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Winegrowers Can't Rely on El Niño

February 2016
by Jane Firstenfeld
napa reservoir rain
A vineyard reservoir overflows Tuesday in the Oak Knoll AVA of Napa Valley. In spite of intense seasonal rains, water researchers say these winter storms are unlikely to repair the damage done by a four-year drought.
Sacramento, Calif.—The much-anticipated El Niño winter has brought some precipitation to parched California and begun to replenish the vital Sierra Nevada snowpack. But according to experts including the National Weather Service in Sacramento, a single “normal year” will not redeem the state from the ravages of a four-year drought.

Reservoirs have slowly begun refilling from historically low levels, and according to a Jan. 15 report on the water blog Maven’s Notebook, which monitors California water issues, “El Niño is not fizzling.”

Laurel Rogers, who handles communications for the U.S. Geological Survey California Water Science Center in San Diego, told Wines & Vines, “Water storage is key. It’s a big deal, in the reservoirs and mountain snowpack.” Rogers explained that snowpack data uses an April 1 deadline when estimating water equivalent because the last snow has typically fallen by April 1.

“It’s very important for planning. But if it all melts at once, we can’t capture it. We hope for a cool spring where it melts gradually.” Meanwhile, Rogers said, “We’re trying to work on the infrastructure and sustainability plans for the future. We’re trying to look at innovative ways to put new tools in the box.”

Additionally, she said, “Neither the (U.S.) Bureau of Reclamation nor the (California) Department of Water Resources have announced their initial water allocations yet for this year, so the water operators of these agencies probably cannot tell you much about water availability or allocations at this point.” The Department of Water Resources’ Data Exchange Center, meanwhile, shows that reservoir conditions are still well below normal.

Dr. Claudia Faunt oversees the Water Science Center. She told Wines & Vines, “In general, farmers are going to use the best available, cheapest water. In the western part of the Central Valley, for a long time they pumped a lot of groundwater, causing subsidence (sinking) of the water table. Now, state and federal engineered canals and projects deliver more water.”

The center looks at water supply, groundwater and seasonal patterns, Faunt said. “Fruit and nuts are permanent crops, a big investment that cannot be left fallow.” Because water has gotten expensive, some farmers have changed their crops, she noted.

“I don’t know the right answer,” Faunt acknowledged. “We’re trying to put together new answers. The groundwater system is a bank account, and the interest rates are changing. You have to decrease what you’re taking out or put more in. People need to think about becoming more efficient and use excess water in efficient ways. The easy answers have been tried—it will take some creativity.”

Despite the recent precipitation, she pointed out, “There is a general loss of soil moisture. It’s a big balancing game. I think agriculture uses water conjunctively, a combination of both surface and groundwater.”

She noted, though, that drilling deeper to reach groundwater sources results in more salinity in the water—not a healthy thing for grapevines. Among the industry players, “Gallo Winery has been very progressive,” Faunt said.

Can old ways bring new solutions?
Graphics from The National Drought Mitigation Center show that most of California’s wine country remained in moderate to severe drought conditions as of Jan. 17.

Paso Robles, Calif., one of the grapegrowing regions hit hardest by the drought, has seen above-average precipitation for the 2015-16 season, with rainfall surpassing the 17-year average of 4.7 inches with 6.6 inches of rain.

In the Central Valley city of Madera, however, readings are less positive. The 2015-16 precipitation total (2.82 inches) falls short of the 4.02 historical average.

Dan Sumner, director of agriculture issues at the University of California, Davis, pointed out that almost every vineyard in the state’s Central Valley relies on supplementary irrigation from a mixture of federal and state-supplied water. “It’s much more important in a drought. They must tap reservoirs, drill or buy water. We’re starting this year with empty reservoirs.”

Researchers at UC Davis are looking into more efficient methods to keep vineyards green. “We can drive along the highway and look at vineyards with micro-drip systems, which put the water right on the roots, and think how efficient that is. They’ve been doing it for a generation, and that’s one reason we have groundwater problems now.”

If micro-drip or other irrigation systems are in fact depleting groundwater levels, what is left for agriculture in a historically dry state? “What we are doing over the next few years is to try flooding fields during winter wet systems,” Sumner said. “We have people on campus measuring how much winter flooding will benefit almonds, alfalfa and vines.” Deep flooding during winter storms would, they believe, recharge groundwater supplies.

The mental image of deliberately flooded vineyards is perhaps disconcerting, but it’s not new technology. Nat DiBuduo, long-time president of Allied Grape Growers, a marketing cooperative serving some 600 grower-members in California, recalled his father flooding his fields in the mid-20th century.

“The vast majority of vineyards are irrigated. Most comes from groundwater or reservoirs,” he said. “In the San Joaquin Valley, it’s predominantly groundwater.” A little bit of seasonal rain will not replenish the supply. “It’s taken centuries to build.”

Flooding pr ovides two things, DiBuduo said. “It puts water down and the excess goes into ground” instead of running off into bays and estuaries. In soils that are excessively salty, the moisture goes below the vine root zones. “When you flood, the root zone is out of the middle of rows. It’s old-style farming.

Pumping too much groundwater creates another problem, he said. “Imagine an inflated water balloon between two layers of dirt. If you suck that water out, you can’t blow the balloon back up. We’ve got to come up with solutions. Farming’s been around for a long time, and farmers are optimists. We’re all survivors.”

Paso faces decision
Dr. Lowell Zelinski, a viticulture consultant and vice president of the Independent Grape Growers of Paso Robles Association, agreed. “Rainfalll here is OK but not great. It’s better than it has been, but not sufficient to affect groundwater. Typically our rain comes in the spring, so we’re still optimistic.”

Paso faces a political dilemma this year. A proposal to establish a new water district will come before voters March 8. The proposal asks landowners and registered voters if they want a district; funding is another question.

“I’d like to see the district formed,” Zelinski said. He thinks the district is likely but voters won’t pass funding for one. An emergency moratorium on new groundwater extraction in San Luis Obispo County was enacted by the Board of Supervisors, but “that lasted about two hours,” he said. “If you have an acre or 20 acres without a well, it’s now just rangeland.”

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