Comment submitted by Peter Ernst

Comment — Docket ID EPA-HQ-OW-2025-0654 Re: Proposed Rescission of PFAS Limits for PFHxS, PFNA, HFPO-DA, and Hazard Index Mixtures Submitted via regulations.gov by July 20, 2026 By: Will Willauer, President, Nantucket Tipping Point, Nantucket, Massachusetts Nantucket sits on a single federally designated sole source aquifer (49 FR 2952, 1984). We have no other water. We know PFAS is in it: one of our public wells has been shut down for PFAS since 2022, and testing at a town parcel under state investigation found PFAS in groundwater from 4.9 to 22.3 parts per trillion. The current nationwide screening for these four chemicals (UCMR5) ends in 2025. After that, the 2024 rule is what keeps them measured — it makes every affected water system test for them on an ongoing basis and report the results. This rescission removes that. Once the one-time national survey closes and the rule is gone, routine testing for these four PFAS stops. That matters because you cannot rebuild a limit later — through the "correct" process EPA says it wants — without ongoing data. Rescind the requirement, and the record needed for any future decision simply stops growing. Voluntary disclosure won't fill the gap, because local disclosure doesn't last. Our town's water-quality webpage posts only the current year's report; last year's is taken down when the new one goes up. To check whether a system's PFAS levels are rising over time, a resident has to use the Internet Archive or file a records request. Federal monitoring data, by contrast, stays in a federal database. That durability is what rescission would remove for these four chemicals. Request: If EPA rescinds these limits on legal grounds, keep the ongoing testing and public-reporting requirements for these four PFAS in place until any new limit is finalized, and keep those results in a lasting federal database. A rescission that also ends the data collection defeats the corrected process it claims to make possible.