Groundwater Ambient Monitoring & Assessment (GAMA)


What is GAMA?

The Groundwater Ambient Monitoring and Assessment Program (GAMA) is a statewide, comprehensive assessment of groundwater quality designed to help better understand and identify risks to groundwater resources. GAMA is being implemented by the State Water Board.

The USGS is the technical lead for the Priority Basin Project (PBP), one of components of the GAMA Program. The USGS is sampling groundwater at many locations across California in order to characterize its constituents and identify trends in groundwater quality. The results of these tests will provide information for water agencies to address a variety of issues ranging in scale from local-water supply to statewide resource management.

Well Owners Needed!

We're looking for domestic well owners to participate in our groundwater sampling study.

  • Free and extensive information on well water quality
  • USGS data can be used to meet state, county, and local sampling requirements

USGS staff member collecting groundwater samples from a domestic well near Stockton, CA.

The Groundwater Ambient Monitoring & Assessment Priority Basin Project (GAMA-PBP) is conducting water-quality assessments of shallow aquifers, the groundwater resources typically used for private domestic and small system drinking-water supplies. We need wells to sample, and volunteer well owners who participate in the study will receive a free chemical analysis of their well water.


See if we have a study near you!

What to Expect as a Participant

Where does GAMA go?

California was divided into Provinces, Study Units, and Study Areas in order to assess groundwater quality.

Click on one of the Provinces in the map to obtain more information.

Select a Province to navigate to study unit. San Diego Transverse and Selected Peninsular Range Klamath Mountains Modoc Plateau and Cascades Northern Coast Ranges Central Valley Sierra Nevada Southern Coast Ranges Basin and Range Desert

Water Quality Results

Explore and download groundwater-quality results with the new webmap!

Screen shot of the groundwater quality results mapper

This interactive webmap plots water-quality data from domestic and public-supply wells sampled by the USGS for the California GAMA Priority Basin Project, and allows users to download datasets.

Go to the Webmap