PORTAGE, Ind. - The beaches along Lake Michigan at Indiana Dunes National Park are back open Thursday.
A rust-colored liquid was dumped into the water from U.S. Steel over the weekend.
Beaches were closed while Indiana took at look at what was in the water, finding there was a high level of iron in the liquid.
But, a water plant will remain closed, and Indiana is still investigating if U.S. Steel broke federal pollution laws.
U.S. Steel did not indicate what concentrations of iron were detected in the discharge, and it was not immediately clear whether the release posed any threat to public health, the environment or wildlife.
The U.S. Environmental Protection Agency said Tuesday that it was awaiting results from its own samples of the plant’s discharge and would provide an update once those results are analyzed.
Gabriel Filippelli, a professor or earth sciences at Indiana University-Purdue University Indianapolis, said the test results released by U.S. Steel were vague but that, "in general, iron itself is just kind of a nuisance rather than a contaminant that requires a significant amount of intervention."
With testing still underway, however, Filippelli said it remained to be seen whether the discharge could have contained toxic heavy metals such as mercury or lead, or other contaminants.
The Associated Press contributed to this report.