FRESNO, Calif. (AP) — Farmers in the nation’s largest irrigation district on Tuesday voted against participating in Gov. Jerry Brown’s $16 billion plans to build two giant tunnels to re-engineer California’s north-south water delivery system.

The Westlands Water District was considered a key player in the project’s success or failure having already having invested millions toward planning. But the vote means it will not commit to shouldering a share of the hefty construction costs.

Administrators at Westlands, which supplies water to hundreds of family farms and some large corporate farms, had recommended that its farmers support the tunnels only if the costs are spread out to other agencies in proportion to how much water they get from the state, making it more affordable for the agricultural district.

Thomas Birmingham, general manager of the Westlands district, said he believes the 7-1 vote against the project might kill it.

Westlands is the first water district to vote on the project. Water districts for the Silicon Valley and those in the farm-rich Central Valley and Southern California are due to vote in the coming weeks.

John McManus, the executive director of the Golden Gate Salmon Association, said the water district’s decision was a major blow to the project.

“The takeaway from today’s vote is that the current twin tunnels plan is dying from its own weight,” said McManus, who organization has been a vocal opponent to the project. “It’s way too big and expensive, even for the growers in the desert-dry western San Joaquin Valley who need the water the most. There’s no doubt that the existing method of transferring northern California water south is deadly for salmon and other wildlife and absolutely could be improved upon, but not by this behemoth.”

The tunnel project is the biggest proposed for California in more than a half-century, but has no firm financial commitments from local water districts.

The vote comes a day after The Associated Press reported newly revealed state plans to put dozens more water agencies and millions of families and farmers on the hook for funding the tunnels.

Brown is pressing to secure the project before he leaves office next year. It calls for building two 35-mile-long (56-kilometer-long) tunnels east of San Francisco to deliver water from the Sacramento River mostly to farms and cities hundreds of miles away in central and Southern California.

Backers say the tunnels will stabilize flows, bolstering endangered fish and ensuring a reliable water supply. Critics say the project will be used to drain Northern California dry and further harm native fish.

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