Groundwater Sustainability Priority Areas

Groundwater Sustainability Priority Areas (GSPAs) are locations where groundwater levels in deep wells (deeper than 200 feet) have been declining for more than a decade. Currently, the Sonoma Valley Basin has two priority areas:

1. El Verano Priority Area: An oval area centered in El Verano, from approximately Boyes Blvd to Leveroni Road

2. Eastside Priority Area: A diamond shaped area centered around the intersection of Napa Rd. and 8th St. East, from approximately Highway 121

The priority designation allows for more careful review of new wells and provides an opportunity to carry out grant-funded projects, programs and policies that will help us to better measure, monitor, and reduce groundwater use.

Take a closer look at the priority areas on our Data Dashboard! Turn on the Groundwater Sustainability Priority Areas layer to view.

Mapping

GSA technical staff have mapped the priority areas based on:

1. Geologic conditions (Subbasin boundaries and Eastside Fault)
2. Spatial distribution of wells exhibiting measured chronic groundwater-level declines
3. Locations of representative monitoring points with existing or projected minimum threshold exceedances
4. Locations of reported dry wells and dry-well susceptibility analysis
5. Spatial distribution of estimated groundwater use.

Potential Future Solutions

Based on ongoing groundwater decline in the priority areas, it is clear that focused efforts are needed to reverse the trend. The GSA is evaluating the potential costs and benefits of the following projects, policies and programs to ensure that limited resources are effectively used:

• Extending recycled water pipelines
• Installing meters on wells
• Expanding water conservation programs
• Aquifer Storage and Recovery (ASR) projects
• Other projects to enhance recharge by capturing wintertime surface water supplies to help replenish the groundwater system

The GSA is also considering innovative options for limiting or mitigating permitting of new groundwater uses within the Priority Areas. Potential future programs include:

• Mandatory metering
• Well permitting changes
• Developing a groundwater trading system to allow low-use water users to virtually ‘share’ their groundwater with higher-use neighbors.