Under the Sustainable Groundwater Management Act (SGMA), Groundwater Sustainability Agencies must evaluate their Groundwater Sustainability Plans (GSPs) every five years to assess progress toward achieving groundwater sustainability. The Vina Subbasin’s first GSP Periodic Evaluation will be submitted to the California Department of Water Resources (DWR) in January 2027.

This webpage provides information related to the Periodic Evaluation, including new data, studies, and projects completed since the adoption of the GSP (see Table 1 and links below). These updates help the GSA assess whether the current plan remains effective or whether adjustments to the basin description, sustainability criteria, or management approach may be needed.  This [Annotated Outline] document is based on DWR guidance and shows the required sections of the Periodic Evaluation with notes specific to the Vina Subbasin included.

The focus of this first Periodic Evaluation is to address the Department of Water Resources’ 6 Recommended Corrective Actions (from the 2023 Determination Letter) and provide a written assessment of GSP implementation. Once submitted, DWR will complete its Periodic Review of the Vina GSP and issue a determination of the status of the Plan: Approved, Incomplete, or Inadequate.

For those interested in more detail, additional supporting materials are available on the Periodic Evaluation Supporting Documents page.

Groundwater Dependent Ecosystem Technical Study

This technical study presents the results of a desktop analysis of groundwater dependent ecosystems (GDEs) in the Vina Subbasin. The study evaluates the relationship between groundwater levels and vegetation, refines the identification of likely GDEs, and helps improve understanding of how groundwater conditions may affect these important environmental resources.

The findings from this analysis will help inform updates to the Groundwater Sustainability Plan (GSP), including monitoring approaches, Sustainable Management Criteria, and future projects and management actions. This work supports the ongoing GSP Periodic Evaluation and planned amendments in response to recommendations from the California Department of Water Resources.

Public comment on this and other Sustainable Groundwater Management (SGM) grant-funded studies is welcome. Comments will be compiled and shared with the Stakeholder Advisory Committee (SHAC) and the GSA Board as part of ongoing GSP implementation, project development, and future grant applications.

Please submit written comments using the form linked below or by email to:
VinaGSApubliccomments@chicoca.gov

Comment Form

Vina_GSA_GDE_TM.pdf

 Strawman Proposals – for consideration and discussion

The following strawman proposals (i.e. a preliminary, rough draft intended to spark discussion and gather feedback) are provided to facilitate discussion and solicit public input on specific topics identified in the RCAs and Determination Letter.  Any input received will be incorporated into and inform materials prepared for consideration by the Stakeholder Advisory Committee (SHAC) and then brought forward to the GSA Boards for decision making.

Land Subsidence_Memo and Strawman Proposal_4.24.2026.pdf

 Table 1. Summary of New Information Since 2022 GSP Adoption

Joint GSP Evaluation - North Sacramento River Corridor TM.pdfInter-basin Flow Evaluation with Regional Model TM.pdfGroundwater Monitoring Network Enhancements TM.pdfButte County Evaluation of Monitoring Network Memo.pdf2025 Groundwater Quality Trend Monitoring TM.pdfButte Basin Groundwater Model Updates TM.pdfAEM-Based Evaluation of Vina Monitoring Wells (1).pdf