The controversy is decades old. Yet the pointed nature of the criticism – and the eagerness of even Democratic lawmakers to challenge Brown on a day in which tradition suggests restraint – laid bare how significant a test of Brown's political abilities the $14 billion project may be.
Immediately following Brown's speech, Assemblywoman Kristin Olsen, R-Modesto, issued a statement panning the Democratic governor's plan to divert water to the south. Sen. Lois Wolk, D-Davis, said the project is "expensive and controversial, and the science is not there."
Less than a year after Brown persuaded lawmakers to approve a $68 billion high-speed rail project, Assemblywoman Susan Talamantes Eggman, D-Stockton, said, "I think he gets the train or the tunnels. I don't think he gets both."
For years, California politicians have struggled to mediate the competing water interests of farmers, environmentalists, Delta residents and Southern Californians.
Brown may not be asking the Legislature for its approval. The water project he proposes would be financed by water users and permitted administratively by the state and federal governments, and there is no technical requirement that Brown obtain the Legislature's blessing.
Yet the project is tied politically to an $11.1 billion water bond scheduled for the November 2014 ballot. The Legislature has withdrawn the bond from two previous elections, in 2010 and 2012, and Brown has urged lawmakers to revise the measure to reduce its cost and improve its chance of passing.
Funding included in the bond for dams, wastewater treatment and other water infrastructure projects could be necessary to ease opposition to Brown's plan.The support of key lawmakers could also help head off litigation by foes of the project.
The water diversion tunnels Brown proposes are intended to improve the way water is diverted from the Delta. Rather than diverting from the south Delta, which alters habitat by reversing the natural flow direction, the tunnels would divert freshwater directly from the Sacramento River near Courtland.
Proponents of the project say it will improve the Delta ecosystem and protect from levee failures and sea level rise a water supply used by some 25 million Californians. Critics fear it will harm the Delta ecosystem and farm economy.
Natural Resources Secretary John Laird said Friday the administration is seeking input from every stakeholder, including lawmakers. "We want to work with the Legislature to do whatever can be helpful to people around the state on water," said Laird, a former assemblyman. "Everything is balancing interests, and it's our goal to balance the interests as fast as possible after including everybody and talking to everybody."
As governor before from 1975 to 1983, Brown did seek – and obtained – the Legislature's support for a water project similar to the one he is proposing now.
In a State of the State address more than 30 years ago, Brown called the project "an investment in the future." The project was undone by the electorate, defeated in a referendum in 1982.
In his speech on Thursday, Brown spent less than two minutes on the subject.
"My proposed plan is two tunnels 30 miles long and 40 feet wide, designed to improve the ecology of the Delta, with almost 100 square miles of habitat restoration," Brown said. "Yes, that's big. But so is the problem."
Brown has Democratic supermajorities this year in both the Assembly and the Senate, but it is unclear how helpful Assembly Speaker John A. Pérez said Brown's proposal is "one very good option," but not the only one.
"The final determination on what those infrastructure decisions are will be something that all members of the Legislature will be engaged in," the Los Angeles Democrat said. "Look, you can look at the pre-existing plan, and if you go and ask the 120 members of the Legislature, you'll get 143 different ideas."
The project is part of the Bay Delta Conservation Plan. A draft environmental report is expected next month.
Meanwhile, Brown is just beginning to interact with new members of a Legislature that convened its largest freshman class this year since 1966.
"I think he's smart enough and experienced enough to know that water politics in California is always contentious," said Jack Pitney, a government professor at Claremont McKenna College.
Pitney described Brown's prospects for the water project as "tough, but I wouldn't rule it out."
Even with skeptical lawmakers, he said, "You know, governors do have leverage. There are other things that these folks want."
Both Pérez and Senate President Pro Tem Darrell Steinberg, D-Sacramento, have rallied support in their houses for Brown before, including on high-speed rail.
"I'm not ready to sign off on any particular size tunnel, but I think the idea that we both have to restore the ecosystem of the Delta and at the same time provide water reliability conveyance for the entire state by going around the Delta is true, and accepted," Steinberg said. "And I accept it, and I'm ready to work with the governor to figure out the details."