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Groundwater Information Center

Information About Groundwater in California

  • Groundwater Basics
      Groundwater Basics

      Meeting California's water needs presents new challenges and highlights the importance of educating the public about groundwater resources. Actions to increase the overall water supply will require more understanding and protection of groundwater, especially from contamination and overuse. Monitoring and evaluation must be continued so that future groundwater issues are not overlooked or misunderstood. Proper stewardship of California's groundwater is important to avoid quality degradation and land subsidence. Groundwater issues vary statewide, making it most suitable to local management.

      This 'Groundwater Basics' section is intended for the general public, non-technical readers, teachers and students for an easy understanding of the basics of groundwater. For additional general groundwater information, see Chapter 6 of DWR's Bulletin 118 California's Groundwater Update 2003.

      The following topics are discussed in this Groundwater Basics section.

      Hydrologic Cycle - illustrates and describes how groundwater relates to the continuous process by which water is circulated throughout the Earth and its atmosphere.

      Relationship between Groundwater and Surface Water - illustrates and describes the general relationship between the interaction of groundwater and surface water.

      Commonly Used Groundwater Terms - refers to a list of commonly used groundwater terms and provides links to additional terms related to groundwater.

      Water Fact Sheets and Related Links - provides links to various DWR and other agencies published fact sheets, bulletins, booklets, reports and studies with respect to groundwater in a general or regional context.

      Contacts for general Groundwater Information in California - provides DWR contacts for groundwater information in California.

  • Management
      Groundwater Management In California

      Groundwater management, as defined in DWR Bulletin 118, Update 2003, is the planned and coordinated monitoring, operation, and administration of a groundwater basin or portion of a groundwater basin with the goal of long-term sustainability of the resource. Groundwater management needs are identified at the local water agency level and may be directly resolved at the local level. If groundwater management needs cannot be directly resolved at the local agency level, additional actions such as enactment of ordinances by local governments, passage of laws by the Legislature, or decisions by the courts may be necessary to resolve the issues. The State's role is to provide technical and financial assistance to local agencies for their groundwater management efforts.

      California Statewide Groundwater Elevation Monitoring (CASGEM)

      In 2009, the Legislature passed SBX7 6, which establishes, for the first time in California, collaboration between local monitoring parties and DWR to collect groundwater elevations statewide and that this information be made available to the public. For more information, visit DWR's California Statewide Groundwater Elevation Monitoring (CASGEM) website.

      California Statewide Groundwater Elevation Monitoring (CASGEM)


  • Bulletin 118
      California's Groundwater Published

      The California Department of Water Resources (DWR) has long recognized the need for collection, summary, and evaluation of groundwater data as tools in planning optimal use of the groundwater resource. An example of this is DWR's Bulletin 118 series. Bulletin 118 presents the results of groundwater basin evaluations in California.

      The long-awaited update to California's Groundwater, Bulletin 118 was released to the public in early October 2003. Bulletin 118 - Update 2003 is the first comprehensive report on groundwater since 1980 when Bulletin 118-80 was published.

      Online technical descriptions and GIS compatible maps of 515 groundwater basins and subbasins were part of the effort to publish the bulletin. The basin/subbasin descriptions include information about the geology, groundwater quantity and quality, and current groundwater management practices in the basins.

      The list of all Bulletin 118 publications, statewide and region-specific, is available at the Bulletin 118 website.

      Bulletin 118 web site is organized in the following topics:

         Bulletin 118 - Update 2003

         History of Bulletin 118

         Statewide and Region-specific Bulletin 118 Reports

         Groundwater Basin Maps and Descriptions


      Bulletin 118 - Update 2003 Report Cover

      Cover Page of California's Groundwater, Bulletin 118 - Update 2003 Report (October 2003)

  • Data
      Groundwater Data and Monitoring

      Groundwater data and monitoring go hand-in-hand. Data collection, through monitoring, and subsequent data analysis are critical components for effective management of groundwater. Groundwater level and quality data can help determine baseline or ambient conditions and identity trends in a basin over time. Measurements of groundwater levels and quality in wells provide the most fundamental indicator of the status of this resource and are critical to meaningful evaluations of the quantity and quality of groundwater and its interaction with surface water (U.S.G.S. Circular 1217).

      Groundwater Data
      California Statewide Groundwater Elevation Monitoring (CASGEM) establishes collaboration between local monitoring parties and DWR to collect groundwater elevations statewide and that this information be made available to the public.

      Water Data Library (WDL) contains hydrologic data (groundwater level data and some groundwater quality data) for over 35,000 wells California. The data is collected by DWR Region Offices and dozens of local and federal cooperators. WDL's easy on-line data retrieval provides information quickly!

      Groundwater Monitoring Data Available by Regions
         Groundwater Level Monitoring
         Groundwater Quality Monitoring

      Other Local Data Available by Regions
         Groundwater Basin Assessments
         Land Subsidence Data
         Well Completion Reports Data

      Other Useful Data & Monitoring Links
      IWRIS   |   GAMA   |   USGS   |   Geotracker   |   Envirostor

  • Wells & More