After almost two years of rulemaking and stakeholder input, Michigan promulgated maximum contaminant levels (MCLs) for seven specific per- and polyfluorinated substances (PFAS) on August 3, 2020.  The list of seven drinking water standards shown on the table below will be the longest list of PFAS drinking water standards in the US and includes some of the most stringent limits developed by regulators to date.

Specific PFASMCL (ng/L)

As part of the new rules, public water systems in Michigan will be required to sample for PFAS at least annually.  More frequent sampling will be required if results are not in compliance with any of the standards. 

The promulgation of the drinking water standards has ramifications beyond drinking water and public water systems.  Part 201 groundwater cleanup criteria, previously set at the EPA’s Health Advisory Level of 70 ng/L combined PFOS and PFOA, will be immediately reduced to the individual drinking water standards for PFOS and PFOA.  The Michigan Department of Environment, Great Lakes, and Energy (EGLE) reports that this reduction in the groundwater criteria will result in 42 new PFAS sites in the state based on current investigations.  The other five PFAS noted in the table above with drinking water standards are not subject to the immediate inclusion into groundwater standards and would require a separate rulemaking process to promulgate.

So, what does this mean for Wisconsin?  Science and data are available from Michigan’s drinking water rulemaking for use for setting standards in Wisconsin.  The Wisconsin Department of Natural Resources (WDNR) and Department of Health Services (DHS) are currently conducting two separate rulemaking processes concerning setting NR 140 groundwater standards for PFAS and subsequent drinking water and surface water quality standards.  Groundwater standards are reviewed and adopted in cycles.  Cycle 10 includes PFOS and PFOA and Cycle 11 includes 34 PFAS compounds including the five other PFAS that will have MCLs in Michigan.  Cycle 10 is estimated to be promulgated in spring/ summer of 2022 and Cycle 11 is estimated to be promulgated in spring/ summer of 2023.

– Jeff Ramey, TRC Companies