Basin Prioritization

Basin prioritization is the process of ranking of groundwater basin importance statewide, focusing on basins producing more than 90% of California's annual groundwater.


Legislation enacted in California's 2009 Comprehensive Water package required DWR to prioritize California groundwater basins in order to help identify, evaluate, and determine the need for additional groundwater level monitoring. The Sustainable Groundwater Management Act (SGMA) further required DWRto develop the initial groundwater basin priority by January 31, 2015. Using the California Statewide Groundwater Elevation Monitoring’s (CASGEM) 2014 Final Basin Prioritization results, the initial prioritization under SGMA designated 127 medium and high priority groundwater basins.  These 127 basins account for approximately 96 percent of groundwater use in California and 88 percent of the state’s population.

The California Water Commission requires a statewide prioritization, to the extent that data are available, of California's groundwater basins using the following eight criteria (Water Code §10933):


  1. Population
  2. Rate of population growth
  3. Number of public supply wells
  4. Total number of wells
  5. Total irrigated acreage
  6. Degree to which persons overlying the basin rely on groundwater as their primary source of water
  7. Documented impacts on the groundwater within the basin, including overdraft, subsidence, saline intrusion, and other water quality degradation
  8. Any other information determined to be relevant by the department, including adverse impacts on local habitat and local streamflows

A priority designation of high, medium, low, or very-Low is assigned to each groundwater basin. For details on how changes in priority affect local agency compliance with SGMA, refer to establishment of Groundwater Sustainability Agencies (GSAs).

In January 2014, we conducted five workshops to introduce draft 2014 Basin Prioritization results and solicit public commentsFinal 2014 Basin Prioritization results are compiled into a summary table  available in PDF or Excel formatYou can also visit our Groundwater Information Center Interactive Map, a web-based application that includes a layer depicting Basin Prioritization information.

CASGEM BP 2014 Final Table
CASGEM Basin Prioritization 2014 Final Results ( XLSX) | (Publish Date:
Detailed spreadsheet of 2014 Final Basin Prioritization Results which includes values used in determining the individual component ranking values, organized by basin number.
CASGEM BP Process 2014
CASGEM Basin Prioritization Process 2014 ( PDF) | (Publish Date:
This report provides a detailed explanation of the Basin Prioritization Process and includes an appendix with figures and tables describing 2014 Basin Prioritization results.
CASGEM BP Brochure
CASGEM Groundwater Basin Prioritization Brochure ( PDF) | (Publish Date:
Brochure summarizing Basin Prioritization criteria and process.
CASGEM Basin Prioritization FAQ ( PDF) | (Publish Date:
Following the release of the 2016 Basin Boundary Modifications, DWR began the process of re-prioritizing California’s 517 groundwater basins (Water Code 12924(b)). Prioritization could change for some basins due to the consideration of impacts from local habitat and local streamflows, the change in area of basin as a result of boundary modifications, correcting errors in the dataset, and requests from local agencies. DWR will conduct workshops to present the draft results and solicit public comments. 

Contact Information

Northern Region
Michelle Dooley
Senior Engineering Geologist
2440 Main Street
Red Bluff, CA 96080

North Central Region
Bill Brewster
Senior Engineering Geologist
3500 Industrial Blvd
West Sacramento, CA 95691

South Central Region
Mike McKenzie
Senior Engineering Geologist
3374 East Shields Avenue
Fresno, CA 93726

Southern Region
Timothy Ross
Senior Engineering Geologist
770 Fairmont Ave, Suite 102
Glendale, CA 91203

DWR Headquarters
Brett Wyckoff
Senior Engineering Geologist
901 P Street
P.O. Box 942836
Sacramento, CA 94236