While public officials at the local, state and federal level―in legislatures, courts and executive suites―incoherently stumble about in search of a consistent policy to govern marijuana, California’s northern backwoods appear to have been heavily impacted by rogue growers.

It has been assumed that the state’s legalization of medical marijuana in 1996 and its recognition of nonprofit cooperatives as dispensaries in 2004 increased growing in Northern California, but assessments of the effects of cultivation have been anecdotal, limited in scope and shaped by the political agenda of the story teller.

But real nonetheless.

Anthony Silvaggio, an environmental sociologist at Humboldt State University's Institute for Interdisciplinary Marijuana Research, produced a video in November 2012 of his Google Earth fly-by over Humboldt County and identified more than 600 grow spots, many of them industrial-strength. He likened the devastation to that done by the timber industry that preceded it.

But last week, the state Department of Fish and Wildlife (DFW) released a report (pdf) that got a little more specific about damage it says is inarguably being done to rivers and streams. Department biologist Scott Bauer used Google Earth to scan the watersheds around two tributaries of the South Fork Eel River in Humboldt, did comparisons with satellite data from past years and figured how much water the illegal grows were using.

Bauer identified 550 grows with 19,000 plants in each of the two watersheds and calculated they consumed 20% to 30% of the Redwood Creek and Salmon Creek. He assumed that each plant would need 6 gallons of water per day through its approximated 150-day growing season.

“We knew people were diverting water for marijuana operations,” Bauer told the Associated Press. “We didn't know they could consume all the water in a stream.”

Silvaggio said the accepted range of water use is between 3 and 6 gallons per day, meaning the damage could conceivably be half what Bauer projected. But no one is underestimating the transformation that is taking place in the marijuana agricultural heartland.

Rivers that are home to endangered salmon and steelhead trout are drying up. Hillsides are being denuded and pesticides are flowing downstream into the water supply. But this is an area that has not recovered from the ravages of timber harvesting and is being buffeted by global warming, the drought and suspect land management. So it’s hard to pin all the problems on pot growers.

Silvaggio acknowledged in his video’s voice-over that he was observing just a small section of marijuana growing, but he assumed the problem was widespread and serious. He also laid the problem at the feet of the federal government, which is “all over the board” on what it wants, vacillating between prohibition and respect for state’s rights.

 “If we didn’t have prohibition, I wouldn’t be talking to you about this issue,” he said.

–Ken Broder

To Learn More:

Is Marijuana Destroying California’s Water and Wildlife? (by Anna Brones, Care2)

Study Finds Medical Pot Farms Draining Streams Dry (by Jason Dearen, Associated Press)

Marijuana Farms Endanger California Wildlife (by Kristina Chew, Care2)

Multi-Agency Operation Breaks Up Elaborate Marijuana Camp (California Department of Fish and Wildlife)

A Growing Issue: Resource Impacts of Medical Marijuana Cultivation (California Department of Fish and Wildlife) (pdf)