Power down of last resort

On July 22, roughly 7.5% of NorthWestern Energy’s Montana customers received a message from the utility company about a potential power shutoff. The warning came both digitally and via mail to 30,000 energy consumers located in or adjacent to heavily forested areas of the state.

“Our wildfire specialists have identified your property to be within a high‑risk area,” the email read. “Due to living in a high‑risk wildfire area, we want to help you prepare for service interruptions and public safety power shutoffs.”

To many energy consumers, public safety power shutoffs were a hitherto unheard of means of managing the risks that wildfire poses to utility infrastructure and the threat of damaged utility infrastructure sparking fire.

According to NorthWestern Energy’s 2024 Wildfire Mitigation Plan, “these outages involve de-energizing electrical infrastructure in specific areas, during periods of time where the risks of continuing to operate electrical infrastructure are unacceptably high.” 

In a follow-up announcement posted to its website on July 24, NorthWestern clarified that “a PSPS is not imminent at this time.”

The company released its most recent wildfire mitigation plan in May, introducing a PSPS protocol “for situations where the risks of continuing to operate electrical equipment are unacceptably high.” While the inclusion of a PSPS marks a shift from NorthWestern’s 2022 wildfire mitigation plan, which did not outline a PSPS policy, the 2024 plan emphasizes NorthWestern’s efforts to avoid the need for public safety power shutoffs by monitoring the weather and taking additional power line maintenance precautions.

Those precautions include the efforts of a “Wildfire Situational Awareness Team” to scrutinize climate conditions and work alongside the utility staff who maintain “protective equipment devices” that isolate abnormalities or malfunctions in power lines, known as faults, throughout NorthWestern’s electricity grid.

“If the protection system is good, within a fraction of a second they should isolate the fault,” said Hashem Nehrir, an emeritus professor of electrical and computer engineering at Montana State University who studies electric grid systems. 

According to NorthWestern, relays are often re-energized immediately after a fault is detected and the line de-energized. 

“That changes during fire season,” NorthWestern Energy Public Relations Specialist Jo Dee Black said. “Those are set to a different mode and they do not automatically reset.”

Typically, relays are the first line of defense against line faults. During fire season, according to Black, utility patrollers often assess a deactivated area before re-energizing the line rather than relying on automated relays. 

Other Montana power companies deploy a similar, though not identical, set of tools for managing wildfire risks. Flathead Electric Cooperative, an Evergreen-based energy provider with more than 50,000 members in Montana, maintains a wildfire mitigation plan that explicitly does not include use of public safety power shutoffs.

“There are major negative impacts on fire response, water supply, public safety, and emergency communications should a fire occur while a portion or the entire Cooperative’s system is de-energized,” the plan reads. “The Cooperative believes that the risks of implementing a PSPS far outweigh the chances that the Cooperative’s electric system would cause a wildfire.”

Montana-Dakota Utilities Company, which operates power lines in eastern and central Montana, is currently developing a wildfire mitigation plan and considering development of a public safety power shutoff plan, according to spokesperson Mark Hanson.

To date, NorthWestern has never executed a PSPS procedure. According to Black, “public safety power shutoff is a last resort.”