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Statewide PFAS Survey of Public Water Supplies
Statewide PFAS Survey of Public Water Supplies
Public water supplies may be large, like the Great Lakes Water Authority, which serves 3.7 million residents, or they may be smaller, such as a supply serving a manufactured housing community. Some public water supplies get water from groundwater, some from surface waters (lakes or rivers) and some blend groundwater and surface water sources together. To ensure the drinking water for the largest portion of Michigan residents was tested for PFAS, beginning in April 2018, the Michigan Department of Environment, Great Lakes, and Energy (EGLE) implemented a statewide survey to test Michigan's public water supplies across several phases of sampling.
Prior to the beginning of this statewide survey, the United States Environmental Protection Agency (USEPA) set a Lifetime Health Advisory (LHA) level for two PFAS in drinking water: perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). The LHA level is 70 parts per trillion (ppt, equal to 70 ng/L) for PFOA and PFOS combined, or individually if only levels for other PFAS chemicals. In the absence of a promulgated drinking water PFAS standard(s) at the time, the State of Michigan used 70 ppt for decision making purposes during the statewide survey.
If you receive a water bill, your water comes from a public water supply. If you do not pay for your water, you are likely on a private well. Approximately 75% of Michigan residents get water from a public water supply. Approximately 25% are on private wells.
What has the statewide testing initiative involved?
- Phase I of the statewide PFAS survey initially included community water supplies with their own source, as well as schools on their own well. This list was expanded to also include childcare providers and Michigan Head Start programs on their own well.
- Phase II of the statewide PFAS survey expanded the sampling list to include additional noncommunity public water supplies serving sensitive populations.
- Approximately 80 public water supplies tested during Phase I and Phase II of the statewide survey have returned results greater than 10 ppt total tested PFAS. EGLE placed these supplies onto a quarterly sampling schedule from 2019 - 2020, to help determine if PFAS levels in these supplies changed over time and to help prioritize and direct recommendations and further actions.
- Approximately 70 public water supplies sampled in Phase I use surface water as a source. These supplies were sampled monthly in 2019, and every other month in 2021, to assess whether PFAS levels change over time in Michigan’s surface water sources. Additional sampling is planned for 2022.
During the statewide survey, only three supplies were found to have PFOS+PFOA over the USEPA LHA. Details on the response actions related to these three can be found here:
Understanding the sample results
*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 tables:
- WSSN: Water Supply Serial Number; unique identifier for each public water supply
- The System Type column lists the category assigned to each public water supply
- ADFSTC: Adult foster care provider (Type II Noncommunity Water Supply)
- CHLCMP: Children’s Camp (Type II Noncommunity Water Supply)
- DAYCARE: Childcare provider or MI Head Start (Type II Noncommunity Water Supply)
- INDUS: Industrial (Type II Noncommunity Water Supply)
- MEDCAR: Medical care provider (Type II Noncommunity Water Supply)
- MOTEL: Motel (Type II Noncommunity Water Supply)
- MUN: Type I Community Water Supply
- OFFICE: Office (Type II Noncommunity Water Supply)
- PARK: Park (Type II Noncommunity Water Supply)
- SCH: School (Type II Noncommunity Water Supply)
- TRB: Federally Recognized Tribal water supply
- The Location Name column lists further details about where the specific sample was collected, consistent with its designation in the Safe Drinking Water Information System (SDWIS).
- The SysLocCode, SysSampleCode, Lab Name Code, LabSdg columns include contractor-designated codes for sample specific information, consistent with the corresponding analytical report.
- The Position Source column indicates where the sample’s geographic location was obtained, for the purpose of the MPART PFAS Information System Web Map.
- The Phase Code and Task Code columns indicate the phase of sampling within the Statewide Survey.
- Sample Date: The date samples were taken at the water supply.
- Treatment Status: Indicates the treatment status of the sample
- Analytical Method: Analytical method utilized
These analytical results include detections for 14 – 28 PFAS analytes, depending on the analytical method used. Each result has a "flags" column that corresponds to important data qualifiers.
Understanding the flags: Contaminant data often include flags, also known as qualifiers, which are notes attached to data that gives detailed information about that particular result. In the drinking water PFAS data layer, PFAS analytes associated with a “U” flag were not detected in the sample and therefore a null value is displayed. “J” flagged results indicate an estimated concentration as the result is above the minimum detection limit (MDL) but below the laboratory reporting limit. “J-“ flagged results indicates an estimated concentration as the result is above the minimum MDL, below the laboratory reporting limit, but biased low. “UJ” flagged results indicates a not detected at the value estimated reporting limit. “R” flagged results indicate a rejected sample as serious quality control issues render the result value bot usable. “*” flagged results indicates that the result values have not been verified.
- HFPO-DA (Hexafluoropropylene oxide-dimer acid, also referred to as "GenX") is a regulated analyte in Michigan with with an MCL = 370 ppt
- PFBS (Perfluorobutane sulfonic acid) is a regulated analyte in Michigan with with an MCL = 420 ppt
- PFHxA (perfluorohexanoic acid) is a regulated analyte in Michigan with with an MCL = 400,000 ppt
- PFHxS (perfluorohexane sulfonic acid) is a regulated analyte in Michigan with 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 with an MCL = 8 ppt
- PFOS (perfluorooctane sulfonic acid) is a regulated analyte in Michigan with 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
- na: not applicable