The U.S. Coast Guard closed a 15-mile stretch of the Ohio River today after at least 5,000 gallons of fuel oil spilled from a 60-year-old power plant owned by Duke Energy near Cincinnati. It was not clear if the oil had been contained or if there was any impact on wildlife or drinking water.

The U.S. Coast Guard closed a 15-mile stretch of the Ohio River today after at least 5,000 gallons of fuel oil spilled from a 60-year-old power plant owned by Duke Energy near Cincinnati.

The spill occurred late on Monday during a "routine transfer of fuel oil" at the W.C. Beckjord plant in New Richmond, Duke said. It began at 11:15 p.m. and was stopped 15 minutes later. It was not clear if the oil had been contained or if there was any impact on wildlife or drinking water.

"We are still assessing the situation and any effects that may occur," a spokeswoman for the company said this morning. Intake for drinking water has been closed on the river, she said.

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 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, about 20 miles east of Cincinnati, 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 3 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.