CLEVELAND (WKZO) -- The US Coast Guard is investigating what's being described as a mysterious black sheen that appeared on Lake Michigan this week. It was first reported Monday around the southern part of the lake, especially in Indiana. Swimmers were coming out of the water with a slick, slimy back substance on them.
Petty Officer First Class Jeremy Thomas, with the Coast Guard, says they still can't figure out what the stuff was. They're planning an analysis and are reviewing security footage to see if they can find anyone dumping any mysterious substances into the water.
Thomas says, luckily, Mother Nature helped clean up the sheen when heavy rains came through the region this week.