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Flint River Watershed

Flint River Watershed

Updated: March 2025

The Flint River drains portions of seven counties in mid-Michigan. The watershed is more than 1,300 square miles and consists of hundreds of tributary creeks, lakes, and the Flint River proper. In 2013 the Department of Environmental Quality (DEQ, now EGLE) detected PFAS in samples from the Flint River. The discovery of the elevated concentrations of PFAS in the Flint River has led to numerous investigations of potential sources and mitigation efforts, including Gilkey Creek and Lapeer Plating and Plastics. These investigations have also led to fish consumption advisories to protect the public, which are available on the Department of Health and Human Service’s (DHHS) Eat Safe Fish webpage.  PFAS refers to the entire family of per- and polyfluoroalkyl substances.  One of the most commonly detected substances is perfluorooctanesulfonic acid (PFOS), in part because it bioaccumulates, or builds up, within aquatic organisms compared to the water in which they live in.  This is why we typically measure PFOS concentrations in water in parts per trillion (ppt) whereas in fish it is commonly measured in parts per billion (ppb).

The city of Flint currently obtains its drinking water from the Great Lakes Water Authority, which was tested in November 2017 and found not to have detectable levels of PFAS.  Additionally, EGLE’s statewide PFAS survey of public water supplies began testing the Great Lakes Water Authority in 2018.  For latest test results, contact the Great Lakes Water Authority directly or refer to the MPART Statewide Drinking Water PFAS Testing Initiative.

The timeline below discuss PFAS investigations, findings, and MPART sites located in the Flint River Watershed.  Please note that not all MPART sites directly impact the Flint River and its tributaries, but all are included that are located within the watershed.  All MPART sites, by definition, have had PFAS above groundwater criteria.  For current information about these MPART sites, see the linked MPART site webpages.

Source reduction and control strategies are being or have been implemented watershed wide, and routine surface water and fish tissue monitoring will continue to assess the impact of these strategies on the Flint River Watershed. Periodic updates to the timeline, for significant work, will continue.

Reports

  • None at this time.

Next Steps

  • EGLE is awaiting the PFAS results for fish collected from the Holloway Reservoir and the south branch of the Flint River in 2020.
  • EGLE will conduct the POCIS study in 2021 to monitor PFAS trends in the Flint River watershed.
  • EGLE will continue to monitor PFAS in fish from the Holloway Reservoir in 2021.
  • Work under the Industrial Pretreatment Program (IPP) PFAS Initiative will continue for the Flint WWTP, Genesee County Ragnone WWTP, and the Lapeer WWTP.  These municipalities will be continuing to evaluate and reduce sources of PFOS and PFOA, as well as consider local PFAS regulatory options.

Investigation Timeline