CDFW Scientists Publish Groundbreaking Work on Marijuana’s Effect on the Environment

Environmental scientists with the California Department of Fish and Wildlife (CDFW) recently published a first-of-its-kind study that clearly shows that water used for growing marijuana has a devastating effect on fish in the state.

The study showed that during drought conditions, water demand for marijuana cultivation exceeded stream flow in three of four study watersheds. The resulting paper, entitled “Impacts of Surface Water Diversions for Marijuana Cultivation on Aquatic Habitat in Four Northwestern California Watersheds,” concludes that diminished stream flow from this water-intensive activity is likely to have lethal to sub-lethal effects on state and federally listed salmon and steelhead trout and will cause further decline of sensitive amphibian species.

The study was published online in the scientific journal PLOS One and can be found   here.

By using online tools to count marijuana plants and measure greenhouses, and conducting inspections of marijuana cultivation sites with state wildlife officers and local law enforcement, CDFW scientists quantified plant numbers and water use. Utilizing stream flow data provided by staff at the National Oceanic and Atmospheric Administration (NOAA), CDFW determined water demand for cultivation could use more than 100 percent of stream flow during the summer dry season in three of four study watersheds. Stream flow monitoring conducted by CDFW in the summer of 2014 appeared to verify these results.

“All the streams we monitored in watersheds with large scale marijuana cultivation went dry,” said CDFW Senior Environmental Scientist Scott Bauer, lead author of the research paper. “The only stream we monitored that didn’t go dry contained no observed marijuana cultivation.”

Additional negative impacts of trespass grows include wildlife poisoning, human waste and trash, and soil and water pollution.

Trespass grows also contribute human waste and trash, pollute soil and water, and poison wildlife.

CDFW’s Law Enforcement Division works closely with dozens of other state and federal agencies to eradicate illegal marijuana grows on public, tribal and private lands as well as protect the state’s natural resources.

“This research paper demonstrates the importance of greater regulatory efforts by state agencies to prevent the extinction of imperiled fisheries resources,” said CDFW Assistant Chief Brian Naslund. “CDFW’s new Watershed Enforcement Team (WET) was created with just that in mind.”

The WET program works with agency partners to protect public trust resources from the negative effects of marijuana cultivation, which include both excessive water use and pollution.

CDFW will continue to monitor the effects of water diversion for marijuana cultivation on stream flow through the summer of 2015.

Marijuana cultivation is legal in California if growers have the proper CDFW lake and streambed alteration permits. Responsible growers help conserve the state’s natural resources and are less likely to be subject to enforcement action.


Drought Woes Continue at Shasta Valley Wildlife Area

As of mid-January, the historic drought continues at Shasta Valley Wildlife Area. Last year’s wet season wasn’t very wet, with rain and snowfall at about 20 percent of normal. This was on top of the previous year, 2013, that was also considered dry by regional climatologists. The consecutive dry years resulted in two out of three water storage reservoirs being dry, or nearly so. The third reservoir, Trout Lake, is down about 40 percent. The wildlife area staff was unable to flood seasonal wetlands for the fall migration and had to cancel some public hunting programs.

A very wet December brought hope that this year would be wetter. The Little Shasta River swelled with runoff from the moist Pacific storms. Wildlife area staff took advantage of this opportunity and was able to divert a substantial amount for a few weeks. That flow has subsided now. What’s left is a long range forecast with little hope for significant rain and snow, and still nearly dry reservoirs. On top of that, snow pack in the watershed is only about 30 percent of normal. Typically, the heaviest rainfall occurs in this area in December and January, with February also an important month. Whether or not the drought continues will depend upon what happens in the next six weeks.

~Text and photos contributed by Wildlife Habitat Supervisor R. Robert Smith

Bass Lake Drought November 2014

Bass Lake Drought, November 2014.

Steamboat Lake, January 2015.  The fence post in the foreground marks the lake level when full.

Steamboat Lake, January 2015. The fence post in the foreground marks the lake level when full.