"An unknown amount of oil leaked from BP Plc's Whiting refinery in Indiana into Lake Michigan after a mechanical glitch on Monday afternoon, the company confirmed on Tuesday.
The discharge had stopped, the leak was contained, and no injuries were reported, the London-based company said in a statement on Tuesday.
As crews worked on the cleanup, the effect on Lake Michigan was not immediately clear. About 60 percent of the lake is covered in ice, according to the National Oceanic and Atmospheric Administration.
BP laid down boom on the water to keep the leak from spreading and said the oil was confined to a cove between the refinery's wastewater treatment plant and a steel mill."