Board hears proposed PFAS notification and response level changes; OEHHA recommends 1 μg/L PFHxA NRL

At an informational hearing on Aug. 6, State Water Board staff presented proposed revisions to notification levels and response levels for several PFAS compounds and received an OEHHA recommendation for a new PFHxA notification level.

What staff proposed

- PFOA and PFOS: DDW proposed lowering the notification level (NL) for each compound to 4 nanograms per liter (ng/L) to align with the current U.S. EPA maximum contaminant level (MCL). Staff recommended no change to the existing response levels (RLs) while the federal MCL schedule is implemented.

- PFHxS: staff proposed converting the existing RL of 20 ng/L (single confirmed sample) to a 10 ng/L running annual average. The change would harmonize the metric with other PFAS RLs and mirror the U.S. EPA approach for PFHxS.

- PFHxA: OEHHA recommended a new NL of 1 microgram per liter (1 μg/L = 1 part per billion). Chris Banks, senior toxicologist at OEHHA, summarized the derivation: OEHHA screened the literature, identified a small set of animal studies (Loveless et al., NTP and others), used benchmark‑dose modeling of critical endpoints (nasal cavity degeneration, decreased thyroid hormone), applied a composite uncertainty factor (300) and a 20% relative source contribution to reflect non‑water exposure, and rounded a calculated protective concentration of 0.8 μg/L up to 1 μg/L.

Health and statutory context

- Staff explained that notification and response levels are advisory levels derived under Health and Safety Code section 116455 and that PFAS have a statutory notification requirement under Health and Safety Code section 116378 when a monitoring order triggers detection: either public notification or removal of the affected source from service is required by the statute.

- DDW emphasized that NLs and RLs are non‑regulatory advisory tools but that PFAS statutory notification obligations require action when monitoring orders detect PFAS under the cited code sections.

Numbers and potential impacts (staff analysis)

DDW provided a caution: the system counts shown were worst‑case scenarios based on single‑sample maxima from the historical dataset and therefore overstate likely operational impacts. Using that approach, staff estimated — again, as a worst case — that changing PFHxS RL from 20 to 10 ng/L could affect roughly 41 systems (about 67 wells) in the historical dataset; lowering PFOS NL from 6.5 to 4 ng/L might affect about 51 wells under the single‑sample accounting; and changing the PFOA NL to 4 ng/L might touch another set of systems (staff noted a data‑entry typo in one slide and applied caveats to each count). DDW told the board that running annual average calculations and updated monitoring will change these counts prospectively and that co‑occurrence of PFOA/PFOS with other analytes often means systems already managing those compounds will be able to address related detections.

Stakeholder comments

Representatives of water utilities and associations urged attention to funding, operational flexibility, and compliance timelines. Megan Murphy of the California Municipal Utilities Association asked that state funding be prioritized to help systems meet monitoring and treatment costs and recommended that monitoring for federal compliance be at the point of entry; DDW staff said federal compliance monitoring is point of entry, but the state sampling order samples sources to provide blending and source‑contribution information. Nick Blair (ACWA) and Sue Mossberg (CA‑NV AWWA) requested stakeholder engagement for economic feasibility assessments and additional time for MCL compliance if a statewide MCL is adopted.

Board and staff comment

Board members asked for clarity on monitoring locations and on how notification requirements interact with treatment and blending. DDW said source monitoring helps staff and systems understand which wells contribute PFAS, how blending affects entry‑point concentrations, and how permits should reflect operational contingency plans if a blending well goes out of service.

Next steps

Staff said the presentation was informational and that they will accept public comment before issuing final NL/RL revisions. If no substantive new information requires additional review, DDW anticipated issuing the revised NLs/RLs in September; they also reiterated that they expect to publish a January 2026 sampling order to align federal monitoring compliance schedules.

Provenance

Topic introduction excerpt: "It is 10:15. We can bring ourselves back. Appreciate the break. We're moving on to item number 6, where we'll hear an update on the proposed revised notification response levels for PFOA, PFAS, PFHXS, and proposed, notification response levels for PFHXA." (Transcript segment starting 4665.59)

Topic finish excerpt: "That wraps up item number 6 and is bringing us to just the final 2 items of, this 2 day board meeting." (Transcript segment starting 7800.185)

Ending

DDW will accept public comment and technical input before issuing any revised notification or response levels. The board will be briefed again as staff finalize any issuance and as OEHHA and the water board coordinate on health‑based inputs for rulemaking.