A Northern California water agency has voted to support Gov. Jerry Brown's plan to build two massive tunnels to remake the state's water system, renewing momentum behind the controversial project.

The Santa Clara Valley Water District board voted 4-3 Tuesday to support the $17 billion project and to commit up to $650 million to help pay for it.

The board's vote in a packed chamber followed a four-hour discussion of the project in the Sacramento-San Joaquin Valley Delta.

Unions and Silicon Valley's largest business group had recommended a yes vote. But environmental groups urged a no vote, saying the project would harm wildlife and water quality in the Delta and San Francisco Bay,