Groundwater Monitoring San Mateo Plain Basin

The County of San Mateo Sustainability Department administers groundwater monitoring in the San Mateo Plain Subbasin (Basin) of San Mateo County. Following completion of the San Mateo Plain Groundwater Basin Assessment in 2018, the Basin has been under continuous groundwater monitoring and is sampled biannually with data uploaded to the California Statewide Groundwater Elevation Monitoring (CASGEM) online system. The California Department of Water Resources (DWR) has approved the County's CASGEM Monitoring Report, and the Basin has maintained a Very Low Priority status through continued sampling and reporting. The CASGEM Program, created by the DWR under SBx7-6, establishes a permanent, locally managed system for tracking groundwater elevations. Local agencies can volunteer to be “Monitoring Entities,” responsible for overseeing groundwater monitoring in their basins. If local agencies do not assume this role, DWR will default to managing it, potentially affecting the eligibility for certain state funding. The goal of this project is to maintain the Very Low Priority status through continued biannual sampling and reporting, which is crucial for regulatory compliance and securing funding.