KAHLOTUS, Wash. --- The Army Corps of Engineers said oil has slowly leaked into the Snake River at Lower Monumental Lock and Dam in southeast Washington over seven months.

The federal agency, which operates the dam, said Tuesday that an estimated 742 gallons (2,808 liters) of oil leaked into the water in that time. Workers were working to remove oil from the turbine hub and prevent further oil from being released into the river.

The suspected leak was first reported Thursday. A hydroelectric generator will be shut down until repairs are made.

The Army Corps' Don Redman said because the generator is constantly operating, a slow leak of a very small volume of oil per hour wouldn't likely have been noticeable during normal operations. He said the agency will work to prevent future leaks at its facilities.