A modest bump in the allocation of water being released from Northern California will make billions of additional gallons available to Southern California water agencies, according to state and local experts. The extra amount may help serve as drought insurance for years ahead, water managers say.
The state Department of Water Resources announced on Tuesday, Jan. 28 it has raised the allotment of requested supplies delivered by the State Water Project from 15% to 20%, which amounts to a total allocation of about 526,709 acre-feet for Southern California water agencies for 2025, or just under 172 billion gallons of water.
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Of that amount, Metropolitan Water District of Southern California, the largest wholesaler of water in the state, is scheduled to receive 382,300 acre-feet, the most of any agency, the DWR reported. Previously, under the 15% allocation set in December, MWD was to receive 286,725 acre-feet, meaning MWD’s allocation jumped by about 96,000 acre-feet or about 31 billion gallons.
One-acre foot equals 325,851 gallons and is enough to supply three families in Southern California for a year. The State Water Project provides water to 29 public water agencies, serving 27 million Californians.
“It is very good news,” said Bob DiPrimio, president of the San Gabriel Valley Water Co., which serves 290,000 people in 16 cities. “It is a good sign.”
While drought conditions persist in Southern California despite the past weekend’s rain and snow storms, storms in late November and December in Northern California — a major source of local water supplies — produced runoff that topped off reservoirs already nearing or above historic levels, according to state water resources agencies and water contractors.
The raising of the allocation was the result of assessing the positive effects of more rain and snow that fell in Northern California, a typical evaluation done yearly by state water agencies. While President Trump said turning a valve will bring more water into Southern California for fighting fires, water experts said there is no “valve” that moves water from the Pacific Northwest into California.
Also, there is no shortage of water in Southern California. As of Friday, all of the major reservoirs in SoCal were above their historic average levels, with the largest, Diamond Valley, 97% full. Also, almost all key Northern California reservoirs feeding the SWP are at levels exceeding historic averages.
“This has been debunked over and over again in the past two weeks,” said Peter Gleick, president emeritus of the Pacific Institute, a non-profit water research center based in Oakland, last week. “There is zero connection between firefighting water needs and California’s water policy.”
As of Jan. 29, the following key reservoirs that provide water to the State Water Project — also known as the California Aqueduct, which channels water about 700 miles to Southern California — were filled above historic to-date averages: Shasta, 118%; Oroville, 126%; Trinity, 123%; San Luis, 102%.
In Southern California, reservoirs are also at or above levels expected at this time of year: Castaic Lake, 98% and Diamond Valley near Hemet, 133%.
The recent wetter weather in Southern California has helped firefighters bring the Eaton and Palisades fires that have caused the destruction of thousands of homes just about to full containment, with only mop up of hot spots continuing, according to Cal Fire.
While Southern California has returned to dry conditions, the DWR said more storms are needed to send more Northern California water to the south. And the long-range forecast hints at wet conditions returning in early February in the state.
“We are in the middle of our biggest months for precipitation for California, and unfortunately January has been very dry, putting a significant dent in our season,” said DWR Director Karla Nemeth. “A return to wet weather is critical for our season’s success and it will take many more storms to make up the deficit and further boost water supply deliveries.”
About 27 state water contractors buy water from the SWP, and they are located in Northern, Central and Southern California. They are cautiously optimistic that more storms, particularly in the Sierra Nevada, will result in more water flowing down the state aqueduct.
“We are hopeful that incoming storms will allow for additional allocation increases this season. With each adjustment, our members get more of the water supplies they need to serve the homes, businesses, and farms of a combined 27 million Californians,” said Jennifer Pierre, general manager of the state water contractors, in a statement released on Wednesday, Jan. 29.
Shivaji Deshmukh, general manager of the Chino-based Inland Empire Utilities Agency, called the development “promising,” but said challenges remain. “However, we need to stay mindful that our region has a semi-arid climate and water supply can drastically be affected by such climate characteristics,” he said in an emailed response.
Three Valleys Municipal Water District is a wholesale water agency that delivers mostly imported water from the SWP to half a million people via retail water companies serving Glendora, San Dimas, Pomona, Claremont, Diamond Bar, Rowland Heights, La Verne and parts of Covina.
It buys Northern California water from Metropolitan’s Weymouth Treatment Plant in La Verne, where the water is treated. It also treats SWP water at its Miramar Treatment Plant in Claremont.
“At a 20% allocation, we are not going to have any cuts by any means,” said Matt Litchfield, Three Valleys general manager. “Metropolitan has enough water to meet our needs.”
Another factor besides filling above-ground reservoirs with SWP water is local well water. In Southern California, vast underground aquifers are tapped by wells, which draw up water served to households.
DiPrimio’s agency, for example, relies on wells sunk into the Main San Gabriel Basin, a very large aquifer that he calls an underground, invisible reservoir, which holds 9 million acre-feet of water.
The rains of the last two California winters has produced a considerable supply of water, both locally and from Northern California and the Colorado River Basin, which was used to pour into spreading grounds that allow for seepage into the aquifer for storage.
“The Main San Gabriel Basin is a huge underground reservoir and it is in the best shape it has been in the last 10 years,” he said. The key well, used to measure the underground water level, has been at the highest level in 10 years, he added.
Local rain and snowmelt from last weekend may not reach these spreading grounds because the watershed was so dry the soil sucked up most of the moisture. But the next rainfall and spring snowmelt may be primed to reach groundwater storage sites, he said. “This will add to the local water supplies, eventually,” he added.
But when it comes to Southern California water managers, their eyes are on the weather forecast in Northern California. Litchfield said meteorologists predict “a significant storm” that could bring more snow to the Sierra Nevada, which turns into runoff down the 700-mile conduit.
“Then we will see a better allocation of say, 25%,” he said, adding the caveat: “But you never know.”
Paul Rogers of the Bay Area News Group contributed to this article.