Around 5,000 gallons of fuel oil was inadvertently discharged into the Ohio River on Monday night.
Power company Duke Energy reported that the incident occurred during a routine transfer of fuel oil at its W.C. Beckjord Station, 20 miles southeast of Cincinnati, Ohio. The release was stopped within about 15 minutes.
Water officials said that Greater Cincinnati's drinking water is safe.
Following the spill Duke Energy mobilized internal and external resources, including three vessels on the river that deployed booms to contain and help collect the oil. Northern Kentucky Water District and Greater Cincinnati Water Works were notified, as were local, state and environmental agencies and the U.S. Coast Guard.
"We're working around the clock to rapidly and fully restore the affected section of the Ohio River and coordinating closely with local officials to make sure that drinking water continues to remain safe," commented Lynn Good, president and CEO of Duke Energy, in a statement on Tuesday. She added that the company is taking responsibility for the cleanup.
Sally Thelen, a spokeswoman for Duke Energy, said that the exact cause of the spill was still under investigation but the company believes that one of the valves may have opened, causing an overflow.
The two local water utilities shut down river intake valves soon after the incident occurred. Tony Parrott, director of Greater Cincinnati Water Works, quoted by Cincinnati.com, said that reserves were near capacity and the utility could continue operating with the intakes closed for some time.
Northern Kentucky Water District stated that it would draw water from its reservoirs for as long as possible. In the event that it needs to reopen the intakes, it is capable of fully removing oil from the water.