One mechanism to potentially address seawater intrusion to inject fresh water into the aquifers on the landward side of the intrusion to raise groundwater elevations and help reduce or push back the intrusion. SVBGSA has evaluated this approach in a Preliminary Feasibility Study of Aquifer Storage and Recovery (ASR) Project Concepts to Address Seawater Intrusion (January 2025). The ASR report can be found here.
This study evaluates a project concept in the 180/400-Ft Aquifer Subbasin and Monterey Subbasin Groundwater Sustainability Plans, referred to as the Seasonal Release with ASR project concept. The study resulted in a new project concept, referred to as the New Diversion of Winter High Flows for ASR project concept, Alternatives 1 and 1A.
These ASR project concepts aim to address seawater intrusion while maintaining water supply needs in the Castroville Seawater Intrusion Project delivery area by:
- Increasing surface water diversions for recharge during the wet season
- Injecting diverted surface water inland of the seawater intruded area to raise groundwater elevations
- In the Seasonal Release with ASR project concept, partially recovering injected water during the growing season to augment CSIP supplies and reduce pumping of native groundwater
The study includes a summary report with key findings and 4 technical memoranda. The first considers physical and operational constraints to implementing an ASR project with existing facilities and operations of the Nacimiento and San Antonio Reservoirs, Salinas River Diversion Facility, and CSIP, and identifies new infrastructure that would be needed (TM-1). Permitting and regulatory requirements are identified, including those related to water rights (TM-2). Available water quality data are summarized, and a sampling plan for further analysis of treatment requirements is recommended (TM-3). Lastly, the results of groundwater flow modeling are provided (TM-4).
This study has been closely coordinated with the Monterey County Water Resources Agency.