced last August between another Washington utility with a Colstrip stake, Puget Sound Energy, and power plant co-owner Talen Energy.
Avista’s 222-megawatt share of Colstrip is divided between the powerplant’s surviving generators, Units 3 and 4. Dan Vermillion, Avista CEO, told an audience gathered for a lobbying event at the Great Northern Hotel in Helena that the terms are still being set, but that the company will keep its environmental cleanup liability, as well as its share of the Colstrip transmission line.
