“It remains unclear how much oil spilled into the lake or how long the discharge continued. 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.

Mike Beslow, the EPA’s emergency response coordinator, said there appeared to be no negative effects on Lake Michigan, the source of drinking water for 7 million people in Chicago and the suburbs. The 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.

Initial reports suggest that strong winds pushed most of the oil toward a sandy cove on BP’s property between the refinery and an Arcelor Mittal steel mill. A flyover Tuesday afternoon revealed no visible oil beyond booms laid on the water to prevent the oil from spreading, Beslow said.

‘There is no known impact to wildlife or human health at this time,’ Beslow said.

Frigid temperatures caused some of the oil to harden into a waxy consistency that made it easier to collect, said Scott Dean, a BP spokesman. Crews used vacuum trucks to suck up any liquid oil that washed ashore.”