Michigan environmental regulators are urging residents to avoid going into parts of the Huron River and several of its tributaries.
Several thousand gallons of liquid containing hexavalent chromium were released by Wixom auto parts manufacturer Tribar Technologies.
Hexavalent chromium is a carcinogen that is harmful to they eyes, skin, and respiratory system.
Michigan Department of Environment, Great Lakes, and Energy spokesperson Jill Greenberg says it's too early to consider punishment for the company.
"At this point, you know, we're just investigating and as that continues, if penalties are warranted we will definitely consider those."
More than five miles of the Huron River are affected, including Kent Lake and Hubbell Pond. Officials say nobody should swim in, drink from, or eat fish caught in those waters.
There's currently no danger to drinking water.
