From the State Water Resources Control Board:

The Groundwater Ambient Monitoring and Assessment (GAMA) Program includes several projects to meet the statutory requirements of Groundwater Quality Monitoring Act of 2001 and GAMA Program goals. As California’s most comprehensive and state-of-the-art groundwater research program, these projects inform citizens, community water systems, environmental groups, and state and federal agencies.

The Priority Basin Project provides a comprehensive statewide assessment of groundwater quality to help identify and understand the risks to groundwater. The project started assessing public system wells (deep groundwater resources) in 2002 and shifted focus to shallow aquifer assessments in 2012. Since 2002, the U.S Geological Survey (USGS), the project’s technical lead, has performed baseline and trend assessments and sampled over 3,000 public and domestic water supply wells that represent 95% of the groundwater resources in California. The program will be shifting to its third decadal phase (beginning around July 2024) by assessing the drivers of groundwater change, while continuing trends and shallow aquifer sampling on a reduced level, as well as publicly accessible online tools.

New publications

• Responses and explanatory factors to groundwater quality change during drought:
  • Levy, Z. F., Jurgens, B. C., Faulkner, K. E., Harkness, J. S., & Fram, M. S. (2024). Basin-scale responses of groundwater-resource quality to drought and recovery, San Joaquin Valley, California. Hydrological Processes, 38(4), e15131. https://doi.org/10.1002/hyp.15131
  • The accompanying data release:Levy, Z.F., 2024, Groundwater-Quality Time-Series Analyses and Potential Explanatory Factors of Drought-Response Patterns at Public-Supply Wells, San Joaquin Valley, California, 2000-2022: U.S. Geological Survey data release, https://doi.org/10.5066/P1QXC3YS.
• Groundwater Quality in the Southeast San Joaquin Valley:
  • Burow, K.R., Shelton, J.L., and Fram, M.S., 2024, Status of water quality in groundwater resources (assessment of domestic resource and comparison to public resource) used for drinking-water supply in the southeastern San Joaquin Valley, 2013–15—California GAMA Priority Basin Project: U.S. Geological Survey Scientific Investigations Report 2024–5009, 135 p., https://doi.org/10.3133/sir20245009.
  • Balkan, M., Burow, K.R., Shelton, J.L., and Fram, M.S., 2024, Data sets for: Status of Water Quality in Groundwater Resources Used for Drinking-Water Supply in the Southeastern San Joaquin Valley, 2013-2015 – California GAMA Priority Basin Project: U.S. Geological Survey data release, https://doi.org/10.5066/P9DCTLXV.
• Domestic supply assessment in the Mojave study unit:
  • Groover, K.D., Fram, M.S., and Levy, Z.F., 2024, Status and understanding of groundwater quality in the Mojave Basin Domestic-Supply Aquifer study unit, 2018—California GAMA Priority Basin Project: U.S. Geological Survey Scientific Investigations Report 2024–5019, 62 p., https://doi.org/10.3133/sir20245019.

Visit the State Water Board GAMA page.

Visit the USGS GAMA page.