02.09.2017  
 

Some Lodi Vineyards Underwater for Weeks

Rivers of storms delay operations as Mokelumne River overflows its banks

 
by Jane Firstenfeld
 
wine grape lodi vineyard flood
 
Ann-Marie Koth and Phil Silver kayak through the Kerner block of Mokelumne Glen Vineyards in the Mokelumne River Sub-AVA of Lodi. Credit: Brett Koth
Lodi, Calif.—Wine grape vineyards in the Lodi district continue receiving rain, and more is predicted for the next week. Low-lying vineyards have not been able to absorb all the water, and growers cannot predict when they might be able even to begin pruning.

Levees near the Mokelumne River have been especially vulnerable to flooding, according to Stuart Spencer, program director for the Lodi Winegrape Commission. High water levels and high flow rates already have breached some of its levees. He reports that the 28 weather stations in the Lodi district have recorded 19-26 inches during this winter season, compared a departure from the 30-year average of 17.91 inches per year.

With the river water already above vineyard levels, there is nowhere for the water to go, and until the rain stops, no way to predict when the vineyards will become passable. From a vineyard manager’s perspective, Spencer said, bud break is still at least a month away.

He also mentioned the possibility of damaging beaver incursions among the vines. When rivers overrun their banks, the large rodents may move into vineyards and gnaw on the vines. Growers may not even know this has happened until they can closely examine the vineyards. Sometimes, he said, they may sever the vine but abandon it if it is supported by trellis wires on the cordons.

Most Lodi area vineyards are drip irrigated, according to Spencer.

Mike Anagnos at Sunwest Ag Service oversees some 120 acres of Lodi-area vineyards. A few of these vineyards have remained underwater for a month, some with more than 3 feet of standing water. Lower level vineyards adjacent to the Mokelumne River are most affected. The river overflowed its banks, adding to the load in the vineyards, and the water has nowhere to go, Anagnos said.

“Normally we’d be pruning now,” Anagnos commented. He’s been tending these farms since 2004. The first time he suffered flooding was in 2007, when his tractor got stuck in the water and mud and two more tractors were needed to extricate it. Still, he hopes this year’s abundant water will help keep phylloxera and nematodes in check.

Professor Andrew Waterhouse in the Department of Viticulture and Enology at the University of California, Davis, confirmed this latter assumption. “A good flood will kill phylloxera, but the soil column has to be saturated with water. Persistent standing water should lead to saturating the soil totally. This does work well in sandy soil. Even irrigation flooding can suppress phylloxera in sandy soil,” he said, adding that this may not be true of other soil types.

Markus Niggli, winemaker at Lodi’s 4,000-case Borra Vineyards, works with 165 acres of vines planted on 8-12 different soil types. “Sandy loam absorbs nicely; wherever there’s clay, you don’t want to be,” he said. His Viognier vines near the Mokelumne River are currently 6 feet underwater and have been inundated for three weeks. “At this point it doesn’t hurt. We haven’t pruned, except for the Zinfandel, but we’re coming close to bud break.”

With precipitation relentlessly falling and the river still near the tops of the levees, there is nowhere to pump the water out. The later it gets, the more difficult it will become to maintain vineyards. Niggli still doesn’t know how multiple years of drought affected less-established vineyards, where he said the soil was “like concrete.” With ample water, he expects the roots will grow deeper. Niggli said that while normally he’d see bud break the second or third week of March, he hopes the stormy winter will cause a delay. 

The longer view
On Feb. 8, the California Department of Water Resources (DWR) released a statement sharing that NASA mapping had discovered land was sinking rapidly in certain areas of the San Joaquin Valley, putting aqueducts and flood control structures at risk
 
DWR director William Croyle said, “The rates of San Joaquin Valley subsidence documented since 2014 by NASA are troubling and unsustainable. Subsidence has long plagued certain regions of California. But the current rates jeopardize infrastructure serving millions of people. Groundwater pumping now puts at risk the very system that brings water to the San Joaquin Valley. The situation is untenable.” He added that DWR is conducting its own study of the effects of subsidence along the 444-mile California Aqueduct and other state water projects, hoping to identify potential actions to remediate damage and focused triage.

“Long-term subsidence already has destroyed thousands of public and private groundwater well casings in the San Joaquin Valley. Over time, subsidence can permanently reduce the underground aquifer’s water-storage capacity,” he warned.

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