June 4, 2020

San Francisco Bay Region Issues Risk-Based Screening Levels for PFAS at Cleanup Sites

Holland & Knight Energy and Natural Resources Blog
Letitia D. Moore
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California continues to develop tools for evaluating per- and polyfluoroalkyl substances (PFAS) at cleanup sites. In May 2020, the San Francisco Bay Regional Water Quality Control Board issued an "Interim Final Environmental Screening Levels (ESLs) for Two Per- and Polyfluoroalkyl Substances (PFAS): Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoate (PFOA)" Memorandum setting groundwater and soil ESLs addressing direct exposure, ecotoxicity and ingestion risk levels for PFOS and PFOA. The PFAS ESLs are part of the ongoing effort by the San Francisco Regional Water Board to "provide conservative screening levels ... to help expedite the identification and evaluation of potential environmental concerns at contaminated sites."1

The Interim Final PFAS ESLs Memorandum identifies:

  • soil ESLs for 1) terrestrial habitat, 2) leaching to groundwater and 3) direct exposure human health risk
  • groundwater ESLs for 1) aquatic habitat ecotoxicity, 2) seafood ingestion and 3) direct exposure human health risk

For groundwater direct exposure ESLs, the Regional Water Board selected 1.7E-03 microgram per liter (µg/L) (PFOS) and 5.4E-04 µg/L (PFOA). The ESLs are delineated as guidance and not mandatory, but the Regional Water Board will require technical analysis to justify use of alternative screening levels.

The PFAS ESLs Memorandum also describes the Regional Water Board strategy for identifying and prioritizing potential sites for PFAS testing, as well as additional investigation and cleanup. The Regional Water Board will prioritize sites with industrial, manufacturing or firefighting facilities/processes that have a history of using PFAS. The Regional Water Board potential priority sites include:


• firefighting practice training areas

• carpet manufacturers

• semiconductors

• textile manufacturers and processors

• electronics manufacturers

• former chrome plating and finishing facilities

• mining industry (copper, gold, aluminum, vanadium and uranium)

• surface coatings/paints/varnish manufacturers and high volume users

• cardboard/paper packaging manufacturers

• manufacturers of nonstick or known PFAS-containing products


PFAS-containing products include dental floss, nonstick cookware, food packaging materials, waterproof and water repellant textiles, polishes, waxes, cleaning products, medical garments, adhesives, cosmetics, hair conditioners and lotions.

The highest priority for testing will be given to those sites with potential spills or releases that could impact drinking water or aquatic resources. Although time and resources will dictate the pace at which the Regional Water Board investigates potential sites, we can expect that the approach detailed in the Memorandum will influence the Regional Water Board response to ongoing cleanups and voluntary cleanups. Furthermore, the Regional Water Board acknowledges that investigation of categories of sites is also under consideration.

California pursued investigations within industry categories in the past and can be expected to do so again. In 2019, the State Water Board initiated a statewide investigation with orders issued to commercial airports, municipal solid waste landfills and plating facilities. Additional orders were issued to hundreds of public water systems. A similar statewide investigation of wastewater treatment plants, oil refineries and bulk terminals is anticipated in 2020.


1 The San Francisco Regional Water Board has set ESLs for more than 100 chemicals that "address a range of media (soil, groundwater, soil gas, and indoor air) and a range of concerns (e.g., impacts to drinking water, vapor intrusion and impacts to aquatic habitat)."

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