An Indiana steel plant dumped toxic levels of cyanide and ammonia-nitrogen in the Little Calumet River, killing fish and shutting down parts of the Indiana Dunes Wednesday.
The Indiana Department of Environmental Management, which is leading the investigation, said a steel plant belonging to ArcelorMittal released excess amounts of cyanide and ammonia-nitrogen into the east branch of the river, causing several fish to die.
The department said it requested ArcelorMittal to help cleanup the spill and monitor the chemical concentration in the Little Calumet River.
The National Park Service said it closed the water out to 300 feet at the Portage Lakefront and Riverwalk beach area of the Indiana Dunes National Park. Portions of the Little Calumet River were closed between Highway 149 and 249, the park service said. The trails remain open.
The waters will remain closed until the cause of the spill is determined, the park service said. Residents were told to avoid eating fish from the affected area.
A spokesperson for ArcelorMittal said in a statement that the company was "concerned" about the cyanide and ammonia levels in the water, and that it was investigating the source and working with all agencies involved.
"We will continue to work closely with the agencies involved and provide updates as appropriate," ArcelorMittal's statement reads, adding that the company was also notified of an oil spill at the Port of Indiana, which it also continues to investigate.
"ArcelorMittal Burns Harbor is committed to environmental compliance and takes both situations very seriously," the company said. "We will continue working cooperatively with the agencies involved on each matter to identify the responsible party and/or source and address accordingly."