PORTER | State officials said Tuesday they think they know the source of the substance found floating in Lake Michigan on Monday that closed beaches in Porter.
Preliminary tests show the substance is tricalcium orthophosphate, an anti-caking agent used as a food additive and in industrial applications, said Dan Goldblatt, spokesman for the Indiana Department of Environmental Management.
Goldblatt said a Porter plant, which he did not identify, manufactures the material.
Additional tests are needed to confirm the nature of the substance, he said. Those results are not expected until later in the week.
Representatives from the U.S. Coast Guard combed through a week of records on vessels passing through the Port of Indiana and ruled out the port as a source, according to the agency. The Coast Guard also ruled out the steel company ArcelorMittal as a source.
Goldblatt said the material, discovered Monday afternoon by swimmers who emerged from Lake Michigan covered in a dark, glittery film, was found in a plume in the water two miles long and a half mile wide. The Coast Guard received a report Monday afternoon that the substance had reached Michigan City.
"We haven't determined if the concentrations were enough to cause any health threats," Goldblatt said.
Adults and children who came into contact with the material Monday were not reporting any adverse health effects as of Tuesday morning, Goldblatt said.
Indiana Dunes State Park beaches remained closed Tuesday as a precaution. Beaches at Indiana Dunes National Lakeshore were open with a swimming advisory due to the substance, spokesman Bruce Rowe said.
Goldblatt said the state is advising anyone who sees the substance in the water not to touch it as a precaution.
IDEM also is investigating reports of a glittery dust found on lawns in Hammond's Robertsdale neighborhood earlier this month. The state is trying to determine if there is a link between the substance found in Hammond and material found in Lake Michigan, Goldblatt said.
"We don't know if we'll be able to link the two," Goldblatt said.
In addition to the warning to stay out of the water to avoid the substance Tuesday, the National Weather Service advised beachgoers against hazardous conditions.
The Weather Service issued a beach hazards statement indicating waves as high as 6 feet could pound beaches and create dangerous rip currents and structural currents through 5 p.m. Wednesday.
Temperatures hovering around 60 degrees at the lakefront Tuesday afternoon also were keeping beachgoers away.