State Water Board: 70% of AB 178 disadvantaged‑community wells sampled; PFAS detections mixed

State Water Resources Control Board officials on Aug. 6 gave a midterm briefing on the 2024 order implementing Assembly Bill 178, reporting results from a statewide sampling effort of disadvantaged‑community wells.

The Division of Drinking Water (DDW) said field teams have sampled roughly 2,500 of the 3,600 wells on the order — about 70% complete — at a pace of roughly 156 wells per month. "PFAS is a 4‑letter acronym, but it is a class of chemicals that is over 10,000 strong," Dan Newton, assistant deputy director for DDW's Northern Field Branch, told the board.

Why this matters: AB 178 funded one‑time, no‑cost sampling in disadvantaged communities to reveal statewide occurrence patterns rather than only testing near known release sites. The dataset is large and geographically broad, officials said, and staff will use findings to refine testing methods and to inform future monitoring and potential treatment or regulatory approaches.

Most important findings presented

- Targeted testing (EPA Method 533 for drinking water analytes) detected at least one of the 25 targeted PFAS analytes in about 10% of wells sampled so far. DDW said the majority of detections were among the more historically studied carboxylates and sulfonates such as PFOA and PFOS.

- Absorbable organic fluorine (AOF), used here as a proxy for broader PFAS mass (EPA method 1621 as stated in the briefing), had a presence in about 36% of tested wells; DDW reported current AOF limits of detection around 600–700 parts per…