Although cannabis remains illegal under federal law, Americans consume an estimated 2,500 to 5,000 metric tons of marijuana each year, according to estimates from the Rand Drug Policy Research Center. About 30 million Americans smoke or eat cannabis products annually, and about 6 million people use pot daily. Weed is the second-most popular recreational substance in the nation, behind alcohol.

Two-thirds of the pot consumed in the United States comes from Mexico, while about one-fifth of it is grown domestically, according to Rand estimates. California produces more weed than any other state, and according to a 2010 Central Valley High Intensity Drug Trafficking Area program report, may account for as much as 79 percent of all domestically grown marijuana. And the epicenter of domestic cannabis cultivation are Humboldt, Mendocino, Lake, and Trinity counties in Northern California.

The federal Drug War also has had a huge impact on these Northern California counties, said Corva, a Sarah Lawrence College professor who spent several years in Humboldt doing an ethnographic history of pot-growing, and now also runs a cannabis cultivation think tank in Seattle. Big swaths of Northern California were ravaged and abandoned by logging in the 19th and 20th centuries, and then some of those areas were re-settled by back-to-the-land hippies in the 1970s, Corva noted. Many liberal activists had dropped out of society after the upheavals of the 1960s, and for them, dope was just another plant in the garden.

Today, one out of every four dollars in Humboldt County's economy can be traced to the weed industry, and the area's rise to dominance in marijuana production can be traced directly to the Drug War. Until the late Seventies, America got its pot from international sources — mainly Mexico, but also Panama, Colombia, and Thailand, Corva noted. But then in 1975, the federal government paid for a campaign to spray Mexican pot fields with the herbicide Paraquat, setting off a cannabis supply scare that permanently altered the trade. It was one of the first campaigns of the nascent international war on pot.

To avoid Paraquat, Corva said, health-conscious Americans started to grow more of their own dope, and they got really good at it. Up in the remote hills of Humboldt, hippie growers perfected strong, new strains and techniques that ended up transforming their communities. By 1980, international interdiction drove the price of seedless marijuana to $2,000 per pound. And the potential for such immense profits pulled a generation of Humboldters into the dope trade.

Humboldt weed became an international brand name by 1983, when helicopters from the Campaign Against Marijuana Planting (CAMP) began buzzing above the area, and armed troops started coming in to chop down grows. To counter-act CAMP, growers moved their plants further into the shade and spread out their farms, but they also went indoors. CAMP drove prices even higher, and inadvertently created the high-potency indoor marijuana that now dominates the California market, Corva noted.

And make no mistake: People grow pot for the money — either to save cash by growing what they need personally or to make money by selling it themselves, exporting it to other states, or cultivating it for medical pot collectives. Americans spend an estimated $15 to $30 billion per year on weed. The value of the nation's cannabis per square-foot is five times greater than that of poppies or coca, according to Rand.

Currently, a pound of Mexican marijuana costs $50 in Mexico, $500 when it crosses the border, and up to $1,400 by the time it reaches New York. And a pound of high-grade California indoor-grown marijuana sells for $2,000 here and $4,000 on the East Coast.

Research shows that traffickers make about $1 for every mile they drive east from California. But that figure doesn't reflect the actual cost of producing marijuana; rather, it reflects the risk involved in doing so. As much as 90 percent of the cost of pot is its risk premium, according to Rand. About 750,000 people are arrested annually for violating marijuana laws, and 40,000 people are in state or federal prison for it. In 2010, the government seized roughly 10 million outdoor plants.

Raising the price of drugs was one of the chief goals of the Drug War, Corva noted. The thinking was: price increases would dissuade impoverished users. What actually happened is the potential for intense profits drew the impoverished into the drug trade.

Today, pot is one of the top fifteen cash crops in the United States, Rand reports. And it's no longer confined to just Northern California. There are black market plantations hiding throughout the state's 20 million acres of national forest, as well as in large tracts of private and tribal lands.

Media portrayals of marijuana farming over the decades typically focused on the guns and violence associated with drug cartels. But in 2013, environmental harms became the central focus of the War on Pot.

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From above, the forests of Northern California appear to have chicken pox. Patches of rusty-colored boils dot the rugged, sun-beaten timberlands of southern Humboldt County. Swooping down into the region from the God's-eye view provided by Google Earth, the rusty patches expand to reveal clear-cut hilltops.

Humboldt State University environmental sociologist Anthony Silvaggio counts six hundred of these patches covering the southern section of the county, each one centered over bald mountaintops arrayed with outdoor pot plants and greenhouses. "And that's not all of them. … There are hundreds more."

Zooming in and out on each site on his computer, Silvaggio noted how the farms are collectively sucking fragile watersheds dry. Then there's the illegal logging the rampant use of animal poisons — plus insecticides, herbicides, fungicides — and high-nutrient fertilizers. When the fall and winter rains come, uncontrolled erosion follows. A toxic brew of chemicals and dirt washes downhill into protected areas like the Eel River. The destruction is happening all across California now.

Created in November of 2012, Silvaggio's research video got picked up byMother Jones in February of this year and re-titled "Google Earth Reveals Devastation Caused by Marijuana Growers." A story by The New York Timesfollowed. The Associated Press piled on, and Dan Rather recently toured the region in a helicopter for a report on AXS TV.

In Butte County, Supervisor Connelly takes reporters to trespass grows on steep, 45-degree hillsides on private land. The illegal farms are studded with denuded trees and littered with poisons and fertilizers. During one tour, he looked downhill and described the fall rains sweeping it all — the chemicals and the toxic soil — down into the creeks, rivers, and lakes. "It definitely has gone up in the last few years," he said of the number of trespass grows.

But are the impacts from pot-growing larger, or are we just paying more attention to them? The answer appears to be both.

As far back as 1983, CAMP made mention of environmental damage associated with forest grows, said Silvaggio. "The problem is not new. Everyone has known about this problem for many decades."

For example, the back-to-the-landers who seeded Humboldt's pot industry were tree-hugging environmentalists first, and they have long been furious about the second wave of growers who moved in to wreak the same type of havoc as the loggers once did. Groups like EPIC, Friends of the Eel River, and the Mattole Forest Project have been advocating for clean pot-growing techniques — including water reclamation, erosion control, and organic growing methods — since the Nineties. They've gotten a number of environmental groups in Northern California fired up about the issue for at least a decade.

The clamor for more eco-conscious pot-growing then hit a new peak in 2008 with the Hacker Creek diesel spill that fouled a whole watershed. "That broke the code of silence right there, and then people came out," Silvaggio noted.

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But experts say what has really amplified the issue this year are two factors: Federal law enforcement has made environmentalism a new platform of the marijuana war, and the media, which never tires of stories that combine shadowy, violent drug cartels with weapons, weed, and helicopters, and can now add cute dead animals to the mix.

Humboldt State University sociologist Josh Meisel said he caught a glimpse of the federal government's new messaging on pot two years ago in a meeting with Tommy LaNier, head of the White House's National Marijuana Initiative. According to Meisel, LaNier said federal authorities "recognize that public opinion has shifted and they can't wage this battle on the historic platform of it being an issue of morality."

"The public doesn't buy that anymore," LaNier said, according to Meisel. "We're aren't going to win this as a battle of morality. We have to wage it in terms of the environmental destruction."

And in a podcast produced by the US Forest Service in August 2009, US Drug Czar Gil Kerlikowske said he wanted to build a coalition based on the environmental harms of pot-growing. "What seems to be missing from the regular media reporting on the whole issue is how much damage is occurring to really pristine land," Kerlikowske said.

LaNier said in the same podcast: "We need to bring in … the Sierra Club, environmental individuals; we need to bring in as many people, to get them on our side to go to Congress and say, 'Hey, this is enough. Those are pristine lands that were set aside for the use of the public, not for the production of marijuana.'"

The shift in strategy is traveling up and down the chain of command. For example, in a 2013 report on the results of a Central Valley marijuana sweep dubbed Operation Mercury, Benjamin Wagner, the US Attorney for the Eastern District of California, based in Sacramento, trumpeted the seizure of half a million marijuana plants and the prosecution of 84 suspects. But instead of focusing on charges of drug trafficking, violence, or weapons, Wagner's office highlighted the environmental damage that the suspects had allegedly caused.

One 26 year-old Mexican citizen who was caught growing 16,205 plants in Sequoia National Forest "caused extensive damage to the land and natural resources," Wagner's office stated. "Native vegetation was cut to make room for the marijuana plants and trash and fertilizer containers were scattered throughout the site, including in flowing streams."

Another Mexican citizen who was convicted of growing 8,876 pot plants cut down native oak trees: "the soil was tilled, and fertilizers and pesticides, including a highly toxic and illegal rat poison from Mexico called Fosfuro de Zinc or zinc phosphide, were spread throughout the site," Wagner's office noted.

And even on the White House's web page on marijuana, the environment gets its own section in which the administration states, "Outdoor marijuana cultivation is harmful to the environment."

Corva laughed when I read him the White House's statement. "That's ridiculous," he said. "Outdoor is better.

"Where does this come from?" he continued. "Sensationalist coverage of the exception rather than the rule, and also the conditions of prohibition, basically."

Meisel added: "There's nothing about growing dope that has to involve massive amounts of energy, dangerous chemicals, water diversion, disrespect to your neighbors, and killing animal species — just like we don't have to do that growing tomatoes. And we don't grow tomatoes in Yosemite. These are unintended consequences of the policy, not the plant.

"My sense is that this has become a tool to break the back of the legalization movement," Meisel continued, referring to the decision by Drug War enforcers to shift their rhetoric from the supposed dangers of smoking weed to the environmental damage caused by trespass grows in order to gain support among environmentalists for the War on Pot. "It's a strategy to undermine local growing across the board, as opposed to going after people who are violating environmental laws."

Norms have shifted around marijuana consumption, Silvaggio added. "Presidents have smoked weed. But there's a need to keep it illegal. There's this particular function it provides — that is law enforcement money.

"So they've switched tracks," Silvaggio continued. "And this track has proved very useful."

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But the way to halt environmental harms caused by growing pot isn't through a new campaign against weed; it's through legalization, taxation, and regulation of cannabis, said Humboldt County Sheriff Downey during a public meeting with North Bay Congressman Jared Huffman on August 29. "I've never been a big fan of legalization," Downey told the crowd. "But right now I think that's the most logical way to end this Drug War."

After all, it was the Drug War that sent growers into the forest in the first place. And farming in the woods offers no particular advantage for growers — other than allowing them to avoid detection by law enforcement. "Are they up there for the dry weather, great soil, and ample water?" said celebrity growing instructor Ed Rosenthal. "No, they're up there because it's hard to get caught."

Legalizing marijuana and growing it on traditional farms, alongside other crops, also will eliminate the risks currently associated with pot production and distribution — and will likely reduce costs dramatically. According to Rand estimates, fully legalized, commercially farmed high-grade pot would cost just $20 per pound to produce. And low-grade weed would cost only $5 per pound. With profit margins so low, there simply would be no incentive to spend four filthy months growing weed in bear-infested backwoods, Silvaggio and other advocates of legalization point out.

Plus, farming marijuana out in the open would be much better for the environment — there would be no need, for example, to siphon water illegally from creeks and streams. And pesticide and insecticide use could be regulated — like they it is for any other crop. "If it was grown like corn or hemp, it would be regulated, including the discharge of chemicals and the amount of water used and the way you grade," said Connelly. In addition, organic pot-growing likely would sprout as a major industry.

And because cannabis is a highly productive plant, it wouldn't take up that much farmland. According to a Rand study, just 10,000 acres of intensively farmed land could grow all the dope Americans consume each year. California's estimated share would total only 1,600 acres. By comparison, the state currently dedicates about 150,000 acres to pistachio growing each year.

The relaxation of pot prohibition has already caused price drops in California, Colorado, and Washington, but this half-solution has caused existing farmers to plant more to make up for lost profits. It's going to take a true market crash from national legalization and regulation to halt wildland growing forever. "I think we'd see a decrease slowly in environmental harms and then it would be minimal," Silvaggio said. "Long-term, we'd see a recovery in the ecosystem."

Silvaggio also argued that the news media needs to start sharing the stories of growers who farm sustainably in Humboldt and how they do it. "There's a total disregard for interviewing and talking with communities that are growing ecologically sensitive weed.

"Prohibition has failed and it needs to end," he continued. "If we didn't have prohibition, we would see this problem go away."