Despite widespread flooding, mudslides and other catastrophic damage from the back-to-back atmospheric rivers that have been pummeling California this past week, water managers are still ringing alarm bells over the lack of snowpack in the Sierra Nevada, a critical water source for the state. As of Thursday, the Golden State’s snowpack stood at 75% of average for the date.
California, however, is far from alone in its snow woes. The entire American West has been plagued by unseasonably warm temperatures and rain that melts snow, compounding what the National Oceanic and Atmospheric Administration (NOAA) has been referring to as a “snow drought.”
As of Sunday, 78% of snow monitoring stations in the West measured below normal snowfall. Oregon’s snowpack got a bit of a boost from the storms, but it still sits at just 74% of normal for this time of year. In Washington State, this snow drought is far worse—some of the worst conditions in the nation—with much of the western part of the state receiving almost half of its average snow water equivalent.
The repercussions will stretch far beyond mountain ski slopes down to the region’s vineyards. Here’s how.
From Water to Wine
It’s no secret that crops—even drought-tolerant grapes—need water. But while it may seem like any precipitation will do the trick, farming requires a complex balance of rain and snow.
Precipitation is caught in two ways: groundwater and surface water. Groundwater is absorbed through the soil, where it seeps into permeable rock shelves that form underground aquifers. These underground storage systems seal in water and prevent evaporation.
But soil can only absorb so much, and some topography, like mountains, don’t contain large sections of porous rock that allow water to seep deep into the ground. Instead, water runs off along the surface into streams, ponds and reservoirs.
Snowpack, essentially deep layers of snow that get compacted underneath one another, is like a cheat code for this storage system. Below-freezing temperatures in the mountains allow moisture to linger and melt later in the year, replenishing reservoirs that have been drained from use and evaporation. This is why snow has become a crucial supply of water in western regions that experience dry summers and prolonged periods of drought. In California, for example, a substantial one-third of the water supply comes from snowpack.
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While rain, such as those from last week’s storms, fills ponds and reservoirs that grape growers rely upon, lower-than-average snowpack leaves questions for this summer. Cody Copp, assistant professor and horticulturist at Oregon State University, explains: “As winter snowfall shifts instead to rain, less water of this precipitation is ‘stored’ for use in irrigated agricultural regions that rely heavily on surface water.”
But that doesn’t mean farmers and households who use groundwater will be unaffected. Across the United States, water levels in aquifers have been dwindling. As previously mentioned, once saturated, soil loses its ability to soak in additional water. So, downpours like ones that have recently blasted across the West Coast are unable to seep into the ground to replenish these subterranean reservoirs. Many are being drained at a far faster rate than they can recharge. This is why, after years of drought, groundwater has become an increasingly contentious topic.
Because of groundwater overdraft, the Oregon Water Resources Department is seeking to update its permitting process to prevent tens of thousands of wells from going dry. In parts of California—for the first time in the state’s history—there are talks of imposing legal limits on how much can be extracted. “Your well is not just a magical fountain you can turn on,” says Charles McKahn, owner and winemaker of McKahn Wines in Napa Valley.
A healthy system of surface water, fed by snow, helps reduce the need to turn on that fountain.
“A huge snowpack, that’s what it takes,” explains Andrew Quady, CEO and winemaker of Quady Winery in California’s San Joaquin Valley. “It melts slowly through the spring, refilling the reservoir. A lot of farmers are linked to a system of those canals. The hope is the ‘ditch water’ can get you through into August, sparing the well’s groundwater as much as possible.”
Even those who dry-farm benefit from snowpack. Because snowpack moves slowly and steadily through the watershed, it keeps soil saturated longer, reduces erosion and helps to clean the surface water. Pounding rain brings water but also erosion, which negatively impacts soil quality and stability, disrupting the delicate balance dry farmers work so hard to achieve in their vineyards.
When precipitation comes in a massive deluge, foregoing or even melting snow, it ripples through the ecosystem the entire year. Vineyards get an overabundance of water when it’s not quite as critical, but far less when it’s desperately needed by the vines, when the fruit begins to set and start to ripen (a stage referred to as “veraison”). “These boom-and-bust cycles are something we have to get used to—one-time precipitation events versus gradually coming,” says Dylan Walker, sales manager and winemaking assistant at RoxyAnn Winery near Medford, Oregon. “We have to adjust how we store and use water.”
How Winemakers Are Weathering the Storm
There are three keys to making the most of every drop. “We want to see our ponds full, recycle as much [water] as we can and not overdraft our groundwater,” says McKahn.
Less is certainly more when it comes to watering these days. A study in 2021 from the University of California at Davis reported that growers could water with half of previous irrigation levels without affecting quality. Smaller canopies and wider spacing help vines use less water and stretch roots further to find water. At the Delmas/SJR Winery near Walla Walla, Washington, the mini-head-trained technique with vines grown very low to the ground reduces water needs despite their easy access to a groundwater system from the nearby Walla Walla River.
“We are able to bury the trunk, head and first few bud positions on each shoot during the winter,” says Brooke Delmas Robertson, director of winemaking. “And in years when water is a concern, our vines have the stress training built-in already.”
The Delmas team takes advantage of well and canal water when irrigation is needed. Many wineries without direct access to canals and streams capture and store precipitation in retention ponds. However, this isn’t a one-size-fits-all solution.
More water-saving action will likely be needed in some wine-growing regions this year. Oregon, for example, has been hit with multiple atmospheric rivers this season, like California, but did not accumulate the same level of snowpack as the Golden State.
RoxyAnn Winery is one of many vineyards in the southern part of the Beaver State that currently has a full pond but lower-than-average reservoirs. A technique called pressure bombing helps the team measure hydration levels in the vines. Vineyard workers take leaf samples from quadrants, seal them in a pressure chamber and introduce nitrogen to force sap from the leaf to measure hydration stress. This enables the team to water the vines precisely. “Then you’re only using what you really need,” says Walker.
Though watering less is a hot topic in the wine world, one of the industry’s buzziest movements is effective water reclamation. On average wineries create 6 million gallons of wastewater from cleaning for every gallon of wine made. Several technologies help wineries remove harmful chemicals, like nitrate, from this effluvia, making it safe to reuse for irrigation.
Traditionally, oxygen aeration was used to slowly remove chemicals. New systems, using everything from enzymes to electrically active microbes, speed up this reclamation process and make it more efficient. One of the most popular new innovations is Biofiltro’s “worm-powered wastewater solutions.” Quady is one of many winemakers who have invested in the technology, which uses a series of pH adjustments to filter wastewater through beds of earthworms. The invertebrates uptake nitrate, making the water that seeps through safe to apply to the landscape.
Ultimately, in the face of more frequent droughts and a changing climate, growing wine grapes demands flexibility and fortitude. “We’re at the mercy of Mother Nature,” says Walker. “We farm regardless and make wine regardless. So we get what Dioynisus gives us.”
Published: February 9, 2024