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I woke to heavy banging on my front door. It was 3 a.m. on Wednesday and the first phase of what would become a complete evacuation of Calistoga. I gathered my things and rushed outside to find my neighbors huddled in small groups discussing the only route out of town as feathers of gray ash drifted down from an eerily burgundy-colored sky.

“There’s a mandatory evacuation in north Calistoga, but where we are we’re only under an advisory to leave,” said Bruce Regalia, one of Napa Valley’s famed winemakers. “All the roads out are closed except for Highway 29.”

I nodded slowly, still groggy and reeling from days of little sleep, having spent hours crisscrossing the valley taking photos and talking to winemakers and vineyard experts as I attempted to better understand the impact of what U.S. Rep. Mike Thompson has called, “ the worst fire disaster in California’s history.”

“What about the wine?” I asked, more as a feeble attempt to inject a little humor into the otherwise somber scene than as a real question.

“It’s only wine,” Regalia said and then gave a tempered laugh. “We’ll do what we can when we can, but nothing is worth putting a human life in danger — there’s always another vintage.”

As I drove south to join my wife and children in Los Angeles, I pondered Regalia’s words and how they echoed what I’d heard often during my previous days’ journeys.

First concern: Safety

Speaking to winemakers, winery and vineyard owners, wine scientists and all sorts of wine professionals I heard a consistent theme: that the Napa Valley, and Northern California more broadly, is facing a life-threatening, epic-sized disaster where the first priority must be to keep people safe and secure.

“Our first goal is to keep people safe,” said Garrett Buckland, president of the Napa Valley Grapegrowers Association. “If a vineyard is determined safe, then some of our growers have gone in to assess damage, but some have decided that a few tons of remaining grapes might not be worth the risk.”

Keeping crews healthy

“There are some people that have their crews out there picking, and that’s not OK with all this smoke in the air,” said Kevin Morrisey, winemaker at Ehlers Estate Winery. “We’re lucky that we picked all our grapes prior to the fires, but for those that haven’t they need to wait until the air conditions improve or the crews have proper safety equipment in place.”

“Our crews have all been trained and fit-tested for respirators and so all the crews are utilizing them when out in the vineyards, but I’m not sure what other people are doing,” said winemaker Steve Matthiasson. “People are just trying to make things work. The problem is that we are right in the middle of harvest, which means that tanks are in the middle of fermentation, grapes are still hanging on the vines and there are so many of the crew that make the bulk of their money this time of year that I worry that people might be tempted to loosen standards. I hope they don’t.”

“Some have turned to mechanical harvesters,” Buckland said. “That way they can limit exposure because they have enclosed spaces that are air-conditioned for the driver.”

“Sometimes there’s a tendency for people making wine to go a little cowboy, doing things to make the perfect wine but putting themselves and others at risk in the process,” said Morrisey. “No one needs to be hiking into restricted areas to check on their grapes or a winery. Heading up in the dead of night to perform that one extra punch-down of your wine without power alone is just stupid and puts yourself and others at risk.”

Uncharted waters

Most of those I spoke with were trying their best to remain safe and also take care of business as much as possible. Grapegrowers with any fruit still left on their vines were assessing damage and deciding on next steps.

“We’re at about 75 percent picked in Napa, with about 20 to 30 percent of the cabernet grapes still out on the vines,” Buckland said. “Many growers are deciding between either picking, irrigating or abandoning the crop altogether.”

Buckland said the problem with picking the grapes now is that they’ve been covered by a layer of smoke and ash whose chemicals can impart a campfire aroma to the final wine called smoke taint. On the other hand, because the grapes are ready to harvest, keeping them out longer in an attempt to see if conditions improve has its own risks. Even so, some are considering watering the vines to allow the fruit to hang on for another week, waiting and hoping for less smoke and perhaps a reduction of the film on the grape skins through wind action and time.

My own sampling at some of the finest cabernet vineyards from the southern to the northern end of the Napa Valley revealed the intense woodsy smoky aroma as the predominant flavor.

“Some growers are just going to say it’s not worth the effort or risk to life and limb to bring in fruit that may or may not produce the level of wine desired,” said Roger Boulton, professor of enology in the Department of Viticulture and Enology at UC Davis. “For those grapes that are harvested post-fire there are some unanswered questions because we have never had a situation like this before. In the past, our experiences with smoke taint have been caused by fires that happened weeks prior to harvest. So most of the studies that have looked into the phenomenon are based on different conditions.”

Smoke taint

As smoke and soot settle on the grape skins, some of their chemical compounds adhere to the waxy layer of the grapes. Over time these chemicals are incorporated and metabolized by the fruit, causing a host of negative issues to both flavor and physiology.

Deciding if and when to harvest the grapes is only the first step. Once in the winery, typically red grapes are allowed to ferment into wine for days, sometimes weeks, so that the color and tannic profiles of the wines are allowed to be infused with the otherwise, initially, nearly colorless grape juice. But with the smoky residue on the skins winemakers are faced with a dilemma: trying to optimize color extraction while minimizing smoky flavors. And the problem is that there seems to be no one best approach.

“Our goal is to get the color but not the smoke,” said winemaker Bryan Parker of Rutherford Hill Winery. “We still have some fruit out and hope to bring it in, process it very gently and keep the free run separate from the pressed lots. However, one of the problems that is being exacerbated by the fires is that power has been spotty, which means we have needed to watch things extra closely.”

Many of the winemakers described a similar approach; however, some are considering adding in enzymes to help break down the skins faster, releasing their color quickly and then pressing off the unfinished wine in increasing concentration, or “pressed lots,” which can then be tested for smoke taint over time.

“One of the problems is that the smoke-taint molecules can become bound to sugar molecules, making them heavy,” Boulton said. “However, as the wine finishes fermentation or ages, these larger molecules begin to break down, releasing them beyond our perception threshold, so an early sample that does not display smoke taint may sometime in the future. So keeping the lots separate is important.”

Beyond separation

Other techniques for limiting smoke taint may include quickly heating the grapes to a very high temperature, referred to as flash detente.

“I haven’t picked anything due to low air quality and wineries operating at limited capacity but plan to do some flash detente to help the smoke,” said Alisa Jacobson, head winemaker at Joel Gott wines. “Limiting skin contact is the main goal. The flash helps because you get your extraction quickly so you don’t sacrifice quality — the quick heat volatilizes all aromatics, including the smoke. We’ve had smaller fires in wine country for the last few years, so I’ve played around with different winemaking techniques, but this is unprecedented.”

Others are considering washing the grapes with ozone spray, but Boulton recommends against this untested and potentially unsafe practice.

“Some might be considering desperate actions, but using ozone to spray down grapes will not have the intended effect and might actually cause other negative aromatic-related issues and also could be dangerous for those conducting the process,” he said.

Buckland agrees that using ozone to wash grapes would need to be conducted with caution.

“Using ozone for this is not something that I’d recommend,” Buckland said. “I’ve never really heard of this being done, and ozone use requires respirators and other safety precautions.”

Washing grapes may have limited effect anyway because most of the off-tasting chemicals are absorbed into the grapes water-resistant waxy coat.

Experimenting and testing

Beyond limiting skin contact, some winemakers will be conducting a variety of experiments to see what works best.

“I hear that some are thinking about adding enzymes to the fermenting wine to help extract color fast, but this will also extract all the other stuff they are attempting to avoid, too,” Regalia said. “I don’t recommend it.”

Loss of water and power

I found skeleton crews of a few mask-clad employees trying to make do with limited resources at nearly every winery I visited and every winery is finding it difficult to manage.

“We haven’t had power for the last 36 hours or so,” Matthiasson said.

Depending on the winery, not having power can result in limited well water, loss of temperature controls leading to overheated fermentation and also hot conditions for crews. And although many wineries have back-up generators, some have found it hard to keep them full of fuel and a few have found that the power was insufficient to run the powerful cooling units.

“We have a generator and it helps. We still don’t have power, but we’re making do,” said Cherie Melka, winemaker and co-owner of the new Melka winery north of St. Helena on the Silverado Trail. “This is some way to launch our new winery,” she laughed.

Surrounded by her new facility, she shook her head. Small containers of grapes were stacked in what would have been a chilled cold room waiting to be processed.

“We’ll get through this and I am hoping for the best,” Melka said and then quietly, almost as if to herself, “and the fruit looks so great.” She held up a cluster as if in evidence.

Concern for fermented or aging wine

Many of the winemakers said they were concerned that even the wines that were already fermented might be affected by the smoky air and soot. However, according to Boulton, wine that has already been fermented should not be affected.

“It’s really a question of physics,” Boulton said. “The surface-to-air ratio of the processed wine should not allow smoke taint to be a factor in wines that are going through — or have finished — fermentation.”

Nevertheless, if surface area is the key variable, then some winemakers worry about their practice of aerating wine through processing, such as pump-overs.

“We are taking precautions to limit the exposure of the wine to air,” Parker said. “No one has ever experienced anything like this before and so we are learning as we go. It might just be some insurance, but we’ll do what we need to do.”

Most wines exposed to smoke this year are likely to be sent off for testing and even filtered to remove off flavors. My personal experience in 2008 with smoke taint suggest this has limited benefits but perhaps the tools and techniques for testing and filtering have improved since then.

Living in chaos

“It’s like a whole can of worms and we’re just going for it here,” Matthiasson said. “It’s chaotic and we’re in uncharted territory — you’re just out there trying your best, experimenting. Trying to emphasize safety, and then in the winery treating it like our version of triage. We’re concerned about our employees, family and friends, and our own safety. Then the power’s out at the winery, ash is falling from the sky, we spent all night last night on ember patrol in the vineyards and then we’re trying to make the wine well in all this chaos.”

Normally when smoke taint is suspected in either grapes or wine, samples are taken to a laboratory such as ETS or Scott Labs for further testing. However, because of the level of smoke in the air and limited power, even the labs are having trouble.

“The labs can’t test because they are full of smoke themselves,” Matthiasson said. “That is even if we could get samples to them. Lots of our people have been evacuated to shelters.”

“The Napa Valley Grapegrowers have some resources on our site that growers and vintners will find useful,” Buckland said. “We are working hard to keep things organized and updated, but that will come over time. Our first priority is safety.”

The Napa Valley Vintners also have a resource page set up on their site that includes ways for the public to donate.

Each person I spoke with sounded tired but resolute, often reminding themselves that safety was the priority.

“Making wine is what we do and we all take pride in our craft,” Matthiasson said. “We are each trying to do our best in what are unimaginably challenging conditions. We’re waiting for power for days and then it comes on and we’re thinking, ‘Quick, let’s get the wine in tank set and ready if and when the power goes out or we get evacuated’ — we want to leave the wine in all the various stages in good condition. But when we do get the call to leave, I hope everyone takes that seriously. There’s always another vintage.”

“It’s chaotic and we’re in uncharted territory — you’re just out there trying your best, experimenting. Trying to emphasize safety, and then in the winery treating it like our version of triage. We’re concerned about our employees, family and friends, and our own safety. Then the power’s out at the winery, ash is falling from the sky, we spent all night last night on ember patrol in the vineyards and then we’re trying to make the wine well in all this chaos.” Steve Matthiasson