Aquifer Storage & Recovery (ASR) Pilot Program
Storing Water for a Drier Future: The City of Petaluma ASR Pilot Project
Most of the City of Petaluma's water comes directly from the Russian River. Each winter, excess water flows from the Russian Rivers and reservoirs to the ocean. What if we could save some of that clean water underground, for use during dry months and drought emergencies? That’s exactly what Petaluma’s Aquifer Storage and Recovery (ASR) Pilot Project is designed to explore.
What Is ASR?
Aquifer Storage and Recovery (ASR) is an innovative and cost effective water management strategy that stores treated drinking water in underground aquifers during wet years, then recovers it for use when water is scarce. It improves supply reliability, reduces pressure on other water sources, and supports long-term groundwater sustainability, all while using existing infrastructure.
About the Petaluma Pilot
Petaluma’s Aquifer Storage and Recovery (ASR) Pilot Project at the Del Oro Well is designed to test whether storing treated drinking water underground can be a safe and effective strategy in our local groundwater basin. The project involves injecting treated potable water into a deep aquifer and then recovering that water for use. This approach allows us to store water when it is available and use it when it is needed most.
The pilot will include multiple recharge and recovery cycles. During a recharge cycle, a set volume of high quality drinking water from Sonoma Water will be injected into the Del Oro Well over the course of several days. After a period of rest, the water will be pumped back out through the same well to simulate recovery during drought or high demand conditions. Staff will evaluate how much water can be successfully recovered, how quickly it can be extracted, and whether there are any changes in water quality throughout the cycle.
To support data collection, two monitoring wells will be installed next to Del Oro Park. A deep monitoring well will track aquifer behavior and water quality changes at depth, while a shallow well will monitor for any interaction between the aquifer and nearby Adobe Creek.
The results of the pilot will help assess whether ASR is a viable long term water supply solution for Petaluma and will inform future planning and coordination across the region.
Project Timeline
- March–June 2025: Regulatory permit review and approval
- June 2025: Monitoring wells installed
- August 2025: ASR pilot begins with first recharge cycle
- August–November 2025: Groundwater and water quality monitoring
- December 2025–January 2026: Data analysis and final reporting
Regional Collaboration
This project is part of a coordinated regional effort exploring the potential for ASR across Sonoma County. Petaluma is working alongside neighboring agencies as well as the Petaluma Valley Groundwater Sustainability Agency to share technical approaches, compare data, and align public communication as more pilot activities take shape across the region.
