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Watershed Moment

Of grapes, frost, fish and ice

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There is a sorrowful, scraggly specimen of a grapevine that lives in the northeast corner of a rocky little hillside vineyard directly under a black oak tree. It never really got a chance to flourish, and it never produces anything more than a handful of tiny berries for the birds to eat. This year, the downtrodden little vine just let its freak flag fly—unfurling a bright green leaf or two, waving at the sun, in early February.

The freaky thing about it is that in normal years, this particular half acre of Zinfandel can't be bothered to leaf out until Easter. That's just fine for the shiftless, procrastinating crew tasked with pruning the vineyard—a crew of one, yours truly. And lucky for me, most of the vines slumbered on into March.

Grapevines "spring forward" according to the weather, not the calendar. Because the winter was mild through January and February, grapevines throughout California began to wake up early, ready for the growing season. The quality of the 2015 vintage isn't necessarily a concern—in the North Coast, some winemakers say, great wines have been made from early harvests.

The real danger is frost. Even after a balmy spring day, Jack Frost, in the form of a radiation frost event, can displace warm air near the ground and freeze the tender new shoots. It won't kill the hardy grapevine, but when it grows back, it will offer half or less of the original crop.

If a little sparkly frost on the vines is bad, you might think that spraying a vineyard with water and making it into an icicle landscape would be a total disaster. Instead, it's a counterintuitive strategy that growers have employed for decades to protect their vines. Think of the ice in a highball. The ice isn't just making the whisky colder, it's using the comparative warmth of the whisky in order to melt into water. The reverse happens when water condenses to ice: a little heat is released, protecting the grapevine's tiny leaves even while they're encased in a layer of ice, as pictured above.

Near the Russian River, problems arise when everyone and their neighbor is pumping water out of streams all at once, and stranded fish become collateral damage. This year, during an official frost season that began March 15 and runs through May 15, vineyard operators in the Russian River Valley watershed are required to file and comply with the Water Demand Management Program in cooperation with the North Coast Water Coalition in order to take water from the river or from wells adjacent the river. Now, growers will have to keep one eye on the thermometer and another on the water gauge. And they'll be praying that Jack Frost doesn't get too freaky on them this year.

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