California Statewide Groundwater Elevation Monitoring (CASGEM)
Authorized by SBX7 6, enacted in November 2009

California Statewide Groundwater Elevation Monitoring Program Overview

Quick Hits

Senate Bill X7 6
Assembly Bill 1152


In California, groundwater accounts for about 30 percent of the total water supply. During dry years, it is at least 40 percent of the supply. With a projected population of 46 million by the year 2020, California's reliance on groundwater will increase significantly. In order to protect and sustain the state's precious groundwater supply, proper management of this limited resource is imperative. Monitoring groundwater elevations is a fundamental component of successful groundwater management. However, groundwater elevation monitoring networks have not been adequately established for all of California's groundwater basins. This lack of data limits the ability to accurately monitor groundwater conditions in basin aquifers, and limits our ability to adequately plan for future water supply demands.

On November 4, 2009 the State Legislature amended the Water Code with SBx7-6, which mandates a statewide groundwater elevation monitoring program to track seasonal and long-term trends in groundwater elevations in California's groundwater basins. To achieve that goal, the amendment requires collaboration between local monitoring entities and Department of Water Resources (DWR) to collect groundwater elevation data. Collection and evaluation of such data on a statewide scale is an important fundamental step toward improving management of California's groundwater resources.

In accordance with this amendment to the Water Code, DWR developed the California Statewide Groundwater Elevation Monitoring (CASGEM) program. The intent of the CASGEM program is to establish a permanent, locally-managed program of regular and systematic monitoring in all of California's alluvial groundwater basins. The CASGEM program will rely and build on the many, established local long-term groundwater monitoring and management programs. DWR's role is to coordinate the CASGEM program, to work cooperatively with local entities, and to maintain the collected elevation data in a readily and widely available public database. DWR will also continue its current network of groundwater monitoring as funding allows.

The law anticipates that the monitoring of groundwater elevations required by the enacted legislation will be done by local entities. The law requires local entities to notify DWR in writing by January 1, 2011 if the local agency or party seeks to assume groundwater monitoring functions in accordance with the law.

Overview of SBX7 6

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.

SBX7 6 provides that:

  • Local parties may assume responsibility for monitoring and reporting groundwater elevations.
  • DWR work cooperatively with local Monitoring Entities to achieve monitoring programs that demonstrate seasonal and long-term trends in groundwater elevations.
  • DWR accept and review prospective Monitoring Entity submittals, then determine the designated Monitoring Entity, notify the Monitoring Entity and make that information available to the public.
  • DWR perform groundwater elevation monitoring in basins where no local party has agreed to perform the monitoring functions.
  • If local parties (for example, counties) do not volunteer to perform the groundwater monitoring functions, and DWR assumes those functions, then those parties become ineligible for water grants or loans from the state.