Submerged oil recovery on the Kalamazoo River. Image: U.S. Environmental Protection Agency website

Today, a year after the oil spill on the Kalamazoo River in southern Michigan, it still poses a major cleanup challenge, the Associated Press reports.

Enbridge Inc., the owner of the pipeline that caused the 800,000-gallon oil spill, has an Aug. 31 deadline given by the Environmental Protection Agency to clean up the oil.

But the oil footprint is larger than anticipated and many pockets of oil may not have been identified.  Regulators told the Associated Press that this could mean the cleanup may continue for a couple of years.

Enbridge says more than 90 percent of the oil has been recovered. Environmental Protection Agency officials said they want to reopen part of the affected river segment this year, the Associated Press reported.

Currently more than 500 workers are involved in the cleanup.