On behalf of the County of San Mateo, EKI Environment & Water, Inc., Todd Groundwater, and HydroFocus, Inc. (the Project Team) have prepared this report to summarize the efforts and results of the San Mateo Plain Groundwater Basin Assessment (Project). The Project was conducted by the County, with the support of the Project Team, to comprehensively evaluate the San Mateo Plain Groundwater Subbasin as defined by the Department of Water Resources (DWR).