Latest update — power restored. A late-night electrical and transmission failure at the Fort Peck Dam hydroelectric facility in Montana triggered a fire near the powerhouse and knocked out electricity to about 3,157 NorthWestern Energy customers in the Glasgow area on September 3, 2026. NorthWestern Energy says the outage began at about 11 p.m. and all affected customers had power back by approximately 12:17 a.m. on September 4. No injuries were reported. The U.S. Army Corps of Engineers said the flames affected the exterior area of the powerhouse and that internal power-generation components were not believed to have been damaged. USACE later listed the Fort Peck hydroelectric generating units as restored to service following the fire.
The incident drew immediate attention across northeast Montana because Fort Peck is not simply a local utility site. The federal project on the Missouri River contains two hydroelectric powerhouses and is tied into a regional transmission network. A visible fire at that location, followed by a widespread blackout, naturally raised questions about whether the dam itself had failed or whether the power plant had suffered major internal damage. The information released on September 4 points instead to an electrical/transmission equipment failure near the powerhouse, not a failure of the earthen dam.
In this article:
What Happened at Fort Peck Dam?
The fire developed late Thursday night, September 3, at the Fort Peck hydroelectric complex near Glasgow, Montana. Local radio station KLTZ reported witness accounts of a loud explosion before flames became visible near the powerhouses. The more precise utility timeline begins at approximately 11 p.m., when NorthWestern Energy recorded a power outage affecting 3,157 customers in the Glasgow area.
Valley County Emergency Services Manager Ed Malone told KFYR that a transformer failure brought down a live power line, which then ignited a grass fire near the facility. NorthWestern Energy separately said a Western Area Power Administration transmission line serving its substations and distribution lines went out of service. Those descriptions are not necessarily contradictory: the transformer or associated electrical equipment failure appears to have occurred within the same transmission event that removed the WAPA line from service.
Important: Current reporting describes an electrical fire associated with the powerhouse/transmission equipment. It does not describe a breach or structural failure of the Fort Peck earthen dam.
Why Did More Than 3,100 Customers Lose Power?
Fort Peck's generating facilities feed power into a larger transmission system rather than directly supplying only the nearby town. According to NorthWestern Energy, the WAPA transmission line involved in the incident receives power from the federal Fort Peck Hydroelectric Project and the Eastern Interconnection, then serves NorthWestern Energy substations and distribution lines.
When that transmission line went out of service, customers downstream of the affected substations lost power even though the fire itself was localized. WAPA crews were able to bypass the affected equipment at Fort Peck and restore transmission service. NorthWestern Energy then restored electricity to all affected customers by about 12:17 a.m. on September 4 — roughly 77 minutes after the reported 11 p.m. outage start.
Fort Peck Fire and Power Restoration Timeline
| Time | What happened |
|---|---|
| Late evening, Sept. 3 | Witnesses report a loud explosion and visible fire near the Fort Peck powerhouses. |
| About 11 p.m. | NorthWestern Energy records an outage affecting approximately 3,157 Glasgow-area customers after the WAPA transmission line goes out of service. |
| Overnight | WAPA crews bypass affected equipment at the federal Fort Peck facility to re-establish transmission service. |
| About 12:17 a.m., Sept. 4 | NorthWestern Energy reports power restored to all affected customers. |
| Sept. 4 | USACE lists Fort Peck hydroelectric generating units as restored to service following the fire. |
Was the Fort Peck Dam or Powerhouse Damaged?
The most important distinction is between the dam itself, the powerhouse buildings, and the electrical/transmission equipment connected to the generating station. KFYR reported that the U.S. Army Corps of Engineers said flames affected only the exterior of the powerhouse and that internal power-generation components were not believed to be damaged. No injuries were reported.
USACE's September 4 news listing later stated that the Fort Peck hydroelectric generating units had been restored to service. That is a strong indication that the incident did not produce the type of catastrophic internal turbine or generator damage that a visible powerhouse fire might initially suggest.
Current status: power to affected customers was restored overnight, no injuries were reported, and USACE says generating units were returned to service. Detailed equipment-damage findings may still be refined as inspections continue.
What about the reported transformer failure?
The immediate cause described by Valley County emergency officials was a transformer failure that brought down a live line and ignited grass near the powerhouse. NorthWestern Energy's release focuses on the WAPA transmission line going out of service. Until a final technical investigation is published, it is safest to describe the event as a transformer/electrical transmission failure rather than assign a more specific root cause to one component.
Why Fort Peck's Hydroelectric Powerhouses Matter
Fort Peck Dam is a U.S. Army Corps of Engineers project on the Missouri River in northeastern Montana. USACE's current project fact sheet lists two powerhouses, five Francis-type turbines, and a combined plant capacity of 185,250 kilowatts. The two powerhouses average roughly 1.1 billion kilowatt-hours of generation per year, an amount USACE says is enough to supply a town of about 100,000 people.
Hydropower at Fort Peck was authorized in 1938. Construction of the first powerhouse began in 1941, with initial generation in July 1943; a second powerhouse was constructed from 1958 to 1961. The dam also serves flood-control, navigation, water-supply, recreation, fish-and-wildlife and other authorized purposes, so an electrical incident at the powerhouses is operationally significant even when the dam structure itself is unaffected.
Frequently Asked Questions
Did Fort Peck Dam break or fail?
No dam breach or structural failure has been reported. The September 3 incident involved electrical/transmission equipment near the hydroelectric powerhouse.
How many people lost power?
NorthWestern Energy reported approximately 3,157 customers affected in the Glasgow area.
How long was the Fort Peck power outage?
The utility says the outage began at about 11 p.m. September 3 and all affected customers were restored by approximately 12:17 a.m. September 4, or about 77 minutes later.
Was anyone injured in the Fort Peck powerhouse fire?
No injuries were reported in the available September 4 updates.
What caused the Fort Peck fire?
A Valley County emergency official said a transformer failure brought down a live line and ignited grass near the facility. NorthWestern Energy reported that a WAPA transmission line went out of service. A final technical root-cause report had not been published at the time of this update.
Sources and Live Updates
- KFYR-TV — fire location, reported transformer failure, no injuries and powerhouse-damage update.
- NorthWestern Energy release — 3,157 customers, outage timing, WAPA line and 12:17 a.m. restoration.
- KLTZ/MIX-93 — local witness reports and initial Fort Peck powerhouse fire coverage.
- U.S. Army Corps of Engineers — official Fort Peck Dam and powerhouse specifications.
This article will be updated if USACE, WAPA, NorthWestern Energy or Valley County officials release a more detailed equipment-damage or root-cause report.
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