NorthWestern Energy to Reconnect Transmission; Planned One‑Hour Outage at 2 a.m. Dec 23 for Hi‑Line Customers

Havre, Mont. - Dec. 22, 2025 - NorthWestern Energy will conduct a planned power outage at 2 a.m. on Tuesday, Dec. 23, affecting NorthWestern Energy electric customers along the Hi-Line from the Havre area east to Glasgow, including customers in Big Sandy, Box Elder, Chinook, Dodson, Fort Belknap, Harlem, Hinsdale, Lohman, Malta, Nashua, Saco, Savoy, St. Marie, Wagner and Zurich.

The outage is expected to last approximately one hour.

On Dec. 17, severe winds damaged the transmission powerline serving NorthWestern Energy customers along the Hi-Line. To maintain service, NorthWestern Energy connected to a transmission line with the Western Area Power Administration (WAPA) that included energy source feeds from Fort Peck Hydro Generation and the Eastern Interconnection until repairs to the normal source could be completed. Transmission powerlines deliver power to the substations and distribution powerlines that serve customers.

Crews safely completed repairs to the 75-foot-tall powerline structure. With repairs finished, NorthWestern Energy must reconnect customers to normal transmission powerline configurations.

"Thanks to WAPA's cooperation and coordination, our customers along the Hi-Line didn't face an extended outage from this transmission line damage," said NorthWestern Energy Vice President Transmission Mike Cashell. "Using the WAPA line kept the lights on while our crews worked on other Hi-line customer outages first, then safely repaired the transmission line."

With repairs finished to our transmission line, a planned power outage is required to safely reconnect to NorthWestern Energy's transmission system.

NorthWestern Energy is coordinating with critical services and local officials in Hill, Blaine, Phillips, and Valley counties to minimize impacts during the planned outage.

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NorthWestern Energy - Delivering a Bright Future

NorthWestern Energy, provides essential energy infrastructure and valuable services that enrich lives and empower communities while serving as long-term partners to our customers and communities. We work to deliver safe, reliable, and innovative energy solutions that create value for customers, communities, employees, and investors. We do this by providing low-cost and reliable service performed by highly-adaptable and skilled employees. We provide electricity and / or natural gas to approximately 842,000 customers in Montana, South Dakota, Nebraska, and Yellowstone National Park. Our operations in Montana and Yellowstone National Park are conducted through our subsidiary, NW Corp, and our operations in South Dakota and Nebraska are conducted through our subsidiary, NWE Public Service. We have provided service in South Dakota and Nebraska since 1923 and in Montana since 2002.

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Jo Dee Black

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