Is Pot-Growing Bad for the Environment?
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.’ ”