Sonoma County, Calif., Experiments With Groundwater Banking

Groundwater banking, if successful, has the potential to store surface water during wet periods for extraction during dry months

Sonoma county experiments with groundwater banking

Sonoma County, Calif., has begun experimenting with groundwater banking to bulk up their rapidly depleting groundwater reserves. The Sonoma County Water Agency is pumping water from the Russian River into Sonoma Valley groundwater reserves with the goal of storing wintertime surface water for extraction during dry summers, according to Sonoma News. The project is currently in the testing phase and the agency is monitoring the quality of water extracted from the aquifer. 

The Petaluma Argus-Courier reports that groundwater levels in Sonoma Valley have dropped as much as 30 ft in the past 15 years and salt water intrusion from San Pablo Bay has impacted water quality. Additionally, California’s 515 groundwater basins have a combined storage capacity of 850 million to 1.3 billion acre-feet, while surface water storage from reservoirs is less than 50 million acre-feet, making groundwater storage a much more viable option for water storage during droughts.

“This groundwater banking method has the potential to benefit city residents,” Sonoma Mayor Madolyn Agrimonti said, “If this study works as anticipated, we could someday be using more plentiful wintertime Russian River water to improve the resiliency and reliability of our local water supply, ensuring that groundwater is available during droughts and emergencies.”

Thus far, the water agency has poured in 500,000 gal of Russian River water and raised the water level in a well drilled near the Sonoma Veterans Memorial Building parking lot by approximately 35 ft. In subsequent stages of the groundwater banking project, 1.5 million gal of water will be poured in the aquifer.

For the Sonoma County Water Agency, the next step is to monitor water quality and quantity to determine if incorporating river water alters the groundwater positively and is a sustainable solution.