Illegal marijuana farming has been moving from the Sierra foothills and mountains to the Valley floor, law enforcement officials say, and they suspect it has something to do with California's controversial medical marijuana law.
The theory is that growers, facing increased law enforcement pressure, have abandoned mountain and foothill hideouts and headed to the Valley because of the opportunity to grow black market marijuana under the veil of legality.
For the past three years, authorities have found fewer pot farms on public lands in the Sierra Nevada and more in the flatlands, they say. Discoveries of pot farms have been widespread this year in farming areas of Stanislaus, Madera, Fresno, Tulare and Kern counties, said Bill Ruzzamenti, executive director of the Central Valley High Intensity Drug Trafficking Area task force.
And there's a new twist: Often authorities find medical marijuana recommendation letters from physicians posted at the perimeter of big grows – many letters for big operations.
Narcotics detectives believe drug traffickers are in charge of the grow sites. By using a collection of cards obtained by a number of people, or even photocopying cards, they attempt to make the farms appear legitimate, officials say.
"We run into groves with 15 cards to cover the grow," Madera County Sheriff John Anderson said. Some cards recommend a limited number of plants, but not all do. The physician recommendation typically is for as many plants as necessary.
The cards can slow down investigations because investigators must check claims that the pot is medical marijuana and that growers are caregivers who are growing pot for sick friends or family members, he said.
"It's a gray area because of Proposition 215," Anderson said.
Medical marijuana advocates question the motives of law enforcement officers who blame Proposition 215, the voter-approved law that allows individuals to use – and grow – marijuana for medicinal purposes.
"It's a way for law enforcement to smear the medical marijuana community without providing a lot of evidence," said Kris Hermes, spokesman for Americans for Safe Access, a national pro-medical marijuana group based in Oakland.
But investigators point to the sheer numbers of grows and the similarities in tactics.
In Tulare County, 480 marijuana farms and plots have been found on the Valley floor so far this year compared to 220 last year, officials said.
And Ruzzamenti says that based on flyovers of Valley marijuana farms, he estimates at least 1 million marijuana plants are under cultivation this summer.
Officials acknowledge there may be other factors behind the trend. For one thing, it's a lot more convenient to run a business closer to where people live.
In the mountains, traffickers have to divert streams for irrigation and haul supplies such as food and fertilizer into remote areas. Not so in the Valley, where water and road networks are more plentiful.
"It's easier," said Tulare County sheriff's Lt. Tom Sigley. "They can go to Jack in the Box for lunch."
Investigators also suspect Mexican drug cartels are behind some of the surge.
"It's like they had a board meeting," Ruzzamenti said.
Officials think a cartel might have been behind a big farm they raided last month west of Goshen, where Tulare County deputies found pot fields – some plants were said to be 20 feet tall – where medical marijuana cards were posted.
The growers paid friends and relatives to visit marijuana-friendly doctors to get the "recommend" letters, Sigley said.
Color-copy duplicates of the medical marijuana cards from the Goshen raid were discovered miles away in Plainview at another marijuana farm, he said.
At the two farms, deputies seized 2,500 plants, $56,000 in cash, an assault rifle and records of marijuana sales – clues of potential drug cartel involvement. "Lots of plants, lots of people, lots of money," said Tulare County sheriff's Capt. Mike Boudreaux.
Seven people, including an 87-year-old Farmersville man, were arrested on suspicion of cultivation and conspiracy. Some were Mexican nationals – another potential indication of Mexican drug cartel links, Boudreaux said.
But evidence of a link to cartels isn't always there.
In July, Fresno County deputies and federal agents raided a 54-acre marijuana plantation near Sanger, confiscating 30,000 plants ranging from a few inches to 6 feet tall – all labeled as medical marijuana, said Fresno County Sheriff Margaret Mims.
That site does not appear linked to Mexican drug cartels because the suspects were Laotian, Mims said.
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