Subbasin Conditions


Groundwater conditions in the Solano Subbasin appear to be generally stable. Monitoring in the Subbasin shows short-term groundwater level fluctuations from spring to fall with rising levels occurring in response to groundwater recharge during the winter and lowering levels in the fall resulting from increased seasonal demands on groundwater during the summer. Longer-term trends in groundwater levels are also evident and occur in association with changing hydrologic conditions (i.e., wet and dry periods). Read answers to Frequently Asked Questions and Geology and Groundwater Resources for more information about Groundwater in the Solano Subbasin.


Agencies in the Subbasin have developed an extensive groundwater monitoring network to track groundwater conditions throughout the Subbasin. The Cities of Vacaville, Dixon, and Rio Vista, Rural North Vacaville Water District, Solano Irrigation District, California Department of Water Resources, U.S. Geological Survey, U.S. Bureau of Reclamation, and Solano County Water Agency monitor numerous wells across the Subbasin for groundwater levels and water quality.

Annual Report

The Annual Report provides an update on groundwater conditions in Solano County and the Solan Subbasin, with a summary of estimated water use and groundwater extractions in the Solano Subbasin in accordance with the SGMA requirements for GSP annual reporting. GSAs submit an Annual Report each April 1st. The Solano County and Subbasin Groundwater Sustainability Annual Report for the 2022 water year (October 1, 2021-September 30, 2022) was summited on April 1, 2023 to the Department of Water Resources.

View a snapshot of the Solano Subbasin water conditions in the 2022 The State of the Subbasin Infographic.


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Solano Groundwater Sustainability Agency

810 Vaca Valley Parkway, Vacaville, CA 95688

Tel: 707.451.6090 Fax: 707.451.6099