The following explains how the PFAS Investigations page has transitioned over time, how the Michigan Department of Environment, Great Lakes, and Energy (EGLE) investigations get started and what constitutes a PFAS site.
On November 13, 2017, the Michigan PFAS Action Response Team (MPART) originally listed 28 investigations which included areas of groundwater contamination as well as rivers and public water supplies. MPARTs definition of a “site” changed in 2018 such that a site was where one or more groundwater monitoring result exceeds groundwater clean-up criteria. In August 2018 Gilkey Creek and the Clinton River were no longer classified as a “site” and so were moved to the Watershed Investigations page. Five public water supply locations previously listed as “sites” were moved to a Drinking Water page. Since that time the PFAS Sites page features groundwater investigations being conducted around the state with a result that exceeds groundwater clean-up criteria.
In 2018, EGLE's Remediation and Redevelopment Division established cleanup criteria for groundwater used as drinking water of 70 ppt of PFOS and PFOA, individually or combined.
On August 3, 2020, the groundwater cleanup criteria became 8 ppt PFOA and 16 ppt PFOS. On December 21, 2020, the following 5 additional PFAS compounds became groundwater cleanup criteria: PFNA (6 ppt), PFHxS (51 ppt), PFHxA (400,000 ppt), PFBS (420 ppt), and HFPO-DA (370 ppt). EGLE staff use all 7 PFAS criteria to guide groundwater investigations, protect public health, and identify MPART PFAS sites.