SACRAMENTO -- An expert on California's delta told a panel of the National Academies of Sciences on Sunday that their decisions about the largest estuary on the West Coast could alter how Californians use water.
"I view this as the thorniest water environmental issue in the West," said Jeffrey Mount, a professor at the Center for Watershed Sciences at the University of California at Davis.
The 15-member panel of independent scientists is meeting this week to examine whether the federal government should lift or modify limits on pumping from the Sacramento-San Joaquin Delta, restrictions that farmers blame for a water shortage that has left once-fertile fields to wilt.
At the center of the discussions are two environmental plans written last year by federal wildlife agencies. Both are intended to protect threatened fish by restricting how much water can be pumped from the delta.
The restrictions, combined with a three-year drought, have forced farmers to fallow thousands of acres and cities to impose severe water restrictions.
"We're going to help point the way to the most optimal management solution that can be found," said Stephen Parker, director of the academies' Water Science and Technology Board.
The situation is not so dire in some parts of the valley, including the Modesto, Turlock and Oakdale irrigation districts, which do not draw upon the delta for their water.
The panel, requested by Interior Secretary Ken Salazar, is exploring whether there might be other ways to preserve fish. It is expected to produce a recommendation in March, followed by another year of study about the state of the delta.
The delta, where rivers that drain from the northern and central Sierra Nevada collect, is the hub of California's water supply.
Massive state and federal pumps siphon drinking and irrigation water to more than 25 million Californians and the Central Valley farms that produce half the nation's fruits and vegetables.
But those pumps reverse the delta's flow in some areas, drawing in and killing the tiny delta smelt. The flows misdirect juvenile salmon to interior parts of the delta, meaning tens of thousands of migrating fish may never make it to the sea.
Along with the delta pumping, cities stretching from Northern California to the Central Valley divert fresh river water that otherwise would flow into the delta and out to San Francisco Bay. An estimated half of the water that once flowed through the delta goes elsewhere, altering the fragile ecosystem where hundreds of species live, Mount said.
"This may be the most invaded estuary in the world," Mount told the panel.
While state and federal water officials say the drought has been the biggest culprit in California's recent water troubles, the pumping restrictions have become a political target.
'Lifeblood' of the valley
Gov. Schwarzenegger and several members of Congress from the Central Valley, the area hardest hit by the water shortage, have rallied with farmworkers to call for the restrictions to be lifted.
"Water is the lifeblood of the San Joaquin Valley, and it is for the entire state," Rep. Jim Costa, D-Fresno, told the committee at its opening session. "Without water, you can't grow food and you don't have jobs."
Environmental groups say the plans, called "biological opinions," are necessary to protect the delta smelt, salmon and other vulnerable fish, whose numbers have plummeted over the past decade. They were written by the U.S. Fish and Wildlife Service and the National Marine Fisheries Service.
"They came up with credible plans to restore the estuary and these fish species," said Doug Obegi, an attorney at the Natural Resources Defense Council. "As fish start to do better, those restrictions could be eased."
To comply with the federal rules, state and federal water agencies did not pump an estimated 500,000 acre-feet from February, when the smelt protections were triggered, to June. That was on top of the 1.6 million acre-feet they could not deliver last year to cities and farmers because of low water levels in the state's main reservoirs, said Steve Martarano, a spokesman at the Fish and Wildlife Service.
Additional pumping restrictions to help migrating salmon could take effect this year, further cutting the amount of water farmers and cities receive.
Jerry Johns, deputy director at the state Department of Water Resources, said the amount of water lost from the smelt- related pumping restrictions was equivalent to the amount released from a state reservoir. And the fish have not rebounded, he said.
That suggests the population's decline may be related to a combination of factors, including agricultural chemicals or invasive species.
"Just controlling exports is not currently doing the job," Johns said. "There needs to be a broader way to attack this issue and better protect fish and water supply."
Federal wildlife agencies say they have the authority only to regulate pumping by the state and federal water agencies.