In January 2019, the San Francisco Bay Regional Water Quality Board published new Environmental Screening Levels (“ESLs”) for over 100 chemicals found at sites with contaminated soil and groundwater, an update from the prior ESLs published in 2016. ESLs are typically used by the Water Board to determine whether additional investigation is required at a site. However, achieving regulatory site closure does not necessarily require reducing all contaminant levels to below the respective ESLs. The new numbers include significant reductions for screening levels of tetrachloroethene (“PCE”) and trichloroethene (“TCE”) — chemicals commonly associated with dry cleaners and metal degreasers.