In Giorgi's jurisdiction, the majority of the people arrested or investigated are originally from the state of Michoacan, where marijuana growing and immigration to the U.S. are entrenched.

In their hometowns, growers have to sell their marijuana to cartels for a fraction of what they could make in California. When they come north, they see opportunity in the state's vast wilderness. They have the know-how and perseverance to set up clandestine farms and live for months at a time in extremely rugged spots. Loncheros — lunchmen — often make weekly supply runs in the middle of the night, bringing food, beer and fertilizer. The workers wear camouflage, often sleep in the brush-covered tents, cook on propane stoves in crude kitchens and supplement their food by poaching deer and other wildlife.

Giorgi says these organizations can still be well-financed, heavily armed and dangerous.

Mendocino County Sheriff Tom Allman realized at a community meeting in 2010 how bad the situation was in the Mendocino National Forest when five of the eight people who went to the microphone said basically: "I was out in the national forest … herding cows or sheep or hiking or fishing. And someone shot at me. So I'm not going into the national forest."

The following summer, Allman helped lead a task force on a three-week purge of pot from the area. They pulled out 632,000 plants, 42 miles of irrigation line and 52 tons of garbage. Agents arrested 132 people and confiscated 38 guns.

Is the forest safe today? "I'll put it this way," Allman said. "I'd go camping in the National Forest, but I wouldn't let my sister go."

Would he camp unarmed? "No."

A Mexican-born grower working just outside Mendocino National Forest said the cartels may not run the grows, but the criminal ties to Mexico are vastly complex and dangerous. He hears stories all the time of drug gang shakedowns, and workers held captive in the forest, with threats to their families back home.

"There was a guy working right here," he said, pointing over the hill from his grow, "he thought he was working in Texas."

The grower operates in the quasi-legal medical marijuana world and has contacts on the public land grows. He asked to remain anonymous because he feared for his safety.

He said he thinks law enforcement has little grasp of what's going on because no one arrested will put their family at risk to speak with them, even for a lighter sentence.

Lanier said agents are making progress. This season, they have seized about 3 million plants, less than half the number of last year. But with such a shadowy enemy, success is hard to gauge.

It's not clear if the numbers mean fewer plants are being grown on public land, or just fewer are being found. Since the state Campaign Against Marijuana Planting was disbanded last year, agents spend less time on aerial surveillance. And local sheriffs in pot-growing counties like Mendocino and Humboldt have far less resources devoted to seeking out and eradicating plants than they had in the past.

"It's hard to know if there's less being grown if you're not looking," said Humboldt County Sheriff Lt. Steve Knight.

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The investigation into the Kern County grow, just south of the Sequoia National Forest, began when a game warden spotted spilled fertilizer at a road turnout that had been a drop-off spot for marijuana growers four years before.

The warden set up surveillance and saw a Jeep Cherokee dropping off supplies several times. Two wardens pulled over the driver, Francisco Barrazarivas, for speeding one night in July. While one officer conducted a field sobriety test, the other placed a GPS device on his car, according to an affidavit filed with the search warrant.

Barrazarivas drove to a house in Bakersfield and was seen transferring two dark bags to a sedan, which was unloaded five houses up the block.

That second house was associated with a man named Ignacio Gomez, an illegal immigrant from Michoacan suspected to be the leader of a group that grows marijuana on public lands in Kern and Tulare counties, according to a Forest Service report included in the affidavit.

The raids come in the early morning Aug. 3.