Power production stopped at Ice Harbor Dam near Burbank after two small fires were discovered at 9 a.m. Thursday.
The fires were inside two cabinets holding electrical components for two of the dam's six generators, according to the Army Corps of Engineers. Three generators were operating at the time.
Power for dam facilities stopped, but power was being pulled off the electrical grid within 30 minutes for basic facility operations. The navigation lock returned to service at 12:40 p.m.
Snake River flows previously passing the dam via power generation are being passed through the spillway.
The fires did not last long because of the design and content of the electrical cabinets, Army Corps officials said. The fire produced some smoke, but it quickly cleared, they said.
Operations staff at the dam are evaluating the generators and their electrical and mechanical components to determine the extent of any damage and are working to restore power generation capability.
An investigation into the cause of the fires is planned.