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Ann Arbor Municipal Water Treatment Plant

Updated: January 29, 2019

The city of Ann Arbor Water Treatment Plant has PFAS detections in the raw and finished water below the United States Environmental Protection Agency (USEPA) Lifetime Health Advisory (LHA) level of 70 parts per trillion (ppt) for PFOA and PFOS.

The city of Ann Arbor continues to test both finished drinking water and the river source water for PFAS on a monthly basis. The City provides regular updates to the public on the low levels being reported in the drinking water on the City of Ann Arbor Water Treatment webpage. The City also provides updates to the public on their efforts to use granular activated carbon (GAC) to remove the PFAS in the drinking water.

  • On March 5, 2014, drinking water samples were taken as required by the USEPA under Round 3 of the Unregulated Contaminant Monitoring Rule (UCMR3) (for more details on the UCMR program, visit the USEPA’s UCMR website). PFOS was detected in the drinking water sample at 43 ppt.
    • The city of Ann Arbor informed their customers and began conducting investigative sampling.
    • This investigative sampling identified the Huron River as the source.
    • As of January 2019, there is currently an active investigation along the Huron River.
  • In November 2017, the city of Ann Arbor began piloting two of its existing filters with full GAC.  The remaining 24 filters have GAC underlain by six inches of sand. 
  • On July 17, 2018, the city of Ann Arbor’s municipal supply was tested as part of the Michigan Department of Environment, Great Lakes, and Energy (EGLE)'s statewide initiative to test all public water supplies and schools with their own wells. Both the finished water and the intake for the supply were sampled.
  • On August 27, 2018, the results were sent to the city of Ann Arbor. Finished water results were 4 ppt PFOA+PFOS; and intake results were 11 ppt PFOA+PFOS. Results from this testing are available on EGLE's public water supply statewide sampling survey page.