Californians approved billions for new water storage. Why hasn’t it gotten built?

In 2014, during the throes of last decade’s drought, California voters approved billions of dollars for infrastructure that would catch and store much-needed water from winter storms. The hope was to amass water in wet times and save it for dry times.

Nearly 10 years later, none of the major storage projects, which include new and expanded reservoirs, has gotten off the ground.

As the state experiences a historic bout of rain and snow this winter, amid another severe water shortage, critics are lamenting the missed opportunity to capture more of the extraordinary runoff that has been swelling rivers, flooding towns and pouring into the sea.

The seven dedicated storage projects funded by voter-approved Proposition 1 remain in various stages of planning. Many are big ventures, including the proposed Sites Reservoir in the Sacramento Valley that would be California’s eighth-largest reservoir. Such efforts require years of design, permitting and fundraising and are not easy to build. Still, some say progress has been too slow given the dire need for water.

“We’re in a climate emergency and we need to start acting with some urgency here,” said Adrian Covert, senior vice president of public policy for the Bay Area Council, which advocates for businesses in the Bay Area. “When you’re talking about storage projects and dams, they are going to last 100 years and you want to get it right and caution is appropriate. At the same time, you have to deliver results.”

Gov. Gavin Newsom has weighed in, too, pledging to expedite the construction of new storage facilities by providing additional funding and removing “permitting barriers,” not unlike his predecessor, Jerry Brown, who similarly tried to accelerate the work.

This month, California’s Republican congressional delegation, including Reps. David Valadao of Hanford (Kings County) and Tom McClintock of Elk Grove (Sacramento County) expressed concern about the lack of storage, sending a letter to Newsom and President Biden urging a boost in capacity in light of the recent precipitation.

The barrage of atmospheric rivers that has pounded the state since late December has yielded near-record amounts of both rain and snow.

As much clamor as there has been for more storage, however, water experts warn that it may not be the panacea that advocates profess, specifically reservoirs. Constructing reservoirs is expensive, meaning the water they sell may be cost-prohibitive for some, while the increase in water supply is likely to be small and not worth the money given California’s increasing aridity.

With the warming climate, the state is not only seeing more intense droughts, alongside more intense storms, but more of the precipitation is falling as rain instead of snow. Snow has historically provided a second wind for reservoirs, melting after the wet winter season and giving the lakes an additional hit of water.

“Storms like this just don’t come that often, so you can’t always expect to fill your storage,” said Jeffrey Mount, a senior fellow at the Public Policy Institute of California’s Water Policy Center. “What you want is reliable supply and this (type of storage) is not very reliable. You don’t know when you’re going to fill it.”

“There are better ways to improve your water supply,” he said.

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Proposition 1, which passed with 67% voter approval, authorized $7.1 billion of bond funding for water projects, the largest chunk of which was earmarked for storage, about $2.7 billion.

Two new major reservoir proposals were initially selected to receive bond money, but one of the projects on the San Joaquin River didn’t get enough to move forward, leaving the 13-mile-long Sites as the biggest venture. Others include the expansion of two reservoirs in the Bay Area, Los Vaqueros Reservoir in Contra Costa County and Pacheco Reservoir in Santa Clara County. Most of the remaining initiatives seek to store water underground by replenishing aquifers.

A small water recycling program on farmland in Sacramento County and the enlargement of Los Vaqueros are expected to be the first to receive final checks from the state, perhaps this year. For other projects, including the Pacheco Reservoir,it could be several more years.

The length of time it has taken to select and finance these efforts was largely intentional. To win broad support for the bond measure in 2014, Prop. 1 put several conditions on the funding, including a requirement that the storage projects show “public benefit,” followed by an elaborate process to rank that quality. It took three years just to gather applications.

“Any large-scale water storage project is complex and requires a high degree of planning, engineering, construction, significant financing, and coordination with existing water infrastructure and operations,” said Paul Cambra, spokesman for the California Water Commission, which is in charge of awarding the bond money.

The proposition also is funding just a fraction of each project, meaning even after the cash is doled out, proposals will move forward only when additional money is secured.

Advocates of the $4 billion Sites Reservoir say they’ve lined up their remaining financing — about $875 million is expected from Prop. 1 — but the balance relies on a mix of still pending federal funds and commitments from statewide water agencies. Some water agencies have worried that the price they’ll have to pay for future reservoir water will be too high as project operators seek to recover their costs.

The cost of building reservoirs has skyrocketed as new reservoir sites have become trickier to engineer. The best spots have been taken by the state’s 1,500 existing reservoirs.

A best-case scenario would have Sites Reservoir up and running just after 2030. According to the state, the expansion of Pacheco Reservoir could be finished at about the same time while the extension of Los Vaqueros could come a year sooner.

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While completing the Prop. 1 projects would bring considerable storage — an estimated 2.8 million acre-feet of water capacity — it’s a relatively small amount given the state’s total capacity.

California’s existing reservoirs can store 43 million acre-feet of water, according to the Public Policy Institute of California. An acre-foot of water is about enough to supply two households for a year.

Additionally, the actual amount of water the projects would hold would be far less because the reservoirs wouldn’t consistently fill.

The Prop. 1 reservoir proposals, according to Jay Lund, director for the Center for Watershed Sciences at UC Davis, in the end may amount to a 1-2% increase in water supplies.

Lund and others say the real promise of the ballot measure may be in its prescription for underground water storage. The idea of channeling runoff during wet periods into aquifers where cities and farms can pump it out is generally a lot less expensive than building reservoirs and has greater potential.

The amount of underground space currently available may be three times the state’s total reservoir capacity, according to one estimate.

There are several means of stockpiling water in aquifers, from simply spreading water across fields and letting it soak in to injecting the water through deep wells. Treated wastewater and stormwater caught in cities can be fed to aquifers, as can floodwater.

Prop. 1’s earlier rounds of funding aided a smattering of water projects that weren’t necessarily designed for storage but help put water underground. The money dedicated specifically for storage is planned for large groundwater projects in Kern County, Los Angeles County and the Inland Empire, with the first expected to come online in Antelope Valley in 2026. Similar projects are in the works independent of the bond money.

Recognizing the benefit of aquifer storage, the California Department of Water Resources and State Water Resources Control Board on Friday promoted their recent efforts to help landowners divert excess flows from Mariposa Creek in Merced County into the ground. The project targets floodwater like that produced in recent storms.

“Trying to recharge our aquifers, that is where our greatest storage opportunity lies,” said Heather Cooley, director of research at the Pacific Institute, a water research center in Oakland. “This is not easy to do and it’s not fast, but that’s the direction we need to head.”

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