California may lose 10% of its water supply but a solution ‘is right under our feet.’ | Opinion

California’s rivers are once again surging with winter runoff, a beautiful sight after several consecutive dry years. Sacramento-area water providers have been working together to capture as much of excess water as possible for use during drier days. Yet, we could be doing so much more with additional support from state and federal decision-makers.

Additional water storage is right in front of our eyes — or, more specifically, right under our feet.

The City of Roseville, for example, captured surplus flows from Folsom Reservoir and stored this water in the groundwater aquifer using specialized Aquifer Storage and Recovery wells. Just a year ago, Roseville stored enough water to fill 160 Olympic-sized pools. Later, in 2022, we delivered that water to customers, leaving water in Folsom Reservoir to benefit our environment.


Other water providers stored water underground through a strategic yet more indirect route that maximizes how our natural infrastructure already works. The Sacramento Suburban Water District operates the region’s largest network of groundwater wells — 70 in total — but does not have its own right to access river water. This winter, the district temporarily delivered treated river water to customers via our partnership with the City of Sacramento, which has surface water rights. The City of Sacramento also shut down some of its groundwater wells and delivered more river water to its customers. This allowed our groundwater aquifer to recharge, resulting in banked water for future use.

All of this is part of what we call the Sacramento Regional Water Bank, our system of underground water reserves that we pump and refill over and over again to serve capital-area water users. The aquifers underlying the Sacramento region have enough capacity to store twice the volume of water as Folsom Reservoir.

Thanks to steady investments over several decades, we can reliably withdraw and refill 60,000 acre-feet of groundwater every year, irrespective of extremes in conditions — enough to meet the drinking water needs of 180,000 families for a year.

Local water providers are working to expand water banking as we face the ever-familiar impacts of climate change, resulting in rain and snowfall falling earlier in the winter in more explosive bursts. This creates a Catch 22 for our water system: the need to release water from Folsom Reservoir to protect our community from flood rather than storing water for the dry days ahead.

Led by the Regional Water Authority, we have embarked on a process to engage the public in how a larger-scale water bank could operate in the Sacramento region. We are continuing to pursue state and federal funding to offset ratepayer costs and estimate the Water Bank can increase its present deliveries to 90,000 acre-feet — enough to serve 270,000 households annually. This will require another $300 million investment to build more wells, pumps and plumbing.

State and federal decision-makers must make groundwater recharge a priority.

According to Gov. Gavin Newsom’s Water Supply Strategy, hotter and drier weather conditions spurred by climate change could reduce California’s water supply by up to 10% by 2040. Groundwater recharge is the only solution that can meet the scale of this loss, and it’s the lowest-cost option per acre-foot.

The California Department of Water Resources estimates the potential for recharge at 13 million acre-feet each year — double the total amount of water currently used by urban California. Stanford University has put the cost of recharge at less than the cost of conservation, typically thought of as the cheapest water reliability option.

The California legislature should set statewide targets for increasing below-ground water storage. State Sen. Angelique Ashby, representing Sacramento and Elk Grove, has introduced Senate Bill 659, which would make it a state policy to achieve 10 million acre-feet of groundwater recharge annually.

The boom-and-bust cycle of weather we’ve been living with will occur more often with climate change. State and federal support is critical to creating a 21st-century water system to capture the storms when they roll through to create a brighter water future for every Californian.

Sean Bigley is assistant environmental utilities director for the City of Roseville. Dan York is general manager of the Sacramento Suburban Water District.