New operating rules for massive Delta systems will increase water deliveries to Southern California cities and some growers. Salmon numbers could drop, especially in dry years.
By Alastair Bland, Cal Matters
State and federal water officials announced today their long-awaited new rules for operating two massive water delivery systems that serve 30 million Californians and much of the state’s farmland.
The rules will oversee operations of the State Water Project and the federal Central Valley Project, which carry water from Northern California rivers south to San Joaquin Valley farmers, Los Angeles area residents and many other water users in the southern half of the state.
Deliveries will increase for major urban water suppliers and many farms, while they’ll be cut for some farmers. Schedules for releasing water from Lake Shasta, the state’s largest reservoir, will be revised.
Chuck Bonham, director of the California Department of Fish and Wildlife, said the new rules represent the best path forward for the competing interests of cities, farms and fish. “It’s good for both people and the environment,” he said. “It’s the expression of what people want from us.”
The regulations, which take effect immediately, replace a set last modified in 2019 through a contentious revision by the first Trump administration, which state officials protested because it was expected to harm salmon and other Delta fish.
But environmental groups say the rules from the Biden and Newsom administrations are even worse than the Trump policy in terms of protecting the state’s iconic Chinook salmon, endangered Delta smelt and other fish.
A federal environmental review last month concluded that some salmon, which already are in dire shape, would be harmed by the new operating plan, with numbers of young salmon expected to drop.
“I’m concerned that the alternative adopted today will adversely harm fish that are already in danger of extinction,” said Ashley Overhouse, water policy advisor at Defenders of Wildlife.
Many farm groups and urban water districts applauded the new path forward, commending it as the best of several alternatives analyzed by state and federal officials for maintaining water supplies while protecting the environment.
For a consortium of water suppliers representing 27 million people in much of California, stretching from the Bay Area to San Diego, and 750,000 acres of farmland, the new plan is particularly beneficial. The rules will slightly increase their average annual deliveries of Delta water and, in drought years, cause no significant change. That includes the giant Metropolitan Water District, which provides much of the water used by 19 million Southern Californians in six counties.
But for some San Joaquin Valley farmers, water deliveries could drop by almost 20% in dry years, with slighter cuts in wetter years. Still, they have voiced their support for what they consider a plan that is overall protective of water supply.
The new plan comes as a disappointment for the Westlands Water District, the nation’s largest agricultural water supplier, which provides water for crops in Fresno and Kings counties. Growers there will lose some of their water, which district officials said has a disproportionate impact on their region.
“This inequity alone provides ample justification for” rejecting the new rules, the Westlands district wrote in a public comment last month. “It overlooks broader economic ripple effects, particularly on businesses dependent on agricultural workers.”
The federal and state agencies rejected another alternative, drafted with environmental groups, that would have sharply cut water exports. Average river flows through the Delta and into the ocean would have increased, improving river conditions and increasing fish populations, according to modeling by the Bureau of Reclamation.
No one knows what President-elect Donald Trump will do about the Delta rules when he enters the White House, but he has complained frequently about California “wasting water” by sending it into rivers and the ocean for fish.
In September, while campaigning in Southern California, Trump said he would turn on a giant “faucet” and promised Californians “more water than you ever saw and the smelt is not making it anyway…All those fields that are right now barren, the farmers would have all the water they needed.”
The two massive Central Valley water systems — operated by the California Department of Water Resources and the U.S. Bureau of Reclamation — have long formed the nexus of disagreements between water supply advocates and environmentalists, who fault them for devastating the region’s ecosystem.
According to an analysis released by the Bureau of Reclamation in November, the new rules will harm several protected species of fish. More cold water will be kept in Lake Shasta and released in the summer and fall as salmon spawn, resulting in more fish being born. But it fails the fish in subsequent life stages, ultimately leading to fewer juveniles, according to the federal agency’s report.
In critically dry years, winter-run Chinook could produce 23% fewer juveniles than baseline conditions — which are already tipping the fish toward extinction. Even in wet years, the modeling shows, winter-run juvenile salmon numbers will decline.
But while some fish would be harmed, two federal agencies responsible for protecting the species said the new operating rules are “not likely to jeopardize (their) continued existence.” If the agencies had found “jeopardy” of extinction, it would have triggered a protracted and complex federal process under the Endangered Species Act.
The new rules do not end the decades-long wars over Delta management or determine its entire fate. While they specifically cover operation of the two water delivery systems, they are just one part of the state’s broader Bay-Delta Water Quality Control Plan, an overarching state regulation now undergoing a separate, controversial update process.
Sometime in the next year, the state water board will vote on a new water-quality plan that would either impose rules that dramatically increase minimum flow requirements through the Delta or adopt a set of so-called voluntary agreements that commit water users to restoring stream habitat for salmon and other fish.
Also posted today …
- Reclamation greenlights action plan for the long-term operation of the Central Valley Project and State Water Project. press release from the Bureau of Reclamation
- New federal actions will help California better manage water supply, press release from Governor Newsom
More coverage of biological opinions …

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