This page includes brief descriptions for each data layer that appears in Your Water Data and is available for interaction and visualization in California Water Data Tool. Where available, spatial data (shapefiles) and metadata are available for download as (.zip) files. If using any data layers or related information for analysis or reporting, please cite according to each layer’s guidelines.
This shapefile contains a feature class with polygons that represent exclusive Groundwater Sustainability Agencies (GSA) formed under the Sustainable Groundwater Management Act (SGMA). The exclusive GSA boundaries were downloaded from the Department of Water Resources’ SGMA Dataviewer (October 7, 2019). Multiple spatial analyses were undertaken to populate the fields you see in the summary data table of the California Water Data Tool. To estimate a count of each entity per GSA, the Community Water Center spatially joined the following fields to the exclusive GSA boundaries: private domestic wells locations, public supply well locations, community water systems, and severely disadvantaged and disadvantaged census places (see metadata for more details).
The drought scenario results for Central Valley private domestic wells were aggregated to GSAs (see Gailey 2020). This information is viewable in the California Water Data Tool in the summary table and in the Groundwater Supply- Drought Scenarios section. Results from all scenarios are included in this download. Note that for the drought analysis results at the GSA level, there may be only partial data support for some areas. To evaluate this consideration, review the area covered by the Alluvial Boundary found in the Other Boundaries section.
Download the Shapefile and Metadata (.zip)
This shapefile contains a feature class with polygons that represent the 58 counties in California. Multiple spatial analyses were undertaken to populate the fields you see in the summary data table of the California Water Data Tool. Information on the number of domestic wells and population reliant on domestic wells is based on data from Pace et al. (2019). Intersecting county boundaries with other layers generated: Groundwater Sustainability Agency boundaries (Number of GSAs), Bulletin 118 Groundwater Basins (Number of Sub-basins), Census Places (Number of Disadvantaged Communities, Number of Severely Disadvantaged Communities). Similar to information available in Demographics, county-level information is available for race/ethnicity and median household income and other variables, based on the 2017-2021 American Community Survey 5-Year Estimates.
The drought scenario results for Central Valley private domestic wells were aggregated to counties (see Gailey 2020). This information is viewable both in the summary data table and as a layer in Groundwater Supply. Results from all scenarios are available for download as part of this shapefile. Note that for the drought analysis results at the county level, there may be only partial data support for some areas. To evaluate this consideration, review the area covered by the Alluvial Boundary found in the Other Boundaries section.
Download the Shapefile (County.zip)
This shapefile contains a feature class with polygons that represent selected community water system boundaries from the Tracking California Water System Service Areas Tool (Tracking California), formerly known as the Water Boundary Tool. This layer includes the boundaries or services areas of 2,851 active, community water systems as of January 2019. To gather this information, first, the ‘active’ status of community water systems from Tracking California was verified in the State Drinking Water Information System. Then, the boundaries were cleaned and wholesale community water systems were removed with the assistance of California Office of Environmental Health Hazard Assessment’s (OEHHA), using the methods used for CalEnviroScreen 3.0 (see CES 3.0, 2017 for more information). This layer is available as an interactive layer with summary information for each system in the data table and as a standalone reference layer, which can be found under Groundwater Users – Community Water Systems.
Characteristics for each community water system available in this layer are the result of several different research efforts. The metadata file documents the methodology and data source for each characteristic. Only certain community water system characteristics are available for download, as indicated in the metadata file. The drought scenario results are only available for small community water systems, those serving fewer than 10,000 people, in the Central Valley (see Gailey 2020).
Download the Shapefile and Metadata (.zip)
If using for analysis or reporting, please cite the Community Water System Boundary dataset as:
Pace, C., Balazs, C., Cushing, L., Morello-Frosch, R. (2019) UC Berkeley Water Equity Science Shop. Community Water System Boundaries.
Contact: Clare Pace, Ph.D., MPH, cpace@berkeley.edu, UC Berkeley, Environmental Science Policy and Management, Water Equity Science Shop.
This shapefile contains a feature class with points that represent the locations for all municipal or public supply wells from the Department of Water Resources’ Online System for Well Completion Reports (OSWCR). This shapefile contains a feature class with point data for 7,158 public supply wells with spatial reference, selected from the OSWCR system by Dr. Rob Gailey, based on a downloaded .csv file of well completion reports (WCRs) (Nov. 16, 2018). Latitude and longitude coordinates supplied in the .csv file were used to plot public supply WCRs as points (see Gailey 2020).
Download the Shapefile and Metadata (.zip)
If using for analysis or reporting, please cite the public supply well location dataset as:
Gailey, R. (2019) Public Supply Well Locations. CWC Drinking Water Tool.
This shapefile contains a feature class with points that represent the locations for all private domestic wells, including those that may not be in current use, or that may be in an area with no population, or that are within the boundaries of a community water system. These data came from the Department of Water Resources’ Online System for Well Completion Reports (OSWCR ). This shapefile contains a feature class with point data for 327,252 domestic wells with spatial reference. Private domestic wells were selected from the OSWCR database based on a downloaded .csv file of well completion reports (WCRs) (Sept. 19, 2018). Unique WCRs referring to domestic wells were included. Latitude and longitude coordinates supplied in the .csv file were used to plot WCRs as points. If latitude and longitude coordinates were not available, these values were calculated by joining WCRs to Public Land Survey System (PLSS) sections and calculating the center of a PLSS section. PLSS sections are approximately 1×1 mile grid squares and the PLSS file was downloaded from the U.S. Bureau of Land Management.
Download the Shapefile and Metadata (.zip)
If using for analysis or reporting, please cite the domestic well location dataset as:
Pace, C., Balazs, C., Cushing, L., Morello-Frosch, R. (2019) UC Berkeley Water Equity Science Shop. Private Domestic Well Locations.
Contact: Clare Pace, Ph.D., MPH, cpace@berkeley.edu, UC Berkeley, Environmental Science Policy and Management, Water Equity Science Shop
This shapefile contains a feature class with polygons that represent likely private domestic well communities. This layer combines four data sources to identify likely private domestic well communities at the Public Land Survey System (PLSS) section level: 1) domestic well locations, 2) 2010 census block-level population estimates, 3) community water system locations, and 4) residential parcel locations. The PLSS section grid (approximately 1×1 mile grid squares) is the underlying geographic unit to define areas served by domestic wells. A likely domestic well community is defined as a section that has at least one domestic well, intersects a populated census block (2010) and a residential parcel, and is not served by a community water system. Because there are areas where people may be living and for whom we have no drinking water source information, we have provided additional downloadable data on potential well communities, which are defined as PLSS sections that intersect a populated census block and are not served by a CWS, but the level of confidence about whether they drink from wells is lower. Please consult the complete methodology described in Pace et al. 2019.
Three key attributes of this layer, as displayed are:
Note: the attributes in the Domestic Well Communities layer are only available for sections classified as “likely” or “potential” domestic well areas. This excludes sections located in areas served by a community water system (CWS) and sections in unpopulated census block areas. Additionally, the count of domestic wells in each section from this layer may not be identical to the count of domestic wells from the All Private Domestic Well Location layer, which contains all private domestic wells (the entire ‘universe’ from OSCWR).
Download the Shapefile and Metadata (.zip)
If using for analysis or reporting, please cite the domestic well community dataset as:
Pace, C., Balazs, C., Cushing, L., Morello-Frosch, R. (2019). UC Berkeley Water Equity Science Shop. Domestic Well Community Boundaries Version 1.0.
Contact: Clare Pace, Ph.D., MPH, cpace@berkeley.edu, UC Berkeley, Environmental Science Policy and Management, Water Equity Science Shop
This shapefile contains a feature class with polygons that show water quality values assigned from the California Office of Environmental Health Hazard Assessment’s (OEHHA) CalEnviroScreeen (CES) 3.0 dataset, to the 2,851 community water systems in the Drinking Water Tool. Current data displayed on the Drinking Water Tool shows values from CES 4.0, which used monitoring data from the State Water Resources Control Board (SWRCB) Water Quality Monitoring (WQM) database. The Drinking Water Tool currently contains data for arsenic, nitrates, hexavalent chromium, and 1,2,3-Trichloropropane. These four contaminants were selected due to their acute or carcinogenic health effects. Future iterations of this tool will include data on additional high priority contaminants. The CES 4.0 downloaded reported water quality results from 2011-2019 from the SWRCB WQM database for all active drinking water systems. “Active treated” samples were primarily evaluated, as these represent water delivered to the consumer. Delivered water could include sources sampled post-treatment or sampled from “untreated” sources. Approximately 3% of the data came from “raw” water samples because the systems had no treated or untreated source classifications. Complete methods used in CES 4.0 are available from OEHHA (CES 4.0, 2021). Only certain community water source characteristics are available for download, as indicated in the Community Water System layer metadata file. The drinking water contaminant data is available for download from OEHHA for community water systems (CES Indicator – Downloads).
Download the Metadata
If using for analysis or reporting, please cite the water quality dataset as:
Pace, C., Balazs, C., Cushing, L., Morello-Frosch, R. (2019) UC Berkeley Water Equity Science Shop. Community Water System Boundaries- Water Quality.
Contact: Clare Pace, Ph.D., MPH, cpace@berkeley.edu, UC Berkeley, Environmental Science Policy and Management, Water Equity Science Shop
This shapefile contains a feature class with polygons that represent the Public Land Survey System (PLSS) sections (approximately 1×1 mile grid squares) and populated areas with private domestic wells and water quality values assigned to PLSS sections of the Private Domestic Well Communities in California. It was generated by the Water Equity Science Shop (WESS) research team using water quality values provided by the State Water Resources Control Board and developed for the Safe and Affordable Funding for Equity and Resilience (SAFER) Program’s 2022 Aquifer Risk Map. This dataset was used to assign contaminant concentrations for arsenic (As), nitrate as nitrogen (N), 1,2,3-trichloropropane (1,2,3-TCP), and hexavalent chromium (Cr6) to populated PLSS sections that were not served by community water systems. These four contaminants were selected due to their acute or carcinogenic health effects. Future iterations of this tool will include data on additional high priority contaminants. The Aquifer Risk Map utilized data from the State Water Resources Control Board’s Groundwater Ambient Monitoring & Assessment (GAMA) dataset, a groundwater information system that integrates water quality data from various sources.
Complete methodology is available in the GAMA Needs Assessment White Paper “Methodology to estimate groundwater quality assessed by domestic wells.
Existing groundwater quality data in the GAMA Groundwater Information System was filtered by time and depth to better represent domestic well water quality. The water quality estimation layer consists of a twenty-year average detection level per Public Land Survey System (PLSS) section per chemical. Complete methodology is available from the SWRCB (Aquifer Risk Map, 2022). The groundwater contaminant data is available for download from the Aquifer Risk Map.
Handling non-detects
Results reported as “non-detects” in this dataset were assigned a value equal to the detection limit at the time the sample was collected. If the sample had no associated reporting limit, the most closest earlier measurement with a known reporting limit was assigned (GAMA Needs Assessment, 2020).
Download the Metadata
If using for analysis or reporting, please cite the water quality dataset as:
Methodology notes for the 2022 Aquifer Risk Map created in support of SB 200 to help prioritize SAFER funding for domestic wells and state small water systems at risk for water quality issues.
A drought scenario in this tool is a scenario of groundwater level decline that is based on observations from the 2012 to 2016 drought. Groundwater level declines for each scenario were based on a scaled version of the 2012 to 2016 drought. These scaling factors (0.5, 0.75 and 1.0) reflect the Drought Scenarios of 50%, 75% and 100%. The drought scenario analysis considers how declining groundwater elevations might reduce well production potential as well as what mitigation measures might be required to maintain supplies. Selecting between these scenarios communicates the estimated impacts and costs on either private domestic or small water system wells (<10,000 people served) in the Central Valley. The starting groundwater levels for the analysis are fall 2014, and the 2012 to 2016 drought groundwater levels were defined by fall 2011 (pre-drought) and fall 2016 (late drought) levels. Please consult this analysis’s report for more information: Gailey 2020.
Impact and cost calculations were performed for each Public Land Survey System section (approximately 1×1 mile grid square) where information is available for both a well’s depth and groundwater levels during the 2012 to 2016 drought. This set of data layers are feature classes with polygons that represent domestic wells at the section level or a small community water system. For small community water systems, results are aggregated to the community water system’s boundary or service area. The results for both public supply wells and private domestic wells are defined as follows:
Note: When interpreting aggregating impacts for groundwater sustainability agencies and counties, there may be only partial data support for some areas and blank values indicate there was no data available for analysis. No designation is made to indicate partial data support. Results for several counties are incomplete given the spatial boundary (Alluvial Basin) of the analysis undertaken: Alameda, Contra Costa, El Dorado, Mariposa, Napa, San Benito, San Luis Obispo, and Tuolumne. Please consult this analysis’s report for more information: Gailey 2020.
Download the Shapefile and Metadata for all Drought Scenarios: (DomesticWells.zip | WaterSystems.zip )
Download Results Table (.xlsx)
If downloading or using for analysis or reporting, please cite as:
Gailey, R. (2020) California Supply Well Impact Analysis for Drinking Water Vulnerability Webtool.
Demographic information is available for three census geographies: places, tracts, and block groups. Places include incorporated places, which are legal entities like cities, and census-designated places, which are statistical entities created by the Census for unincorporated communities with settled concentrations of population that are identifiable by name but not located within an incorporated place. Census tracts and block groups are geographic entities within a county: census tracts generally have 1,000 to 8,000 people but aim to have around 4,000 people. Census block groups are a statistical division of tracts, and typically have 600 to 3,000 people. For each geography, layers show estimated 5-Year Averages from the American Community Survey of the US Census (ACS) (2017-2021). The ACS includes estimates of social and economic characteristics for people living in housing units and group quarters. Available information from the ACS includes median household income, disadvantaged community status (DAC), and race.
If using for analysis or reporting, please cite the demographic dataset as:
U.S. Census Bureau, 2017-2021 American Community Survey 5-Year Estimates.
The median household income (MHI) values are the estimated 5-year averages from the American Community Survey of the US Census. Income data is collected annually from a sample of census block groups and combined as a period estimate to describe the average characteristics of the population/housing over the data collection period. The MHI income is defined as the MHI in the past 12 months (in 2017 inflation-adjusted dollars) (see Table B19013).
In California, a disadvantaged community (DAC) is one with an average median household income (MHI) of less than 80% of California’s overall MHI. A severely disadvantaged community (SDAC) is one with an average MHI of less than 60% of California’s overall MHI (California Public Resources Code). This layer shows both DAC and SDACs, based on the 2017 American Community Survey of the US Census 5-year data. In 2017, the statewide MHI was $67,169. The calculated DAC threshold is $53,735 and the calculated SDAC threshold is $40,301. In the California Water Data Tool, census geographies with MHIs below $53,735 are labeled DACs and MHIs below $40,301 are labeled SDACs. Any census geographies with incomes above these thresholds, or with missing data, do not appear.
The California Water Data Tool uses race/ethnicity variables included in the 2017 American Community Survey (ACS) 5-year average (see Table B03002). Data is based on respondents’ self-identified ethnicity and race. Each category is shown as a percent of the total population for each census geography. In the shapefiles available for download, each race/ethnicity category includes a population count, percent of that geography’s total population, and ACS’s margin of error calculations. ACS definitions of race/ethnicity categories are displayed as follows:
Download shapefiles: (Places.zip| Tract.zip| BlockGroup.zip)
The boundary of California’s 80 state assembly districts, based on boundary lines published by the California Redistricting Commission (Data Source).
The boundary of California’s 40 state senate districts, based on boundary lines published by the California Redistricting Commission (Data Source).
Public Land Survey System (PLSS) is one way to subdivide and describe public land in the U.S., it is divided into 6-mile square units called townships. Townships are then further subdivided into 36 1×1 mile square sections (Data Source). Township boundaries are included in the California Water Data Tool to indicate the spatial resolution of the water quality data that is used for the likely private domestic well communities water quality layers.
The alluvial boundary defines the extent of the alluvial deposits in California’s Central Valley including the Sacramento, San Joaquin, and Tulare Lake groundwater basins as defined by California’s Department of Water Resources Bulletin 118 (Data Source). The alluvial boundary in the California Water Data Tool indicates the geographic extent of the drought scenario analysis for private domestic wells and small community water systems in the Central Valley.
California’s groundwater basins are defined and characterized by the Department of Water Resources’ Bulletin 118 (B118), the official publication on the occurrence and nature of groundwater statewide. Since the Sustainable Groundwater Management Act (SGMA) was passed, Bulletin 118 also provides Groundwater Sustainability Agencies with key information: Critical Conditions of Overdraft, Basin Boundaries, and Basin Priority (see Bulletin 118). The California Water Data Tool visualizes Bulletin 118 groundwater basin priority results from the Department of Water Resources’ basin prioritization process and critically overdrafted basins.
2019 SGMA Basin Prioritization
This layer shows the 515 groundwater basins in the state of California; visualized by the SGMA basin prioritization levels (December 2019). Basin prioritization is a process of classifying the State’s 515 groundwater basins (as identified in Bulletin 118) into one of four categories high-, medium-, low-, or very low-priority based on components identified in the Water Code. SGMA requires medium- and high-priority basins to develop groundwater sustainability agencies (GSAs), develop groundwater sustainability plans (GSPs) and manage groundwater for long-term sustainability.
Critically Overdrafted Basins (2018)
This layer shows the 21 groundwater basins that have been categorized as critically overdrafted of the 515 groundwater basins in the state of California (December 2019). Groundwater basin overdraft happens if the average annual amount of water extracted exceeds the long-term average annual supply of water to the basin. Consequences of overdraft can include seawater intrusion, land subsidence, groundwater depletion, and/or chronic lowering of groundwater levels. In response to SGMA, DWR evaluated California’s groundwater basins for conditions of critical overdraft in 2015 with information available from the SGMA Dataviewer.
Download the Shapefile and Metadata (.zip)