A turbine generator at The Dalles Dam, just north of The Dalles, OR, leaked 53 gallons of oil into the Columbia River, said officials at the U.S. Army Corps of Engineers.
The cause of the leak is still under investigation. The leak was first suspected May 31, said Sarah Bennett, a spokeswoman for the Army Corps in Portland.
The unit was taken from the river for analysis sometime after and it was confirmed Thursday to have been spilling oil.
The damaged unit, which generates electricity from running water, will remain out of the water as technicians try to determine what caused the leak, Bennett said.
This is the second reported oil leak at the dam this year. A blade seal that failed caused another unit to leak 470 gallons of oil in March. That unit has since been repaired.