Environmental Screening Levels (ESL)

Environmental Screening Levels - (Interim Final - Februrary 2016)

The Environmental Screening Levels (ESL) provide conservative screening levels for over 100 chemicals commonly found at sites with contaminated soil and groundwater. They are intended to help expedite the identification and evaluation of potential environmental concerns at contaminated sites. ESLs 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 life). These ESL documents are prepared by staff of the San Francisco Bay Regional Water Quality Board (Water Board). Information provided in the document is not intended to establish policy or regulation.



Major updates and minor revisions to the ESLs will be posted to this website when needed. The current major update (e.g., Feb 2016) and minor revision (e.g., Rev #) version is listed on the top of the Table Index and in the footer of each sheet within the ESL Workbook. The following link (ESL Status Sheet) provides the current revision number and lists the most recent changes for that revision. In addition, an electronic notification will be sent to persons on the ESL mailing list when the ESLs are updated or revised. You can join the ESL mailing list by going to the Water Board's website (or from the Water Board's home page, click 'Email Subscriptions' under Resources on the lower left toolbar). Once there, click on the ESL box under the General category.


For further information about ESLs and risk assessment contact:
  • Nicole Fry
    SF Bay Regional Water Quality Control Board
    1515 Clay Street, Suite 1400
    Oakland, CA 94612
    Tel: 510-622-5047
    Email: ESLs.ESLs@waterboards.ca.gov

Supplemental Information


A master's thesis completed in December 2011 presents the first regional estimate of background arsenic concentrations in the San Francisco Bay Region. The proposed upper estimate for background arsenic (99th percentile) within undifferentiated urbanized flatland soils is 11 mg/kg.