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Boats are seen in Shasta Lake as the shoreline is exposed by low water levels on Aug. 26, 2022.

A boat pilots across Shasta Lake, which has dipped to below-average levels after three years of drought, as seen on Aug. 26, 2022.

California cities and farms should brace for little or no water from the state’s big reservoirs in the coming year, a prospect that signals more water restrictions for households and more fallowed fields in the farm belt.

The warning was delivered Monday by state and federal water officials who said they are preparing for the possibility of a fourth year of drought. Both are considering, at least initially, reduced allocations for the many water agencies that contract for reservoir supplies from California’s sprawling water projects.

The past three years, as tracked between October and September, marked the driest three-year period on record in California, yielding a statewide average of just over 46 inches of precipitation. Typically, California gets closer to 65 inches over three years. While no one knows for sure what the coming months will bring, many believe the odds favor another dry year, particularly in light of the warming climate.

“We can’t just continue to think of drought as something that happens occasionally,” said Jeanine Jones, drought manager for the California Department of Water Resources. “We’re really transitioning to different conditions that we need to plan for and adapt to.”

The October-through-September period, known as the “water year,” is relevant because it covers the entirety of the state’s fall-to-spring wet season. As of the end of this water year, total storage in the state’s reservoirs stood at just 69% of the historical average.

Managers of the State Water Project, operated by the Department of Water Resources, and the Central Valley Project, operated by the federal Bureau of Reclamation, both say they expect to significantly cut back water allocations for a third straight year, barring a barrage of miracle storms.

The projects each consist of numerous reservoirs in the Sierra Nevada and southern Cascades that carry water through a network of pumps and pipelines to irrigation districts and urban suppliers across the state. Most of this water comes from snowpack, which makes up nearly a third of California’s supply.

In the Bay Area, the Santa Clara Valley Water District, which serves nearly 2 million people, and the Zone 7 Water Agency in the East Bay, which serves about 260,000 people, lean heavily on project deliveries. The San Francisco Public Utilities Commission, by contrast, is not affected because it runs its own waterworks.

Last year, the allocation from the State Water Project, which supplies mostly urban areas, was reduced to a mere 5% of what was requested. The Central Valley Project, which supplies mostly agriculture, has a more nuanced means of appropriation, but most of its contractors also received little or no water. Both projects, though, worked to accommodate the basic “health and safety” needs of communities.

Project operators have not detailed exactly what next year’s allocation will be. But Karla Nemeth, director of the Department of Water Resources, said Monday that the December projection for the State Water Project, a good indication of how much water will follow, would be “low.” Ernest Conant, director of the Bureau of Reclamation’s California-Great Basin region, said it would be difficult to meet all the water demands.

As of the end of the water year, storage in the Central Valley Project, which includes giant Shasta Lake, was about 3.6 million acre-feet, or about 30% of capacity. That’s only slightly better than last year’s 3.2 million acre-feet, which went down as one of the lowest levels of storage in state history. Storage in the State Water Project ’s seven largest reservoirs was just over 2 million acre-feet, or just under 40% of capacity and also below where it typically stands this time of year. Lake Oroville is the centerpiece of the state system.

The lack of reservoir deliveries this year was responsible for the fallowing of more than a half million acres of farmland that typically grow almonds, grapes, tomatoes, rice and myriad other crops, according to numerous estimates. That’s the most acreage left empty in California in recent memory.

Meanwhile, in urban areas, many utilities have begun restricting water use while Gov. Gavin Newsom has asked residents to voluntarily cut back 15%, compared to water use in 2020. Data released Monday shows only a 4% statewide reduction since the governor’s plea in the summer of 2021.

State officials, however, insist progress is being made. In July, the last month for which there is data, Californians cut back 10.5%, compared to 2020.

“Really, this puts California solidly back on track when it comes to saving water,” said Charlotte Ely, a conservation supervisor at the State Water Resources Control Board.

Newsom has threatened to put in place mandatory water restrictions for cities and towns if there isn’t improvement and water conditions don’t get better. But so far, he hasn’t resorted to this tactic.

State and federal water officials, like most people, hope the coming year is wet. But many fear that a third year of a La Niña weather pattern, on top of the warming and drying climate, will mean more drought.

The La Niña, defined by cool sea surface temperatures in the central and eastern equatorial Pacific, can push the jet stream north and result in fewer winter storms hitting Southern California. The weather pattern, however, is a largely imperfect forecasting tool and what it means for Northern California fluctuates.

“There’s a lot of uncertainty right now,” said Mike Anderson, climatologist for the Department of Water Resources.

Kurtis Alexander is a San Francisco Chronicle staff writer. Email: kalexander@sfchronicle.com Twitter: @kurtisalexander

Kurtis Alexander is an enterprise reporter for The San Francisco Chronicle, with a focus on natural resources and the environment. He frequently writes about water, wildfire, climate and the American West. His recent work has examined the impacts of drought, threats to public lands and wildlife, and the nation's widening rural-urban divide.

Before joining the Chronicle, Alexander worked as a freelance writer and as a staff reporter for several media organizations, including The Fresno Bee and Bay Area News Group, writing about government, politics and the environment.