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As cannabis production has ramped up in Northern California to meet the demand for medical and black-market marijuana, the ecological impacts of its cultivation have ballooned. From shrunken, muddy streams to rivers choked with algae and wild lands tainted with chemical poisons, large-scale cannabis agriculture is emerging as a significant threat to the victories that have been won in the region to protect wilderness, keep toxic chemicals out of the environment, and rebuild salmon runs that had once provided the backbone of a coast-wide fishing industry. Ad Policy

River advocate Scott Greacen has spent most of his career fighting dams and the timber industry, but now he’s widened his focus to include the costs of reckless marijuana growing. Last year was a time of region-wide rebound for threatened salmon runs, but one of his colleagues walked his neighborhood creek and sent a downbeat report that only a few spawning fish had returned. Even more alarming was the condition of the creek bed: coated with silt and mud, a sign that the water quality in this stream was going downhill.

“The problem with the weed industry is that its impacts are severe, it’s not effectively regulated, and it’s growing so rapidly,” says Greacen, executive director of Friends of the Eel River, which runs through the heart of the marijuana belt.

That lack of regulation sets marijuana’s impacts apart from those that stem from legal farming or logging, yet the 76-year-old federal prohibition on cannabis has thwarted attempts to hold its production to any kind of environmental standard. As a result, the ecological impact of an ounce of pot varies tremendously, depending on whether it was produced by squatters in national forests, hydroponic operators in homes and warehouses, industrial-scale operations on private land, or conscientious mom-and-pop farmers. Consumers could exert market power through their choices, if only they had a reliable, widely accepted certification program, like the ones that guarantee the integrity of organic agriculture. But thanks to the prohibition on pot, no such certification program exists for cannabis products.

To understand how raising some dried flowers—the prized part of the cannabis plant—can damage the local ecosystem, you first have to grasp the skyrocketing scale of backwoods agriculture on the redwood coast. Last fall, Scott Bauer of the California Department of Fish and Wildlife turned a mapping crew loose on satellite photos of two adjoining creeks. In the Staten Island–sized area that drains into those streams, his team identified more than 1,000 cannabis farms, estimated to produce some 40,000 small-tree-sized plants annually. Bauer holds up the maps, where each greenhouse is marked in blue and each outdoor marijuana garden in red, with dots that correspond to the size of the operation. It looks like the landscape has a severe case of Technicolor acne.

“In the last couple of years, the increase has been exponential,” Bauer says. “On the screen, you can toggle back and forth between the 2010 aerial photo and the one from 2012. Where there had been one or two sites, now there are ten.”

Each of those sites represents industrial development in a mostly wild landscape, with the hilly terrain flattened and cleared. “When someone shaves off a mountaintop and sets a facility on it,” Bauer says, “that’s never changing. The topsoil is gone.” The displaced soil is then spread by bulldozer to build up a larger flat pad for greenhouses and other farm buildings. But heavy winter rains wash some of the soil into streams, Bauer explains, where it sullies the salmon’s spawning gravels and fills in the pools where salmon fry spend the summer. Ironically, these are the very impacts that resulted from the worst logging practices of the last century.

“We got logging to the point that the rules are pretty tight,” Bauer says, “and now there’s this whole new industry where nobody has any idea what they’re doing. You see guys building roads who have never even used a Cat [Caterpillar tractor]. We’re going backwards.”

Then there’s irrigation. A hefty cannabis plant needs several gallons of water per day in the rainless summer growing season, which doesn’t sound like much until you multiply it by thousands of plants and consider that many of the streams in the area naturally dwindle each August and September. In the summer of 2012, the two creeks that Bauer’s team mapped got so low that they turned into a series of disconnected pools with no water flowing between them, trapping the young fish in shrinking ponds. “It’s a serious issue for the coho salmon,” Bauer says. “How is this species going to recover if there’s no water?”

The effects extend beyond salmon. During several law enforcement raids last year, Bauer surveyed the creeks supplying marijuana farms to document the environmental violations occurring there. Each time, he says, he found a sensitive salamander species above the grower’s water intakes, but none below them, where the irrigation pipes had left little water in the creek. On one of these raids, he chastised the grower, who was camped out onsite and hailed from the East Coast, new to the four- to six-month dry season that comes with California’s Mediterranean climate. “I told him, ‘You’re taking most of the flow, man,’ ” Bauer recalls. “’It’s just a little tiny creek, and you’ve got three other growers downstream. If you’re all taking 20 or 30 percent, pretty soon there’s nothing left for the fish.’ So he says, ‘I didn’t think about that.’ ”

While some growers raise their pot organically, many do not. “Once you get to a certain scale, it’s really hard to operate in a sustainable way,” Greacen says. “Among other things, you’ve got a monoculture, and monocultures invite pests.” Spider mites turn out to be a particular challenge for greenhouse growers. Tony Silvaggio, a lecturer at Humboldt State University and a scholar at the campus’s year-old Humboldt Institute for Interdisciplinary Marijuana Research, found that potent poisons such as Avid and Floramite are sold in small vials under the counter at grower supply stores, in defiance of a state law that requires they be sold only to holders of a pesticide applicator’s license. Nor are just the workers at risk: the miticides have been tested for use on decorative plants, but not for their impacts if smoked. Otherwise ecologically minded growers can be driven to spray with commercial pesticides, Silvaggio has found in his research. “After you’ve worked for months, if you have an outbreak of mites in your last few weeks when the buds are going, you’ve got to do something—otherwise you lose everything,” he says.

Outdoor growers face another threat: rats, which are drawn to the aromatic, sticky foliage of the cannabis plant. Raids at growing sites typically find packages of the long-acting rodent poison warfarin, which has begun making its way up the food chain to predators such as the rare, weasel-like fisher. A study last year in the online scientific journal PLOS One found that more than 70 percent of fishers have rat poison in their bloodstream, and attributed four fisher deaths to internal bleeding triggered by the poison they absorbed through their prey. Deep in the back-country, Silvaggio says, growers shoot or poison bears to keep them from raiding their encampments.

The final blow to environmental health from outdoor growing comes from fertilizers. Growers dump their used potting soil, enriched with unabsorbed fertilizers, in places where it washes into nearby streams and is suspected of triggering blooms of toxic algae. The deaths of four dogs on Eel River tributaries have been linked to the algae, which the dogs ingest after swimming in the river and then licking their fur.

The cannabis industry—or what Silvaggio calls the “marijuana-industrial complex”—has been building toward this collision with the environment ever since California voters approved Proposition 215 in 1996, legalizing the medicinal use of marijuana under state law. Seven years later, the legislature passed Senate Bill 420, which allows patients growing pot with a doctor’s blessing to form collectives and sell their herbal remedy to fellow patients. Thus were born the storefront dispensaries, which grew so common that they came to outnumber Starbucks outlets in Los Angeles.

From the growers’ point of view, a 100-plant operation no longer had to be hidden, because its existence couldn’t be presumed illegal under state law. So most growers stopped hiding their plants in discreet back-country clearings or buried shipping containers and instead put them out in the open. As large grows became less risky, they proliferated—and so did their effects on the environment. Google Earth posted satellite photos taken in August 2012, when most outdoor pot gardens were nearing their peak. Working with Silvaggio, a graduate student identified large growing sites in the area, and posted a Google Earth flyover tour of the region that makes it clear that the two creeks Bauer’s team studied are representative of the situation across the region.

With all of the disturbance from burgeoning backwoods marijuana gardens, it might seem that raising cannabis indoors would be the answer. Indoor growers can tap into municipal water supplies and don’t have to clear land or build roads to farms on hilltop hideaways. But indoor growing is responsible instead for a more insidious brand of damage: an outsize carbon footprint to power the electric-intensive lights, fans and pumps that it takes to raise plants inside. A dining-table-size hydroponic unit yielding five one-pound crops per year would consume as much electricity as the average US home, according to a 2012 paper in the peer-reviewed journal Energy Policy. All told, the carbon footprint of a single gram of cannabis is the same as driving seventeen miles in a Honda Civic. In addition, says Kristin Nevedal, president of the Emerald Growers Association, “the tendency indoors is to lean toward chemical fertilizers, pesticides and fungicides to stabilize the man-made environment, because you don’t have the natural beneficials that are found outdoors.”

Nevertheless, the appeal of indoor growing is strong, explains Sharon (not her real name), a single mother who used to raise marijuana in the sunshine but moved her operation indoors after she split up with her husband. Under her 3,000 watts of electric light, she raises numerous smaller plants in a space the size of two sheets of plywood, using far less physical effort than when she raised large plants outdoors. “It’s a very mommy-friendly business that provides a dependable, year-round income,” she says. Sharon harvests small batches of marijuana year-round, which fetch a few hundred dollars more per pound than outdoor-grown cannabis because of consumers’ preferences. Sharon’s growing operation supports her and her teenage daughter in the rural area where she settled more than two decades ago.

Add up the energy used by indoor growers, from those on Sharon’s scale to the converted warehouses favored by urban dispensaries, and the impact is significant—estimated at 3 percent of the state’s total power bill, or the electricity consumed by 1 million homes. On a local level, indoor cannabis production is blocking climate stabilization efforts in the coastal city of Arcata, which aimed to cut its greenhouse gas emissions by 20 percent over twelve years. But during the first half of that period, while electricity consumption was flat or declining slightly statewide, Arcata’s household electrical use grew by 25 percent. City staff traced the increase to more than 600 houses that were using at least triple the electricity of the average home—a level consistent with a commercial cannabis operation.

The city has borne other costs, too, besides simply missing its climate goals. Inexpertly wired grow houses catch fire, and the conversion of residential units to indoor hothouses has cut into the city’s supply of affordable housing. Last November, city voters approved a stiff tax on jumbo electricity consumers. Now the city council is working with other Humboldt County local governments to pass a similar tax so that growers can’t evade the fee simply by fleeing the city limits, says City Councilman Michael Winkler. “We don’t want any place in Humboldt County to be a cheaper place to grow than any other. And since this is the Silicon Valley of marijuana growing, there are a lot of reasons why people would want to stay here if they’re doing this,” he says. “My goal is to make it expensive enough to get large-scale marijuana growing out of the neighborhoods.”

A tax on excessive electricity use may seem like an indirect way of curbing household cannabis cultivation, but the city had to back away from its more direct approach—a zoning ordinance—when the federal government threatened to prosecute local officials throughout the state if they sanctioned an activity that is categorically forbidden under US law. Attempts in neighboring Mendocino County to issue permits to outdoor growers meeting environmental and public-safety standards were foiled when federal attorneys slapped county officials with similar warning—illustrating, yet again, the way prohibition sabotages efforts to reduce the industry’s environmental damage.

Indeed, observers cite federal cannabis prohibition as the biggest impediment to curbing the impacts of marijuana cultivation, which continues to expand despite a decades-long federal policy of zero tolerance. “We don’t have a set of best management practices for this industry, partly because of federal prohibition,” says researcher Silvaggio. “If a grower comes to the county agricultural commissioner and asks, ‘What are the practices I can use that can limit my impact?’, the county ag guy says, ‘I can’t talk to you about that because we get federal money.’ ”

Faced with this dilemma, observers have proposed a spectrum of solutions. A group of patient-growers banded together as the Tea House Collective to make their low-impact farming methods a central part of their marketing to prospective members. “It’s about knowing your local farmer, the way ‘locavore’ is overtaking organic food,” says collective founder Charley Custer. Other growers tout peer pressure and education as a way to goad their fellow farmers to do better, and have put together their own guide to best practices.

Activist Greacen proposes tailoring the tactics to each style of cannabis farming. Cannabis farms on public land spread chemical fertilizers and poisons into wildlife strongholds and leave behind a mess because they have no long-term stake in the property. “It’s a lot like other kinds of rogue industry, like gold mining in Brazil,” Greacen says. “If we can’t get the feds and the cops to mobilize at the scale we need, we may need to consider going out there with large numbers of people in the early spring, walking the most vulnerable places, and scaring these guys out.”

At the other end of the spectrum, he adds, are “touchy-feely small-scale organic folks who just need some more water tanks” so they can capture their irrigation supply in the winter, when it’s plentiful. In between, “you have this vast new industry of fairly large-scale operations on private lands,” where progress is limited by the unyielding federal opposition to cannabis. “The fundamental thing we need is a shift in the stance of the US Attorneys,” he says, “who have blocked efforts to regulate cultivation.” This would allow local governments to set limits on the impact and scale of these operations, license those who agree to abide by the limits, and mow down plants at farms that refuse to get licensed.

Another approach comes from state Fish and Wildlife researcher Bauer, who wants cannabis farmers to know that he doesn’t care what they’re growing, only how they grow it. He’s willing to consider permit applications for farmers to use water from local creeks so that his agency can regulate how much they take, at what time of year, and how to keep the pumps from sucking fish out of the streams along with the irrigation water. “We’re not going to tell you that you can’t do your project,” Bauer says. “We’re going to tell you the right way to do it.”

As evidence that his agency is truly indifferent to the legality of the growers’ trade, he recalls what happened last summer when his team searched cannabis farms for evidence of environmental violations. “I think people were shocked because we didn’t touch a plant,” he says. “They thought we were there to whack their crop.” Instead, the growers were simply cited for illegal water diversion and dumping sediment into the creek. One of the raided farmers said he’d apply for a permit, Bauer says, but he never did.

That grower’s reluctance to come under the umbrella of regulation illustrates one of the central problems in curbing cannabis’s impacts: marijuana growing remains, at its roots, an underground enterprise practiced with an outlaw mind-set. Even though cannabis cultivation has flourished under the ambiguous auspices of California’s medical marijuana laws, the people who are best placed to serve as watchdogs over environmental abuses in their remote areas still feel bound by a code of silence to protect each other from the law.

Sharon is one such person—and it isn’t because she’s happy with the growth of the marijuana business. The relatively large operations in her rural valley have brought noisy generators to the hills where she used to take quiet walks. “There’s a buzz of industry now in my neighborhood,” she laments. Even though her neighbors raise their cannabis under natural light, they rely on generators to power the fans ventilating their greenhouses and to supplement the natural light. Water has become a point of contention as well in late summer, when outdoor plants are at their thirstiest. Sharon shares a water supply with the adjoining properties, which has run dry repeatedly as a nearby family has scaled up its cannabis growing. When that happens, the handful of households who depend on that system have to wait until the creek gradually replenishes their tanks before they enjoy the convenience of running water again. But even so, Sharon couldn’t imagine asking a government agency to intercede if her neighbors’ water use exceeded legal limits. “The taboo is deeply embedded in me,” she says. “I would be an N-A-R-C, and they would be justifiably angry with me.”

These attitudes die hard, and they are rising to the surface as Humboldt County considers a local ordinance requiring cannabis growers to register with the county and meet minimal environmental standards or risk being deemed a nuisance. But a hearing on the ordinance drew a skeptical public. “Registration sounds to me like ‘Come and turn yourself in,’ ” Bonnie Blackberry of the Civil Liberties Monitoring Project told the county supervisors last month. “It seems like that’s asking an awful lot, and I’m not sure you’re going to get a lot of people who will do that.”

The cannabis boom shows no signs of slowing down. Its growth heightens the challenge of bringing the industry into the bright sunshine of environmental protection—not to mention occupational safety and health, farm labor, and payroll and income-tax laws. But that is likely to prove an impossible task so long as the message from Washington is that the right scale for cannabis farming is no farming at all.

In the Special Issue

Katrina vanden Heuvel: “Why Its Always Been Time to Legalize Marijuana”

Mike Riggs: “Obama’s War on Pot”

Carl L. Hart: “Pot Reform’s Race Problem”

Harry Levine: “The Scandal of Racist Marijuana Possession Arrests—and Why We Must Stop Them”

Martin A. Lee: “Let a Thousand Flowers Bloom: The Populist Politics of Cannabis Reform”

Martin A. Lee: “The Marijuana Miracle: Why a Single Compound in Cannabis May Revolutionize Modern Medicine”

Kristen Gwynne: “Can Medical Marijuana Survive in Washington State?”

Atossa Araxia Abrahamian: “Baking Bad: A Potted History of High Times”

Various Contributors: “The Drug War Touched My Life: Why I’m Fighting Back”

And only online…

J. Hoberman: “The Cineaste’s Guide to Watching Movies While Stoned”

Harmon Leon: “Pot Block! Trapped in the Marijuana Rescheduling Maze”