Scientists from the California Department of Fish and Wildlife have published a study, the first of its kind, concluding that in California's current drought, the demand for water to cultivate cannabis has devastating environmental effects. Specifically, in the words of the study published by the scientific journal PLOS One, the effects are "lethal or sub-lethal ... on state-and federally-listed salmon and steelhead trout and to cause further decline of sensitive amphibian species." To put that as simply as possible: Water is running dry and fish are dying, with amphibians at risk, too.

In a drought that could be the new normal, water used for the plant's cultivation exceeded stream flow in three of four watersheds that were studied. “All the streams we monitored in watersheds with large scale marijuana cultivation went dry,” said California Department of Fish and Wildlife Senior Environmental Scientist Scott Bauer, who is the lead author of the study. "The only stream we monitored that didn’t go dry contained no observed marijuana cultivation."

The environmental impact of growing marijuana has been difficult to quantify as it's a clandestine practice usually occurring on private property. As the study puts it, "Marijuana has been cultivated in the backwoods and backyards of northern California at least since the countercultural movement of the 1960s with few documented environmental impacts." So, for their work to evaluate the effects of pot cultivation at the watershed scale, the scientists interpreted high-resolution aerial imagery to estimate the number of marijuana plants being cultivated in four northwestern California watersheds. That took low-altitude aircraft flights and search warrants executed with the help of law enforcement.

"Northwestern California has been viewed as an ideal location for marijuana cultivation because it is remote, primarily forested, and sparsely populated," the study explains. But, unfortunately, here, "unregulated marijuana cultivation often occurs in close proximity to habitat for sensitive aquatic species." In addition to killing salmon who require clean, cold water and "suitable flow regimes," amphibians might also be at risk. The outlook isn't optimistic, either. "Due to climate change, water scarcity and habitat degradation in northern California is likely to worsen in the future." It's a strong argument for all kinds of action, but certainly one against hidden marijuana grows in the region.

Previously: California Has One Year Of Water Left