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GAMA - About

The Groundwater Ambient Monitoring and Assessment (GAMA) Program is California's comprehensive groundwater quality monitoring program that was created by the State Water Resources Control Board (State Water Board) in 2000. It was later expanded by Assembly Bill 599 - the Groundwater Quality Monitoring Act of 2001. AB 599 required the State Water Board, in coordination with an Interagency Task Force (ITF) and Public Advisory Committee (PAC) to integrate existing monitoring programs and design new program elements as necessary, resulting in a publicly accepted plan to monitor and assess groundwater quality in basins that account for 95% of the state’s groundwater use. The GAMA Program is based on interagency collaboration with the State and Regional Water Boards, Department of Water Resources, Department of Pesticide Regulations, U.S. Geological Survey, and Lawrence Livermore National Laboratory, and cooperation with local water agencies and well owners.

In July 2020, the Division of Water Quality (DWQ) Groundwater Ambient Monitoring and Assessment Program (GAMA) released its program evaluation report that summarizes work completed to date and makes recommendations for future efforts. GAMA staff are in the process of implementing many of these ideas, as well as making improvements in response to discussions with users across the groundwater community.

The main goals of GAMA are to:

  • Improve statewide comprehensive groundwater monitoring.
  • Increase the availability to the general public of groundwater quality and contamination information.

More GAMA goals:

  • Establish ambient groundwater quality on a basin wide scale.
  • Continue periodic groundwater sampling and groundwater quality studies in order to characterize chemicals of concern and identify trends in groundwater quality.
  • Centralize the availability of groundwater information to the public and decision makers to better protect our groundwater resources.

California's Groundwater

Over 36 million California residents get their water from a safe to drink public source, while nearly 2 million are served either by a private domestic well or smaller water systems (less than 15 service connections). Private domestic well owners are encouraged to test their well water quality regularly.

Nine out of ten public water systems rely on groundwater for at least a portion of their supply. Contaminated groundwater often results in treatment, well closures, or new well construction, which increases costs for consumers.

In 2012, California enacted the Human Right to Water law, AB 685 (Wat. Code §106.3). The public policy established the right of every human being to have safe, clean, affordable, and accessible water adequate for human consumption, cooking, and sanitary purposes.

California is very reliant on groundwater supplies. Having access to safe, clean water is critical to sustain society, the environment, business, industry, and agriculture. Comprehensively monitoring groundwater quality under the GAMA Program is an important part of managing our water resources.

For more information on public drinking water systems visit the Division of Drinking Water (DDW) Program website or contact a DDW Water District.

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State Water Resources Control Board
Division of Water Quality
Groundwater Ambient Monitoring & Assessment Program (GAMA)
1001 I Street, 15th Floor
Sacramento, CA 95814

Telephone: (916) 341-5577
Fax: (916) 341-5463


To support enhanced groundwater assessment by being a key portal for critical groundwater quality and quantity data and information statewide.


To provide data, information, and tools to enable the public and decision makers to better assess groundwater quality and quantity.