Picture taken from (Field, 2018)

THE EFFECTS CANNABIS

CULTIVATION HAVE ON

THE ENVIRONMENT

ABSTRACTThe growth of the marijuana industry has impacted the economy, the environment and public health in the United States. Although laws legalizing the use, production and distribution of marijuana have progress, they have done so with little regard to the industries impacts on the environment. This paper explores research published addressing the adverse effect that cannabis cultivation can have on environmental health. The paper also provides alternative options to traditional cultivation to assist in encouraging sustainable and safe cultivation practices, while focusing on how we can improve the cannabis industry in California.

Azalia RiveraENVS 190Dr. Foran

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Contents

Introduction ..............................................................................................................................................2

Discussion ................................................................................................................................................4

Cannabis biology and origin ................................................................................................................4

Disconnect between State and Federal Government. ...........................................................................6

Challenges in research .........................................................................................................................8

Pesticide and Plant Growth Regulators (PGR) use and regulation ...................................................10

Indoor cultivation ...............................................................................................................................14

Outdoor cultivation.............................................................................................................................15

Waste management .............................................................................................................................18

Conclusion:.............................................................................................................................................22

Figures and Tables..................................................................................................................................23

Works Cited............................................................................................................................................28

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Introduction

The marijuana industry in the United States has expanded significantly as states begin to

legalize its production, use and distribution. In 2015, 15 states had legalized the medical use and

distribution of marijuana (Carah et al, 2015), supporting a $2.4 billion industry (Butsic and

Brenner, 2016). As of 2018, 29 states have legalized the medical use and distribution of cannabis

and 9 states including California, have legalized the recreational use and sale of cannabis

(Gorrie, 2018). McVey, 2018 estimated that by 2022 the marijuana industry could reach $75

billion (Figure 1). The passing of Proposition 64: the Control, Regulate and Tax Adult Use of

Medical Marijuana Act (AUMA) in 2016 made the distribution and cultivation of marijuana

legal for both medicinal and recreational purposes in California. As of 2017 the National

Institute on Drug Abuse found that 45.2% of US persons ages 12 or older reported using

marijuana throughout their lifetime (Table 1) (National Institute on Drug abuse, 2019).

AUMA has dramatically increased the demand thus increasing the horticulture of

cannabis without much regard to its effects on the environment. Bezdek et al, 2017 reports

cannabis production is accountable for 3-6% of the United States electricity consumption and 5-

10% of Californians energy use. Indoor cannabis production alone can consume 6 times more

energy than the average commercial business (Bezdek et al, 2017). Cannabis cultivation can

involve activities that negatively affect land management practices and further degrade the

environment including habitat fragmentation, illegal water diversions, and contaminating water

supplies (Short-Giannotti, 2017).

Increasingly, evidence has illustrated the environmental effects of cannabis cultivation,

particularly the use of pesticides and nutrient additives to ensure the production of a large

healthy crop yield quickly. Lack of regulation on pesticide use during cannabis development has

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resulted in records indicating that the toxicity of pesticides used can vary from causing organ

damage to being skin irritant (Cuypers et al, 2017). The effects pesticides have on an individual

can depend on how it is ingested. Inhalation has been reported as having the most adverse effects

on the body because when inhaled pesticides are absorbed directly into the bloodstream. Cuypers

et al, 2017 found evidence that supports the theory that cannabis crops still have traces of

pesticides used during the growing period once harvested putting consumers at risk of inhaling

pesticide residues. Sullivan et al, 2013 found that nearly 65.9% of glass pipes and water pipes

with and without filters tested positive for pesticide residues. Without regulations on pesticide

use during developmental stages, cannabis consumers are at risk for hidden toxicological threats.

Indoor cultivation typically has high energy demands (Table 2). Indoor cultivation

requires a temperature of 75 Degrees and high levels of Carbon dioxide (CO2) to promote ideal

outdoor conditions to simulate optimal productivity (Bezdek, 2017). Marijuana farmers will

increase the CO2 available in grow rooms because cannabis is a carbon sink and large amounts

of CO2 help it thrive. This can be done by burning propane or natural gas within the grow room

which requires additional ventilation (Mills, 2012). Although this information is focused more on

small scale indoor growing operations, it should still be taken into consideration because there is

a large population of growers still partaking in small scale farming. A web survey conducted by

The Global Cannabis Cultivation Research Consortium on primarily small scale growers in 11

countries reported that respondents from the US, UK, Canada and Finland were more likely to

grow indoors than outdoors (Potter et al, 2015). The survey also reported that 75% of individuals

grew their own cannabis because it was cheaper than going out and buying it (Potter et al, 2015).

Despite the lack of energy use outdoor cultivation can be detrimental to our

environment’s health because of its impacts on land and land management. The offset of

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California's rainy season and marijuana’s main growing season has created a need for cultivators

to locate farms in watersheds where water is readily available through the dry season. The use of

pesticides and excessive nutrient runoff in outdoor growing sites pollute and further degraded

natural ecosystems. Northern California is popular for outdoor cannabis cultivation because of its

secluded forest, especially prior to the legalization of cannabis production. This is problematic,

specifically in secluded natural landscapes like the “The Emerald Triangle” which has become

increasingly at risk for habitat fragmentation and deforestation (Wang, 2017). Many of these

sites are located within sensitive habitats which further stresses endemic and endangered

dependent on those landscapes (Butsic, 2016). Farm location can create other problems like soil

erosion, introducing sediments and nutrients into streams and causing landslides (Wang, 2017).

This report will evaluate the effects traditional cannabis cultivation methods, specifically

indoor and outdoor cultivation, has on the environment. The report will also identify alternatives

to traditional cultivation methods by focusing on aquaponics as an alternative method of

cannabis cultivation. Although aquaponic systems are similar to hydroponic systems, they differ

in that aquaponic systems use fish and fish waste as a natural fertilizer for the plants in the

system eliminating the dependence on chemical additives. When aquaponics is implemented

correctly, it is a closed system that requires little added water or nutrients making it an ideal

alternative for cannabis cultivation.

Discussion

Cannabis biology and origin

There is debate amongst scientist as to how to differentiate the variants of cannabis.

Initially, using the geographic origins and the reproductive parts of plants, Swede Carl Linnaeus

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concluded that there was one species, Cannabis sativa with five variants (Laursen, 2015). As

time progressed, using chemistry and morphology, Cannabis indica was distinguished as a new

species of Cannabis by Jean-Baptiste Lamarck (Laursen, 2015). Later, Ernest Small found that

Cannabis in fact has only one species, Cannabis sativa with multiple variants (Laursen, 2015)

which has backing in the botany community. However, more recent evidence suggest that there

are in fact two species with multiple variants of each species. Yet, the debate continues with new

technology being developed to assist in better differentiating types of marijuana. The

differentiation of Cannabis as either ‘Hemp’ or ‘Marijuana’ by government officials is vital

during enforcement of drug laws in relation to cannabis. Marijuana has been defined by law

officials as the intoxicating variant of cannabis, whereas hemp has been defined as the non-

intoxicating version (Cherney & Small, 2016). Although the minimum level of 1%

Tetrahydrocannabinol (THC) is required to have an intoxication effect (Cherney & Small, 2016),

governments have deemed cannabis plants with less than 0.3% THC as hemp and those with

more as marijuana (Laursen, 2015). For the terms of this paper no species will be identified, and

all variants of the plant will be referred to as cannabis, marijuana or hemp to prevent confusion.

In the Jepson Manual only one strain of Cannabis is mentioned, Cannabis sativa: Hemp,

Marijuana which is considered to be the non-drug form of the cannabis plant by law

enforcement. Cannabis is described as an erect annual with unbranched hairs, the inner bark is

fibrous, and the plant is dioecious meaning a plant either produces male or female reproductive

parts but not both (Patterson et al, 2012). The female flowers have psychoactive resin

(Tetrahydrocannabinol) which is what gives the plant its intoxicating effects when consumed

(Patterson et al, 2012). Most of the known lineages seem to be capable of producing viable

offspring from hybrids (Laursen, 2015). In the marijuana sector, individuals differentiate

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marijuana by strains named by breeders (Laursen, 2015). Cannabis can be used as a medicine,

the stems fibers can be used for rope, fabric, paper, etc (Patterson et al, 2012). It is believed to be

native to Asia but has been cultivated in the U.S. for centuries and is found commonly in

disturbed areas (Patterson et al, 2012).

Marijuana is a water dependent crop that thrives in moist soils (Bauer et al, 2015).

Reports suggest that an individual cannabis plant requires between 3.8 to 56.6 Liters of Water

Per Day (LPD) but averaging at 18.9-22.7 LPD (Bauer et al, 2015). Withholding water during

early developmental stages could stunt floral formations (female inflorescences and intercalated

bracts) which is the part of the plant that is typically harvested for profit. The optimal growing

season for marijuana is between May and September. This conflicts with northern California’s

wet season where approximately 95% of the precipitation occurs between October and April

(Bauer et al, 2015). Yet, nearly 75% of the marijuana consumed in the United States is produced

in California (Carah, 2015) The lack of precipitation has driven many growers to choose land

with year round water services to secure irrigation through hot and dry summers for cultivation

sites (Bauer et al, 2015).

Disconnect between State and Federal Government.

The classification of marijuana by the federal government as a schedule one drug makes

the use and production of marijuana illegal federally under the United States Controlled

Substance Act (CSA) (Bezdek et al, 2017). This creates a complex legal status for marijuana

when production is legal at state level yet still subject to federal drug laws. The legal status of

cannabis has forced growers to establish farms in secluded areas like the “Emerald Triangle”

which includes Humboldt, Trinity and Mendocino County (Butsic and Brenner, 2016). The

Emerald Triangle is dominated by dense forest, steep rugged terrain and consist of remote

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sparsely populated area making it ideal for growers that want to remain discrete (Bauer et al

2015). The complexity of the legal status of marijuana has established a distrust between growers

and law enforcement (Bauer et al 2015).

Initially Humboldt and Mendocino County had some of the most lax regulations on the

marijuana production. The state Senate Bill 420, The Medical Marijuana Program Act (MMPA),

granted each county in CA the power to interpret and implement regulations on marijuana use,

possession and agriculture for medicinal purposes, clarifying Proposition 215 which exempts

permitted patients using medical marijuana from criminal laws (Senate Bill No. 420, 2003;

Ballotpedia, 2019). In Humboldt county, qualified patients and their caregivers were allowed to

grow any number of plants within a 100 square foot plot (Short-Gianotti et al, 2016). After

discovering the impacts that both indoor and outdoor grow sites have on the environment,

Humboldt and Mendocino County placed restrictive guidelines on marijuana production.

Humboldt County’s Ordinance 2328 (2004) required marijuana growers to comply with

state regulations on activities that affect waterways while encouraging growers to practice

environmental stewardship as well as limiting the amount of plants that can be grown in on a plot

(Short-Gionnati et al, 2016). This was later revised by Humboldt County’s Ordinance 2525

(2014) which restricted growers to a plant canopy of 100 square feet on plots less than one acre

and a 200 square foot plant canopy on plots between one and five acres (Short-Gionnati et al,

2016). Mendocino county implemented a permit program, Mendocino county code 9.3 (2010),

which limits the amount of plants that can be cultivated on a plot to 25 cannabis plants per grow

site despite the number of qualified growers using the area (Short-Gionnati et al, 2016). The

county code requires qualified growers to pay permitting fees, participate in 4 annual

inspections, install security measures and requires growers to comply with state environmental

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regulations (Short-Gionnati, 2016). Although the permit program proved to be successful, the

involvement of the federal government led Mendocino County to revise the permit program

(Short-Giannotti et al, 2016). Federal official’s used court orders to have access to counties

inspection and registration records to assist with locating and raiding grow sites (Short-Giannotti

et al, 2016). Mendocino County later revised permit programs to eliminate inspection and

registration requirements, but still requires limits on the amount of plants that can be grown at a

cultivation site. In 2014, a spending bill was released prohibiting the US Justice Department

from spending money to enforce the federal ban on marijuana in states that have legalized the

use of medical marijuana in hopes of mending distrust between growers and law-enforcement

(Halper, 2014).

The diversion of water from most of Northern California’s watersheds must be registered

with the State Resources Control Water Board (SWRCB), whether it is for domestic or

agricultural purposes, and are restricted to standards set by the California Department of Fish and

Wildlife to protect natural ecosystems (Bauer et al, 2015). Despite the requirement for marijuana

farmers to comply with California’s environmental regulations, especially those pertaining to the

state’s water laws, numerous growers have been recorded as not reporting their water diversions

in the Northern California basin (Bauer et al, 2015). The lack of reported water diversions limits

the SWRCBs ability to regulate water use in these watersheds. This combined with the common

distrust established between growers and law enforcement allows for the assumption that the

majority of cannabis farmers do not want to risk identifying themselves by registering water

diversions.

Challenges in research

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The complex legal status of marijuana has made research difficult by limiting who can

and does participate in research and what data is collected (Short Giannotti et al, 2016). In

interviews conducted with researchers focusing on the environmental impacts of cannabis

horticulture, Short-Giannotti et al, 2016 found that as of 2008 agency staff were aware of the

environmental impacts cultivation has but were unable to address it because of lack of legislative

direction. Social and economic aspects also come into play when addressing the lack of research.

Academic research has a lack of funding because universities have deemed marijuana as non-

academic and as having nothing to do with natural resource and ecological management

practices (Short Giannotti et al, 2016). It has also proven difficult to find research assistants that

lack bias or political motives (Short Giannotti et al, 2016). Safety concerns also limit the

undertaking and quality of field research. Marijuana grow sights are typically secured by armed

guards and have hidden traps to deter anyone from discovering the cultivation site. Researchers

will avoid collecting data in areas that present any evidence of being cultivation site, unless they

are accompanied by law-enforcement officers (Short-Giannotti et al, 2016).

Reliance on law-enforcement has constricted study designs by only including sites that

have been discovered and raided by law enforcement, thus excluding most legal marijuana

production from research (Short-Giannotti et al, 2016). This creates a biased in research studies

because research sites center around those that are prioritized by law enforcement. Which puts

research at a disadvantage because law-enforcement does not accommodate to the time sensitive

needs that most test require. For example, researchers testing water quality for traces of

pesticides must collect samples after the first rain event of the year to gather accurate data on a

sites runoff (Short-Giannotti et al, 2016). Lack of diversity on site selection due to dependence

on law enforcement officials has encouraged researches to use aerial imagery to identify grow

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sites. However, Bauer et al, 2015 found that aerial imagery is most effective on large scale

cultivation plots in forest clearings greater than 10 meters squared because forest canopy cover

and shadows can hide individual plants or small sites. To avoid detection, growers plant cannabis

on wide spacing in small canopy forest canopy openings (Bauer et al, 2015). Which indicates

than even in cases where cultivation sites are identified, many sites are looked over because of

lack of visibility.

Pesticide and Plant Growth Regulators (PGR) use and regulation

Pesticide and chemical use during the cultivation of marijuana is a complex and

controversial topic between the marijuana industry and those concerned about environmental and

public health. As research increases it has become apparent that regulations are necessary to

address the impacts on the health of consumers and organisms that are dependent on nearby

habitats (Subritzky et al, 2017). When regulations are being implemented, the needs of the

cannabis industry should be met to ensure the production of a quality product. When left

unchecked, growers will continue to disregard the risks on the health of consumers and the

environment (Subritzky et al, 2017). If regulators can limit the pesticide and chemical use

acceptable during marijuana production, California can limit the amount of chemicals and

pesticides that this ecosystems are exposed to.

Subritzky et al, 2017 defines a pesticide as “any substance or mixture of substances

intended for preventing, destroying or controlling any pest or unwanted organism causing harm

during or otherwise interfering with the production, processing, storage, transport or marketing

of a crop. This includes substances intended for use as growth-regulator, defoliants, or desiccants

and any substance applied to crops, either before or after harvest to protect the commodity from

deterioration during storage and transport.” Plant growth regulators (PGR) are chemicals used to

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produce ideal plants that are more uniform with high levels of THC (Subritzky et al, 2017).

PGRs are becoming more popular amongst those growing for medicinal purposes, however

harvested plants tend to have traces of PRGs (Subritzky et al, 2017). PRGs when consumed can

cause infertility, cancer and liver damage (Subritzky et al, 2017).

Regulations on pesticide use during cultivation have been lax despite its legal status.

Regulators are becoming more concerned of the health effects that pesticides and PGRs can have

on consumers. As mentioned in the introduction, inhalation of a pesticide by smoke is one of the

most toxic ways to ingest a pesticide (Cuypers et al, 2017), yet smoking is one of the most

common ways marijuana is ingested (Pacula et al, 2015). Beyond public health, the use of

pesticides can contaminate entire ecosystems stressing and risking organisms in nearby habitats.

In 2000, the California Fish and Wildlife Services reported that 70% of the animals they had

tested returned with traces of Anticoagulant rodenticides (Thompson et al, 2014). Anticoagulant

rodenticide, a type of pesticide that was created to deter rodents from crops, exposure can lead to

wildlife population declines as well as act as an inhibitor for anti-predator, pathogen and parasite

defenses (Thompson et al, 2013). Pesticide contamination often occurs near agricultural fields,

urban or suburban areas (Thompson et al, 2013). However, there has been an increase in the

amount of cases where organisms native to undeveloped landscapes are being affected by

rodenticide poisoning (Thompson et al, 2013). In many of these cases the only anthropogenic

exposure that these landscapes have was pinpointed to illegal marijuana cultivation sites

(Thompson et al, 2013).

Gabriel et al, 2012 found that 83% of Pacific Fishers (Pekania pennanti) sampled and

submitted by the US Forest Service Kings River Fisher Project and the UC Berkeley Sierra

Nevada Adaptive Management Project tested positive for at least one anticoagulant rodenticide

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compound. Fishers are considered to be a species of conservation concern in the western US

because populations are small and highly fragmented (Thompson et al, 2013). The status of

Fishers makes them vulnerable to disease and spontaneous events like wildfires and natural

disasters. Fishers have been under state and federal protection by the US Forest Service, the

United States Federal Endangered Species Act and California and Oregon Endangered Species

Act (Thompson et al, 2013). Though they have been in protection for nearly 40 years, the Fisher

populations have not expanded or recolonized much of their historical habitat (Thompson et al,

2013).

Researchers at the UC Berkeley Sierra Nevada Adaptive Management Project Fisher

research team discovered a Fisher in 2009 whose death was linked to anticoagulant rodenticide

exposure. The discovery of this deceased Fisher was concerning because as mentioned earlier,

anticoagulant rodenticides are commonly used in conjunction with anthropogenic developments.

A Fishers habit in the Sierra Nevada’s consist of mountainous terrain between 1000 and 2400

meters which do not come into contact with anthropogenic exposure (Thompson et al, 2013).

However, upon discussing with law enforcement it was discovered that the area has had reports

of illegal marijuana farms (Thompson et al, 2013). After conducting test along the west slope of

the southern Sierra Nevada, the High Sierra Nevada and Bass Lake Ranger Districts of the Sierra

National Forest (California), Thompson et al, 2013 found a positive correlation between the

number of cannabis cultivation sites that a Fisher comes into contact with and rates of Fisher

mortality.

Though organisms can be exposed to pesticides in numerous ways by agricultural and

urban use, regulations have been implemented to prevent exposure in large amounts and avoid

sensitive habitats. The lack of pesticide regulations on cannabis cultivation specifically has

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enabled growers to use whatever pesticide is readily available despite toxicity levels. Cuypers et

al, 2017 focuses on illegal marijuana farms raided in Belgium. Although the information was

collected in another country, the paper presents information on how cultivators are using

pesticides on their marijuana plants. Cannabis growers are spraying plants directly with any

available pesticide instead of mixing environmentally friendly pesticides in irrigation water.

(Cuypers et al, 2017). Most growers use pesticides during different developmental stages to

protect crop yield (Cuypers et al, 2017). As plants reach maturity, they attract additional pest

which establishes a need for pest management (Cuypers et al, 2017). Pesticide use during later

developmental stages creates a toxicological threat to consumers (Cuypers et al, 2017). The use

of pesticides on cannabis plants is not regulated by the US Food and Drug Administration and

the Environmental Protection Agency due to the federal prohibition of cannabis, which creates a

public health concern (EPA, 2017; US Food and Drug Administration, 2018).

Growers will ‘flush’ plants in an attempt to rid any traces of pesticides, yet no studies

have been conducted which affirm that this method is able to remove pesticide residues. The

process of flushing requires the grower to halt all pesticide use for two weeks and only rely on

pure water, typically right before harvest to purge plants of pesticide and chemical traces

(Subritzky et al, 2017). Despite assumed positive intentions, flushing has proven to be more

problematic than a resolution when addressing the toxicant issue. In many cases, flushing will

merely reduce pesticide residue to levels so low that they initially receive a non-detect status

(Subritzky et al, 2017). Cannabis concentrates tend to intensify the dangers of pesticide residue

even when they are not detected in lab test (Subritzky et al, 2017). When a second test is

conducted on the final product, especially in the case of THC and Cannabinol (CBD)

concentrates, lab test can come back positive because residuals tend to increase during the

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extraction process (Subritzky et al, 2017). This established a distrust between manufactures,

cultivators and testing laboratories, especially when manufactures have products recalled

because cultivators reported to manufacturers that the labs results on the product came back as

non-detect (Subritzky et al, 2017).

Despite the federal prohibition, Colorado was the first state in the United States to take

measures towards testing marijuana products for pesticide residue before distribution (Subritzky

et al, 2017). Colorado government offers a separate license which allows testing labs to analyze

plant matter for traces of pesticides and other chemicals that can cause harm and threaten public

health (Subritzky et al, 2017). Colorado wanted the process of regulating pesticides to be

collaborative amongst all stakeholders and to no surprise the biggest push back came from the

cannabis industry (Subritzky et al, 2017). As a huge stakeholder, the cannabis industries input

was highly valued due to experience in the field. There is a concern of biased in these reports

because as with any crop, marijuana farmers are concerned with pest management. One of the

central concerns within the marijuana industry about pesticide regulations stemmed from the fear

of losing plants to pest because the loss is not covered under insurance. The cannabis industry

felt as if limitations on pesticide use would make crops more vulnerable to failure. Manufactures

and cultivators feel as if testing is not as conductive as it is perceived to be because of the lack of

clarity when determining if a product has potentially harmful residual levels. The cost of testing

is another factor that has made regulations difficult. The Humboldt county ordinance draft 2010

reported testing as being unaffordable with test cost averaging between $300-$500 with

additional cost per pound of marijuana and type of test run (Carah et al, 2015).

Indoor cultivation

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Indoor cultivation techniques tend to consume large quantities of energy, in California

indoor cultivation production consumes 9% of household electricity (Bezdek, 2017). Most

indoor cultivation operations use lighting that is equivalent to that of hospitals, with an average

energy intensity of 2283 kWh/kg in the United States (Mills, 2012). The high energy

consumption required by indoor grows stem from a growers need to mimic outdoor conditions

(Mills, 2012). Illegal grow houses seeking discretion will use air-cleaning, noise and odor

suppression machines as well as separate electric/gas/diesel generators that tend to be inefficient

(Mills, 2012). In California cannabis production is responsible for 3% all of energy use (Mills,

2012) and Colorado found that approximately 1,200 legal growers used as much power as 35,000

households (Nestor, 2017). Indoor cultivation is assigned the blame for the high energy usage

associated with cannabis production because outdoor cultivation typically has little energy

requirements. The increase of individuals producing marijuana has led to an increase of resource

demand thus creating the need of new policies, taxes, and fees being implemented in areas where

legal marijuana cultivation has been established.

Outdoor cultivation

Outdoor cultivation encompasses grow sites located outdoors as well as those in

greenhouses that do not require excessive energy use and rely primarily on natural elements like

sunlight to encourage plant growth. Instead of requiring energy intensive practices, outdoor

cultivation risks land management by degrading the environment via land clearing, illegal water

diversions, polluted water runoff, etc. Outdoor cultivation presents a popular alternative amongst

cannabis growers. Decorte, 2010 reported that 53.3% growers in Belgium preferred to grow

outdoors. In the United States, Kotch et al, 2016 estimates that approximately half of the grow

sites identified by the DEA were located outdoors. 44% of marijuana plants discovered and

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eradicated by the federal government were located in national forest in California, Oregon and

Washington (Kotch et al, 2016).

Land clearing for cannabis horticulture is responsible for fragmenting forest into smaller

more isolated patches (Wang et al, 2017). Wang et al, 2017 found a significant change in

Humboldt County landscape resulting in an increase of fragmented small forest patches with

more exposed edges and reduced core areas over a 13 year period. This change can be accredited

to cannabis cultivation because the only other stressor present is timber harvest. Timber harvest

typically creates isolated smaller fragments of forest as well, but the forest patches have regular

patterns whereas land clearing for cannabis cultivation does not (Wang et al, 2017). Generally

land clearing for cannabis cultivation generates proportionally greater losses of core area and

increases forest edge and shape complexity (Wang et al, 2017).

Forest fragmentation in national parks can put biodiversity hotspots at risk of failure.

Fragmentation, isolation and shape of forest patches can change the density and persistence of

organism populations inhabiting the patches (Magrach, 2011). The irregular distribution of

cultivation sites has generated more isolated patches of forest. When searching for an ideal

cultivation site the majority of cultivators will choose an area based primarily on physical

accessibility and access to nearby roads and water sources (Bouchard et al, 2011). The ideal

location for a grow site is relatively close to both water for irrigation and a nearby by

road. Bouchard et al, 2011 reported that 75% of grow sites discovered were located within 175

meters of a road, deeming road access as a driving factor for location. Approximately 25%

growers stayed within 92 meters of a water source, however the mean distance from a water

source was 380 meters (Bouchard et al, 2011). As for physical accessibility most growers stayed

within an elevation of 200 meters, however 25% growers were located at elevations above 350

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meters (Bouchard et al, 2011). Location of sites prioritizing accessibility, water and road access

explains the irregular distribution and strong spatial clustering of marijuana grow sites (Short-

Giannotti et al, 2016). As cannabis cultivation continues to gain popularity, the spatial

distribution of sites need to be taken into consideration during mitigation to minimize the

impacts on natural ecosystems. It can be assumed that this pattern of small grow sites

fragmenting forest will continue because currently in California outdoor cannabis cultivation is

limited to 0.4 ha per site (Wang et al, 2017).

Beyond habitat fragmentation, outdoor marijuana cultivation has been reported as being

responsible for illegal water diversions and altering watersheds. Marijuana plants are a water

intensive crop requiring approximately 18.9-22.7 LPD of water which explains why outdoor

cannabis cultivators prefer locations in sensitive watersheds (Figure 2) (Bauer et al, 2015; Wang

et al, 2017; Bouchard et al, 2011). Bauer et al, 2015 depicts the effects that cannabis cultivation

have on 4 watersheds in Northwestern California, it’s primary findings suggest that most

marijuana grow sites are not distributed well thus stressing streams where water is being

diverted. Bauer et al, 2015 estimated that within the study site, watersheds had an average of

between 23,000- 32,000 marijuana plants requiring a total of 523,144 - 724,016 LPD of water.

Even though water use estimates have large ranges making most regulators hesitant on

implementing legislation targeting water use, one cannot be ignore the effects water diversions

have on watersheds. Bauer et al, 2015 found that water diversions in 3 out of 4 sites could be

responsible for completely dewatering streams. Even in cases where streams are not dewatered,

decrease in flow alters the chemistry in streams by increasing temperature, changing pH and

alkalinity (Bauer et al, 2016). Changes in water chemistry and flow often result in an increase in

amphibian and anadromous fish mortalities (Bauer et al, 2016). In the 4 watersheds studied,

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summer flows tend to be so low that they can barely support the SWRCB guidelines on water

diversion without the cannabis industries additional water diversions (Bauer et al, 2015).

Lack of accountability has enabled cultivators to use surface water at the expense of these

sensitive watersheds. Bauer et al, 2015 found that even in situations where growers have on-site

water supplies, direct surface water diversions continue until the source is depleted. Only when

the water in streams is dried up will the water that was stored earlier be used. The complexity of

the legal status of marijuana cultivation contributes to most cultivators’ absence of

environmental stewardship. Pesticides used at outdoor marijuana grow sites tend to find a way

into ecosystems, entering food chains and threatening organisms in nearby ecosystems (Carah et

al, 2015). The inadequacy of incentives and impracticability of being environmentally conscious

because of costs and risks at these grow sites has led to large amounts of litter and poaching

being reported at grow sites (Short-Giannotti et al, 2016).

Waste management

Organic waste produced by the cannabis industry has been estimated at several million

pounds in the United States (Gorrie, 2018). Organic waste typically includes failed plants,

leaves, buds, seeds and stem and root balls along with growing mediums that are no longer

viable (Gorrie, 2018). The legal status of marijuana makes waste management difficult for

marijuana cultivators whether or not they are growing within the parameters that the state allows

(Gorrie, 2018). To insure discretion most growers are hesitant to risk discovery using traditional

waste management methods seeing that obtaining a warrant is not necessary for law-enforcement

to search garbage (Gorrie, 2018). To implement these regulations states hold cultivators

responsible for keeping track of organic waste, some jurisdictions go as far as requiring each

plant to have an ID and tracking tag and for senior managers to accompany waste to any external

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disposal site (Gorrie, 2018). Although waste typically has little to no potency regulators still

require evidence of all waste activity and marijuana waste must store in a secure area with

limited access and constant surveillance (Gorrie, 2018). This prevents black market growers

from stealing waste products to support their farms.

Gorrie, 2018 describes a few general options for waste management within the cannabis

industry. Compost is often the most sought out method of disposal, however regulations on

cannabis organic waste make it difficult for growers to use compost as a disposal method. States

like Oregon limit on site compost to 100 tons annually, preventing pollution or odor issues

(Gorrie, 2018). If waste is combined with equal parts of another organic or inorganic matter

making the product unrecognizable (50/50 ratio), it can be sent to a landfill or composting

facility (Gorrie, 2018).This can pose a problem in areas with small composting facilities that

need to dispose of large quantities of marijuana waste since smaller facilities tend to lack the

non-cannabis products to meet the required 50/50 ratio (Gorrie, 2018). The Bokashi process uses

waste to create a liquid fertilizer, however is difficult to create these fertilizers as the amount of

activator required in this process is difficult to estimate (Gorrie, 2018). The Micron Wastes

system turns cannabis waste into a liquid residue that enables sewer disposal but requires

cleaning to render the product non-potable and disposable (Gorrie, 2018).

Alternatives and mitigation

A major barrier in building a sustainable cannabis industry stems from lack of knowledge

as to how to implement sustainable practices within the cannabis industry. Chouvy et al, 2018

describes modern cannabis cultivation techniques adopted in Morocco that mimic techniques

used in other agricultural practices. These methods include cultivation of high yielding varieties,

seedlings planted on raised nursery beds typically in greenhouses, single row planting using drill

20

and transplanting methods, drip irrigation, mulching with hay, drying plants in indoor dust free

facilities, individual harvesting techniques and excessive fertilizer use (Chouvy et al, 2018). The

legalization of recreational use of marijuana in California has increased demand making large

scale industrialization similar to that established in Morocco a realistic possibility for California's

future. Both large and small scale agricultural practices can stress the surrounding environment.

To minimize impacts that the cannabis industry has on the environment education opportunities,

incentives and legal repercussions should be implemented. Subritzky et al, 2017 suggest that

jurisdictions consider using tobacco as a reference when drafting regulations on the use of

pesticides during marijuana cultivation since tobacco and marijuana share similar attributes.

Investments in funding and expanding testing labs to improve the current testing laboratories

already established should be prioritized. Developing guidelines of practices that cultivators

should follow to encourage safer cultivation practices.

While regulators may have difficulty enforcing legal repercussions in relation to

marijuana production due to the complex legal status of cannabis use and production, reward

based programs established within states where cannabis is legal can directly address the

issue. Denver has begun to take steps towards encouraging a sustainable future within the

cannabis industry. To encourage cannabis retail businesses to strive for suitability the Denver's

Department of Environmental Health has opened their Certifiably Green Denver retail

certification to cannabis dispensaries, recognizing sound environmental resources and business

management practices (Andrle, 2017). The first cannabis facility to receive the city of Denver’s

Certifiably Green certification, L’Eagle led by co-owner Amy Andrle, is actively breaking

barriers in the cannabis industries sustainability movement (Ruby-Cisneros, 2018). L’Eagle is a

zero waste facility, located in a warehouse in downtown Denver which combines a retail

21

business and cultivation facility (Ruby-Cisneros, 2018). L’Eagle is focused on conserving

energy, water and resource management. L’Eagle is a prime example of how to produce a quality

product while minimizing effects on the environment as well as public health. Even pest

management practices have been modified to minimize negative impacts. L’Eagle uses Organic

Materials Review Institute rated pesticides derived from all natural ingredients (Ruby-Cisneros,

2018). L’Eagle’s storage of water intended for irrigation use overnight is considered to be one its

most effective conservation practices (Ruby-Cisneros, 2018). Cannabis cultivation typically

requires an average water temperature of 70 Degrees Fahrenheit for irrigation (Ruby-Cisneros,

2018). Storing cold water overnight assists in limiting energy usage required to heat up irrigation

water by bringing the water to room temperature before the next day (Ruby-Cisneros, 2018). The

Cannabis Sustainability Work Group lead by the Denver's department of Environmental Health

promotes non-regulator sustainable strategies by developing educational resources including a

best management proactive manual, and sponsorship of the organic cannabis associations’ annual

cannabis sustainability symposium.

Agricultural methods like large scale outdoor and hydroponic horticulture can have

detrimental impacts on the environment because the excessive use of fertilizer and chemical

additives. Though hydroponics can conserve water, hydroponic growers tend to be dependent on

chemical nutrients to support crop yield (Suhl, 2016). Lenton et al, 2018 reported that

hydroponic growers are 12 times more likely to use chemicals to support crop yield than natural

growers. Chemicals used during developmental stages of marijuana cultivation tend to remain

present after harvest and have adverse effects on public health (Subritzky, et al 2017, Cuypers,

2017, Lenton et al, 2018). Large scale outdoor cultivation tend to require excessive fertilizer use

to accommodate for poor soil quality and encourage a healthier crop yield (Short-Gianotti et al,

22

2016). In 2003, Morocco's large scale outdoor cannabis agricultural sites reported using

approximately 600 tons of synthetic fertilizers (Chouvy et al, 2018). The United States Forest

Service reported that approximately 1 pound of fertilizer is used for every six marijuana plants

produced in outdoor cultivation (USFS, 2009). Excessive fertilizer use can pollute surface water

and contribute to eutrophication increasing the occurrence of algal blooms in nearby watersheds

(Short-Gianotti et al, 2016).

Implementing aquaponics in cannabis cultivation can decrease reliance on chemical

nutrient additives and excessive fertilizer use unlike hydroponics and large scale outdoor

cultivation. Green Relief, a licensed marijuana cultivation facility located in Hamilton, Ontario is

the planets first cannabis provider using aquaponics as a sustainable cultivation technique (Green

Relief, 2019). Aquaponics is the combination of hydroponic agricultural systems and aquaculture

creating a sustainable soil-less form of agriculture. Aquaponic systems provide nutrients to

plants via recycled water from fish tanks. Fish excrete feces in the water creating waste

byproduct and organic matter which is then filtered through the plant roots. Plants uptake fish

waste and organic waste as fertilizers, supporting plant growth and cleaning the water so that it

can be cycled back to the fish tanks (Suhl, 2016). The only way water can escape from the

system is through evaporation and evapotranspiration which assists in water conservation (Suhl,

2016). Green relief reports that while using aquaponics they are able to produce 10 times the

average crop yield while using 90 % less water than conventional cultivation techniques (Green

Relief, 2019).

Conclusion:

It is clear that the expansion of the marijuana industry if not managed properly will

continue to have adverse effects on the environment. As legislation and research develop it has

23

become apparent that presently cannabis cultivation is damaging ecosystems and increasing

energy demands. California has taken the lead in the nation’s sustainability and environmental

stewardship movement but has yet to implement regulations that specifically target cannabis

cultivation. This stems from a lack of support from organizations that are under control the

federal government. Within the last five years there has been legislation passed (assembly bill

243, 266 and state bill 64) which requires the development of land use ordinances, permits for

water diversions, and enforcing of seed-consumer tracking amongst cannabis growers (Butsic,

2016). However, most outdoor farms in Northern California are located in secluded areas that

require access to private road making it difficult to implement these laws. The lack of enforced

legislation combined with the increase of marijuana cultivation due to legalization of recreational

cannabis use will allow growers to expand farms in fragile areas.

There is a lack of knowledge and research on how to implement safe and sustainable

practices in cannabis cultivation. Only recently was the effects that pesticide residue introduced

to human body through cannabis consumption recognized. Lifting the federal prohibition on

cannabis can make it easier implement regulations preventing the distribution of cannabis

products with pesticide residue levels that pose a health risk. By redirecting the sales tax imposed

on marijuana to fund research projects that explore cultivation alternatives and education

programs focused on implementing sustainable agricultural practices, California can minimize

the effects cannabis cultivation has on the environment. While the cannabis industry is still

establishing itself measures need to be taken to ensure that it is moving towards a green future.

Figures and Tables

24

Table 1Drug Time

PeriodAges 12 or

OlderAges 12 to

17Ages 18 to

25Ages 26 or

Older

Marijuana/ Hashish

Lifetime 45.20 15.30 52.70 47.50

Past Year 15.00 12.40 34.90 12.20

Past Month 9.60 6.50 22.10 7.90

(Table 1: National Survey on Drug Use and Health: Trends in Prevalence of Marijuana/ Hashish for Ages 12 or Older, Ages 12 to 17, Ages 18 to 25, and Ages 26 or Older; 2017 (in percent).) (National Institute on Drug abuse, 2019).

25

Figure 1

(Figure 1: Estimated Economic impacts of the United States 2017-2022.) (McVey, 2018).

26

(Table 2: Depicts the standard energy model for small scale indoor cultivation sites) (Mills, 2012)

27

Figure 2

(Figure 2: Map of Humboldt County, California depicting the number of cannabis plants in each watershed.) (Wang et al, 2017)

28

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