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Cleanup crews deploy boom along the Lake Michigan shoreline near the BP Whiting Refinery in Whiting, Ind., March 25, to recover crude oil discharged from the refinery.

(U.S. Coast Guard)

Pollution response teams discuss cleanup plans along the Lake Michigan shoreline near the BP Whiting Refinery in Whiting, Ind., on Wednesday, March 26.

UPDATE: Lake Michigan oil spill estimate doubles in size, possibly up to 1,600 gallons, BP reports

WHITING, IN -- A BP incident management team said an initial visual estimate showed between 377 and 755 gallons of crude oil spilled into Lake Michigan when a malfunction occurred at an Indiana refinery Monday, U.S. Coast Guard representatives said.

A cleanup team of eight people returned to the shore of BP's Whiting Refinery for three hours Wednesday, March 26. The crew observed "minimal" oiling along the shoreline, according to a Coast Guard release. More oil was manually cleaned from the shoreline after crews removed 1 centimeter tarballs from the sand on Tuesday.

The company notified the Coast Guard, Environmental Protection Agency and Indiana Department of Environmental Management after discovering the spill late Monday afternoon. It's believed a malfunction occurred with a crude oil distillation unit, sending oil into the refinery's cooling water outfall and into the lake.

BP representatives said crews have recovered the majority of oil that was visible in the cove-like area along the shoreline between the refinery and a nearby steel mill. Booms and vacuum trucks were used to contain and remove surface oil. Crews also manually collected oil that was pushed to shore by wind.

A view from a Coast Guard helicopter Tuesday showed the spill appeared to be contained to the cove area on BP property.

Coast Guard representatives said BP's team will continue engineering analyses to determine the exact amount of oil discharged.

A spokesperson for the Indiana Department of Environmental Management on Tuesday said the environmental impact appeared minimal and there were no indications that drinking water was threatened.

Philip Willink, senior biologist with Chicago's Shedd Aquarium, said Lake Michigan wildlife should not suffer any long-term effects based on information released by BP and the federal agencies handling the spill. Prolonged ice cover on the lake kept many native fish species off-shore, he said.

"Right now the fish are still in deeper water and haven't come back in yet," Willink said. "I think BP kind of got lucky with their timing. If it happened earlier, if (Lake Michigan) was still ice-covered, it probably would have been hard to do something about."

Fish typically return closer to shore in April, Willink said.

Very low levels of petroleum can impact fish and other wildlife, causing birth defects. Willink said the spill sounds minor, but wildlife and environmental experts hope preventative measures are taken.

"Everybody's looking very closely at this," he said.

Angie Jackson covers public safety and breaking news for MLive/The Grand Rapids Press. Email her at ajackso3@mlive.com, and follow her on Twitter.