Using These Tools


The Drinking Water Tool was developed with two user pathways. The first, Your Water Data, allows you to learn about water management, supply, and quality based on a specific address. The second pathway, California Water Data, provides both interactive layers with summary data tables and a series of reference data layers that allow you to overlay or compare data. Information on the development processes of new data only available in this tool is available on the Methodology page. The Data page provides a brief data layer description and zipped data folders for downloads.

This Using These Tools page navigates you through the California Water Data part of this webtool. It highlights several elements to consider when reviewing a groundwater sustainability plan (GSP) and planning for drought-resilient rural communities and small water systems. It introduces you to key webtool features and the information available in California Water Data. Additionally, the Drinking Water Tool’s GSP Review Guide was developed to show how data layers in the California Water Data mapping tool can help you assess whether the Groundwater Sustainability Plan (GSP) in your area sufficiently addresses drinking water needs. It was created by combining the Groundwater Leadership Forum’s GSP review template with data layers in California Water Data. Download the Drinking Water Tool’s GSP Review Guide here.

Navigating Your Water Data

The Your Water Data pathway helps you answer the question: Where Does My Drinking Water Come From?  It provides a data-driven answer based on the community water system boundaries and private domestic well communities in the tool. Before getting results, you must confirm whether you receive drinking water from a water system or from a private domestic well.  Results for water management, supply and quality are contingent on data availability for the address selected. 

Navigating California Water Data 

Using the Interactive Layers

The top three layers are interactive and provide you with a snapshot of the data: Groundwater Sustainability Agencies (GSA), Counties, and Community Water Systems. Only one interactive layer can be turned on at a time. No layers are displayed until a layer is selected.  A pop-up tour is available to help you navigate the different data layers. A data table will appear in the left-hand menu based on the selected interactive layer.


  1. In the top-left corner, enter an address of interest: the map will zoom to that address.
  2. Once a layer is turned on, hover or click inside a boundary on the map to reveal its name. When clicked on, the map view will zoom to the selected entity.
  3. Once an interactive layer is selected, a second search box appears below the layer which allows you to search by the name of the GSA, county, or water system. The map view will zoom to the selected entity.

Using Reference Layers

The remaining data is organized into five reference layer categories, each with different data sets. Click the blue info-bubble next to any layer to see its description. These layers are not interactive– you cannot click on the map to learn more or isolate a census place name, or specific data value. They are useful for visualizing data in relation to each other and in relation to the interactive layers to answer questions like the following:

  • What is the estimated concentration of nitrates in groundwater compared to the maximum contaminant level for domestic well communities in my groundwater sustainability agency (GSA)?
    With the interactive Groundwater Sustainability Agencies layer selected, select Water Quality > Likely Private Domestic Wells > Nitrate.
  • Where are water systems possibly serving a disadvantaged community?
    With the interactive Community Water Systems layer selected, select Demographics > Census Places > Disadvantaged Communities.
  • Where are the areas that rely on private domestic wells in my county?  
    With the interactive Counties layer selected, select Groundwater Users> Likely Domestic Well Communities

The Other Boundaries category includes groundwater sustainability agency and county boundaries, for use if these interactive layers are not selected.  Additional boundaries, like state Senate and Assembly Districts or Bulletin 118 groundwater basins, can serve as a backdrop for understanding other data layers. This category includes two layers that automatically appear depending on other data selections. The Township Boundary (PLSS) shows the spatial resolution of the water quality data from which the private domestic well water quality layer has been estimated; it is set to appear anytime you select a contaminant layer for Private Domestic Wells (arsenic, nitrates, hexavalent chromium, and 1,2,3-Trichloropropane). The Alluvial Boundary shows the geographic extent of the drought scenario analysis; it is set to appear anytime you select a Drought Scenario result under Groundwater Supply.

Questions or comments? Please contact the Community Water Center.