Valley Water Collaborative

The Valley Water Collaborative (VWC) is a nonprofit organization that addresses groundwater quality issues, especially nitrate contamination across Central Valley basins. Since 2021, it has provided domestic well testing and replacement water to affected residents, expanding its work to the Delta-Mendota Subbasin in early 2025.

 

The Delta-Mendota Subbasin, managed by 23 GSAs under the Sustainable Groundwater Management Act (SGMA), operates under a single Groundwater Sustainability Plan (GSP) revised in 2024 and now overseen by the State Water Resources Control Board. To streamline efforts and avoid overlap, the GSAs and VWC have formalized a Memorandum of Understanding (MOU) focused on improving service delivery and ensuring safe drinking water access.

 

Key Provisions of the MOU

  • Coordinate groundwater monitoring, domestic well testing, and mitigation of dry wells.
  • Avoid duplication in data collection, monitoring, and public outreach.
  • Continue VWC’s well testing and replacement water services for wells exceeding contaminant standards.
  • Share data and collaborate on outreach related to the Domestic Well Mitigation Policy.
  • Jointly develop and share monitoring networks and results.
  • Consider future GSA financial contributions for VWC’s local services.

 

Within the Patterson city limits, there are approximately 28 domestic wells, primarily located in the Villages of Patterson and Zacharias annexation areas. These wells are covered by both the MOU and the Domestic Well Mitigation Policy until future infrastructure allows for city water connections. Public water supply wells are not included, as they are already monitored by the city. This MOU is independent of other VWC efforts under the CV-SALTS program, such as wastewater-related nitrate sampling.

 

Overall, the partnership enhances efficiency, coordination, and compliance, ensuring residents have reliable access to safe drinking water while reducing overlap in efforts. For more information on the other services the VWC provides, please visit their website https://valleywaterc.org/


VWC Memorandum of Understanding (MOU)