An oil spill from a northwestern Indiana refinery affected roughly a half-mile section of Lake Michigan's shoreline near Chicago earlier this week, officials said.
Crews for the oil giant BP worked into Wednesday afternoon to clean up the spill, which appears to have been contained, the Detroit Free Press reported.
The company deployed absorbent booms around the spill site, said Mike Beslow, of the Environmental Protection Agency's Region 5.
A spokesman for BP said the affected area was a cove along Lake Michigan where the company's Whiting refinery covers about 1,4000 acres.
No oil was spotted outside the containment area after the U.S. Coast Guard flew over the site.
The Grand Rapids Press reports BP estimates between 377 and 755 gallons of crude oil spilled into the lake. The company believes a malfunction occurred with a crud oil distillation unit, which caused the spill.