Newsom says California needs to build a water tunnel. Opponents argue costs are too high.
Water passes from Clifton Court Forebay through an inlet toward the State Water Project’s pumping plant. The Newsom administration is seeking to build a tunnel that would create a second route to transport water to the pumping plant. Photo: Paul Kuroda/LAT
This article originally appeared on the Los Angeles Times website on August 20, 2025.
By Ian James
As Gov. Gavin Newsom pushes for building a giant water tunnel beneath the Sacramento-San Joaquin River Delta, his administration says it’s the “single most effective” way for California to provide enough water as a warming climate brings deeper droughts and more intense storms.
But environmental advocates and political leaders in the Delta, among others, condemned a new state analysis that draws that conclusion, arguing the tunnel construction would harm the environment and several types of fish and push water rates much higher for millions of Californians.
The potential costs of building the 45-mile tunnel are generating heated debate. The state has estimated the project, if water agencies participate and contribute, would cost $20.1 billion. But in a separate analysis, economic research firm ECOnorthwest found the costs would probably range from about $60 billion to $100 billion or even more.
“Unfortunately, the Newsom administration is brushing over and leaving out the real costs of the tunnel, both to the ratepayers and taxpayers and the environment,” said Carolee Krieger, executive director of the California Water Impact Network, a nonprofit group that commissioned the economic analysis.
She said the high costs would fall largely on people in Southern California through their water bills, and that there are better and more economical ways of securing water supplies for the region.
The Newsom administration released the report Tuesday outlining actions it said would “climate-proof” the state water system so that it can operate for generations in hotter, drier conditions.
Department of Water Resources Director Karla Nemeth wrote that the State Water Project — the system of aqueducts, pipelines and pumping plants that delivers supplies from the Delta to farmlands and cities — now “needs revitalization,” and that “maintenance of the aging project and a modernized tunnel system to transport water under the Delta are the most valuable adaptations.”
The department said in a written statement that the state’s 2024 estimate was prepared according to industry standards and that the ECOnorthwest report appears to be based on unsupported assumptions that “overestimate the cost.”
Newsom, who is set to leave office after 2026, has said the tunnel plan, called the Delta Conveyance Project, is essential for the state’s future and has made it a central priority.
Since May, the governor has sought to fast-track the plan by short-cutting permitting for the project and limiting avenues for legal challenges, saying the effort should not be held back by delays and “red tape.” But legislators representing areas around the Delta have fought attempts to adopt the governor’s plan.
The Newsom administration continues to advocate with legislators to accelerate the project, said Tara Gallegos, a spokesperson for the governor. She said in an email that the legislative proposal is “aimed squarely at removing bureaucratic processes and pointless delays that create unnecessary costs to taxpayers — something Californians have been very loudly and clearly in support of preventing.”
Meanwhile, the State Water Resources Control Board is considering a petition by the Newsom administration to amend water rights permits so that flows could be diverted from new points on the Sacramento River where the tunnel intakes would be built.
The tunnel would create a second route to transport water to the south side of the Delta, where pumps send it into the aqueducts of the State Water Project and onward to cities and farmland. According to the state’s plan, the tunnel would be about 36 feet wide on the interior and buried about 140 feet to 170 feet underground.
Lawmakers who represent the Delta region criticized the state report as flawed, saying it overlooks the project’s costs and their concerns that it would damage the ecosystem and harm communities and farms in the area.
In a joint statement, state Sen. Jerry McNerney (D-Pleasanton) and Assemblymember Lori D. Wilson (D-Suisun City) said the Newsom administration has made false claims about what they view as an “extremely costly and environmentally destructive project,” and that “there are far more affordable alternatives to the tunnel project that are much better for the environment, including increasing water recycling and groundwater storage.”
Communities in the Delta would be overtaken by extensive construction work for years, they said.
Seeking to address those concerns, Newsom earlier this month announced a plan to create a $200 million program to address or minimize or address the effects of construction on local communities.
Delta community advocates dismissed that as a hollow attempt to sway some local people, and said they believe the project would be disastrous for local farms and the estuary’s struggling fish species, including Chinook salmon and steelhead trout.
Some said they see political ambition driving the project. Newsom apparently “wants to have something for his campaign when he runs for president,” said Brett Baker, a lawyer representing the Central Delta Water Agency and its agricultural landowners, who are challenging the project in court. Baker said the governor seems to be hoping “to put his name on it to say he did something. So I think he’s become a little bit more desperate.”
The project is in an extensive planning stage, and preliminary planning costs are being paid by 18 water districts, including agencies that supply farmland in the San Joaquin Valley as well as urban agencies in Southern California and Silicon Valley.
The largest share of those costs, about $142 million, is being paid by the Metropolitan Water District of Southern California, which delivers water for 19 million people. The MWD isn’t expected to decide whether to invest in building the tunnel until 2027.
Managers of the Eastern Municipal Water District, which serves about 1 million residents in western Riverside County and northern San Diego County, are among those supporting Newsom’s plan.
“The existing conveyance system in the Delta is not sustainable and threatens water supply reliability,” said Joe Mouawad, Eastern Municipal’s general manager. “We’ve worked diligently over years and decades to diversify our water supply portfolio and provide resilient local water supply, but imported water is still going to be a critical source for our customers and for our communities.”
Mouawad noted that the area has some of the fastest growth in California, and he said the Newsom administration’s strategy is a “well-thought-out approach” to meeting long-term water supply needs.