City Council Agenda Report Meeting Date: October 6, 2026 TO: City Council
FROM: Brendan Ottoboni, Director of Public Works – Engineering RE: Vina Groundwater Sustainability Agency
REPORT IN BRIEF:
City Staff and a representative of the Vina Groundwater Sustainability Agency (GSA) will provide a presentation on the status of the Groundwater Sustainability Plan Periodic Evaluation and Plan Amendments.
RECOMMENDATION:
Receive an informational presentation regarding the Vina Groundwater Sustainability Agency’s (GSA) draft Periodic Evaluation and amended Groundwater Sustainability Plan (GSP) and provide direction regarding potential City comments to the Vina GSA.
FISCAL IMPACT: Budgeted: (No) Supplemental Required: (No) The City of Chico is a Member Agency of the Vina Groundwater Sustainability Agency and contributes staff time, information, and facilities within available resources.
DISCUSSION:
BACKGROUND
The Vina Groundwater Sustainability Agency (GSA) adopted its Groundwater Sustainability Plan (GSP) in 2022 to guide sustainable groundwater management within the Vina Subbasin. The City of Chico is a member of the Vina GSA and participates on both the GSA Board and Management Committee. The GSP is required to be evaluated at least every five years through a Periodic Evaluation (PE). If significant changes are made to the GSP, an Amended GSP must be submitted with the PE
BENEFICIAL USES AND USERS IN CHICO
The City of Chico is located within the Vina Chico Management Area. Beneficial uses and users in the Vina Chico Management Area include municipal water supply, domestic wells, and environmental resources such as groundwaterdependent ecosystems.
Municipal Water Supply
Municipal water within Chico is supplied entirely from groundwater through Cal Water wells. For the Chico Management Area, the existing groundwater-level Minimum Threshold of 85 feet above mean sea level is retained for the municipal/domestic RMS network. Groundwater levels have remained above established Minimum Thresholds during GSP implementation.
Domestic Wells
Within the Chico Management Area, the amended GSP identifies 387 domestic wells, approximately 35 of which could be at risk if groundwater levels reach the Minimum Threshold of 85 feet above mean sea level. The Minimum Threshold was established considering domestic well depths and the protection of sustainably constructed wells. Groundwater
levels have remained above the Minimum Threshold during GSP implementation. Groundwater levels have remained above established Minimum Thresholds during GSP implementation.
Environmental Resources
A significant change in the amended GSP is expansion of the monitoring network for shallow groundwater and groundwater-dependent ecosystems (GDEs), specifically within the City of Chico to protect the urban forest.
As part of the amended GSP, two shallow monitoring wells within the Chico Management Area have been added as Representative Monitoring Sites (RMS). These RMS wells have a minimum threshold set 30-feet below ground surface which corresponds to the assumed rooting depth of Valley Oaks, which was determined in conjunction with the City’s Urban Forester.
POTENTIAL POINTS FOR CITY COMMENT
The expanded monitoring network, specifically within the City of Chico, represents an important step toward addressing a previously identified data gap. Because the Periodic Evaluation and GSP amendment establish the framework for groundwater management over the coming years, Council may also wish to provide comments identifying City interests that should continue to be considered as the GSA implements and refines the Plan.
At Council direction, comments to the Vina GSA could include the following:
• Identify and consider beneficial uses and users within the Chico Management Area that may be affected by groundwater conditions and implementation of the amended GSP. • Support the addition of two shallow Representative Monitoring Sites (RMS) in the Chico Management Area to improve monitoring of groundwater-dependent ecosystems, including Chico’s urban forest. • Support continued monitoring and evaluation of groundwater conditions affecting beneficial uses and users within the Chico Management Area; including municipal supply, domestic wells, Tribal and cultural interests, interconnected surface waters, and groundwater-dependent ecosystems. • Encourage evaluation of groundwater trends before Minimum Thresholds are reached, particularly where monitoring indicates potential impacts to beneficial uses and users, such as domestic wells, Valley Oaks and other groundwater-dependent ecosystems.
• Offer the City as a partner in monitoring groundwater-dependent ecosystems within the Chico Management Area, including opportunities to coordinate groundwater monitoring with observations of tree health, vegetation condition, and other indicators that may improve understanding of groundwater-dependent resources.
NEXT STEPS
The general public review period for the draft Periodic Evaluation and amended GSP closes October 26, 2026.
Comments received earlier in October can be incorporated into materials considered by the Stakeholder Advisory Committee and GSA Board as the documents move toward final consideration. The Joint GSA Boards are currently scheduled to consider final approval in December 2026, with submission to DWR anticipated in January 2027.