California’s proposal to build a tunnel to move water around the Sacramento-San Joaquin River Delta is inching forward as Gov. Gavin Newsom nears the end of his time in office, but the path toward construction remains uncertain. Newsom said the project cleared another hurdle last week after the Delta Stewardship Council voted 6-1 to require state water officials to address only two of the many challenges opponents raised. Yet the push still faces a separate set of obstacles, including court rulings that have disrupted financing plans and regulators’ remaining water-rights decisions.
The proposal, which supporters call the Delta Conveyance Project and critics call a harmful intervention into a vulnerable ecosystem, has been debated for more than half a century. In the latest version of the plan, the state would pipe Sacramento River water through a 45-mile bypass to a reservoir on the California Aqueduct, sending more water south as drought risk and climate-related extremes intensify, project backers have said.
Delta communities and environmental groups oppose the tunnel, describing it as a water grab that could devastate one of the country’s largest estuaries. They say the project would harm wildlife, towns and long-established farms in the Delta region. State officials and major water suppliers, including agencies responsible for delivering water to cities and farms, argue the project is needed to safeguard supplies for roughly two-thirds of Californians against threats they describe as climate change and natural disasters.
The Delta Stewardship Council is the state agency tasked with refereeing aspects of the debate. After weighing opponents’ challenges, the council voted last week to require the Department of Water Resources to address only two of the issues, according to the staff process that led to the 6-1 decision. Newsom framed that vote as a victory, saying, “we are closer than ever to seeing this important piece of infrastructure completed.”
Still, water-watchers and policy experts described the vote as progress that does not end the fight. Jeffrey Mount, a senior fellow at the Public Policy Institute of California, said, “These are all existential.” He argued that the project’s remaining hurdles are significant, and that even if the tunnel is eventually built, it will depend on a sequence of decisions that extend beyond the council’s latest directive.
The Delta is already under severe stress, with residents, environmentalists and fishing interests warning that further changes could worsen conditions. Supporters point to what they describe as the practical problem of climate-driven swings in rainfall and the need to protect water supplies. Project officials have also pointed to timeline estimates; Carrie Buckman, environmental program manager for the tunnel project at the Department of Water Resources, said she is optimistic that construction could start as soon as 2029 and last around 13 years.
Opponents point to the broader history of the plan as a sign that the project can remain mired for years, even as political support changes. The tunnel approach traces to earlier efforts, including a peripheral canal proposal that voters rejected in the 1980s during Gov. Jerry Brown’s first stint as governor. Brown later returned to office and continued the push, and successive governors advanced what is now described as twin tunnels within Newsom’s Delta Conveyance Project, which remains stuck in planning.
The fight also remains tied to financing and legal authority. Officials have said the plan’s estimated cost is high, with the Department of Water Resources estimating around $20.1 billion, while an economic assessment commissioned by opponents estimated costs could reach $60 to more than $100 billion. State water managers planned to issue revenue bonds repaid by water agencies and ultimately their customers, but a trial court ruled that California’s water code did not give the Water Resources department “carte blanche” to proceed and that the financing plan “exceeded its delegated authority.” The Third District Court of Appeal agreed, and in April the California Supreme Court declined to review the case.
Buckman said the department still plans to issue bonds and is figuring out its next steps, while opponents and legal representatives argued financing is not settled. Kelley Taber, an attorney representing opponents, said no water agency has committed to paying for a tunnel and that none is likely to do so until the department can finance it. She added that federal agencies and irrigation districts already opted out. Jennifer Pierre, general manager for the State Water Contractors, said, “Ag, at large, cannot afford to pay for large infrastructure projects,” though she also said the costs do not lessen the perceived need for the project.
Beyond money and legal authority, state regulators still face major water-rights questions that could shape whether the tunnel can divert Sacramento River water. Regulators are holding hearings that could last through the summer on whether the Department of Water Resources may divert water into the proposed tunnel intakes. Buckman and others have said Newsom has advocated for a Delta tunnel since early in his governorship and that the governor has championed legislative fixes aimed at addressing financing and other roadblocks.
The question of who leads the effort next is central for both supporters and critics. Pierre said the tunnel need remains and must continue, while Mount said the outcome will likely turn on the next governor’s priorities and the people appointed to key leadership positions. He said it was “hard for me to imagine that if Brown and/or Newsom weren’t all in on this, it would have gotten this far,” underscoring how much the project’s progress has depended on sustained political backing.
On the ground in the Delta, residents describe the proposal not as an abstract policy debate but as an intrusion into long-running ways of life. Duane Martin Jr., a third-generation cattleman, said he is concerned about truck traffic, noise and construction activity, including a planned roughly 200-acre pile of tunnel muck on land where his family has grazed cattle for decades. He also questioned whether the state’s planning adequately weighs the impacts on the community itself, saying, “It’s the community that they’re going to impact — those of us that have lived here most of our lives.”
Martin said the tunnel project could permanently change the Delta area, a concern that intersects with other regional efforts. In one example, the Sacramento Area Sewer District plans to pipe recycled water onto nearby farmland through the Harvest Water project, described as an initiative covering 16,000 acres and aiming to create seasonal feeding grounds and rest stops for migratory birds, including protected sandhill cranes. The district has already received more than $400 million for Harvest Water, and it says funding depends on environmental benefits such as habitat.
The tunnel project could collide with that plan, because state water managers have targeted similar land for a construction complex that would include a permanent excavated-material mound up to 15 feet tall. The Delta Stewardship Council ordered the Department of Water Resources to resolve conflicts with the Harvest Water project’s siting or explain why that would not be possible, according to the council’s staff report. Taber said the council’s action amounted to a mixed victory for opponents, calling the Harvest Water site issue what she described as “the most obvious fatal flaw” among challenges raised against the project.
Buckman disputed the council staff assessment in a letter, saying the tunnel project cannot avoid the entire Harvest Water footprint and that the habitats opponents cite do not yet exist. She said the department would “work promptly” to address the issue. Even if the department can resolve the conflicts to the council’s satisfaction, the state could still need to buy or seize land for the work, and in this case the landowner declined to speak on the record.
Martin said he expects a fight over the land under eminent domain and said he intends to stay and contest it. He said, “They’re gonna have to take it,” adding, “I’ve got a lot of friends that leave, but I ain’t about to quit. I’m a fighter, and I’m going to stay here and fight for it to the death.”