Transformer failure reported at Fort Peck Dam causes brief Montana outage
Sept 2026Published 25 Sept 2026Responsible editor: Chief Editor
- Where
- Fort Peck Dam in northeastern Montana
- What
- Failed transformer started grass fire next to powerhouse
- Injuries
- None reported
- Cause
- Not reported
- Outcome
- Supply restored before generators returned after checks
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Companies named in the reporting of this entry (being named is not a finding of fault): Army Corps of Engineers, NorthWestern Energy, Western Area Power
What happened
On 3 September 2026, a fire broke out in grass next to the powerhouse at Fort Peck Dam in northeastern Montana. Local emergency services said a failed transformer knocked a live power line to the ground and set the grass alight. The outage affected 3,157 NorthWestern Energy customers in the Glasgow area, and supply was restored by about 12:17 a.m. Three hydroelectric units that had been running were taken offline for roughly four hours while safety checks were completed.
Nobody on site was injured, and staff on duty were evacuated. Local fire crews and project staff put the grass fire out. The Western Area Power Administration bypassed the damaged equipment, which is why customer supply returned before the generators did. The Army Corps of Engineers said the fire stayed outside the powerhouse, that nothing inside was immediately affected, and that the three units later returned to operation. The cause of the failure has not been stated publicly.
Contributing factors
Local emergency services attributed the fire to a failed transformer and a live line on the ground. Grass was reported next to the high-voltage equipment. The Corps release described a grass fire outside the building and did not name the failed component. The cause remains under investigation.
Lessons learned
- Grass next to high-voltage equipment can turn an electrical fault into a fire that requires local crews to extinguish.
- A grid bypass can restore customer supply before on-site generators return after safety checks.
- Taking units offline when the grid link is lost protects machinery until checks are complete.
More lessons on fire suppression and firefighting, outages, backup supply and restoration, from every incident on the register.
Not yet known
- Cause of the transformer failure
- Age and model of the transformer
- Duration of full site recovery
- Cost of repairs and lost generation
This entry is updated when these are reported. Get an alert for the next one like it.
Source
Published 2026-09-25. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
