By GOSIA WOZNIACKA and HANNAH DREIER
SACRAMENTO, Calif. (AP) -- California and federal officials announced plans Wednesday for a massive twin tunnel system to carry water from the Sacramento-San Joaquin River Delta to farmland and cities.
Gov. Jerry Brown and Interior Secretary Ken Salazar unveiled the proposal at a Sacramento press conference.
Supporters say the tunnels will guarantee a stable water supply for Californians and protect the water delivery system from earthquakes. But opponents argue the project could destroy the already fragile delta ecosystem.
Officials said California's water system is unsustainable from an environmental and economic perspective, and that the proposal would help achieve both a reliable water supply and a healthy delta ecosystem. They said the proposal includes over 100,000 acres of floodplains and tidal marsh habitat restoration.
Tunnel construction itself would cost about $14 billion and would be paid by water users. Officials said taxpayers would bear the $10 billion cost of habitat restoration, but a water bond that could provide some money for restoration was moved to November 2014.
"A healthy delta ecosystem and a reliable water supply are profoundly important to California's future," Gov. Brown said. "We know there are a couple of big issues, earthquakes and climate change. And this facility is absolutely essential to deal with both of them."
The proposal is "essential to stopping California's water wars," Salazar said.
Building the tunnels would move the point of water diversion from the south end of the delta to the north end, so that the impact of reversed flows caused by the current "fish killing pumps" on salmon, sturgeon and other species would be reduced and fewer fish would be caught and killed in the delta project pumps, Salazar said.
Fish mortality will drop from 95 percent, Salazar said -- although the project is yet to study the fish screens it would use.
And the tunnels would guarantee a certain level of pumping, so farmers would know how much water they are going to get, he added.
"We will never be able to negate some of that uncertainty because we can't control Mother Nature and we can't control the weather. But we can create more certainty," Salazar said.
The tunnel would have the capacity to divert 9,000 cubic feet of water per second. The tunnels would be sized to handle even more water and the extra space would allow the water to move by force of gravity, to reduce energy use and save on costs, officials said.
But the tunnel proposal is facing stiff opposition from delta residents, some environmental groups and Northern California legislators.
State officials admit they don't know just how much water would be diverted through the tunnels or how habitat restoration and decreased flows would affect the fish. They say these questions would be answered through scientific studies that accompany construction over the next 10-15 years.
Opponents argue it would devastate the delta region, including its ecosystem and agriculture-based economy. They say it's unacceptable to proceed with building the tunnels without knowing up front their impact on imperiled fish species such as salmon and smelt. Officials said the amount of water to be pumped would depend on what is good for the fish.
Formed by the confluence of California's two longest rivers -- the Sacramento and the San Joaquin -- the delta supplies drinking water for two-thirds of Californians and irrigates nearly 4 million acres of farmland.
The ecosystem's rapid deterioration and the crash of once-abundant fish populations a decade ago has spurred regulations that limit delta pumping, especially during dry years. Farmers in the Central Valley say the restrictions have forced them to fallow productive land.
Wozniacka reported from Fresno, Calif.
Copyright 2012 The Associated Press.