In 2019, the Attorney General of Illinois joined in a letter with 22 other states in urging Congress to address the public health threat associated with per- and polyfluoroalkyl substances (PFAS). This approach was no surprise, as the Illinois Environmental Protection Agency (IEPA) had, since 2018, determined that it was time to start assessing PFAS in the environment. See Annual Groundwater and Drinking Water Program Review (IEPA June 2018).

Subsequently, the IEPA decided to sample for 18 PFAS compounds in 118 community water supply wells and 32 surface water intakes, selected on a random basis, to evaluate the extent that PFAS compounds were present. See Annual Groundwater and Drinking Water Program Review (IEPA 2019). IEPA’s expectation was that a response strategy would be necessary should PFAS concentrations exceed of concern in any well.

As part of its overall PFAS strategy, earlier this year the IEPA also released Draft Rules for Outreach to amend its Class I and Class II groundwater standards found at Title 35 Part 620. In the Draft Rules, IEPA proposes the following standards for PFAS compounds:

CAS No.              Constituent                                                  Standard (mg/L)


375-73-5             Perfluorobutane Sulfonic Acid (PFBS)      0.14

335-46-4             Perfluorohexane Sulfonic Acid (PFHxS)   0.00014

375-95-1             Perfluorononanoic Acid (PFNA)                0.000021

335-67-1             Perfluorooctanoic Acid (PFOA)                  0.000021

1763-23-1          Perfluorooctane Sulfonic Acid (PFOS)      0.000014

—                   PFOA and PFOS Combined                        0.000021

According to IEPA’s Public Hearing and Other Notices page, last visited on April 9, 2020, the comment period had been scheduled to end on February 29th. Presumably, the IEPA will incorporate any comments into a formal rule proposal later this year. Meanwhile, the sampling should occur simultaneously.