The latest setback for the Grand Valley’s wine industry can’t be seen, it can only be tasted.

Smoke from the Pine Gulch Fire settled in the area, blocking the sun for days, and may have been absorbed by grapes in vineyards across the Grand Valley, leading to a phenomenon known as smoke taint.

The closer the grapes are to harvest, the more susceptible they are to taint, and with the thick smoke from the fires settling in right in the middle of harvest, it’s caused a huge concern.

“The timing was about as bad as it could be,” said Miranda Ulmer, viticulture specialist at the Colorado State University extension office. “Vineyards here have never seen this before. This one is bad because of how close it is to the largest wine region in the state.”

Smoke taint happens when compounds from smoke — called free volatile phenols — are released from burning wood and bind onto the sugars within a grape’s skin. Drinking smoke-tainted wine has been likened to licking an ashtray and affects red wines more so than others. Even thoroughly rinsing grapes with water probably won’t help to keep the taint from overwhelming the grapes.

Two of the key indicators of whether or not smoke has binded to the sugars are sky visibility and presence of ash.

“If visibility is beyond (6 to 10 miles), you’re probably fine. We had some days where you couldn’t see that far and there was ash falling from the sky,” Ulmer said. “If there’s ash on your grapes, chances are they have smoke taint.”

Restoration Vineyards, at 3594 E½ Road outside Palisade, is in the midst of its grape harvest.

Gary Brauns and his wife, Linda, who is also the winemaker, are dealing with about half of their crop compared to last year because of grapes lost to earlier freezes.

When harvest began this week, Restoration sent some of its grapes to be tested for smoke taint at ETS Laboratories in California, the premier wine lab in the western U.S.

ETS is backlogged with testing batches throughout California and Colorado. Results could now take as long as three weeks, but the Braunses are assuming the grapes have been tainted.

“I can see Grand Mesa and the Bookcliff Mountains from our property. Two weeks ago, I couldn’t see any of it. Visibility was maybe a mile,” Brauns said. “We had some ash here, too. Some of the staff was vacuuming it off of the seating. It was apocalyptic.”

Because of the backlog at ETS Labs, it’s unclear how many vineyards have been affected by smoke taint and to what degree. Smoke taint is especially prevalent in vineyards in Australia and California, but both are at, or near, sea level and have thinner grape skins.

Jenne Baldwin-Eaton has been involved in the wine industry in the valley since 1994 and has never seen a fire this bad this close to grape ripening.

“Our grapes here have thicker skin,” Baldwin-Eaton said. “I have seen some samples come back with low levels of smoke taint. We still don’t know how much smoke is needed, and we don’t know what role high elevation and temperature play.”

Thick skins might make the grape less permeable for the volatile phenols, but there isn’t enough data on smoke taint at this elevation, Ulmer said.

In fact, it’s a phenomenon potentially exclusive to the Grand Valley. This is one of the highest elevations for grape growing in the world, only rivaled by areas in China and Argentina.

As Restoration waits on results, the staff is continuing with its harvest. White wine doesn’t use any skin and isn’t barrel aged, so it will be able to hit the shelves in about four months, Brauns said. Restoration will also be able to make rosé wine because it uses less grape skin.

One silver lining is that because Restoration is operating with less crop, fewer grapes will be impacted by the smoke, Gary Brauns said. He said if the wine is ashy and therefore doesn’t meet their standards, it won’t be sold.

Restoration, which produces about 90% of the wine it sells, has a deal with a seller to not have to pay if any shipments are tainted. It also has smoke taint and crop loss insurance for its own grapes.

“It’s kind of a back-handed blessing when you think about it,” Brauns said.