Michigan Adopts New Standards for PFAS in Drinking Water & Groundwater

August 14, 2020

Establishes maximum contaminant levels with implications for monitoring requirements & cleanup criteria

On July 22, 2020, the Michigan Department of Environment, Great Lakes, and Energy (EGLE) announced the adoption of a ruleset that creates comprehensive legislation limiting per- and polyfluoroalkyl substances (PFAS) in drinking water. Official as of August 3, these regulations, the first of their kind in Michigan, cover approximately 2,700 public water supplies throughout the state.

The new rules establish maximum contaminant levels (MCLs) for seven PFAS compounds (Table 1). MCLs are defined as the highest concentration of a substance legally allowed in public drinking water systems. Michigan's new MCLs are below current U.S. Environmental Protection Agency (EPA) health advisory levels of 70 ng/L for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), individually or combined.

Table: Michigan MCLs for PFAS in Drinking Water

Perfluorononanoic acid (PFNA)

6 ng/L

Perfluorooctanoic acid (PFOA)

8 ng/L

Perfluorooctanesulfonic acid (PFOS)

16 ng/L

Perfluorohexanesulfonic acid (PFHxS)

51 ng/L

Hexafluoropropylene oxide dimer acid (HFPO-DA)

370 ng/L

Perfluorobutanesulfonic acid (PFBS)

420 ng/L

Perfluorohexanoic acid (PFHxA)

400,000 ng/L

Michigan's new rules also have implications on monitoring requirements for public water suppliers. Suppliers must monitor treated water at representative points within the distribution system to determine compliance with drinking water standards. Regardless of PFAS sampling results from Michigan's 2018/2019 Statewide PFAS survey, each supplier is required to begin monitoring within six months of the effective date of the rule. If any PFAS compound listed in Table 1 is below the reporting limit (2 ng/L), EGLE may allow for annual water supply monitoring for that compound; if detected above the reporting limit, multiple samples must be collected per quarter until it is determined that the water within the distribution system is consistently below the MCL.

Michigan's drinking water standards have an immediate effect on groundwater cleanup criteria for PFOA and PFOS. The new groundwater criteria are 8 ng/L for PFOA and 16 ng/L for PFOS — lowered from the previous groundwater clean-up criteria of 70 ng/L for PFOA and PFOS, individually or combined. As a result of the new drinking water and groundwater standards, the Michigan PFAS Action Response Team (MPART) will investigate an additional 42 sites across the state, including landfills and former plating or manufacturing sites.

How Exponent Can Help

Exponent's expert consultants in regulatory compliance, contaminant fate and transport, and analytical chemistry help clients navigate the current regulatory landscape and manage their ongoing environmental liabilities. Our multidisciplinary team of scientists and engineers considers both state and federal regulations when developing strategic solutions for our clients' needs. Exponent can help with selecting appropriate methods and laboratories for PFAS analyses based on the intended use of the data; source identification, chemical fingerprinting, and fate and transport analyses of PFAS in the environment; and reviewing and commenting on proposed state and federal regulations for PFAS compounds.