California Gov. Gavin Newsom is pushing to lay the groundwork for a $20 billion water tunnel in the Sacramento-San Joaquin River Delta before his term expires, while state regulators are pondering whether to grant a key authorization, according to The Los Angeles Times.
The State Water Resources Control Board is holding a series of hearings on a Newsom administration petition to amend water rights permits. That would allow water flows to be diverted along the Sacramento River where the intakes of the 45-mi. tunnel would be built, the Times reported.
State plans call for construction starting in late 2029 with completion in 2042.
Both the Newsom administration and water agencies have questioned how the board's officials are handling parts of the process, according to the Times.
Delta Conveyance Project supporters contend that the state needs to build new Delta infrastructure to protect the water supply from climate change and earthquake risks. Some Southern California water agencies are providing funding for planning work in support of the project.
Opponents, who include Northern California agencies, environmental advocates and native tribes, counter that the project would be too expensive and harm the environment, fish species and communities.
A new tunnel would create a second route to transport water to the state's pumping facilities on the Delta's south side. The aqueducts of the State Water Project there deliver water to 27 million people and 750,000 acres of farmland, the Times reported.
During a state Senate subcommittee hearing on April 3, 2025, Department of Water Resources Director Karla Nemeth said the existing system is "starting to really underperform," and said the tunnel, if it existed now, could have captured more water during storms over the last three years.
State officials estimate that climate change could reduce average supplies available from the State Water Project by up to 23 percent by 2045.
Nemeth said the new tunnel would slow the decline and restore approximately 16 percent of that lost supply, according to the Times.
