How groundwater banking today secures Sacramento’s water future | Opinion
For generations, Californians have relied on the Sierra snowpack as a critical part of our water supply — providing about a third of the water we depend on each year. Times are changing.
While California’s weather has always had its swings, the long-term reliability of that natural storage system is now at risk. Climate change is expected to significantly reduce the water historically supplied by snowpack, and this winter is demonstrating what that shift looks like.
In the Sacramento region, water agencies have a proven way to manage that kind of variability: the Sacramento Regional Water Bank. While the state may be drought-free for the first time in 25 years, the goal is to always be ready when the weather inevitably turns dry.
Like a savings account, a Water Bank makes it possible to deposit water during wet times and withdraw it during dry times. The Sacramento region’s Water Bank can hold enough water to fill Folsom Reservoir twice and can offset the loss of snowpack projected with climate change.
Recent storms brought significant rainfall to Northern California, filling reservoirs and saturating soils. At the same time, snowpack in the Northern Sierra remains below normal — just 61% of average — because many of those storms were warm and fell as rain instead of snow. The result is water that arrives earlier in the year, when it is harder to store for use later in the summer and fall.
That contrast matters. It highlights a growing reality for California: precipitation totals alone no longer tell the water supply story. Timing and form matter as much as volume.
Historically, snowpack served as the state’s largest water bank of sorts, accumulating gradually in winter and melting slowly through spring and summer. With warmer winter storms that will become more frequent, the runoff from will move quickly through rivers and reservoirs. That’s because dam operators cannot store this water because they must keep empty reservoir space available to protect downstream communities if storms intensify, meaning much of that water has no place to go but downstream.
This timing mismatch between when water arrives and when it’s needed is the core challenge California now faces. That’s where banking groundwater comes in.
How groundwater banking works
The basic concept is to maximize the use of water when Nature provides it. When surface water is available in rivers and reservoirs, for example, water providers use it instead of pumping nearby groundwater. Every gallon of surface water delivered to customers in place of groundwater leaves water stored beneath us. This approach, known in the industry as in-lieu recharge, is the backbone of groundwater banking in our region.
Over time, this approach has translated into real, measurable gains. Over the past 25 years, local water suppliers have recharged nearly 900,000 acre-feet of water underground. In 2024 alone, Sacramento-area water providers banked more than 35,000 acre-feet of water — nearly 11.5 billion gallons — by using surface water instead of groundwater whenever conditions allowed. That is enough water to supply more than 100,000 households for a year.
Across the region, water suppliers have built this capacity one project at a time, supported by more than $180 million in state grants, modernizing existing wells, adding specialized wells capable of pumping water into aquifers and improving connections between systems.
The benefits go beyond water supply reliability. By banking water underground, water suppliers reduce pressure on rivers during dry years — leaving more water in the lower American River when fish need it most, supporting cooler temperatures and healthier habitat.
Snowpack will continue to fluctuate. What must remain consistent is how California adapts. The answer is clear: the state must invest in systems that can capture water when it’s available so that it’s there when needed.
With proven projects, strong safeguards and transparent accounting, our region should be first in line for that investment. Groundwater banking is a proven, scalable strategy for managing water in a changing climate, and one that is already delivering real benefits today for the Sacramento region.
Jim Peifer is executive director of the Regional Water Authority, representing nearly two dozen water suppliers serving 2.2 million people in the Sacramento region.