Think back to those torrential rains that hit Southern California in December, and on Jan. 1 when storms drenched pancho-wearing Rose Parade marchers, float riders and umbrella-hoisting onlookers in Pasadena.
To water supply managers in Los Angeles County, rain is not an inconvenience. It is a windfall.
Since local rain accounts for 40% of the region’s drinking water supply, folks from Los Angeles County Public Works were busy making sure it got captured and sunk into reservoirs and groundwater basins as non-rainy day storage. As the storm season ended, they tallied up their wins:
L.A. County captured a whopping 120.3 billion gallons of stormwater for the 2025-2026 storm season that ran from early October through April 15. The rain-gain was oceans more than last year’s total of just 11.9 billion gallons, the county announced earlier this week.
In fact, it’s enough captured stormwater to meet the needs of 3 million people for a year.
“That is great. It is incredibly impressive,” said Bruce Reznik, the executive director of L.A. Waterkeeper, a nonprofit that advocates for stormwater capture, water resilience and protection of local waterways. “It speaks to what the county has been doing for decades to capture water.”
Of course, Mother Nature deserves a lot of credit.
“This season’s rainfall translated into a significant increase in stormwater capture, which reflects the performance of the county’s flood control infrastructure, as well as our coordinated stormwater management efforts,” said Mark Pestrella, director of L.A. County Public Works.
While the system of 14 major dams and 27 gravely, porous spreading grounds across the county is the human side of the equation, they aren’t going to help anyone unless there’s wet stuff falling from the sky.
And in the 2025-2026 storm season, downtown Los Angeles recorded 16.9 inches of rainfall, about 110% of its annual average. If you look at the previous storm season, that had only brought 6.6 inches of rain, or less than half the annual average of 15.4 inches.
Stormwater captured in dams, reservoirs and spreading grounds figured out to be an amazing 185% of average for this time of year, the county reported.
“This season brought a significant increase compared to last year, showing the system is working as intended,” wrote Elizabeth Vazquez, spokesperson for Public Works in an emailed response.
These eye-popping numbers did not escape county Third District Supervisor Lindsey Horvath, who in November led the way for passage of the OurCounty Sustainability Plan. For an Earth Week moment, sustainability and environmental success came together.
“Capturing more stormwater here in Los Angeles County is one of the most powerful opportunities we have right now to strengthen our local water supply,” she said. “Every gallon we capture reduces our reliance on imported water, protects affordability of future supply and helps build more resilient communities as we adapt to our changing climate.”
Reznik agreed. However, he said more needs to be done to become water independent for 10 million county residents. That’s because about 60% of the county’s yearly water supply is purchased or imported water from the Colorado River Basin and from the snowmelt in the Sierra Nevada.
Imported water is more costly. And local water supplies, properly stored in local reservoirs and in vast underground reservoirs called aquifers, cost less. Local water is also more reliable, even though predicting rain in the Mediterranean climate of Southern California is about as easy as choosing a winning Super Lotto number.
While averages are mathematically calculated, the rainfall totals run from near zero to up to 20 or more inches a year. That drives pocket-protector wearing water engineers a little crazy, because steady outcomes are what these men and women live for. There’s nothing normal about Southern California’s storm season. Retired Caltech/JPL climatologist Bill Patzert used to say “normal” is only a button on a washing machine.
When climate change is added to the “normal” fluctuations in the rainy seasons, that makes collecting local water more important, said Reznik.
That’s because the Sierra snowpack is all but gone this year due to a fast melt during a hotter March, he said. So the water folks celebrated a year of more local water, but less water available that can be piped from Northern California.
“The great news is there, but there is a potential for a lot more,” he said.
Reznik said while the San Gabriel River system and adjacent spreading grounds, stretching from Irwindale to Long Beach, work exceptionally well, capturing 90% of the local runoff that percolates into underground basins for later use, that’s not true of some other waterways in the county.
“The L.A. River is exactly the opposite,” Reznik said. “About 85% to 90% of that water runs off to the ocean.”
He’d like to see more stormwater capture in the L.A. River. “There is a lot of untapped potential for stormwater capture in the San Fernando Valley,” he said.
The county totals include stormwater captured and spread into existing San Fernando Valley areas, including: Pacoima Spreading Grounds, Hansen Spreading Grounds in Lake View Terrace and Lopez Spreading Grounds in Sylmar. Water spread here soaks into the San Fernando Valley aquifer.
To increase local storage, Reznik wants to see more smaller and mid-size projects in the San Fernando Valley and South LA, such as removing hardscape like blacktop from schools and parks and creating more green space. This will allow rain to soak down into the aquifers, instead of running off into storm drains and into the ocean.
Replacing residential front lawns with native grasses and soils is another way of increasing more stormwater capture, he suggested.
“You almost want to create a city of sponges,” he said.
On the larger scale, old quarries in the area of the Upper L.A. River can be converted into spreading grounds. “We should do a mix of size of projects,” he said.
With all the rain this past storm season, should Angelenos sit back and do nothing?
“We will always need to conserve water. While this was a good year, we may move back to dry years,” Reznik said.