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Compliance Monitoring in Public Water Supplies

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Compliance Monitoring in Public Water Supplies

The Michigan Department of Environment, Great Lakes, and Energy (EGLE) developed Maximum Contaminant Levels (MCLs) for seven PFAS compounds in Michigan, which took effect in August 2020. These MCLs amend existing rules for public drinking water supplies under Michigan's Safe Drinking Water Act (SDWA), affecting approximately 2,700 public water supplies statewide.

Following the initial compliance monitoring period (August 2020 - February 2021), all supplies required to conduct ongoing compliance monitoring under the SDWA were assigned a sampling schedule based on their initial result.

For PFAS MCLs, the standard compliance monitoring schedule is quarterly - this applies to any supply which has a detection for one or more PFAS analytes with an MCL, above the method reporting limit. A supply may be reduced to an annual monitoring schedule if they demonstrate PFAS levels consistently and reliably below the MCLs.

Compliance with PFAS MCLs for a supply is determined based on a running annual average for each compound, calculated at each sampling point. A supply is not out of compliance until either 1) one full year of quarterly sampling is complete, or 2) fewer samples cause the running annual average to exceed one or more MCLs. If a supply is determined to be out of compliance with one or more PFAS MCLs, the supply is required to notify the public within 30 days.

Compliance Monitoring Results (since August 3, 2020)

The initial compliance monitoring period ran from the date of MCL promulgation (August 3, 2020) until February 3, 2021, and included two groups of supplies:

  • Those supplies which had collected a sample during EGLE's statewide PFAS survey and returned a PFAS result with a detection greater than half of one of the proposed MCLs AND those supplies which had not previously collected a PFAS sample during EGLE's statewide PFAS survey, would sample during the first full quarter following promulgation (October 1, 2020 - December 31, 2020).
  • All remaining supplies which had collected a sample during EGLE's statewide PFAS survey would sample during the first six months following promulgation (August 3, 2020 - February 3, 2021).

Quarterly sampling for PFAS MCL compliance monitoring began on January 1, 2021, and follows the following schedule each year:

  • Quarter 1: January 1 – March 31
  • Quarter 2: April 1 – June 30
  • Quarter 3: July 1 – September 30
  • Quarter 4: October 1 – December 31

Sampling for PFAS MCL compliance for those supplies on an annual schedule runs concurrently with quarterly sampling.

Sample results collected for PFAS MCL compliance are listed in the table, below.

  • *Results are provided in parts per trillion. A part per trillion (ppt) is the equivalent of 1 drop of water in 20 Olympic-size swimming pools

    Definitions of the information provided in the sampling results table:

    • WSSN: Water Supply Serial Number; unique identifier for each public water supply
    • Collection Date: The date samples were taken at the water supply.
    • The System Type column lists the type of public water supply
      • CWS: Community Water Supply (Type I)
      • NCWS: Noncommunity Water Supply (Type II)
        • Non-transient: Non-transient noncommunity water supplies (Type II) are monitored for compliance under Michigan's SDWA.
    • PFAS analytes are listed in individual columns (ppt). These include the 18 PFAS compounds tested under EPA method 537.1. If the result listed is "ND" the lab did not detect, or find, that PFAS was in the water sample above the method reporting limit.
      • HFPO-DA (Hexafluoropropylene oxide-dimer acid, also referred to as "GenX") is a regulated analyte in Michigan with an MCL = 370 ppt
      • PFBS (Perfluobutane sulfonic acid) is a regulated analyte in Michigan with an MCL = 420 ppt
      • PFHxA (perfluorohexanoic acid) is a regulated analyte in Michigan with an MCL = 400,000 ppt
      • PFHxS (perfluorohexane sulfonic acid) is a regulated analyte in Michigan with an MCL = 51 ppt
      • PFNA (perfluorononanoic acid) is a regulated analyte in Michigan with an MCL = 6 ppt
      • PFOA (perfluorooctanoic acid) is a regulated analyte in Michigan with an MCL = 8 ppt
      • PFOS (perfluorooctane sulfonic acid) is a regulated analyte in Michigan with an MCL = 16 ppt
      • 11Cl-PF3OUdS (11-chloroeicosafluoro-3-oxaundecane-1-sulfonic Acid) is currently a non-regulated analyte in Michigan
      • 9Cl-PF3ONS (9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid) is currently a non-regulated analyte in Michigan
      • ADONA (4,8-dioxa-3H-perfluorononanoic acid) is currently a non-regulated analyte in Michigan
      • NEtFOSAA (2-(N-ethylperfluorooctanesulfonamido) acetic acid) is currently a non-regulated analyte in Michigan
      • NMeFOSAA (2-(N-methylperfluorooctanesulfonamido) acetic acid) is currently a non-regulated analyte in Michigan
      • PFDA (perfluorodecanoic acid) is currently a non-regulated analyte in Michigan
      • PFDoA (perfluorododecanoic acid) is currently a non-regulated analyte in Michigan
      • PFHpA (perfluoroheptanoic acid) is currently a non-regulated analyte in Michigan
      • PFTA (perfluorotetradecanoic acid) is currently a non-regulated analyte in Michigan
      • PFTrDA (perfluorotridecanoic acid) is currently a non-regulated analyte in Michigan
      • PFUnA (perfluoroundecanoic acid) is currently a non-regulated analyte in Michigan
    • Sample Number: The identification number that corresponds to the sample taken.
    • Lab Name: Laboratory providing PFAS analysis via EPA method 537.1.
    • Site Code: Specific sample location, when applicable.
    • na: not applicable

Again, the table below shows PFAS MCL compliance testing results for those public water supplies required to sample under Michigan's SDWA. Additional results will be added as they become available. 

Download the Compliance Monitoring Results dataset

Use the interactive table below to find the supply you're looking for. You can use the search box to find certain keywords, city or county names, or even supply type. Each column in the table is able to be sorted -- simply click or tap on the column header to sort it alphabetically or reverse-alphabetically. To see the complete set of results for a supply, click or tap the + to expand; then the x to collapse.

 

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