A greener grass: Can the environmental impact of cannabis cultivation be reduced?

Nature Portfolio (Springer Nature) | August 28th, 2019

Assessing the presence of current-use pesticides in mid-elevation Sierra Nevada streams using passive samplers, California, 2018–19

U.S. Geological Survey (USGS) | February 9th, 2023

Passive sampler devices were deployed in six northern California streams five times between November 2018 and December 2019 to measure the presence or absence of current-

Passive sampler devices were deployed in six northern California streams five times between November 2018 and December 2019 to measure the presence or absence of current-use pesticides in surface water. In the targeted areas, there are reported pesticide uses for agriculture, commercial forestry, and rights of way maintenance along with unreported pesticide use at private residences and cannabis grow sites. The sites sampled in this study were not previously monitored for current-use pesticides. Streams in the Sierra Nevada foothills of northern California are important habitats for many sensitive species including salmonids, but the logistics of sampling these areas can be difficult using traditional water-quality sampling techniques, especially when sampling watersheds where contaminant transport is episodic. Chemcatcher passive sampling devices and silicone bands were deployed in these areas to concentrate pesticides for days to weeks at a time. The U.S. Geological Survey, in cooperation with the Central Valley Regional Water Quality Control Board, was responsible for developing passive sampler field deployment and laboratory analytical methods for current-use pesticides, providing pesticide measurements from streams in the study region, and determining how well passive samplers detect pesticides in these environments. Six sites were monitored during the study, and passive sampler extracts were analyzed for a total 155 current-use pesticides in this study. A total of 19 out of the 155 pesticides including 9 insecticides, 5 fungicides, and 5 herbicides were detected in extracts from passive samplers. The most frequently detected pesticides were the herbicides hexazinone and dithiopyr, the insecticides bifenthrin and methoxyfenozide, and the fungicide azoxystrobin.

Impacts of Surface Water Diversions for Marijuana Cultivation on Aquatic Habitat in Four Northwestern California Watersheds

PLOS | March 18th, 2015

Marijuana (Cannabis sativa L.) cultivation has proliferated in northwestern California since at least the mid-1990s. The environmental impacts associated with marijuana c

Marijuana (Cannabis sativa L.) cultivation has proliferated in northwestern California since at least the mid-1990s. The environmental impacts associated with marijuana cultivation appear substantial, yet have been difficult to quantify, in part because cultivation is clandestine and often occurs on private property. To evaluate the impacts of water diversions at a watershed scale, we interpreted high-resolution aerial imagery to estimate the number of marijuana plants being cultivated in four watersheds in northwestern California, USA. Low-altitude aircraft flights and search warrants executed with law enforcement at cultivation sites in the region helped to validate assumptions used in aerial imagery interpretation. We estimated the water demand of marijuana irrigation and the potential effects water diversions could have on stream flow in the study watersheds. Our results indicate that water demand for marijuana cultivation has the potential to divert substantial portions of streamflow in the study watersheds, with an estimated flow reduction of up to 23% of the annual seven-day low flow in the least impacted of the study watersheds. Estimates from the other study watersheds indicate that water demand for marijuana cultivation exceeds streamflow during the low-flow period. In the most impacted study watersheds, diminished streamflow is likely to have lethal or sub-lethal effects on state-and federally-listed salmon and steelhead trout and to cause further decline of sensitive amphibian species.

Joint Report to the Legislature on the Department of Fish and Wildlife and State Water Resources Control Board pilot project to address the Environmental Impacts of Cannabis Cultivation (Watershed Enforcement Team)

California State Water Resources Control Board (SWRCB) | March 16th, 2015

This report is in response to the 2014-2015 Supplemental Report for item 3600-001-0001-Department of Fish and Wildlife (Department or CDFW), which provides the following

This report is in response to the 2014-2015 Supplemental Report for item 3600-001-0001-Department of Fish and Wildlife (Department or CDFW), which provides the following directive: “The Department of Finance shall report, on behalf of the Marijuana Task Force, on or before January 10, 2015, to the Assembly and Senate budget committees, on its recommendations to require marijuana producers growing under Proposition 215 protections, to comply with regular permitting, and with any need for regulatory changes to allow law enforcement to accompany regulators for site visits.” In this report, the Department and the State Water Resources Control Board (Water Board)1 provide an overview of the joint pilot project to address environmental degradation resulting from marijuana cultivation, a discussion of the agencies’ interaction with other state agencies, and a discussion of the program’s outcomes between August 2014 and February 1, 2015. This report also describes that the CDFW and the Water Board intend to require that marijuana producers growing on private lands comply with CDFW’s and the Water Boards’ existing and soon-to-be adopted permitting programs and current environmental protection laws. There is no need for a regulatory change that would allow law enforcement to accompany regulators on site visits as that authority currently exists.

Minimizing the Impact of Cannabis Cultivation on California Lands and Waterways

California State Water Resources Control Board (SWRCB) | February 17th, 2017

Following recent changes in state law and voter-approved initiatives, California’s commercial cultivation of cannabis for recreational and medical use is expected to gr

Following recent changes in state law and voter-approved initiatives, California’s commercial cultivation of cannabis for recreational and medical use is expected to grow significantly. The State Water Resources Control Board has adopted a state cannabis policy to set up strict environmental standards, and a permitting system to protect local surface water from dewatering, protect water habitat and prevent pollution in the state’s rivers and streams. Left unregulated, cannabis cultivation can pose serious threats to water quality and the environment. Cannabis cultivation impacts include the release of fertilizers, pesticides and other supplements that degrade water quality and threaten wildlife. Excessive water diversions can injure fish or even dewater smaller streams. The physical alteration of the land can harm stream habitat and wildlife by the sediment and debris that is deposited in waterways by unregulated cultivation. Overview: The State Water Board’s “Cannabis Cultivation Policy, Principles and Guidelines for Cannabis Cultivation” (Policy) will be implemented through a water quality permit and a water right. The water quality permit is referred to as a Statewide General Order for Cannabis Cultivation Activities (Cannabis General Order). The water right is referred to as a Cannabis Small Irrigation Use Registration. Tiered Approach: The Cannabis General Order consists of a tiered permit structure based on threat to water quality. Tier 1 Cannabis Cultivators have a disturbed area greater than 2,000 square feet and less than 1 acre (43,560 square feet). Tier 2 Cannabis Cultivators have a disturbed area equal to or greater than 1 acre.