Bulletin 118 is California’s official publication on the occurrence and nature of groundwater statewide. Bulletin 118 defines the boundaries and describes the hydrologic characteristics of California’s groundwater basins and provides information on groundwater management and recommendations for the future.
With the passage of Sustainable Groundwater Management Act (SGMA) in 2014, Bulletin 118 now serves an additional role by providing Groundwater Sustainability Agencies (GSAs) with three critical pieces of information regarding groundwater basins: Critical Conditions of Overdraft, Basin Boundaries, and Basin Priority.
In 2020 and every five years after, we will release comprehensive updates to Bulletin 118.
Interim Update 2016
Bulletin 118 statewide reports provide information about the nature and occurrence of groundwater in California with a focus on the state's groundwater basins.
In addition to the statewide editions of Bulletin 118, DWR has published the following limited Bulletin 118 reports that focus on specific areas of the state.
B118 Update 2003 provided online descriptions of California’s groundwater basins and subbasins. The 2003 Basin Descriptions included available information on narrative descriptions of basin boundaries, summaries of the hydrologic and hydrogeologic setting, groundwater storage capacity and water budget, groundwater level and quality trends, well yields, basin management, and references.
The full 2003 Basin Descriptions have not been updated for B118 Interim Update 2016; however, we developed a new procedure for basin boundary descriptions as part of the 2016 Basin Boundary Modification process. As a result, all basins that had boundary modifications in 2016 have revised basin boundary descriptions. We will update basin description information as GSAs implement their GSPs and new and additional information becomes available.
NOTE: The basin boundary descriptions contained in the 2003 basin descriptions are no longer valid for the basins with revised boundaries.
A GIS data set, containing the boundaries for each of California's groundwater basins, is available for download. The compressed downloaded file contains both a shapefile of the basin boundary data, and a geodatabase containing a basin boundary feature class. Metadata is included with each version of the basin boundary data set.
The Bulletin 118 Basin Boundary GIS data can also be accessed through the California Natural Resources Agency’s Open Data Portal. There you will find additional formats, including GeoJSON and KML, available for download. It should be noted that the shapefile available for download on the Open Data web site is projected in WGS84 Web Mercator.
California Statewide Groundwater Elevation Monitoring (CASGEM) Program - collaboration between local monitoring parties and DWR to collect groundwater elevations statewide and make that information publicly available.
Data & Tools
We have a long history of data collection, monitoring, and reporting. With the passage of the Sustainable Groundwater Management Act (SGMA), there is an increased need for local and state agencies and the public to easily access water data in order to make informed management decisions. Here you will find a curated set of data, interactive mapping tools, and reports which are important resources to inform sustainable groundwater management decision-making.
CWP Groundwater Update 2013
California's Groundwater Update 2013: A Compilation of Enhanced Content for California Water Plan Update 2013 compiles and analyzes readily-available groundwater information to characterize California’s groundwater basins, aquifers, and well infrastructure.
Senior Engineering Geologist
901 P Street
P.O. Box 942836
Sacramento, CA 94236