California's $20 Billion Water Tunnel to Move 161 Million Gallons Per Hour

California's long-gestating plan to construct a massive tunnel that will pump water from the state's Sacramento–San Joaquin River Delta to points south will cost $20 billion, according to a new estimate.

Set east of San Francisco, in the San Joaquin Valley, the Delta Conveyance Project is a proposal to build a 45-mile-long, 36-foot-wide tunnel, large enough to transport more than 161 million gallons of water per hour from the Sacramento River into nearby aqueducts for distribution to farms and cities in the south.

For over 60 years, the tunnel has been at the center of heated debates in California. It has sparked water wars, with valley residents, environmentalists, tribes and the fishing industry on one side and state officials and water agencies on the other.

Governor Gavin Newsom has championed the Delta tunnel as his administration's "number one climate resilience program" and hopes to secure necessary permits before his term ends in 2026.

With the new cost estimate — $4 billion higher than the last one in 2020 — state officials expect to help water suppliers in Central and Southern California determine whether it's cost-effective for them to buy water from the tunnel project.

The tunnel would channel water from under the Delta into aqueducts managed by the State Water Project, California's network of reservoirs, dams and canals that supplies water to 27 million people and irrigates 303,515 hectares of farmland. State officials predict the tunnel would yield $38 billion in benefits, mainly due to an increased water supply that's also better protected from natural disasters like earthquakes.

"The benefits clearly justify the costs," David Sunding, emeritus professor at the University of California, Berkeley and leader of the latest analysis, told the Associated Press.

Jennifer Pierre, general manager of the State Water Contractors, an association of the involved water agencies, told the Los Angeles Times: "If we do nothing to shore up the State Water Project's aging infrastructure, California's primary and most affordable water supply faces continued reliability risks and remains vulnerable to increasing weather extremes."

Critics argue that the tunnel will further endanger the Delta's already fragile ecosystem, which supports about 80% of California's commercial salmon fishery — a concern echoed by a previous environmental analysis conducted by the state.

"Instead of foisting the costs of this boondoggle project onto Californians, the state should invest in sustainable water solutions that promise to restore the Delta ecosystem, not destroy it," said Barbara Barrigan-Parrilla, executive director of Restore the Delta, in a press release.

Construction on the project would not start until the end of the decade, with an estimated completion date of 2044 at the earliest.