About two-thirds of the three million litres of oil spilled near Lake Michigan have been cleaned up, Calgary-based Enbridge reported.

An area congressman, meanwhile, accused the pipeline company of being “negligent”.

Last week, a ruptured pipeline leaked about 19,500 barrels into a creek that feeds the Kalamazoo River. Birds and wildlife were coated with oily residue. About 13,000 barrels have now been removed, the company estimated.

“We are making very good progress with regard to spill clean-up,” President & CEO Pat Daniel said Tuesday in a news conference. “There is a remarkable improvement in the quality of the water along the river.”

The company offered to buy any homes within 200 feet of the spill zone. Many residents are worried the incident will diminish real-estate values, Daniel said.

On Monday, Michigan congressman Mark Schauer repeated recent promises to hold Enbridge fully accountable.

“This should have never happened,” he told WKZO News. “This company was negligent in maintaining and repairing their pipe.”

The leak came six months after a warning from the U.S. Pipeline and Hazardous Materials Safety Administration. Corrosion monitoring on the 40-year old pipeline wasn’t being done right, the authority said.

Enbridge now faces Congressional hearings in mid-September, Shauer said. The congressman plans to hold a public hearing near the spill site in the next couple weeks. A government investigation is already underway.

“I’m going to get all the facts,” he said. “People need answers.”

Enbridge has been attacked for its alleged failure to contact authorities as soon as the leak happened. Just recently, an environmental law group announced plans to sue the company.

As the Tyee reported this week, the company has experienced 12 serious incidents -- involving "pipeline mishaps and regulatory penalties" -- in the past decade.

Green groups and other critics have used the recent controversy to attack Enbridge's plans to build a pipeline from Alberta's oil sands to the B.C. coast.

Geoff Dembicki reports for the Tyee.