SACRAMENTO — Gov. Gavin Newsom scrapped a $16 billion plan Thursday to build two giant water tunnels to reroute the state’s water system and instead directed state agencies to restart planning for a single tunnel.

The move is a blow to the vision of his predecessor, Jerry Brown, who had championed two tunnels to divert water from the north to the state’s agricultural center and drier south.

Newsom had signaled the move in his February State of the State address but made the change official when he asked state agencies to withdraw existing permits and start over.

“I do not support the twin tunnels. But we can build on the important work that’s already been done,” he has said.

The state has already spent $240 million developing the project, said Karla Nemeth, director of the state Department of Water Resources. Some of that work will inform the new approach, she said.

Smaller Tunnel Likely to Be Just as Long

Brown wanted to build two, 35-mile-long tunnels to divert water from the Sacramento River, the state’s largest river, to the San Francisco Bay Area, San Joaquin Valley and Southern California. Local water agencies were expected to foot the roughly $16 billion bill.

The smaller tunnel is likely to be just as long and take water from the same places but could be designed differently, Nemeth said. It’s expected to cost less.

The Brown administration had downsized the project to one tunnel in early 2018 as local water agencies balked at picking up the tab.

But the Metropolitan Water District of Southern California, the state’s largest water agency, agreed to cover nearly $11 billion in costs last April, bringing new life to the twin tunnels.