State Water Board briefing: midpoint of statewide PFAS testing finds mixed detections in disadvantaged‑community wells

The State Water Resources Control Board on Aug. 6 received a midterm briefing on a statewide PFAS testing program that has sampled about 2,500 of 3,600 disadvantaged‑community wells and found PFAS signals across multiple laboratory methods, Division of Drinking Water officials said.

The testing is funded and authorized under Assembly Bill 178 and carried out under a 2024 DDW sampling order that targets wells in disadvantaged communities statewide. Board staff said the work is intended to inform how the state regulates PFAS and to identify treatment and response needs in small and vulnerable systems.

Dan Newton, assistant deputy director for DDW’s Northern Field Branch, described the effort as a broad, statewide cross section rather than monitoring only near known release sites. “PFAS is a four‑letter acronym, but it is a class of chemicals that is over 10,000 strong,” Newton said, and the project combines targeted chemical tests, an absorbable organic fluorine (AOF) total‑mass proxy, ultra‑short PFAS testing, and non‑targeted analysis (NTA) developed with EPA Office of Research and Development (ORD) assistance.

Key findings and context

- Scope and pace: The 2024 disadvantaged‑community order covers 3,600 wells; staff reported roughly 70% complete (about 2,500 wells sampled) and a sampling pace of roughly 156 wells per month across about 40 water systems. Contractors include Sacramento State (Office of Water Programs), Geosyntec (field sampling), and Babcock (lab services); EPA ORD provided method development support.

- Targeted tests (EPA method 533): Using the standard drinking‑water targeted method (about 25 analytes), staff reported detections in roughly 1 in 10 wells (about 10%). Those detections were dominated by historically common analytes such as PFOA and PFOS; many of the newer ether and fluorotelomer analytes were rarely detected.

- Concentrations (targeted analytes): For detected analytes, median concentrations were low. Newton said the median PFOA concentration to date is about 3.5 nanograms per liter (ng/L), which he noted is below 4 ng/L (the current U.S. EPA MCL for PFOA). Most measured concentrations were under 20 ng/L, with most data well under 10 ng/L.

- AOF (absorbable organic fluorine) total‑mass proxy: AOF presence was higher than targeted detections — staff reported roughly 36% presence. Current AOF detection limits in the project were about 600–700 parts per trillion (ppt); staff said they are working to lower that limit to roughly 200 ppt, which would likely raise the AOF detection rate. Newton and Wendy Link (Division of Water Quality) emphasized that AOF is a proxy for total PFAS mass and has both strengths and limitations.

- Ultra‑short PFAS and TFA: In a budgetary subset of about 350 wells analyzed for ultra‑short PFAS, staff reported a 100% detection rate for trifluoroacetic acid (TFA). Wendy Link cautioned that the subset was chosen for broad geographic coverage and that TFA’s health effects are not as well understood as for PFOA/PFOS; she said shorter‑chain PFAS are generally considered less bioaccumulative.

- Non‑targeted analysis (NTA): Using high‑resolution mass spectrometry and a spectra library (developed with EPA ORD), NTA identified many additional compounds. Staff reported that nearly 90% of unique chemicals found in NTA so far are not fluorinated and that the team currently has moderate‑to‑high confidence in identification for roughly 94% of the NTA hits; about 6% remain tentative. NTA does not yet provide concentrations in the way the targeted method does but helps identify candidate compounds for follow‑up analysis and method development.

- Geographic pattern: Newton said samples come from “all four corners” of California — urban, rural, agricultural and industrial areas — and the present dataset gives a broad cross‑section rather than only targeting sites near likely releases.

What staff plan to do next

Staff said they plan to finish the one‑time DAC sampling under the 2024 order in early 2026, complete full lab analysis of remaining samples through 2026, and then use the results to inform a possible class‑based treatment or regulatory approach under Objective 3 of AB 178. They also plan to refine AOF and evaluate an alternative total‑mass approach (EOF) and to resubmit NTA results as the global spectra library grows.

Follow‑up with systems

Newton and Link said DDW, Sacramento State/Geosyntec field teams and contract labs are monitoring results and will notify systems when results reach advisory or response thresholds. “When they are triggered at certain concentrations… we have different health‑based advice and packets that we’re handing out to the water systems, which includes links and access to DFA funding,” Newton said. District engineers also will contact affected systems to walk them through options.

Why this matters

Board members repeatedly noted that the results are mixed: targeted detections and concentrations are generally low, which staff described as encouraging, while AOF and ultra‑short analyses show broader occurrence that requires more study. Board member Sean Maguire and others emphasized the need to help water systems plan for potential treatment costs and to prioritize limited funding where public‑health problems are greatest.

Partners and funding

Staff credited substantial federal and state partners, including U.S. EPA Office of Research and Development (ROAR grant/support), Sacramento State (Office of Water Programs) as the contractor, Geosyntec for field work and Babcock Lab for analyses. The project was assembled from multiple grants; staff acknowledged that federal ORD capacity has been a critical technical partner.

Next public steps

Staff said they will continue sampling, refine methods and publish a 2026 monitoring order to complete federal pre‑monitoring under the U.S. EPA PFAS rule. They also said they will publish and take public comment on orders or monitoring plans as required and will provide follow‑up notifications and technical support to systems with concerning results.

Ending

Board members thanked staff for the midterm review and emphasized the need for clear communications and funding pathways for small and disadvantaged systems as the state moves from occurrence monitoring toward potential treatment and regulatory action.