Aquifer Risk Map 2023

The Aquifer Risk Map Web Tool contains all archived maps, including this 2023 Aquifer Risk Map. The Aquifer Risk Map is developed to fulfill requirements of SB-200 (Monning, 2019) and is intended to help prioritize areas where domestic wells and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL). In accordance with SB-200, the map is made available to the public and updated annually starting January 1, 2021. This web map is part of the 2023 Aquifer Risk Map. The Fund Expenditure Plan states the risk map will be used by Water Boards staff to help prioritize areas for available SAFER funding. This web map includes the following layers: Water Quality Risk: water quality risk estimates per square mile section for all contaminants with an MCL. Water quality risk is listed as “high” (average or recent concentration in section is above MCL for one or more contaminants), “medium” (average or recent concentration in section is between 80% - 100% of MCL for one or more contaminants), “low” (average or recent concentration in section is less than 80% of MCL for all measured contaminants) or “unknown” (no water quality data available in section). Individual Contaminant Risk: water quality risk estimates for nitrate, arsenic, 1,2,3-trichloropropane, hexavalent chromium, and uranium per square mile section. State Small Water Systems (DDW): state small water systems (5-14 connections) location from the Division of Drinking Water joined with water quality risk section estimates from the 2023 Aquifer Risk Map. Domestic Well Records (OSWCR): the approximate count and location of domestic well completion reports submitted to the Department of Water Resources. This is used as a proxy to identify domestic well locations. Public Water System Boundaries (DDW): the approximate boundaries of public drinking water systems, from the Division of Drinking Water. For reference only. Census Areas: Census block groups and census tract boundaries containing demographic information from the 2021 American Community Survey (B19013 Median Household Income and B03002 race/ethnicity) joined with summarized water quality risk estimates from the 2023 Aquifer Risk Map (count of high risk domestic wells and state small water systems per census area). Reference Boundaries: Various geographic boundaries including counties, basins, GSA’s, CV-SALTS basin prioritization status, Disadvantaged Community (DAC) status, and legislative boundaries. For reference only. CalEnviroScreen 4.0: CalEnviroScreen scores from OEHHA. For reference only. Groundwater Level Percentiles (DWR): Groundwater depth in various monitoring wells compared to the historic average at that well. For reference only. The water quality risk is based on depth-filtered, de-clustered water quality results from public and domestic supply wells. The methodology used to determine water quality risk is outlined here. For more information about the SAFER program, please email [e-mail]. For technical questions or feedback on the map please email [e-mail].