Aquifer Storage and Recovery In California: Current Projects and Issues

Managed aquifer recharge is becoming an increasingly important tool for providing water supply flexibility and sustainability in California, particularly under the threats of groundwater level decline, drought, and the potential for increasing variability in surface runoff due to global climate change.   Aquifer storage and recovery (ASR) can help address these problems, with the added benefits of facilitating recharge where shallow confining layers make surface recharge impractical, and allowing recovery of water from the same well used for injection.  ASR is a relatively young technology in California, although injection of drinking water to form a barrier against seawater intrusion has been occurring in southern California since the 1950s.  Several dozen ASR projects are currently active in the state, and many others have reached the planning and pilot testing stages over the past decade.  However, not all planned and piloted projects have become operational, despite recent drought conditions that favor use of ASR as a municipal water supply tool.  Technical constraints, such as well plugging, and regulatory issues, particularly related to injected water quality, must be resolved in order for a project to become fully functional.  Where these challenges are successfully addressed, ASR projects can serve as part of a local water management strategy to make water supply more flexible.  Several projects in various stages of development will be featured in this presentation and lessons learned are emphasized.