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FAQ: Cannabis and the Environment

Cannabis Plant
Environment, Great Lakes, and Energy

FAQ: Cannabis and the Environment

Cannabis cultivation and processing are expanding, as hemp and both recreational and medical marijuana products are being legalized across the country. As part of this expansion, it is important to determine what environmental regulations may apply. The Michigan Department of Environment, Great Lakes, and Energy (EGLE) has put together answers to these frequently asked questions to aid in the understanding of these regulations. 

  • Yes. EGLE has developed resources for growers and processors. This guidance information can be found at

  • Odor complaints from the growing in marijuana are typically handled by your local unit of government. You can also file a complaint with Michigan’s Cannabis Regulatory Agency.

    If you have other questions about marijuana or cannabis, check out our Frequently Asked Questions.

  • Across the cannabis industry, there is the potential for significant adverse environmental impacts. Cultivation of cannabis can result in impacts to water quality, emissions of air pollutants, degradation of soils, and increased water withdrawals. The processing of cannabis into the final consumer products may result in additional impacts to water quality and air quality, and the generation of potentially hazardous waste streams. The electricity demands of many indoor operations, as well as the transportation of cannabis products throughout the industry, can result in additional adverse environmental impacts. Fortunately, many of these adverse impacts can be avoided or reduced by utilizing environmental best management practices. It is the responsibility of the cannabis industry to abide by these best management practices and to operate incompliance with existing environmental regulations to minimize their overall environmental footprint.

  • Volatile organic compounds (VOCs) are emitted during the cultivation and processing of cannabis. Emissions of these compounds naturally occur during plant growth. VOC emissions may also occur during the processing of cannabis plants due to evaporation of solvents or other volatile chemicals used during extraction processes. VOC emissions are of concern due to their potential to react with nitrogen oxides in the atmosphere and form ground-level ozone. For more information on ground-level ozone and its impact on human health and the environment, visit the EGLE Ozone webpage.

  • Installing building-wide filtration is recommended to reduce the amount of air pollutants emitted to ambient air. Activate carbon filtration is one of the most used filtration technologies and is effective in reducing VOC emissions and may aid in the reduction of odors. The use of building wide filtration should be paired with negative building pressure to ensure that air is moving through the control system before leaving the building. For extraction processes, the use of proper chemical management practices and closed loop extraction systems can minimize VOC emissions due to evaporative losses.

  • The Air Quality Division does not require an air use permit, also known as a Permit to Install (PTI), for the growing of cannabis because VOC emission rates from cannabis have not been established. Studies of VOC emissions from cannabis are ongoing. The applicability of Michigan's Air Pollution Control Rules may change as more information becomes available. Other activities associated with the growing and processing of cannabis may require an air use PTI. For example, a grow facility may need to build a power plant or install emergency generators. Power plants, emergency generators, essential oil extraction, and other equipment may require a PTI. Contact the Environmental Assistance Center to speak with an expert who can assist you in determining if a PTI is required.

  • The Air Quality Division issues permits to cannabis companies that use essential oil extraction. If your essential oil extraction process uses volatile chemicals, then you may need an air use permit. If your essential oil extraction process does not use chemicals or heat, then the process may not need an air use permit. For example, the cold-press extraction process uses mechanical pressure to squeeze fluids from plant material. However, if you use heat or solvents to process the cold-press extract, you probably need an air use permit. Contact the EGLE Environmental Assistance Center to speak with an expert who can guide you through the permit application process.

  • Odor reduction technologies that may be utilized at cannabis facilities include activated carbon filtration, ozone generation control, as well as misters, foggers, and vaporizers. The most effective odor control option can depend on the activities of the cannabis facility. Generally, activated carbon filtration is recommended due to its known effectiveness in removing volatile organic compounds and other gaseous contaminants from the air stream.

  • There are some odor control technologies that may require a permit to install (PTI) to operate. Odor control systems that inject chemicals through mechanisms such as a spray, mist, or vapor may be required to obtain a PTI. In addition, if your odor control system creates ozone to destroy odors, you may need a permit. On the other hand, if your odor control system removes (rather than destroys) odor-causing chemicals before they leave the building, such as an activated carbon odor control system, you do not need an air use PTI. Contact the EGLE Environmental Assistance Center to speak with an expert who can assist you in determining if a PTI is required.

  • Yes. If you do processing at your facility and extract oils from your plants, you should complete the Calculating Air Emissions from Processing Operations worksheet. Air permits are required prior to construction or installation of any processing equipment. If you have already installed and are operating your equipment, you may still need an air permit. This guidance will walk you through calculating your emissions and next steps for a permit application.

  • The EGLE Air Permits page contains information on the process of applying for and obtaining a permit to install. You may also find additional information on permitting of the cannabis industry at

  • Odors originating from cultivation, processing, or use of cannabis products at residential properties will be handled by the municipality at this time. EGLE is currently in the process of developing guidance for municipalities on handling odor complaints from marijuana facilities.

  • The authority that will handle odors from industrial cannabis sources will vary based on the type of source and whether it is permitted by the EGLE Air Quality Division. Odor complaints from hemp facilities will be managed by the Michigan Department of Agriculture and Rural Development (MDARD) and should be referred to the MDARD Right to Farm Program. Odor complaints originating from industrial-scale cultivation and/or processing of marijuana products that do not have an air use permit will be referred to the municipality. Complaints related to odors originating from sources that do have an air use permit will be handled by EGLE.

  • The Protecting Air Quality when Growing and Processing Marijuana has information about many air-related issues, including more specific information on air permitting and when an air permit is required.

  • Yes. You can mix any solid waste that is not a hazardous waste with marijuana plant waste to make it "unusable and unrecognizable."

  • Yes, but only if the following apply:

    1. The compost facility is registered with EGLE.

    2. The compost facility has obtained approval from EGLE’s Composting Program to take marijuana waste.

    3. The marijuana waste has been made “unusable and unrecognizable” with 50% inert organic materials that can be easily composted by the composting facility.

    4. There are no residual chemicals from the processing of the marijuana left on or in the marijuana waste (i.e., liquid butane, liquid carbon dioxide, etc.).

  • Off-gassing ignitable chemicals like butane and ethanol is prohibited. If you have already generated contaminated waste, please contact EGLE to ensure that the solvent recovery is conducted in a manner that meets the hazardous waste generator treatment requirements found under the Part 5 hazardous waste rules. Any ignitable solvent contaminated debris is regulated as a hazardous waste. Consequently, EGLE encourages extraction be performed to completely remove residual extraction chemicals to avoid generating contaminated plant material that is subject to the hazardous waste regulations. Strict rules apply to managing hazardous waste. It must be managed in closed containers that are label and there are storage time limits that must be met. Facilities that fail to meet the hazardous waste generator accumulation requirements require a hazardous waste storage license.

  • Yes, but only if the following apply:

    1. There are no residual chemicals present in the marijuana waste.

    2. The marijuana waste is completely contained within a composting container, within a building, or under a roof on top of a cement pad. a. If composting outside without cover, approval through Marijuana Regulatory Agency (MRA) and EGLE is required before composting begins. Depending on the scale and type of materials being composted, EGLE may require the facility to obtain a Compost Facility Registration through EGLE’s Composting Program.

    3. All the finished compost product is utilized in the growing operation or is properly disposed of in accordance with MRA rules and regulations.

    4. Michigan’s MRA has approved the use of the finished material in the growing operation.

  • Yes, but you must obtain a Compost Facility Registration and be approved to compost marijuana waste through EGLE's Composting Program. The marijuana waste will still be required to be mixed with 50% inert organic materials to make it "unusable and unrecognizable."

  • Any Registered Composting Facility may seek approval to accept this waste by providing detailed answers to the questions in Compost Plan for Marijuana Waste (Attachment 2) and submitting them to Aaron Hiday, Compost Program Coordinator, at

  • The Solid Waste and Hazardous Waste Regulations for Growing and Processing Marijuana has information about many waste-related issues, including definitions for particular wastes and what can be done with those wastes.

  • The process of growing marijuana requires many additives such as fertilizers, pesticides, and/or nutrients that may become a constituent of the runoff water. In addition, there are often many processes involved in a marijuana grow facility in addition to runoff from watering plants that contribute to the facility’s wastewater, such as but not limited to, reverse osmosis, dehumidification, and water softening. These processes produce a concentrate, condensate, or backwash that can introduce and/or concentrate pollutants in the wastewater. Samples must be taken of the wastewater to determine compliance with the Part 22 standards and to assess the potential impacts to the groundwater and drinking water.

    Agricultural water is defined under MDARD (check reference) and includes watering crops. Marijuana is considered a commercial product, not a crop. As a result, the growing of marijuana is governed by different regulations.

    A permit to process wastewater through the Groundwater Discharge Permit Program will include monitoring for parameters of concern to ensure protection of groundwater and safe drinking water

  • Yes. All marijuana grow facilities that plan on discharging to the ground or groundwater must fill out a Groundwater Discharge Permit Application. If the proposed discharge requires a permit, the EGLE Groundwater Permits Unit will assess the application and issue the appropriate permit. If the discharge qualifies for an exemption, the exemption can be processed based on the information provided through the permit application. Both situations require an application to be completed.

  • All wastewater needs to be accounted for, including floor drains. When listing the gallons per day (GPD) and gallons per year (GPY) on the application, keep in mind that these are maximum values for peak discharge. Methods for measuring wastewater flows through floor drains tend to be site-specific, however, some common methods include use of a pump with a run-time meter on it to move water from a sump pit and into the wastewater treatment system or documentation of the gallons of water used per minute by a portable power washing unit and a record of how many minutes the power washer is used each day. In-line flow metering devices are also sometimes used at facilities as water exits floor drain collection systems and, if possible, should be considered as part of the design process for the wastewater treatment system.

  • All applications can be found on MiEnviro, EGLE's wastewater permitting database. A 2210(y) application should be completed. This is not the guaranteed permit category, but it enables us to gather more information for assessment of the appropriate category. Based on other information we have received from marijuana growing facilities, the 2210(y) permit is applicable. The application can be found on MiEnviro, click "Start New Form" and search for 2210(y) under Form Name. The application is called "Groundwater Discharge Permit Application Site Specific Authorization: Rule 323.2210(y)."

  • No. The EGLE Groundwater Permits Unit cannot advise the facility on the system needed for the wastewater. It is the facility's responsibility to propose a treatment and/or discharge system. The permit writer and technical staff, consisting of soil scientists and hydrogeologists, will review the application, analyze the site conditions, and set permit limits based on the treatment and/or discharge methods proposed. The "Typical Limits for Marijuana Grow Facility Groundwater Discharge" document (Attachment 2) provides a summary of the discharge limits for the most common pollutants of concern at marijuana growing operations. This document may be useful when designing a wastewater treatment and discharge system. While it is not required, it is recommended that marijuana facilities hire an environmental consultant that specializes in wastewater.

  • No. Wastewater from oil extraction would not be permitted with an EGLE groundwater discharge permit due to high levels of pollutants found in the waste stream. If oil extraction occurs at the facility, the wastewater must be disposed of as hazardous waste

  • Yes. The wastewater must be tested for all parameters (non-metals and metals) in the "Part 22 Wastewater Testing Parameters for Wastewater Characterization" document (Attachment 1). Please note that samples must be tested according to the EPA Analytical Method, or SW-846 method listed for each parameter. Wastewater samples should be taken of the combined wastewater from all processes associated with the growing of marijuana that will be discharged to the groundwater. This may include, but is not limited to irrigation runoff, reverse osmosis concentrate, dehumidification condensate, floor drain collection water from grow rooms, and water softener backwash, If the wastewater streams are not combined, please take samples from each process.

  • Any product used at the facility that becomes a constituent of the wastewater generated by the facility is considered an additive according to the Part 22 Groundwater Rules. This may include, but is not limited to, cleaning or sanitizing chemicals, fertilizers, nutrients, pesticides, etc. Please list all additives used on the Groundwater Discharge Application. Please be advised that you may be contacted to fill out additional additive forms, if necessary, based on the additives used.

  • It is not required, but it is recommended that the wastewater from the bathrooms (sanitary sewage) be plumbed separately from the process wastewater. A permit obtained from the local health department would be needed to cover the sanitary sewage discharge.

  • The gallons per day (GPD) should be the maximum volume of all contributing sources of wastewater that will be discharged to the groundwater. Groundwater discharge permits are issued for up to 5 years, so the maximum GPD should take into account plans to expand within that time frame. Keep in mind that the treatment and/or discharge method limitations also need to be considered when determining anticipated maximum flow volume. The gallons per year (GPY) is determined by multiplying the maximum GPD by the number of days in a year that the facility is in operation and discharging.

  • The Protecting Water Resources When Growing and Processing Marijuana Guidance has information about many water-related issues, including water use, land use particularly related to wetlands, and more about wastewater.