CONCORD — Neighbors of a backyard marijuana grow operation say while such a crop may be legal under state law, they fear it could attract crime — a concern city officials share.

The marijuana plants are visible through the home’s fence, and the potent smell has been wafting through the neighborhood, a neighbor told the City Council on Tuesday.

Mayor Ron Leone has asked administrators to present the City Council some options for regulating and potentially banning outdoor medical marijuana cultivation.

A group of neighbors uncovered the operation after smelling an odor resembling a skunk’s and called police, said one neighbor, who gave her name as simply “Evelyn.”

“I was really in shock when I received the news that they had the paperwork from the state that allowed them to cultivate marijuana in their backyard,” Evelyn told the council. “A lot of the neighbors who are upset about this didn’t want to come tonight because they are afraid …. They are afraid for their neighborhood.”

Officials have confirmed that the people living in the home in question are following the guidelines set by Proposition 215, the state measure voters passed in 1996 that allows patients and their designated caregivers to possess and cultivate marijuana for medicinal purposes.

Officials would not release the location of the home, fearing that doing so would endanger the residents and neighbors.

The homeowner growing the marijuana could not be reached, but a man who lives there earlier told KTVU the house is part of a collective that sells its plants to dispensaries.

“A lot of these people are homeowners; they’ve probably been here 20-plus years,” the man, who identified himself as “Joe,” said of his neighbors. “Of course they are more than entitled to be concerned about their neighborhood.”

Vice Mayor Bill Shinn, who spent 30 years with the Contra Costa County Sheriff’s Office, said outdoor operations in residential neighborhoods, while rare, should not be allowed in Concord.

“They end up becoming victims of home invasions,” said Shinn, adding that he supports patients’ rights to use medical marijuana. “Unless we have an absolute ability to control it, it just gets out of hand.”

Several cities around the state have enacted ordinances to regulate, restrict or ban medical marijuana dispensaries, but there is nothing on the books in Concord. A model for what Concord could adopt can be found in Moraga, where in 2011 the Town Council extended its ban on medical marijuana dispensaries to include banning outdoor grow operations after residents complained about one in a neighbor’s yard.

“It’s worked out well,” said Moraga police Chief Robert Priebe. “We have had no issues.”

Concord City Attorney Mark Coon is preparing a memo to present to the City Council at a yet-to-be-decided meeting.

Leone said he sympathizes with the neighbors.

“It troubles me so that’s why I’ve asked the city to look into the possibility of an ordinance that perhaps could restrict the growth to indoors,” he said.

David DeBolt covers Concord and Clayton. Contact him at 925-943-8048. Follow him at Twitter.com/daviddebolt.