The Wisconsin Department of Natural Resources has formally identified General Motors as responsible for cleaning up an area of contaminated sediment in the Rock River near the former assembly plant in Janesville. Gazette reporter Elliot Hughes has learned the DNR issued a letter of responsibility to GM Thursday. It outlines a series of steps the company must take over the next several months to clean the contamination or face “enforcement action” by the DNR. The patch of sediment in question was discovered in January to have elevated levels of polycyclic aromatic hydrocarbons, metals and other semi-volatile organic compounds. That came to light when the city performed a study on how removal of the Monterey Dam downstream could impact the river’s sediment. The contamination is not harmful to humans but could be for certain kinds of aquatic life.
