Wildlife technician Aaron Pole surveys a forest trashed by growers. Carbofuran,… (Genaro Molina, Los Angeles…)
EUREKA, CALIF. — State scientists, grappling with an explosion of marijuana growing on the North Coast, recently studied aerial imagery of a small tributary of the Eel River, spawning grounds for endangered coho salmon and other threatened fish.
In the remote, 37-square-mile patch of forest, they counted 281 outdoor pot farms and 286 greenhouses, containing an estimated 20,000 plants -- mostly fed by water diverted from creeks or a fork of the Eel. The scientists determined the farms were siphoning roughly 18 million gallons from the watershed every year, largely at the time when the salmon most need it.
"That is just one small watershed," said Scott Bauer, the state scientist in charge of the coho recovery on the North Coast for the Department of Fish and Game. "You extrapolate that for all the other tributaries, just of the Eel, and you get a lot of marijuana sucking up a lot of water.... This threatens species we are spending millions of dollars to recover."
The marijuana boom that came with the sudden rise of medical cannabis in California has wreaked havoc on the fragile habitats of the North Coast and other parts of California. With little or no oversight, farmers have illegally mowed down timber, graded mountaintops flat for sprawling greenhouses, dispersed poisons and pesticides, drained streams and polluted watersheds.
Because marijuana is unregulated in California and illegal under federal law, most growers still operate in the shadows, and scientists have little hard data on their collective effect. But they are getting ever more ugly snapshots.
A study led by researchers at UC Davis found that a rare forest carnivore called a fisher was being poisoned in Humboldt County and near Yosemite in the Sierra Nevada.
The team concluded in its July report that the weasel-like animals were probably eating rodenticides that marijuana growers use to keep animals from gnawing on their plants or were preying on smaller rodents that had consumed the deadly bait. Forty-six of 58 fisher carcasses the team analyzed had rat poison in their systems.
Mark Higley, a wildlife biologist on the Hoopa Indian Reservation in eastern Humboldt who worked on the study, is incredulous over the poisons that growers are bringing in.
"Carbofuran," he said. "It seems like they're using that to kill bears and things like that that raid their camps. So they mix it up with tuna or sardine, and the bears eat that and die."
The insecticide is lethal to humans in small doses, requires a special permit from the EPA and is banned in other countries. Authorities are now regularly finding it at large-scale operations in some of California's most sensitive ecosystems.
It is just one in a litany of pollutants seeping into the watershed from pot farms: fertilizers, soil amendments, miticides, rodenticides, fungicides, plant hormones, diesel fuel, human waste.
Scientists suspect that nutrient runoff from excess potting soil and fertilizers, combined with lower-than-normal river flow because of diversions, has caused a rash of toxic blue-green algae blooms in North Coast rivers over the last decade.
The cyanobacteria outbreaks threaten public health for swimmers and kill aquatic invertebrates that salmon and steelhead trout eat. Now, officials warn residents in late summer and fall to stay out of certain stretches of water and to keep their dogs out. Eleven dogs have died from ingesting the floating algae since 2001.
The effects are disheartening to many locals because healthier salmon runs were signaling that the rivers were gradually improving from the damage caused by more than a century of logging.
"Now with these water diversions, we're potentially slamming the door on salmon recovery," said Scott Greacen, director of Friends of the Eel River.
In June, Bauer and other state scientists accompanied game wardens as they executed six search warrants on growers illegally sucking water from Trinity River tributaries. At one, he came upon a group of 20-somethings with Michigan license plates on their vehicles, camping next to 400 plants. He followed an irrigation line up to a creek, where the growers had dug a pond and lined it with plastic.
"I started talking to this guy, and he says he used to be an Earth First! tree-sitter, saving the trees," Bauer said. "I told him everything he was doing here negates everything he did as an environmentalist."
The man was a small-timer in this new gold rush. As marijuana floods the market and prices drop, many farmers are cultivating ever bigger crops to make a profit. They now cut huge clearings for industrial-scale greenhouses. With no permits or provisions for runoff, the operations dump tons of silt into the streams during the rainy season.
Scanning Google Earth in his office recently, Bauer came upon a "mega grow" that did not exist the year before -- a 4-acre bald spot in the forest with 42 greenhouses, each 100 feet long.