Groundwater levels monitored around Chico and Durham have declined 18 to 35 feet over the past two decades. A Vina Groundwater Sustainability Agency evaluation examines groundwater risks in the region. The agency's domestic-well inventory remains a data gap, and its goal is to develop an inventory of active wells.
A May 2025 Vina GSA memo cites DWR well-completion records showing 2,300 wells drilled before 1980 and 1,900 afterward, 4,200 total. DWR requested an analysis of domestic wells that could be impacted at minimum-threshold levels.
Groundwater Objectives and Minimum Thresholds
At Vina, measurable objectives are management goals, while minimum thresholds are lower regulatory limits associated with potentially significant and unreasonable impacts, according to ChicoSol News. The Vina Subbasin is around Chico and Durham in northern Butte County.
Under the plan, a two-consecutive-non-dry-year criterion factors into the response when groundwater falls below minimum thresholds. ChicoSol says groundwater levels have declined overall since 2000, with drought-related low levels.
Advocates Push for Five Specific Changes
The community coalition Groundwater for Butte, which formed in 2023 during pushback against a proposed landowner-voted Tuscan Water District, has requested five changes to the draft plan. The group wants the GSA to raise minimum thresholds, strengthen measurable objectives to protect wells and ecosystems, and remove the two-year and non-dry-year provisions so that declines trigger earlier action rather than more monitoring.
The coalition also wants pre-1980 residential wells and shallow agricultural wells included in vulnerability assessments and mitigation programs, arguing that active wells should not be excluded from protection simply because of their age. Groundwater for Butte has called for cost-effective solutions that reduce groundwater demand while still supporting local agriculture and community benefits, according to Action News Now's reporting on the group's position.
State Oversight and Plan Review
DWR provided recommended corrective actions, including requests for analysis of minimum-threshold impacts and domestic wells. The current periodic evaluation examines domestic-well risks and minimum thresholds.
A May 2025 consultant memorandum from Larry Walker Associates says the Vina Groundwater Sustainability Agency received a DWR Sustainable Groundwater Management Round 2 grant to address data gaps and complete the evaluation.
A December 10 meeting is scheduled to discuss feedback on the evaluation. Residents relying on older wells can weigh in during the review process.
