The U.S. Coast Guard is investigating an oil slick that has closed down an area of beach at the Cheboygan State Park.
Officials say it appears weathered, or used, heavy oil has polluted the stretch of beach, and put a five-by-300 yard sheen on Duncan Bay, in Lake Huron.
The Coast Guard is still trying to figure out what caused the slick. They're investigating two vessels parked nearby.
The slick was originally discovered yesterday afternoon, by a private citizen.