Cannabis Industrial Marketplace

The Environmental Impacts of the Marijuana Industry

Executive Summary

Marihuana cultivation and processing are expanding, as both recreational and medical marihuana products are being legalized across the United States of America (U.S.). ln Michigan, medical marihuana is currently legal, and an initiative to legalize recreational marihuana will appear on the ballot in November 2018. Due to the potential full legalization of marihuana in Michigan, a Michigan Department of Environmental Quality (MDEO) workgroup was formed to assess the environmental risks posed by the marihuana industry.


  • Odor from marihuana cultivation and processing is a major concern. Many people are familiar with the pungent odor from burning marihuana. Foul odors are also generated from the cultivation and processing of marihuana.
  • Processors often use solvents to extract essential oils that contain medicinal and psychoactive compounds. These solvents pose potential public health impacts and may be subject to existing air pollution control rules.
  • Marihuana plants have the potential to emit significant quantities of volatile organic compounds (VOC), which may pose a threat to attainment of the National Ambient Air Quality Standard (NAAOS) for ozone.
  • Depending on the nature, size, and scale of the operation, cultivation and processing facilities may be required to obtain a Permit to Install (PTI), per Rule 2O1 of Part2, Air Use Approval (Parl2 Rules), promulgated pursuant to Part 55, Air Pollution Control, of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended (NREPA).
  • Open burning is another potential concern. The growth and processing of marihuana results in plant wastes, which could pose air quality threats if they were burned as a means of disposal.


  • Any marihuana plant waste should be made unusable and unrecognizable prior to disposal. This can be accomplished by grinding the marihuana waste and incorporating ground, non-consumable materials, such as inedible food waste, kitty litter, municipal solid waste, or other inedible wastes. The mixture should be at least 50 percent non-marihuana waste and should be secured in a locked container until transported off-site.
  • Unprocessed marihuana is currently not listed as a hazardous waste. Characterization determinations could change if the unprocessed marihuana comes into contact with certain listed hazardous wastes during the essential-oil extraction processes.
  • Marihuana byproducts resulting from chemical treatment have the potential to become characteristically hazardous waste. The MDEQ recommends that any treated marihuana or waste byproduct be fully characterized, on a case-by-case basis, before disposal.
  • Inorganic solid wastes can be disposed at a licensed municipal solid waste incinerator or a licensed municipal solid waste landfill.
  • Under current regulations, marihuana plant wastes may be disposed at the following: a licensed municipal solid waste incinerator, municipal solid waste landfill, anaerobic digester, or registered composting facility; or the wastes may be composed on-site.


  • The cultivation of marihuana plants requires significant quantities of water. The use of the State of Michigan Water Withdrawal Assessment Tool (WWAT) will be required prior to beginning any new or increased large quantity withdrawal from groundwater or surface water.
  • A Soil Erosion and Sedimentation Control (SESC) permit will be required for any earth change activity that disturbs one or more acres of land or is within 500 feet of a lake or stream.
  • Construction activities that disturb one or more acres of land and have a point source discharge of storm water to waters of Michigan (streams, rivers, lakes, and wetlands) are required to obtain a National Pollutant Discharge Elimination System (NPDES) Permit.
  • The State of Michigan (State) has assumed authority to administer Section 404 of the federal Clean Water Act (CWA) permitting program, which is the program that regulates the discharge of dredged or fill material into wetlands. The Michigan Department of Attorney General (MDAG) is reviewing if the MDEQ can issue wetland permits for marihuana activities.
  • The State has been delegated authority to administer Section 402 of the CWA, which is the NPDES Program. lf facilities have a direct discharge of pollutants to surface waters, they must apply to obtain an NPDES permit. Further research and/or discussion with the MDAG is needed to determine if the Water Resources Division (WRD), of the MDEQ, needs to add special language in NPDES permits for marihuana operations.
  • The MDEQ does not recommend groundwater (land application) discharges of wastewater from growing or processing facilities.
  • Discharge of wastewater from growing or processing to a septic system is not allowed, as only sanitary wastewater can be discharged to a septic system.
  • The MDEQ has some concerns with contaminated runoff from these sites. Current storm water regulations would not directly apply to marihuana operations.

Key Recommendations

  • Create fact sheets and educational documents for distribution to owners and operators of marihuana cultivation and processing facilities.
  • Develop sample city ordinances or guidance for local governments on how to manage odors, as well as other environmental impacts from the marihuana industry.
  • Review topics where administrative rulemaking may be necessary to properly manage environmental impacts from the marihuana industry and determine if rulemaking is the appropriate avenue for managing these impacts.
  • Continue inter-departmental coordination with the Department of Licensing and Regulatory Affairs (DLARA) and Michigan Department of Agriculture and Rural Development (MDARD); consider developing a task force or formal workgroup to encourage greater coordination across the different agencies impacted by the marihuana industry.
  • Develop internal guidance and policies for how MDEQ staff should handle marihuana facilities moving forward. There is a need for consistency across divisions in how communication, complaints, enforcement, and inspections will be handled.
  • Assist the Bureau of Medical Marihuana Regulation (BMMR) staff in development of a permanent rule set to replace the emergency rules that regulate the marihuana industry.


States that have legalized recreational marihuana are beginning to realize the full extent of environmental impacts associated with the marihuana industry. As marihuana operations continue to expand (Figure 1), state environmental agencies have been working to determine the appropriate method of regulating this industry.

In Michigan, medical marihuana is currently legal and a proposal to legalize recreational marihuana will appear on the November 2018 ballot. Legalization of recreational marihuana could result in a significant increase in production and processing of cannabis. The State must be prepared to address the adverse environmental impacts posed by the marihuana industry. To achieve this goal, the MDEQ formed a marihuana workgroup tasked with assessing the negative environmental impacts that the marihuana industry will have within Michigan.

This white paper examines the environmental impacts posed by the marihuana industry, identifies gaps in the existing regulatory framework, and recommends potential actions the MDEQ may need to take to address the environmental impacts of the marihuana industry.

Definition of marihuana

Cannabis is a tall plant that is cultivated to produce drugs and fiber. Marihuana is the dried leaves and flowers of the cannabis plant that has THC (Tetrahydrocannabinol) in a concentration sufficient to produce a psychoactive effect after ingestion. Marihuana is also a natural source of CBD (Cannabidiol), which is not psychoactive and has medical applications. Hemp is a variety of cannabis that has very little THC and is cultivated for its tough fiber, which is used to make rope, cloth, and other products. Throughout this paper, cannabis will be used when referring to the plant and cultivation, while marihuana refers to the drug and its industry.

Michigan’s Existing Regulatory Framework

Medical Marihuana

Medical marihuana was legalized with the passing of the Medical Marihuana Act of 2008 (MCL 333.26530). The Medical Marihuana Act created a system of registering patients and caregivers, imposed registration, application, and renewal fees, and provided for the promulgation of administrative rules. To supplement the Medical Marihuana Act, the Michigan Legislature adopted the Medical Marihuana Facilities Licensing Act (MMFLA) in 2016, which spells out the licensing requirements for marihuana cultivation, processing, and provisioning operations. Through the MMFLA, BMMR, which is housed within the DLARA, was given the responsibility of licensing facilities that grow, process, transport, and sell medical marihuana in Michigan. ln December of 2017, the DLARA issued emergency administrative rules to implement the MMFLA. These emergency administrative rules specify how facilities can obtain a medical marihuana license, the criteria by which license approval will be assessed, requirements for tracking and monitoring systems, along with several other requirements surrounding the licensing and operation of medical marihuana facilities in Michigan. The emergency administrative rules remain in effect until November 2018. BMMR staff are currently working to develop a permanent rule set that will replace the emergency rules.

Ballot Petition

A proposal to legalize recreational marihuana will appear on the ballot November 2018. This was a result of successful campaign efforts by the advocacy group, Coalition to Regulate Marijuana Like Alcohol. lf passed, the ballot initiative would modify State law to allow legal marihuana possession, use, cultivation, and sale of marihuana for persons 21 years or older. This petition would also allow for taxation of revenue earned from marihuana facilities and would allow for the promulgation of additional administrative rules regarding marihuana possession, use, cultivation, and sale. However, the ballot proposal does not contain language regarding environmental impacts resulting from the legalization of recreational marihuana.

Environmental Impacts of the Marihuana Industry

The marihuana industry consists of five stages: cultivation, processing, distribution, sale, and use. An overview of the process is provided in Figure 2. Cultivation is the stage at which the cannabis plant is grown, either indoors or outdoors. Processing is when the cannabis plant is converted into the final marihuana product that typically involves the use of solvents to extract active ingredients. Distribution involves the transportation of marihuana products to the dispensaries. Marihuana products are sold through dispensaries and used by the consumer.

Environmental impacts from the marihuana industry are most common during the cultivation and processing stages. These stages are the primary focus of the remainder of this whitepaper. Cultivation and processing operations pose several threats to air, water, and land resources in Michigan. Cultivation and processing may be performed at a single facility or at separate operations. The remainder of this section discusses the environmental risks posed by marihuana cultivation and processing operations.

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