Groundwater contamination data was sourced from reports generated by the GeoTracker GAMA (Groundwater Ambient Monitoring & Assessment) database. Data includes concentrations and approximate locations of 39 historically-prevalent groundwater pollutants in public water system wells. Data includes the percent of wells with concentrations above maximum contaminant levels (MCLs) or comparison concentrations (health-based target values from other sources used where no Federal or State MCLs have been promulgated). Groundwater Basin Name, as well as Assembly and Senate district #s are also included.
Information on MCL or Comparison Concentration type is from the State Water Board website.