Why you should care
Because illegal cannabis grows take a toll on public lands.
Pacific fishers, bobcats, northern spotted owls and San Joaquin kit foxes are all listed as threatened or endangered animals under the Endangered Species Act. But there may be a surprisingly simple fix to their status: Legalize cannabis.
Up to 70 percent of the black-market cannabis in California is cultivated on illegal sites, called trespass grows, that are located in national parks and other public lands, according to the Cannabis Removal on Public Lands (CROP) Project, a nonprofit coalition of conservation organizations and government groups. To establish these illicit pot farms, growers raze a section of forest, siphon water from streams for irrigation and use mass quantities of pesticides, turning once pristine wildlife habitats into dead zones.
“Next to climate change and habitat loss, trespass grows are a leading threat to California’s wildlife,” says Jackee Riccio, regional field director of the CROP Project. “What is happening is equivalent to ivory poaching or whaling.”
Thanks to the state’s temperate climate, trespass grows are most common in California, but the illegal operations have been reported in other states, including Oregon and Colorado.
One teaspoon of carbofuran is enough to kill a 600-pound black bear.
During one 2019 reclamation operation, the Integral Ecology Research Center (IERC) worked with government agencies and nonprofits to dismantle 12 illegal cannabis cultivation sites in the Shasta-Trinity National Forest, removing 7,560 pounds of trash and more than 8 miles of irrigation lines that diverted water from local watersheds. During the summer months, growers divert so much water from local streams that it can suck them dry, which has lethal effects on salmon, steelhead trout and amphibians. The IERC estimates that one site in Shasta-Trinity diverted more than 10 million gallons of water from the New River, which supports threatened spring-run chinook and coho salmon.
Rat poisons, aka rodenticides, are used in mass quantities to keep animals from eating plants. Scientists have also found traces of carbofuran, an insecticide that has been banned in the U.S. since 2009, at more than one-third of trespass grows. One teaspoon of carbofuran is enough to kill a 600-pound black bear, according to CROP Project Director Rich McIntyre.
It’s not just rodents like Pacific fishers, a weasel-like mammal that calls the West Coast home, that are suffering from internal bleeding, brain damage and even death as a result of ingesting rodenticides. Toxic exposures are found across the food chain. In a study published in the journal Avian Conservation and Ecology, researchers found 70 percent of spotted owls and 40 percent of barred owls tested positive for rodenticides. The toxins have also been linked to the deaths of other fish, birds and mammals, including mule deer, coyotes and gray foxes.
“The toxicants that we find at trespass grows are used so indiscriminately and trespass grows are so prevalent across the entire state of California that we’re seeing, not regional, not local, but landscape-scale impact on wildlife,” McIntyre says.
Legalizing cannabis could turn this around.
“Dry counties and dry states are feeding the trespass grow issue,” Riccio says. “Prohibition didn’t stop people from drinking alcohol, and it’s not going to stop people from smoking weed … and unless the state wants to be partially responsible for this public health crisis, they need to [legalize recreational cannabis].”
Legalization reduces the number of trespass grows, bringing cannabis cultivation out of national forests and onto agricultural lands. Data from Oregon shows that legalization has put a dent in the number of trespass grows; fewer cultivation sites carved out of the wilderness means less impact on wildlife.
In states that allow legal cannabis cultivation, growers are required to follow strict environmental regulations on water and pesticide use. Carbofuran and several rodenticides are among the toxins included on the list of banned pesticides for permitted cannabis growers in California.
Increased funding would speed up the identification and removal of trespass grows. CROP estimates that it costs an average of $40,000 to clear a single site.
Although recreational cannabis use is legal in 11 states and the District of Columbia, it’s going to take more than legalization at the state level to move cultivation off public lands. McIntyre believes that as long as cannabis remains illegal on the federal level, California will continue to wage war against trespass grows and wildlife will continue to suffer.
“Until such time [that] legalization occurs in other states, to decrease the black-market demand for cannabis, there’s going to continue to be a high demand for black-market cannabis,” McIntyre says.
“Trespass grows on public land [are] slaughtering wildlife,” he continues. “National legalization is part of the answer.”
Jodi Helmer is a North Carolina-based journalist who writes about farming and the environment.