Solano Subbasin Groundwater Sustainability Plan
The Sustainable Groundwater Management Act (SGMA) established a robust framework for the sustainable management of groundwater resources in California.
Resources & Guides
Want to learn more about groundwater in the Solano Subbasin?
About Solano Collaborative
Welcome to the Solano Subbasin Groundwater Sustainability Plan
The Sustainable Groundwater Management Act (SGMA) established a robust framework for the sustainable management of groundwater resources in California. SGMA requires Groundwater Sustainability Agencies (GSAs) to develop, implement, and enforce a Groundwater Sustainability Plan (GSP) for groundwater basins or subbasins that are medium or high priority. The Solano Subbasin is a medium priority subbasin, subject to SGMA.
Projects
Subbasin Conditions
Projects
Solano Collaborative
Projects
Groundwater Sustainability
Lake Solano
About the Solano Collaborative
On January 18, 2024, the California Department of Water Resources (DWR) approved the Solano Subbasin Groundwater Sustainability Plan (GSP). Read DWR’s statement of findings regarding the approval of the Solano Subbasin GSP under SGMA.
The GSP provides a detailed roadmap for the Solano Subbasin to maintain long-term groundwater sustainability, and went into effect when it was submitted to DWR on January 31, 2022. Opportunities for comments, including a public meeting, were posted on the Solano Subbasin GSP website. The GSP was the product of significant collaboration amongst various water management entities in the Subbasin, including the five Groundwater Sustainability Agencies comprising the Solano Subbasin GSA Collaborative, who worked together to fulfill the requirements of SGMA.
Funding
Resources
GSA Board Meetings
Frequently Asked Questions
Are you going to put meters on wells?
At this early stage of SGMA implementation, we don’t know what tools will be used locally to monitor and ensure sustainable groundwater use. SGMA provides an array of regulatory and non-regulatory tools – mostly optional – from which Groundwater Sustainability Agencies (GSAs) can choose to achieve and monitor groundwater sustainability. The local GSAs will have to decide which tools they will use, and well metering could be one such tool. Because the GSAs are seeking to develop a single Groundwater Sustainability Plan (GSP), they will need to collect sufficient data on groundwater conditions in order to demonstrate progress toward achieving the sustainability goal and measurable objectives, but this doesn’t necessarily mean that all wells must be metered. SGMA requires that public stakeholders be engaged in the development and implementation of the Groundwater Sustainability Plan, which will allow additional opportunity for interested stakeholders to provide input on this issue.
Much of the groundwater delivered by local agencies is already metered, and other data sources (such as land use data) provide solid information to estimate groundwater use.
Do I have to share my private well data with the GSAs?
While the existing groundwater monitoring network is quite robust, there are some data gaps in some parts of the Solano Subbasin. It is likely that the Solano Collaborative may ask landowners to volunteer to have data collected at some wells to enhance our knowledge of groundwater conditions in the subbasin. This would likely not require any expenses on behalf of the landowner as the GSAs would use their equipment to monitor the groundwater levels in a landowner’s well.
Does state funding exist to help with SGMA and GSP planning and implementation?
The Solano Collaborative will be pursuing additional grant funds through the upcoming SGMA implementation funding cycle to support eligible Solano Subbasin GSP implementation costs. The GSA Collaborative will continue to evaluate and pursue other grant funding sources as they become available.
Can multiple GSAs create a single GSP for the subbasin?
Yes, multiple GSAs can work together to develop a single subbasin-wide GSP. Multiple GSAs could also develop multiple GSPs that cover the entire subbasin. If multiple GSPs are developed, GSAs must create a “coordination agreement” specifying their roles and responsibilities, and outlining procedures for the timely exchange of data and the resolution of conflicts. Each GSP must utilize the “same data and methodologies” to establish criteria for overall management of the entire subbasin. If multiple GSPs are prepared, the GSAs shall jointly submit the GSPs to DWR by January 31, 2022, explain how the GSPs when implemented together will satisfy all the GSP requirements, and provide the coordination agreement.
What is a GSP?
A Groundwater Sustainability Plan (GSP) is the state-mandated plan to sustainably manage groundwater. Each GSP will contain an assessment of each basin, measurable objectives that are specific, and quantifiable goals for the maintenance or improvement of specified groundwater conditions that have been included in an adopted Plan to achieve the sustainability goal for the basin. The GSP will also include any necessary monitoring, management, enforcement, and other requirements to achieve and/or maintain sustainability.
How do groundwater levels vary year to year?
Groundwater levels vary seasonally and based on location in the Solano Subbasin. Groundwater is generally closest to the land surface in the relatively shallow aquifer zones (including alluvial deposits and the upper zone of the Tehama Formation, see below for explanation of aquifer zones). Shallow aquifer zones are more often relied on by private residences, agriculture, and natural communities. Over the last 30 years, monitoring data show that average depths to groundwater in shallow aquifer zones in spring have been between 15 feet and 35 feet below ground surface. In the fall, average depths to ground water in shallow aquifer zones have been between 15 feet and 45 feet below ground surface. In some areas, such as near the Delta, groundwater is commonly less than 10 feet from the land surface. Deeper aquifer zones (including the middle and basal zones of the Tehama Formation) typically utilized by municipal water systems, have had average depths to groundwater of about 140 feet in spring and about 150 feet in the fall. Groundwater levels in the deeper aquifer zones are not observed to influence groundwater levels in shallow aquifer zones. Information regarding water levels can be viewed on DWR’s Groundwater Monitoring website and at the Solano County Water Agency.