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Recent Storms Demonstrate Benefits of New Spillway for Groundwater Recharge

May 30, 2023

This year’s constant deluge of water after so many years of drought has many Californians asking what we are doing to capture water for later use. California’s future economic vitality depends on our ability to fully take advantage of wet years, as climate change is causing drought years to last longer and become more intense. While surface reservoirs are crucial to our water supply, opportunities to store water underground are just as important. In fact, for many communities around the state lucky enough to have an underground aquifer, with the right infrastructure, they represent a “drought piggy bank” that captures water in wet years for use during dry years.


In one community sitting below Mount Baldy, the Chino Groundwater Basin has been a crucial source of water for generations. The Chino Basin Water Conservation District, founded in 1949, completed a key piece of infrastructure in the fall of 2022, just in time to take advantage of this winter’s storms. A new concrete spillway for Montclair Basin #2, located along the San Antonio Creek Channel, will help capture up to 18 million gallons of additional stormwater runoff for future use.


The $1.05 million project in Montclair was unveiled by CBWCD Board members at a ribbon cutting ceremony on Jan. 19, following a series of major rainstorms. The new spillway allows CBWCD to raise the water level in Montclair Basin #1 by eight feet, which represents 18 million gallons of water.

The Montclair Spillway #2, shown at completion.

“This project is made for winters like this, when we are inundated by rain that we can then capture and store underground for dry times,” said Gil Aldaco, CBWCD Board Treasurer, at the Jan. 19 ribbon cutting ceremony. “Holding the water locally, rather than letting it flow out to the ocean, furthers our goal of preserving and protecting the Chino Groundwater Basin.”


The Chino Groundwater Basin is the tenth largest aquifer in Southern California and provides about half of the water supply for the area. CBWCD has spent decades investing in recharge basins to ensure that water can be put back into the aquifer. The area has a network of basins for both recharge and flood control, owned by CBWCD and San Bernardino County Flood Control District. The organizations work with the Chino Basin Watermaster and the Inland Empire Utilities Agency to maximize the effectiveness and efficiency of all the basins in the area to capture and store as much water as possible, which includes stormwater, recycled water, and imported water from Northern California.


The spillway project was completed in October 2022 with $300,000 in assistance from the American Rescue Plan Act (ARPA) funds, awarded to CBWCD by the County of San Bernardino.

The Montclair Basin Chain is full after a March 2023 storm.

“Our water supply is central to our ability to grow our community and our economy. During the drought, we have been reminded that it is crucial to capture every drop we can for our local supplies,” San Bernardino County Supervisor Curt Hagman said.


The spillway complements a planned inlet diversion project by Inland Empire Utilities Agency that will increase stormwater capture by an additional 96 acre-feet per year – enough to serve almost 200 families for a year. Together, the projects were funded by a $1 million grant from Metropolitan Water District of Southern California’s Stormwater for Recharge Pilot Program.

Read the full issue of California Water Magazine – Inland Empire edition for 2023.

Learn more about California Water Magazine.

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