Workers from BP’s Whiting, Indiana, refinery scoured the beach and deployed booms on Lake Michigan after the discovery of an oil leak.
A malfunction in a cooling unit allowed an unknown amount of crude oil into the lake a few miles from the Chicago city limits.
Workers at the refinery reported an oil sheen on the water about 4:30 p.m. Monday, and an official from the U.S. Environmental Protection Agency said the leak was plugged by the time he arrived at 9 p.m.
The EPA’s emergency response coordinator said there appeared to be no negative effects on Lake Michigan or wildlife.
A helicopter flyover found no evidence of oil beyond the containment booms.
The wind blew the oil into a sandy cove on BP’s property.
Chicago’s 68th Street water intake crib is about eight miles northwest of the spill site, but there were no signs of oil drifting in that direction.
Both of Illinois U.S. Senators called for an investigation into the cause.
BP says it expects to be fined for the violation of the clean water act.