Basin Prioritization

Map of draft 2018 SGMA Basin Prioritization. Contact DWR to receive more information about this map.

Statewide Map of SGMA 2019 Basin Prioritization

Basin Prioritization is a technical process that utilized the best available data and information to classify California’s 515 groundwater basins into one of four categories; high-, medium-, low-, or very low-priority. The technical process is based on eight components that are identified in the California Water Code Section 10933(b).

Each basin’s priority determines which provisions of California Statewide Groundwater Elevation Monitoring (CASGEM) and the Sustainable Groundwater Management Act (SGMA) apply. SGMA requires medium and high priority basins to develop groundwater sustainability agencies (GSA), develop groundwater sustainability plans (GSP) and achieve sustainable groundwater management.

Historically, there have been two basin prioritization projects: 2014 CASGEM Basin Prioritization and SGMA 2015 Basin Prioritization. The latest basin prioritization project, commonly referred to as SGMA 2019 Basin Prioritization, was completed in October 2019. SGMA 2019 Basin Prioritization was based on the same technical process as the previous basin prioritization efforts with minor updates to meet changes to the statue included in the SGMA legislation.

Ninety-four basins and/or sub-basins were identified as medium or high priority in SGMA 2019 Basin Prioritization and will be required to form GSAs and develop GSPs. These 94 basins in combination with adjudicated areas, which have existing governance and oversight in place, account for 98 percent of the pumping (20 million acre-feet), 83 percent of the population (25 million Californians), and 88 percent of all irrigated acres (6.7 million acres) within the state’s groundwater basins.

No future basin prioritization or basin boundary modification projects are planned at this time.

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 format.

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:

The Water Code requires a statewide prioritization, to the extent that data are available, of California's groundwater basins using the following eight components (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).