Is Pot-Growing Bad for the Environment?
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.
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.