(Updates with detail on water supply)
Aug 19 (Reuters) - The U.S. Coast Guard closed a 15-mile stretch of the Ohio River on Tuesday after at least five thousand gallons of fuel oil spilled from a 60-year-old power plant owned by Duke Energy 20 miles east of Cincinnati, Ohio.
The spill occurred at 11:15 p.m. on Monday during a "routine transfer of fuel oil" at the W.C. Beckjord plant in New Richmond and was stopped 15 minutes later, Duke said.
Intakes for drinking water along the river were closed overnight and drinking water has not been affected, said a spokeswoman for the Greater Cincinnati Water Works, though tests continue. The impact on wildlife was so far unclear.
"We notified state and local authorities of the incident and have been working with them throughout the overnight hours," said Chuck Whitlock, Duke Energy president of Midwest Commercial Generation. "We have cleanup crews on site that are identifying the appropriate actions that will be needed to remediate."
The Coast Guard said the river was closed from mile markers 453 to 468, from Cincinnati to Dayton, Kentucky, while it responded to the spill. Three vessels were on the scene on Tuesday deploying oil containment booms and clean-up materials. The Coast Guard's initial estimate was that 8,000 gallons were spilled.
The W.C. Beckjord Station is being retired as a result of new government emissions standards. Four of the plant's six coal-fired units have been closed and the remaining two are expected to shut down by the end of the year. It also has four fuel-oil-fired units that generate power during periods of peak demand.
The Ohio River, which stretches nearly 1,000 miles from Pennsylvania to Illinois, provides drinking water for more than three million people, according to the Ohio River Foundation.
It is also a major artery for shipping grain by barge from the eastern United States to export terminals on the U.S. Gulf Coast. With the corn and soybean harvest still weeks away, however, traffic has been relatively light.
"There is not a lot of stuff coming down the Ohio River right now, but four weeks from now it will be very busy," said Roy Huckabay with the Linn Group, a Chicago brokerage. (Reporting by Edward McAllister in New York, Ashutosh Pandey in Bangalore and Julie Ingwersen in Chicago; Editing by Dan Grebler and James Dalgleish)