WHITING, Ind. -- 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 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 workers who deployed absorbent booms around the spill site, said Mike Beslow, on-scene coordinator for the U.S. Environmental Protection Agency's Region 5.
BP spokesman Scott Dean said the area affected by the spill was a cove at the company's sprawling Whiting refinery, which covers about 1,400 acres.
The spill is about 20 miles southeast of downtown Chicago and three miles south of the farthest part of the city but was not expected to pose any threat to municipal water supplies that draw on the lake's water, Beslow said. Many of Chicago's suburbs, including almost all in DuPage County, also draw drinking water from Lake Michigan.
A Coast Guard flyover of the area Tuesday did not reveal any oil outside the containment booms, Beslow said, "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 of private shoreline the company owns.
The EPA and the 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.
Dean, the BP spokesman, said northerly winds were helping contain the oil by pushing it toward the shoreline.
"It's in the lake, yes, but it's not moving around freely. It's been kind of contained because of the weather and of the geography of the lakefront there," Dean said.
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.
BP initially reported to the EPA that when its workers discovered the spill they observed an oily sheen that covered about 5,000 square yards, said Susan Hedman, the EPA's regional administrator.
Dan Goldblatt, a spokesman for the Indiana Department of Environmental Management, said an agency official who was at the scene around 2 a.m. Tuesday had reported "a large sheen on the lake."
Hedman said the EPA is not aware of any previous oil spills at the site, but the agency is just beginning its assessment of this week's spill.
"EPA's lawyers will be looking into this matter and determining whether or not enforcement action is appropriate," she said.
Two Chicago-area Congressmen released statements Tuesday about the spill. 10th District Rep. Brad Schneider said events such as Monday's spill "reaffirm the necessity of efforts to safeguard the Great Lakes from unjustifiable environmental risk. We can never allow oil drilling in Lake Michigan, and we must oversee and help guarantee the safety of refineries, prevent the spread of invasive species and stop the flow of toxins into the Great Lakes."
And 9th District Rep. Jan Schakowsky said she has been worried about the refinery since it expanded in 2008, including the refining of the heavier crude oil collected from Alberta tar sands, which produces petroleum coke as a byproduct.
"This spill suggests yet another reason that tar sands are wrong for our country and a threat to public health and our environment," Schakowsky said.
•Daily Herald staff writer Susan Sarkauskas contributed to this report.