About 5,000 pounds of methanol leaked from the Dupont plant at Belle into the Kanawha River Tuesday night.
Jimmy Gianato, director of the West Virginia Division of Homeland Security and Emergency Management, said the state received notice of the leak at about 10 p.m. Tuesday.
"Five-thousand pounds is not that much," Gianato said.
The West Virginia Department of Environmental Protection plans to investigate the leak Wednesday morning, he said.
Methanol is a colorless, flammable liquid that is often used for fuel or as an antifreeze or general solvent.