The EPA said it was notified by BP of a minor spill from its Whiting refinery early this week. The company, acting under EPA oversight, has already deployed more than 2,000 feet of containment boom and vacuumed up about 120 barrels of oil-water mixture from the incident site.
In a late Wednesday update, the EPA and U.S. Coast Guard said a team of inspectors that surveyed the Lake Michigan shore to assess the damage.
"The team saw minimal oiling of the shoreline and recommended a small manual removal crew conduct maintenance along the shoreline," the responders said in a statement.
The Whiting refinery, which started operations in 1889, is the sixth-largest refinery in the United States. It processes on average 413,000 barrels of raw crude oil per day.
The EPA said it would continue working with the Coast Guard, state officials in Indiana and BP to clean up the spill.
The cause of the incident remains under investigation.