Known asthe Delta Conveyance Project, a tunnel supported by Gov. Gavin Newsom would take water from the Sacramento River and bypass the vastSacramento-San Joaquin Delta, funneling the flows directly to pumps in the south Delta or straightto Bethany Reservoirat the northern end of the California Aqueduct.
The tunnel proposal, still in the early stages of environmental review, is the latest, scaled-down iteration of thecontentious twin tunnels project, which Newsom scrapped in 2019 in favor of a single tunnel.
The goal, according to state officials, is to make theState Water Project, which provides water to 27 million Californians and 750,000 acres of farmland, less vulnerable to rising seas, earthquakes and the extreme droughts and precipitation shifts of climate change. The massive system transports water through the Sacramento-San Joaquin River Delta to agencies and irrigation districts in the San Joaquin Valley, Southern California, the Central Coast and the Bay Area.
What would a Delta tunnel mean for California? “Ask me that after the EIR (environmental impact review) comes out,” said Greg Gartrell, former water manager with Contra Costa Water District and a consulting engineer. “It all depends on what the rules are for how it gets operated.”
The tunnel, stretching for about 44 miles, would allow the state Department of Water Resources to pipe additional water south to reservoirs, farms and cities. State officials say it would be especially beneficial during storms, when endangered species protections and other restrictions might limit pumping from the existing facility farther south.
Had the tunnel existed during the storms of late 2021, the state agency calculates that the tunnel would have sent236,000 more acre-feet of water to storage— enough to supply 2.5 million people for a year.
Efforts to funnel water around the Delta have been in the works for decades under various names, dating back to the peripheral canalfirst proposed in the 1960sandrejected by California votersin the 1980s.
The costly proposalshave been controversial ever since, with critics concerned that bypassing the Delta could worsen salinity and stagnation, and that years of construction could drive residents and tourists from the region.
The prolonged efforts to build tunnels could be called “the epicenter of the California water wars for almost 60 years,” Gartrell said.
The tunnel would be no quick fix: It would have to clear a gauntlet of permits, hearings and environmental review, including from federal agencies.
The first step is a draft environmental impact review expected later this summer, which would consider all of the alternatives, addressing the amounts of water the three routes would divert from the Delta and how they would affect water quality, the ecosystem and fish.
Next steps include public comment, finalizing the preferred route and deciding whether to move forward. In all, obtaining various permits and designing the prject could take six to eight years, and construction could add another another twelve years, state officials said.
The state would issue bonds, but public water providers that ultimately sign on to receive the tunnel’s water will be on the hookfor paying back the costs, estimatedat just under $16 billion in 2020 dollars. That number is likely to climb, given inflation and risingconstruction costs.
“It’s not like we’re going to turn dirt tomorrow, and we’re gonna set this thing up, and we’re gonna start moving water next year. It’s a long way off,” said Tony Meyers, executive director of the state’s Delta Conveyance Office.”So there’s a lot of time to amend and adjust.”
State officials hope that by piping water from the north and pumping from the existing facilities in the south, the state can capture more water during wet spells to tide water agencies over during droughts.
It’s “not a heart transplant, but a heart bypass,” Meyers said. “We’ve got a system that’s completely clogged up and very difficult to pump water through the Delta with all the restrictions that are on it. And the tunnel gives you a direct line straight to the pump station with the capacity that you’re looking for.”
Crossing Alameda, Contra Costa, Sacramento, San Joaquin, Solano and Yolo counties,the Delta is formed where the Sacramento and San Joaquin rivers come together andflow into the San Francisco Bay.
With 57,000 navigable waterways that draw 12 million visitors a year to its marinas, wineries and small towns, the Delta isCalifornia’s first National Heritage Area. It’s home tomore than 627,000 people, threatened andendangered fish species, a vibrant boating and fishing culture and 1,800 agricultural water users, including vineyards andpear orchards.
Environmentalists and some community activists worry that the tunnel will damage a region that already has been permanently altered by water diversions.
Daniel Armstrong, a 25-year-old construction worker and part-time student, grew up near the location in Hood where the proposed tunnel’s intakes would be constructed. He remembers fishing the waterways with his dad as a child, and the town turning out to watch salmon migrate.
“I have memories as a kid with friends, with my parents literally sitting there and just counting them. You’d get like 200 in the evening,” said Armstrong, now an intern at the advocacy group Restore the Delta. Today, he said, you’re lucky to see a dozen salmon on a good day.
California’swater regulatorssay the Delta is experiencing an “ecological crisis” with a “prolonged and precipitous decline in numerous native species,” includingendangered winter-run Chinook salmonandthe tiny Delta smelt. The reasons include “reduced and modified flows, loss of habitat, invasive species, and water pollution.”
No one knows how exactly the proposed tunnel project will affect the waterways and fish yet — the environmental review will address that. But residents worry that funneling freshwater from the north of the Delta could compound its existing problems, leading to saltier, more stagnant water in the region’s heart.
Rudy Mussi, who farms on Roberts Island and Union Island, worries a tunnel could upset the Delta’s delicate balance that keeps ocean tides from overwhelming irrigation water. In years like this one, when winter rains fail to wash the salt away, seeds fail to germinate, and transplants don’t thrive. “It's not good for any of our crops,” he said.
Carrie Buckman, environmental program manager for the Delta Conveyance Office, said if the tunnel were built, state officials would continue to comply with all water quality rules.
But environmental groups and Delta advocates are skeptical, pointing to the state’s previousviolations of salinity and other requirementsand its repeated requests torelax salinity and flowrules during droughts in four of the last ten years.
“I don't trust how we manage water right now,” said Mike Costello, a fly fishing guide in the Delta. “Are you just going to take, take, take? If that's the case, then no, the tunnel is a bad idea.”
When faced with the state’s last proposal, the twin tunnels,a federal assessmentconcluded it was “not likely to jeopardize” survival of endangered salmon and other fish. But recent research found thatlow flows and warmer temperaturescorrelatewith reduced salmon survival andincreased harmful algal blooms.
Already, less water is making it into the Delta during dry and critically dry years,the Public Policy Institute of California reports— the apparent result of increasing upstream water use.
Scientists agree that a tunnel’s impact on the Delta will depend on how it’s used.
“Just the water diversion itself is not going to make a huge difference, because there's so many things going on in the Delta right now — especially invasive species,”said Peter Moyle, a fish biologist and professor emeritus with the University of California Davis Center for Watershed Sciences. Still, he added, “The ‘devil is in the details’ of operation.”
Fisheries biologistBruce Herboldsaid physical constraints on the amount of water that a tunnel could take, and when, should be built in to ensure that water quality and fish aren't harmed.
Community residents say they have not had enough input in the design and construction plans overseen by the Delta Conveyance Design and Construction Authority, whose board ismade up of water agency representatives. But state officials say that they have sought community input and included plans to reduce noise and traffic.
Nothing will make up for the “peace and serenity that you will rob this agricultural community with this project,” said Anna Swenson, a member of a stakeholder committee from Clarksburg,said at a meeting. “Although all those things sound like they're fixes, all they're doing is putting lipstick on a pig. And it’s not right.”
Kathy Bunton, who owns Delta Kayak Adventures, wonders whether Delta communities would survive the tunnel project.
“I fear that the Delta would eventually just become basically ghost towns,” she said. “It's just heartbreaking.”
Moyle said the project should increase water reliability in the face of what he called a nightmare scenario: levees and islands crumbling under flood waters or an earthquake, and seawater or freshwater rushing into the void. He said the tunnel would be a secure way to continue transporting water from north to south in emergencies.
Moyle’s concern is “what happens if the tunnel does not get constructed,” he said. “Maybe we Californians will be lucky and California’s biggest source of water will continue to flow south and to the Bay Area unabated indefinitely. But don’t count on it.”
Sea level rise, aridification of the West and the resulting salinity in the Delta, “all of these things are going to happen, no matter what. It’s not related to the tunnel,” said Jennifer Pierre, general manager of theState Water Contractors, an association of public water agencies.
The question is, she said, which solution ensures that “all of the users of the Delta are in the best position to deal with these impacts?”
Weighing the cost
The question water agencies will have to weigh is whether a tunnel is worth the price. The local and regional water providers that sign on to receive its supplieswould be responsible for paying back the state for the costs.
Eighteen water agencies have signed on to participate in themore than $340 millionplanning and permitting effort. Included is the giantMetropolitan Water District of Southern California, which supplies imported water used by 19 million people and has agreed to paynearly half of the planning costsover four years.
Steve Arakawa, Metropolitan’s manager of Bay-Delta initiatives, said previous analyses of the twin tunnels project indicated that it would likely be cheaper than alternatives, such as recycled water, stormwater capture or desalination. Metropolitan estimated it would have cost about $4.80 per household every month.
“We would rather invest in this cost to protect that supply, rather than have to replace it at a much higher cost,” Arakawa said.
For other water providers, especially those serving agriculture, the cost is expected to be steep.
“It’s expensive water,” said Tom McCarthy, general manager of Kern County Water Agency, which serves13 local agricultural and municipal water districts. The agency is participating in the planning process on behalf of the cities and towns it supplies, as well as some of its irrigation districts.
“There's not a whole lot of other options,” McCarthy said. “It's commonly known that we're overextended with groundwater.”
Tom Birmingham, general manager of the powerful Westlands Water District, which serves San Joaquin Valley growers, extolled the “eminently good sense” of a tunnel or canal that bypasses the Delta.
But he said the district did not join the previous twin tunnels project because it was concerned that suppliers who get water from the federal Central Valley Project were not guaranteed to actually get the tunnel water. Plus, he said, the federal strategy for divvying up the cost meant it “exceeded what Westlands thought it could afford to pay.”
The costs and benefits of that earlier proposal were disputed, so that’s likely to be a source of contention this time, too.
The state reported$3.1 billion in anticipated net benefitsfrom the twin tunnels for urban water agencies and $400 million for agricultural water providers. Butanother analysis, which received some funding by the project’s opponents, found that costs far exceeded benefits — particularly for agricultural users. The cost is too high “even if they're growing almonds,” a lucrative crop, said Jeffrey Michael of the University of the Pacific’s McGeorge School of Law, who led the assessment.
Michael is waiting to see the draft environmental review before weighing the costs and benefits of the single tunnel. But, he said, the savings from downsizing the tunnel won’t balance out the decrease in water it supplies: “The economics are clearly worse.”