(NVR) - Wine may be the alcoholic beverage that has made Napa Valley famous, but beer is what the locals most prefer to drink.

That's one of the latest information nuggets from a survey of people arrested locally for suspected Driving Under the Influence (DUI).

The survey found that most arrests for drunk driving are of beer drinkers, and most of them are Napa locals, not tourists -- facts that run counter to many people's assumptions.

The reasons are many: wineries are careful to prevent their customers from driving drunk, wine drinkers are more likely to have a designated driver or taxi set up, and despite the name “wine country,” beer drinkers predominate in Napa, members of the DUI Prevention Coalition report.

According to data compiled by the DUI Prevention Coalition, in 2014 there were 361 beer drinkers arrested for suspected DUI, 174 who had drunk hard liquor, and only 114 who had drunk wine. Overall, beer-related DUI's were more than three times as prevalent as wine-related ones.

"Court records will show that the majority of people arrested are Napa residents," said Napa police Lt. Debbie Peecook. "These are not our visitors."

However, some Napans also say they think that the arrests of local beer drinkers, most of whom work in the service industry, reflect unfair targeting of locals rather than the wine-drinking tourists.

“We were kind of sick of wine,” Napa resident Bryan Donovan, who formerly worked as a barback in a winery, said of himself and his co-workers. “We would just go to some dive bar, where they were usually serving beer.”

Donovan witnessed the beer-versus-wine divide firsthand when he worked for the winery, and sees it as a class issue, although not one that was being perpetuated deliberately.

“I did see the highway patrol doing a good job doing traffic stops.  However, I see more traffic stops in the inner city. It’s simply easier. I could see how a local would feel like they’re being unfairly scrutinized.”

The DUI Prevention Coalition allows those arrested for suspected drunken driving to fill out an optional survey at DUI education classes. Among the questions are the type of alcohol consumed, the place of last drink, and the person’s age and occupation.

According to health education specialist Nancy Wynne de Rivera, most survey participants worked in the service industry, mainly as restaurant servers and bartenders. A little over half were between 26 and 46 years old, and most were driving from their homes or friends’ houses.

Peecook said the data reflects historic trends in Napa for the past several years, and believes it is mainly because not only do locals stick around town longer than tourists, but that tourists take more precautions and have a different mindset about drinking.

“A lot of them come in buses,” Peecook said. "If they come with a bunch of people, they usually come with a designated driver. They know they’re drinking.”

The Napa wine industry says it tries hard to make sure winery visitors do not drive under the influence.

“We take responsible hospitality very seriously, and encourage our winery members to do the same,” said Patsy McGaughy of Napa Valley Vintners, an organization that represents more than 500 wineries. “Since 2008, the Napa Valley Vintners has hosted quarterly workshops to certify local winery staff in responsible beverage service.”

McGaughy said that more winery visitors are choosing to take tour buses, taxis, or the VINE bus service rather than driving.