Flint River Watershed

Updated March 8, 2019

Flint River WatershedThe 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) 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 Services' (DHHS) Eat Safe Fish webpage. PFAS is the 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, in the food chain. So, if bluegill have moderate levels of PFOS, a fish like a bass that eats bluegill, will have higher levels because PFOS bioaccumulates up the food chain.

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. For latest test results, contact the Great Lakes Water Authority directly.


  • Water samples from selected rivers, including the Flint River, were analyzed for PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid). Flint River concentrations were below human health screening levels. Additional monitoring was not conducted at that time.


  • The DEQ collected samples from the Flint River. Levels of PFOS in the Flint River at both M-13 (39-42 parts per trillion [ppt]) and near Montrose (50-51 ppt) were higher than those initially measured in 2001 and exceeded the Rule 57 value of 12 ppt PFOS for surface water quality. The samples collected were downstream of Flint’s drinking water intakes, and the results were below the 70 ppt combined PFOS and PFOA advisory level for drinking water.


  • Between April 2014 and October 2015, the city of Flint temporarily drew drinking water from the Flint River. The State has no information to suggest that the concentrations in the river or drinking water supply exceeded the drinking water action level.
  • August – Final results for fish collected from the Flint River near Montrose were received. PFOS levels exceeded DHHS’s screening values, indicating a fish consumption advisory was needed. In addition, the three Flint River species sampled had higher levels of PFOS than those species collected elsewhere from the river.
  • Spring – The updated Eat Safe Fish guidance included new advice due to PFOS in fish. The advisory extended from the Flint River downstream of Mott Dam. (There was no data to indicate contamination extended further upstream.)
  • A surface water sampling plan was developed to determine contamination sources along the Flint River for implementation in 2016. Sampling focused on the Flint River and major tributaries in the immediate vicinity of the city of Flint.


  • July – The DEQ collected samples from the Flint River and significant tributaries in the vicinity of Flint.The results from this sampling showed consistent levels above the Rule 57 water quality standards of 12 ppt PFOS in the Flint River and indicated a source was upstream of Holloway Dam.
  • As part of this effort, the DEQ collected samples at Carpenter Road and M-15, upstream of the city of Flint’s drinking water intake. The results were 14 and 16 ppt, respectively, below the EPA lifetime health advisory level of 70 ppt.
  • The DEQ collected fish from Holloway and Mott reservoirs to be analyzed in 2017.
  • The DEQ developed a plan for additional sampling along the Flint River, including a location on the North Branch of the Flint River and locations on the South Branch both upstream and downstream of the Lapeer Wastewater Treatment Plant (WWTP).



  • The DEQ received results for the fish collected from the Holloway and Mott reservoirs that showed elevated levels of PFAS and supported the conclusion that contamination was coming from upstream of the Holloway Dam and indicated that fish consumption advice due to PFOS for the entire river should be considered. Updated advice was included in the next Eat Safe Fish guide that was released in spring 2018.


  • May 9 – The DEQ collected surface water samples in the Flint River and effluent samples from the Lapeer, Flint, and Genesee WWTPs for PFAS analysis.


  • June 6 – Results of May surface water and WWTP sampling were received and showed elevated (440 ppt) PFOS levels in the Lapeer WWTP effluent.Treated wastewater from the Lapeer WWTP discharges to the South Branch of the Flint River. The city of Lapeer implements an because it accepts wastewater from a categorical industrial user, Lapeer Plating & Plastics (LP & P).
  • One sample location on Gilkey Creek had elevated results of 25 ppt PFOS. Gilkey Creek is a tributary to the Flint River and drains parts of Genesee County, including areas from the cities of Burton and Flint. Effluent from the Flint WWTP also had slightly elevated results of 28 ppt PFOS, leading the DEQ to believe there is likely another significant source of PFOS in the Flint River Watershed.


  • The DEQ conducted a multimedia inspection at LP & P that included a repeat sample of the Lapeer WWTP effluent, along with a sample of the LP & P discharge to the municipal sanitary system. As the only known plater in Lapeer, LP & P was a potential source of PFOS to the sanitary system.
    • The city of Lapeer, assisting with the investigation, took additional sanitary sewer samples of other potential PFOS sources. Results of the DEQ samples received on August 11 indicated the PFOS level in the Lapeer WWTP effluent was five times higher (2,000 ppt) than the level measured in the May sample; the LP & P concentration was also extremely high. City samples indicated that LP & P was its primary source of PFOS.
    • In addition, the DEQ's Remediation and Redevelopment Division collected three soil samples at LP & P due to staining and dead vegetation observed. Samples were analyzed for volatiles and metals. Based on those sampling results, the site is considered a “facility” under Part 201, Environmental Remediation, of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended.


  • August 23 – Due to concern regarding the potential for PFOS contamination of biosolids generated at the Lapeer WWTP, the DEQ asked the city of Lapeer to collect and analyze a sample of their biosolids.
  • August 24 – The city of Lapeer collected a sample of their biosolids as requested the previous day by the DEQ.
  • August 30 – The DEQ conducted a second multimedia inspection at LP & P, additional sampling included: a third WWTP effluent sample, a second sample of the LP & P discharge, samples of selected LP & P process tanks, and a sample of the surfactant/mist suppression product used by LP & P as part of their plating process. In addition, the DEQ collected soil and water samples from outside storage areas and storm water drainage areas at LP & P. LP & P assisted with sampling and provided Safety Data Sheets (SDS) for the materials used in the process tanks that were sampled.


  • September 7 – The DEQ issued a Compliance Communication to the Lapeer WWTP requiring the city of Lapeer to provide information on the actions taken, or to be taken, to address the PFOS discharge to their sanitary sewer from LP & P and to begin planning for an alternative biosolids disposal strategy in the event that land application was not determined to be approvable.
  • September 15 – The city of Lapeer submitted a written response to the Compliance Communication. The response included:
    • Results of the biosolids analysis (2100 parts per billion [ppb] or micrograms per kilogram [µg/Kg]);
    • A copy of the City’s Notice of Violation to LP & P, which required correction of the PFOS discharge to Lapeer’s sanitary sewer by September 26, 2017; and
    • A copy of the Administrative Order to Show Cause, which ordered LP & P to appear at a hearing with the city of Lapeer on September 27 to demonstrate why the city should not pursue additional action.
  • September 25 – The DEQ verbally informed the city of Lapeer that due to the elevated level of PFOS in their biosolids, they would not be approved for land application. There are no regulatory values for PFAS in biosolids, but the DEQ’s preliminary calculations indicated this level was too high.
  • September 25 – Results from the August 30 multimedia inspection indicated that the source of PFOS in LP & P’s effluent was from the etching tanks. The results were provided to the city of Lapeer and LP & P on the same day in order to assist their efforts in eliminating the source. Results from the soil sampling were 14 and 68 ppb PFOS, and the storm water was 760 and 1,200 ppt PFOS.
  • September 29 – the DEQ conducted an inspection at LP & P, with the primary goal of evaluating outside storage practices and collecting effluent composite samples the city of Lapeer had set up. The DEQ received sample results on November 1.


  • October 4 – LP & P submitted an investigation plan to identify the source and pathways of PFOS. The city of Lapeer forwarded the plan to the DEQ for review.
  • October 18 – The city of Lapeer delivered an Administrative Order to Achieve Compliance to LP & P. Among other items, the order requires LP & P to install activated carbon treatment by October 30, 2017, should other corrective actions implemented by LP & P fail to reduce PFOS levels to 12 nanograms per liter (ng/L).
  • October 26 – LP & P were able to clean out their etch tanks and associated units. Normal operations at the facility were resumed the next day.
  • October 30 – The DEQ conducted multimedia inspections at Mid-State Plating, Stokes Steel Treating, and Attentive Industries.All three facilities are located on Kelso Street in the city of Flint and border Gilkey Creek. Mid-State Plating is a metal plating facility. Soil, surface water, storm water, and effluent samples were collected as part of this inspection. Mid-State Plating cooperated with the inspection and provided SDSs of the chemicals used in their process.During the inspection, it was learned that a fire had occurred at Stokes Steel Treating in 2006. The city of Flint obtained a report of the incident from the fire department that indicated 50 gallons of AR-AFFF from the Flint Bishop Airport Fire Department had been requested to put out the fire. Fluoroalkyl Surfactant was listed as an ingredient on the SDS for the foam received, indicating that the foam contained PFAS.


  • November 20 – The DEQ received results from October surface water, storm water, and effluent sampling. Elevated levels in Gilkey Creek were confirmed. In addition, PFAS was detected in the storm water catch basin on Kelso Street. Results indicated Mid-State Plating’s effluent did not contain PFAS.


  • December 18 – the DEQ conducted follow-up investigative inspections of facilities and surface waters within the suspected source area along Gilkey Creek. The DEQ also collected a single surface soil sample from exposed soil at the western edge of the concrete apron at the Stokes Steel Treating facility. Additionally, the DEQ collected four surface water samples at various locations along Gilkey Creek in the vicinity of Kelso Street. Surface water results were lower than in October but still above water quality standards in Gilkey Creek within the city of Flint, east of Center Road, to the discharge point of the creek to the Flint River.
  • Based on the December 18 sample results, potential sources were identified and the DEQ began development of a plan to collect site-specific information such as groundwater samples. Potential sources included Stokes Steel Treating, an industrial site where AFFF was used to put out a fire; AC/Rochester Delphi Plants 400 and 600, a former automotive manufacturing facility where chrome plating was conducted (including the location of their former pretreatment system and sludge/waste disposal area); and Davison Road Landfill West, a former landfill, that is suspected to have accepted automotive manufacturing waste.
  • December 19 – In order to evaluate the potential impact of PFOS-contaminated biosolids at fields used by the city of Lapeer, the DEQ selected one city-owned site (that was repeatedly used) for initial screening. DEQ staff collected three incremental (composite) surface soil samples and one grab surface water sample from a pond located on the eastern side of the field. Sample results were received on January 22, 2018, and averaged 500 ppb PFOS in the soil and 2000 ppt PFOS in the pond. Based on these results, it was determined that additional information on the land application of biosolids from the Lapeer WWTP was necessary.



  • January 11 – A Type II noncommunity well supply serving Applewood Estates – Ruth Mott Foundation was sampled approximately one mile west of the suspected source area and downstream of Gilkey Creek. Samples from the well were non-detect (ND) for PFOS.


  • April 2018 – Groundwater sampling was completed by RACER at Buick City near a suspected former firefighting training area. Three of the eight samples had results over 70 ppt.
  • April 2018 – The DEQ contracted with AECOM to perform monitoring of the field owned by the city of Lapeer that had received biosolids from the WWTP, as well as two additional privately-owned fields. The monitoring plan included soils, adjacent surface waters, drain tiles, and groundwater. A meeting with landowners to discuss the proposed monitoring of the two fields was held on April 11, 2018. AECOM conducted monitoring on the fields from April 26 to May 10. As of September 19, 2018, three out of four draft reports of the monitoring effort were finalized, with one report still under review and expected to be final by the end of October 2018 or early November 2018.
  • April 10 – RACER collected five groundwater samples from monitoring wells at the Davison Road Landfill West site, which is located adjacent to Gilkey Creek upstream of Center Road. PFAS was detected but at levels well below the Part 201 drinking water protection criteria of 70 ppt PFOS/PFOA combined and below the Surface criteria of 12 ppt for PFOS. A map of Gilkey Creek with the potential sources and monitoring results is provided below.

Map of Gilkey Creek PFOS Sample Reults


  • June 4 – The DEQ’s statewide initiative to test all community water supplies and schools with their own wells began in Oakland County, including areas within the Flint River Watershed. Of the results received as of September 19, 2018, no supplies within the Flint River Watershed had returned values above ND.
  • June 8 – The DEQ collected groundwater samples at a location downgradient of the former plating line at the former Delphi Plant 600. No PFAS compounds were detected.
  • June 19 – The DEQ attempted to collect groundwater samples from three potential source locations along Gilkey Creek. The locations included the Former Delphi Sludge waste landfill, the former Delphi WWTP, and Stokes Steel Treating. Groundwater samples were not collected at any of the locations due to conditions encountered in the field. One pore water sample was collected from the bed of Gilkey Creek in the area of Stokes Steel Treating and was submitted to a lab for PFAS analysis.Results of the pore water sample in the bed of the creek was 1,100 ppt PFOS and 140 ppt PFOA.
  • June 19 – The city of Flint sampled the Trichloroethylene (TCE) groundwater clean-up discharge from Delphi Plant 600 to the city's sanitary sewer. Results were received by the City on July 19. PFAS was detected at low levels (4.5 ppt PFOS and 15 ppt PFOA).


  • July 27 – The DEQ collected groundwater samples downgradient of a former Hazardous Waste Storage Unit and a former plating line at the former Delphi Plant 400. The highest level of PFOS detected was 10 ppt.


  • August 1 – The DEQ’s statewide initiative to test all community water supplies and schools with their own wells began in Genesee and Lapeer Counties, including areas within the Flint River Watershed. Of the results received as of September 19, 2018, no supplies within the Flint River Watershed have returned values above ND.
  • August 13 – The city of Flint conducted sampling in three sanitary sewer tributary lines that flow to the East Pump Station. Two of these had PFOS levels below 12 ppt, while the third one, which drains from Buick City, had PFOS levels of 720 ppt.
  • August 15 – The DEQ’s statewide initiative to test all community water supplies and schools with their own wells began in Shiawassee County, including areas within the Flint River Watershed. Of the results received as of September 19, 2018, no supplies within the Flint River Watershed have returned values above ND.
  • August 24 – The DEQ collected sediment samples for PFAS analysis in Gilkey Creek at three locations. Results were ND for two locations and 3.6 ppb in sediments near Stokes Steel Treating.
  • August 27 – The DEQ’s statewide initiative to test all community water supplies and schools with their own wells began in Saginaw County, including areas within the Flint River Watershed. Of the results received as of September 19, 2018, no supplies within the Flint River Watershed have returned values above ND.


  • As of September 2018, the DEQ and Lapeer WWTP had been working with LP & P for a year to reduce/control PFOS discharges to the WWTP and surface waters.  Progress towards the goal of the Lapeer WWTP meeting the water quality standard of 12 ppt in their discharge to the South Branch of the Flint River is being made.  LP & P has implemented extensive corrective actions, including cleaning of tanks, pits, and process lines; installation of an activated carbon pretreatment system; replacement of sections of sanitary sewer line; and eliminating exposure of industrial racks and equipment to storm water.  LP & P plans to implement an approved storm water characterization study in the fall 2018.  A graph of the effluent (treated wastewater) results from the Lapeer WWTP and LP & P (discharge to the Lapeer sanitary sewer) is provided below.

Effluent PFOS Chart for Lapeer and Lapeer Plating and Plastics


  • November 9 – The MDEQ conducted surface water and storm sewer sampling to further delineate potential sources.  Results had elevated levels of PFOS above Rule 57 water quality standards at three storm sewers outfalls in the source investigation area.  Surface water results were slightly elevated above the water quality standards as well. The MDEQ will work with the City of Flint to further evaluate the storm sewers to determine sources.
  • November 16 – The MDEQ collects 6 samples from groundwater monitoring wells at the landfill on the Flint Bishop International Airport’s property. The highest results were 810 ppt PFOS+PFOA, 1,236 ppt Total PFAS.

Map of Gilkey Creek PFOS Results



  • The City of Flint Landfill at the Flint Bishop International Airport becomes an official MPART Site.


  • March 8 – the MDEQ and MDHHS presented at a Town Hall event held by Representatives John Cherry, Sheldon Neely, Sheryl Kennedy, and Tim Sneller at Mott Community College in Flint. View the presentation.