Delaware Likely to Propose State Drinking Water Standards for PFAS

January 18, 2023
Stephen D. Daly, Esq. and Technical Consultant Will Hitchcock
MGKF Special Alert - Delaware Forecast 2023

Last year, Delaware’s Division of Public Health (the “Division”), with assistance from the Department of Natural Resources and Environmental Control (DNREC), proposed maximum contaminant levels (MCLs) for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS)  in drinking water as required by House Bill 8, signed in October 2021 and as previously reported here. The proposed MCLs for PFOA and PFOS were 21 and 14 parts per trillion (ppt), respectively, with a cumulative standard where both are present of 17 ppt.  The proposed MCLs appeared in the August 1, 2022 edition of the Delaware Register of Regulations and were originally anticipated to take effect in early 2023.  However, the Division is now expected to revise and republish the proposed MCLs as a result of the interim Health Advisory Levels (HALs) published by EPA in June 2022 of 0.004 ppt for PFOA and 0.02 ppt for PFOS.  It remains to be seen how the Division will account for EPA’s interim HALs.  The Division could stick with its original proposal, but it is more likely that the Division either adopts the much more conservative interim HALs proposed by EPA, or some intermediate value between its original proposal and EPA’s.  No revised proposal has yet been announced, but this is expected to occur sometime in 2023, at which time the public will likely have another opportunity to comment.  Stakeholders will want to monitor any opportunity to submit public comment, even if comments were previously submitted regarding the Division’s original proposal.  Once the new MCLs go into effect, they will presumably be applied as Hazardous Substance Cleanup Act screening levels for groundwater remediations in Delaware.