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LIVERMORE — A proposal to create a 1.5-acre outdoor marijuana farm on Tesla Road near Livermore raised immediate questions about crime, water use and general odor.

But a new question arose. Can the pungent smell of marijuana grown on fields adjacent to vineyards be absorbed into grapes and taint the wine made from them?

“That concern is not based on total nonsense,” said Anita Oberholster, cooperative extension specialist in enology at the UC Davis Department of Viticulture and Enology. “Nobody knows. But scientifically, it is possible that there is a potential impact.”

Oberholster said the introduction of cannabis among established grape farms could possibly affect people’s livelihoods. California’s grape and wine industry is a $31.9 billion industry with 637,000 acres of wine grapes planted.

Following news about a proposal to create a marijuana farm on Tesla Road near Livermore, the Tri-Valley Conservancy is working on a policy regarding cannabis farming in South Livermore.

“We are carefully gathering information from other wine regions and UC Davis to help determine our position on the issue,” said Mark Triska, who leads the Land Conservation Committee for TVC. “Given TVC’s mission to promote economically sustainable vineyards and orchards, we are concerned with any crop that may have a detrimental impact on Livermore Valley Wine Country and the South Livermore Valley Area Plan.”

Oberholster — who completed a research proposal to study marijuana’s potential impact on grapes — cited data from the University of Adelaide in Australia that showed it is possible that terpenes, the aroma compounds responsible for cannabis odor, could be absorbed into grapes. Researcher Dimitra Capone found the terpenes from eucalyptus trees planted near Australian vineyards affected grapes if they were within 50 meters

Oberholster said she’s been trying to conduct similar research.

“The grape growers in Santa Barbara County have been very worried about the impact of the hundreds of acres of cannabis right next to some of their premium wine regions,” she continued. “We have been urging the board of supervisors there to fund an environmental study to determine the potential impact of cannabis odor on grapes. It may or may not have an impact, and even if it does, we can probably determine a safe distance between cannabis and grapes. This will depend somewhat on the specific site and weather conditions, of course. But still, I think there is an easy solution, if we can just study the potential issue.”

Oberholster said terpenes biosynthesized into wine grapes during the growing and winemaking process could “change the character of the wine significantly.”

“If one terpene or a combination of terpenes overpowers the wine, making it one-dimensional or imparting unpleasant characters to the wine, the wine may be considered tainted,” she said. “Furthermore, absorption of terpenes on the wine grapes could be over the full growth period of the wine grapes, which is several months from pea size to maturity. Thus, a build-up effect is possible within the wine grapes, but needs to be investigated.”

Although federal law continues to make it illegal to use, possess, grow and sell marijuana, voters in California decriminalized the adult-use of marijuana for non-medical purposes and established state regulations for commercial production in 2016. Alameda County updated its code in 2018 to allow permitted cannabis cultivation operations in the unincorporated areas. In Oregon, legal commercial production of cannabis has been in effect for more than five years. Growers must obtain proper permits and adhere to state size limits.

In Oregon last year, two wine growers failed to convince a judge that their crops would be damaged by the scent of an adjacent marijuana operation.

The Associated Press said Yamhill County Circuit Court Judge Cynthia Easterday ruled that Smera Vineyard and Maysara Winery failed to meet the burden of proof to justify blocking the Wagner family from growing and processing its crop.

Calling it a difficult and close decision, Easterday said that while the potential for the smell of marijuana to taint grapes raises “a threat, a risk, and concerns, there is insufficient proof at this time by a preponderance of the evidence that it will damage plaintiffs’ current or future agricultural products.”

The federal case, filed by the Momtazi family, which sold its grapes to the Maysara Winery, is set to go to trial as soon as this month. The Momtazi family alleges that one of its repeat customers cancelled an order for six tons of wine grapes because it contained grapes grown on the section of their property adjacent to the cannabis farm. The customer, the lawsuit said, “believed it was likely the notoriously pungent stench generated by marijuana had contaminated the wine grapes and would adversely influence the wine made from such grapes.”

The lawsuit said the Momtazi farm was unable to market and sell grapes grown adjacent to the cannabis farm because of buyers’ concerns of contamination and has diminished the property value of their vineyard.

The federal lawsuit alleges the cannabis operation violated the Racketeer Influenced and Corrupt Organizations Act, or RICO, because federal law prohibits marijuana operations and sales. The farm, the lawsuit said, is a criminal operation.

Growing cannabis indoors is an option, Oberholster said, but it is more expensive.

In Santa Barbara, Carpinteria Valley residents filed lawsuits against cannabis farmers, saying the pungent odor emitted from their greenhouses wafted over their homes and schools. Some said it caused headaches and breathing problems.

“I was told that tasting rooms in Santa Barbara County had to close because the cannabis smell was so strong, and no one could smell the wines,” Oberholster said. “The smell happens mostly at bloom and processing but can be very strong.”

In August, the Santa Barbara Coalition for Responsible Cannabis signed an odor-control agreement with the Cannabis Association for Responsible Producers to install $20,000 carbon filtration systems on their greenhouses to keep the odor from spreading, the website,, reported.

Oberholster said Lake and Mendocino counties have not experienced issues with their cannabis farms, but the cultivation sites are smaller and longer distances from vineyards.

A study could determine what that distance should be, she said.

“I think cannabis and vineyards can coexist,” Oberholster said. “All we need to do is find the parameters.”