Legal marijuana is in the air across California, but local and state law enforcement agencies say they won’t retire their pot-sniffing narcotics dogs anytime soon.

At first, it might seem like California’s legalization of recreational pot would render canine units’ weed-sensitive noses obsolete. Indeed, some K-9s are being pulled from routine patrols, and new K-9s are sometimes not trained on pot. But police agencies say their drug-trained dogs still have plenty of value, especially when it comes to taking down large-scale drug operations.

“While laws regarding marijuana have changed, certain activities are still considered crimes,” said Giselle Talkoff, spokesman for the San Francisco Police Department. “Laws and regulations still govern sales, possession and transport, [and] there are times when the illegal possession of marijuana can coincide with other crimes.”

Most of California’s drug-trained police canines go through an intensive training program where they learn to bark or sit when they smell heroin, cocaine, methamphetamine or marijuana. The California Highway Patrol, which employs 42 drug-sniffing dogs, trains them for 440 hours before they go out into the field, according to CHP spokesman Mike Martis Jr.

When Colorado legalized recreational marijuana in 2012, police departments there began talking about what to do with their narcotics canines. Some agencies were worried that the dogs would wind up calling unnecessary attention to legal weed, but Denver’s four police dogs have continued to be a key part of the force, said Denver Police Department Capt. James Henning.

Rather than retire expensive animals, “We decided to keep them — and it was a good thing, because the illegal marijuana trade is booming in Colorado,” Henning said. “Legalization has almost made it more necessary to have good marijuana dogs, which is something nobody ever expected.”

San Francisco and San Jose police departments have no plans to retire or retrain their dogs. The Alameda County Sheriff’s Department, which uses narcotics canines on patrol and at the airport, and lends their pooches to Oakland on occasion, is also hanging on to its current contingent, said its spokesman and former K-9 trainer, Ray Kelly.

Those decisions could pose legal problems, both for police and for anyone these dogs call out, according to Lauren Mendelsohn, a criminal defense attorney who specializes in cannabis law.

“Drug dogs are trained to smell four different drugs. They’re not taught to differentiate between them,” Mendelsohn said. “Having a dog indicate they smell something gives an officer probable cause to obtain a warrant.”

However, Prop. 64 specifically states that legal amounts of marijuana and cannabis products don’t create the basis for a search, detention or arrest. A dog that alerts on marijuana could taint an otherwise lawful search that turns up illegal guns or other contraband. “There’s a strong argument that if one of these four-odor dogs smells something, that it violates the statute,” she said. “It will be interesting to see how it plays out in court.”

The Law Enforcement Action Partnership, a national group of current and former police officers who support an end to the War on Drugs, agrees that the use of drug-trained dogs can create legal problems. Rusty White, a spokesman for the partnership and a former canine trainer, said some police departments cut corners by training their own dogs, and their noses might not meet legal standards.

“If anyone is stopped, the first thing you ask is: is the dog proven, is the handler proven in a court of law?” White said.

The U.S. Police Canine Association — a national organization for police departments that work with these dogs — isn’t offering any guidance on what to do when states legalize pot. “It will be up to those agencies to develop a policy that’s best for their community,” said David Ferland, the association’s executive director.

Seattle Police Department spokesman Sean Whitcomb said it is possible to retrain drug-sensitive dogs to ignore marijuana. That’s what his agency did when Washington legalized pot in 2013. Officers have retrained the dogs by not rewarding them for finding pot. “Imagine you’re in an orchestra and you can play the violin, viola and cello. Now imagine you stop playing cello — you’re going to lose your skill,” Whitcomb said.

Most trainers agree the dogs can be retrained, said Bill Lewis II, a spokesman for the California Narcotics Canine Association. However, many say it’s too expensive and time-consuming to bother, he said.

Local and state police agencies say they’ll work around the legal issues by leaving behind narcotics dogs when out on patrol. Instead, they’ll be brought out once a large-scale grow or trafficking operation is suspected.

“Think of the dog as a specialized unit or investigator,” Talkoff said.

And, even though canines cost plenty to train, Kelly of the Alameda County Sheriff’s office says they save about 1,000 officer hours each year searching for drugs, weapons and other contraband, and good ones wind up paying for themselves many times over. One retired canine found $70 million in drugs, he said.

The use of these dogs is evolving as drug laws change, but the dogs are irreplaceable, Kelly said. “There’s no technology yet developed that can replace the nose and ability of a dog. The need for dogs is more and more every year, and the work they do is tremendous.”

---

K-9S BY THE NUMBERS

• Number of drug-sniffing canines certified in 2016: 400
• Number of drug-sniffing canines in California: 800 (estimated)
• Cost per dog: $30,000
• Popular breeds: Belgian malinois, German shepherd
• Length of training: 6 weeks/440 hours
• Average career span of canine unit: 6 to 10 years

(Sources: California Narcotic Canine Association, Alameda County Sheriff’s Dept, California Highway Patrol)

Beth Winegarner is a San Francisco-based freelance journalist and author. Subscribe to the Chronicle’s enhanced cannabis content at www.GreenState.com