Preliminary reports have revealed that several industrial chemicals seeped into Lake Michigan on Monday afternoon, causing officials to keep beachgoers out of the water near Porter Beach.

A preliminary report from the Indiana Department of Environmental Management showed the water contained small concentrations of tricalcium orthophosphate, which is used as a fertilizer and a food additive; maple syrup; and gluconic acid, which is used to clean metals, according to Indiana Department of Natural Resources Officer Gene Davis.

“At this point, we still don’t know if the risk to people is high enough, so we’re waiting on the chemist’s report,” Davis said. “We want to err on the side of caution, so we’ve recommended that people stay out of the water but we’re not closing the beaches.”

Davis said it’s unknown where the chemicals were coming from, but the chemist’s report should give them a better idea.

National Park Service spokesman Bruce Rowe said the waters at the Indiana Dunes National Lakeshore are not closed, but the park does have a swimming advisory. On Monday, Rowe said visitors at Porter Beach noticed that kids were coming out of the water with a sticky film on them. They looked out in the water and there was a large area with a silvery-metallic sheen, so emergency responders were contacted and people were told to get out of the water shortly before 2 p.m., Rowe said.

Rowe said there were no reports of health effects. With winds coming out of the north and 3-foot waves, Davis said the weather conditions should work to disseminate the chemicals throughout the rest of the water, thus breaking up the concentration.

IDEM spokesman Barry Sneed said conclusive results of what caused the milelong sheen won’t be available for about a week. A day later, It appears to have dissipated.

“The good news is it’s not a continuing problem, but at the same time we’re not sure what it was,” he said.

The U.S. Coast Guard, DNR and National Park Service continue to work on finding the source of the sheen.