Crews for oil giant BP worked Tuesday to clean up an undetermined amount of crude oil that spilled into Lake Michigan and affected about a half-mile (kilometer) section of shoreline near Chicago following a malfunction at BP's northwestern Indiana refinery, officials said.
The spill reported Monday afternoon by BP appears to have been contained by company crew members who deployed absorbent booms around the spill site, said Mike Beslow, on-scene coordinator for the U.S. Environmental Protection Agency.
BP spokesman Scott Dean said the area affected by the spill was a cove along the Lake Michigan at the company's sprawling Whiting refinery, which covers about 1,400 acres (566 hectares).
The spill is about 20 miles (32 kilometers) southeast of downtown Chicago but was not expected to pose any threat to municipal water supplies that draw on the lake's water, Beslow said.
A Coast Guard flyover of the area Tuesday did not reveal any oil outside the containment booms, Beslow said during a Tuesday afternoon media briefing, "but there is oil on the beach that is being addressed."
Beslow said BP crews were using vacuum trucks to suck up the corralled oil and were cleaning up oil along 2,700 feet (820 meters) of private shoreline the company owns at the Whiting site, he said.
The EPA and the U.S. Coast Guard were supervising that work, Beslow said.
Beslow said the Coast Guard was working with BP officials to determine how much oil had been discharged into the lake.
BP said in a statement Tuesday evening that it believes that "an upset at a crude distillation unit may have sent crude oil into the refinery's cooling water outfall and then into the lake."
The company said it has taken steps to prevent another discharge and might have an estimate Wednesday on how much oil was spilled.