Well Mitigation Policy
The Delta-Mendota Subbasin GSAs developed a Domestic Well Mitigation Policy to protect disadvantaged communities and ensure access to safe drinking water in compliance with the Sustainable Groundwater Management Act (SGMA). The Policy builds on state and nonprofit guidance and provides a coordinated, transparent process for addressing domestic wells that may fail or experience degraded water quality due to groundwater management actions under the Groundwater Sustainability Plan (GSP).
Since adopting the GSP in 2020, groundwater levels have remained above the 2015 minimum thresholds. The Policy serves as a safeguard if future declines occur. Between 2015 and 2024, only 37 well replacement applications were recorded across the 1,200-square-mile Subbasin.
Key Features of the Policy
- Eligibility: Applies to domestic wells and small water systems (≤14 connections) in use as of November 19, 2024. In Patterson, this applies only to wells within city limits (about 28 private wells).
- Notification & Outreach: Well owners within three miles of a monitoring well dropping below minimum thresholds will be notified and informed about mitigation options.
- Mitigation Measures: Eligible owners will receive emergency water (within 24–72 hours) while the GSA investigates the cause. If groundwater management causes water quality issues (e.g., nitrate, arsenic, or TDS exceedances), mitigation could include bottled water, reverse osmosis systems, or new connections.
- Coordination & Oversight: Disputes will be handled through the Adaptive Management Framework under the Subbasin MOA. The Coordination Committee will review implementation quarterly and reevaluate the Policy every five years.
- Funding: A $300,000 reserve fund will be jointly financed by seven GSAs over three years (about $4,300 annually per GSA) to support up to ten domestic well mitigations per year. Each GSA covers additional local costs for investigations or mitigation within its area.
The Policy poses minimal fiscal impact on the City of Patterson, limited to its contribution to the shared $300,000 reserve and any site-specific mitigation costs within its boundaries. Predictive modeling estimates fewer than three wells per year will require mitigation through 2040, demonstrating that the Policy provides sufficient preparedness while minimizing financial risk.