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The Grass Isn’t Always Greener: The Environmental Effects of Marijuana Cultivation

By Eric Ashby*

I. Introduction

The legal status of cannabis in the United States varies widely by state. In some states the substance is legal for recreational use, a number of states have laws providing for legal medicinal use, and in other states cannabis is completely illegal—as it is under federal law. With the passage of Proposition 64 last November, California became the largest state to legalize marijuana for recreational use.[1] It is estimated that between 60-70% of all marijuana consumed in the United States is grown in California, with sales from that amount estimated to be in the range of $11-$16 billion annually.[2]  The state’s Mediterranean climate, plentiful sunshine, and ample land area make it an ideal location to grow quality marijuana outdoors. But the production of marijuana also involves severe and chronic environmental effects that have been largely ignored in the past.

II. Water

California is a primary agricultural producer in the United States, and the fact that the state has been experiencing a drought for several years is a cause for concern. The high water needs of cannabis—which will only grow as the legal market takes off—are a major issue. Cannabis plants grown outdoors consume approximately 22L of water per plant, per day—twice the amount used to grow grapes or tomatoes.[3] During the growing season the total water use of the cannabis farms in California amounts to around 60 million gallons a day—50% more than the water used by all of the residents of San Francisco.[5] Whereas most farmers growing other agricultural products in California fill water tanks in the winter when streams and rivers are full, many cannabis farmers draw surface water directly during the summer when drought conditions are most severe.[6] Additionally, water is often diverted from sources to feed cannabis plants, which threatens the survival of rare aquatic species.[7]

III. Energy

Cannabis grown indoors requires involves extensive energy usage.[8] The electricity costs of indoor production in the United States have been estimated at $6 billion annually, roughly 1% of total electricity usage nationwide and up to 3% of energy usage in California.[9] The need for high-intensity lights as well as ventilation systems drives this demand.[10] While cannabis grown outdoors uses much less energy because of the lack of a need for lights or ventilation, the outdoor grows still require fossil fuel-powered vehicles to transport supplies, people, and finished product to and from grow sites.

IV. Land and Wildlife

Cannabis grown outdoors can also have severe effects on land and wildlife. Extensive land-clearing and deforestation as well as road construction removes native vegetation and increases soil erosion.[11] Many illegal grow operations also leave large amounts of trash scattered about the land.[12] In an effort to protect cannabis plants, farmers often use heavy amounts of pesticides and chemicals which find their way into the food chain and poison wildlife.[13] In fact, the use of rodenticides have killed large numbers of the Pacific Fisher in California, as well as larger animals which eat smaller rodents and become poisoned themselves.[14]

V. Solutions

Much of the environmental damage caused by marijuana is the product of illegal grow operations. Whereas farmers of other agricultural products abide by a variety of regulations concerning water usage, pesticides, and land use, illegal marijuana farmers disregarded them. This is a major issue because marijuana in California is a larger cash crop than dairy, almonds, and grapes combined.[15] The legalization of marijuana in California will help to bring more transparency to the environmental effects and more accountability to growers. Proposition 64 includes a provision which directs 20% of tax revenues collected from the growing and sale of recreational marijuana to address the environmental damage of marijuana. As part of the licensing requirements, growers will be required to “detail the legal sources of water for their operations,” and “licenses can be denied or alter revoked if the cultivator fails to protect…water quality.”[19] The Bureau of Marijuana Control will also “develop regulations requiring growers, manufacturers, distributors and retailers to comply with state and federal environmental laws.”[20]

However, the quasi-legal nature of cannabis in regards to conflicting federal and state laws still presents a problem. The federal ban on marijuana encourages secrecy and puts state officials at risk of upsetting the Feds by regulating a federally illegal substance in accordance with state laws.[21] As long as marijuana remains illegal under federal law, black market production will still exist and drive demand for illegal grow operations which have drastic environmental effects in states like California.[22] Full legalization at the federal level will increase transparency, and provide for open debate and discussion to find solutions to the most pressing environmental concerns surrounding the marijuana industry.[23] Full legalization will also allow for lower prices nationwide which will cause the black market and its environmentally unconscious growers to dissipate over time.[24] As the largest state in the nation and the largest producer of cannabis, California must lead the way for environmentally conscious regulatory policies as it embarks on its legalization journey beginning in 2018.

The views and opinions expressed in this blog are those of the authors only and do not reflect the official policy or position of the Michigan Journal of Environmental and Administrative Law or the University of Michigan.

*Eric Ashby is a Junior Editor on MJEAL. He can be reached at 

[1] California Proposition 64, Marijuana Legalization (2016), Ballotpedia,_Marijuana_Legalization_(2016) (last visited Mar. 3, 2017).

[2] Jennifer K. Carah et al., High Time for Conservation: Adding the Environment to the Debate on Marijuana Liberalization, 65 (8) BioScience 822-29 (2015).

[3] Id.; The Environmental Impacts of Marijuana in California, Stanford Center on Food Security and the Environment (July 8, 2015),

[5] Growing Pains, The Nature Conservancy-California, (last visited Mar. 3, 2017).

[6] The Environmental Impacts of Marijuana in California, supra note 3.

[7] Carah et al., supra note 2.

[8] Id.

[9] Hilary Bricken, Marijuana’s Environmental Impact and The Laws That Regulate It, Canna Law Blog, Mar. 26, 2015,; Frederick Hewett, The Potential Environmental Consequences of Legalizing Pot in Massachusetts, WBUR, Oct. 13, 2016,

[10] Clayton Aldern, Everything You Need to Know About Pot’s Environmental Impact, Grist (Apr. 19, 2016),

[11] Carah et al., supra note 2.

[12] Mitch Moxley, Green But Not Green: How Pot Farms Trash the Environment, Slate, (last visited Mar. 3, 2017).

[13] Growing Pains, supra note 5.

[14] Moxley, supra note 13.

[15] Mike Sweeney, The Truth About Where Your Pot Comes From, Huffington Post (July 8, 2016),

[16] California Proposition 64, supra note 1.

[17] Growing Pains, supra note 5.

[18] Sarah Bell & Robert Hines, Be Prepared for California’s Environmental Rules: Regulated Cannabis Brings Forth New Water Use Guidelines, Mar. 2017 Marijuana Venture 160 (2017).

[19] Id.

[20] Id.

[21] Id.

[22] Carah et al., supra note 2.

[23] Id.

[24] Diane Toomey, The High Environmental Cost of Illicit Marijuana Cultivation, Yale Environment 360 (July 16, 2015),


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