Three Bay Area water agencies have stored enough water in a huge underground "water bank" to supply nearly a half-million families with a year's worth of water.
But it's uncertain whether they'll be able to bring it to their customers' taps. That's a big problem, especially if the drought extends into a fourth year.
"We're stranded," said Jim Fiedler, chief operating officer with the Santa Clara Valley Water District. "We can't get the water back to us."
Also cut off from their banked supplies this summer: the Alameda County Water District, which serves the Fremont area, and the Zone 7 water district in Livermore, Pleasanton and Dublin.
They've been told that they might be able to get some water in September, but supplies may be limited. So the districts are looking at costly alternatives -- including pumping millions of gallons of water uphill, from south to north.
All three districts -- serving about 2.35 million people -- store surplus water from wet years underground at the Semitropic Water Storage Bank, near Bakersfield. The plan is to withdraw it during dry years -- like now.
Such storage is widely recognized as the least costly and most environmentally sound way to hold a water reserve.
But water banking relies on a complex multiparty agreement -- a "water exchange" -- among the state, the water bank and the water agencies. It's necessary because of water's north-to-south flow.
This is how it is supposed to work: During winter rains, Bay Area water agencies send their state-supplied water southward to the bank, to be put in storage. Then the bank releases the water farther southward, to farmers for springtime irrigation. In exchange, the Bay Area gets those farmers' share of state-supplied upstream water, shipped to the region from the Delta in the summer and fall.
But this year -- in a surprise move to protect the Delta because of the drought -- the state government largely dropped out of this exchange, cutting off the upstream supply.
This caused the routine exchange to break down.
"There has to be water moving through the system ... to make it work," said Jason Gianquinto, general manager of the Bakersfield-based water bank. "If water isn't moving ... then it is stranded where you can't get it."
Everyone knew this was a risk, water managers said. But it seemed remote.
"It was never envisioned that we would have this critical a year, where there would be little or no water allocated," Gianquinto said.
The Santa Clara Valley Water District has an ambitious $5 million plan if expected water allotments don't come through. It will reverse the state's plumbing, pumping its federally supplied water directly out of the bank -- moving it upstream from south to north -- where it can be reached.
Four generator-powered diesel pumps would suck and push the water 75 miles up to farmers who depend on federal water. In turn, the federal government would release an equal amount of water from the San Luis Reservoir to the Santa Clara Valley Water District.
The "reverse flow" project would be only the second time in its history that the California Aqueduct has changed direction. The last time, in 1977, was to send floodwater north.
This project is important because the Santa Clara Valley district depends on the Semitropic water for 25 percent of its treated water.
"There is no margin of error," said Joan Maher, deputy operating officer at the district, which requested water from Semitropic in January.
By fall, she said, "there's a good chance we'll get what we need. But we can't afford to have them tell us it can't be done. Our users depend on us. There's no substitute for water."
As the projects await state approval, the water district is ordering pumps and arranging to rent the power generators. Even if the agency gets some of its promised water, the pumps will be installed for use in any future cutoffs.
But pumping water upstream is not feasible for the other two districts. The Alameda County district, with customers in Fremont, Union City and Newark, may buy more water from San Francisco's Hetch Hetchy Reservoir.
Zone 7 has been unable to get its Semitropic water this summer, but residents have successfully reduced demand, said General Manager Jill Duerig. And, she said, Semitropic has told Zone 7 it can have the relatively small amount it requested, once, as is expected, the state releases some Delta water in the autumn and winter.
Alameda County Water District is hoping conservation, groundwater and buying water will carry it through the drought, said Steve Peterson, the district's operations and maintenance manager.
"We knew there would be risks in advance of entering into this water banking program," he said. "Now it's how we manage those risks."
Because the district withdrew a lot of banked water last year and stored it nearby, this year isn't as bad as it could have been, he added.
The problem highlights the vulnerabilities of California's stressed water supply in this severe drought, said Ellen Hanak of the California Public Policy Institute. Every source of water has some degree of reliability problems, she said.
Groundwater banking is a practical and inexpensive way to augment California's water storage, costing $10 to $600 per acre foot. Reservoirs, recycled city water and seawater desalination all generally cost more, ranging as high as $2,500 per acre foot, Hanak said.
"You can't criticize for having banked down there. It was designed for normal dry years," she said.
"But networks get broken. The most reliable water is under your feet."
Contact Lisa M. Krieger at 650-492-4098.
Santa Clara Valley Water District: 262,665 acre feet
Alameda County: 138,398 acre feet
Zone 7 (Livermore, Pleasanton, Dublin): 81,952 acre feet
Total: 483,015 acre feet