A barge carrying 420,000 gallons of black oil that went aground Wednesday morning on the Nanticoke River in southern Dorchester County was refloated last night after some of its contents were removed to lighten the load, a spokesman for the Coast Guard in Baltimore said.

Petty Officer John Edwards, the spokesman, said about 140,000 gallons was pumped into another barge, and that the vessel was refloated about 7:15 p.m. and towed to a power plant in Vienna, about halfway to its original destination, Seaford, Del.

Edwards said the double-hulled barge was not damaged.

The spokesman said there were no reports of pollution or effects on the nearby Fishing Bay Wildlife Management Area.

He said the barge, which was being towed by the tugboat Gold Coast, owned by Dan Marine, went aground about 7 a.m. Wednesday, and that the crew immediately reported the incident to the Coast Guard.