Greening the Cannabis Industry

Growing cannabis emits volatile organic compounds (VOCs). Marijuana-Infused Product (MIP) facilities or hemp extraction facilities also emit VOCs from solvent extraction processes.

VOCs from the cannabis industry contribute to ozone formation in Denver's ozone nonattainment area. We have recommended best management practices for both grow and MIP facilities to reduce their air quality impacts. 

MIP facilities and any cannabis facility that uses a process boiler or generator may be subject to air pollutant reporting and permitting depending on annual emissions. 

​Cannabis Cultivation Emissions Reduction Fact Sheet

• Best management practices. Emission reduction tips.

Hemp Burning Fact Sheet

• Compliance requirements, best management practices , and emissions reduction tips. 

Solvent Emissions From Extraction Facilities Compliance Guidance

• Emission requirements, compliance tips, solvent extraction use.

Terpene exhaust emissions and impact ozone modeling from cannabis plants at commercial indoor cultivation facilities in Colorado

• Published in: Air and Waste Management Association Journal - April 29, 2022

Indoor monoterpene emission rates from commercial cannabis cultivation facilities in Colorado 

• Published in: Air and Waste Management Association Journal - April 13, 2023 

CO2 Capture and Reuse Pilot Project

• First commercial exchange of recovered carbon dioxide.

Guidance, forms and calculators for boiler and generators 

• Guidance 
• APEN forms and emissions calculator 

In the news

• Colorado leads the nation in Cannabis Sustainability (Boulder Weekly)

• Colorado Adopts New Marijuana Waste Rules to Encourage Composting (Westword)

• Selling greenhouse gas to pot growers (Washington Post)

• Colorado tests program that recycles CO2 from beer breweries for cannabis grows (Leafly)

• The Impact -  marijuana grows and extraction labs harm our air - but here's how pollution is being mitigated (WeedMaps News)

Colorado’s marijuana sector heavily relies on electricity to run artificial lights, as well as air-conditioning and dehumidifiers. With electrical generation being responsible for a large portion of greenhouse gasses and other air pollutants, energy efficiency has an impact on air quality in Colorado.

The first step to improving your energy usage is tracking your usage and establishing a baseline.

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Colorado Energy Office - Cannabis resources 

The cannabis industry produces a variety of waste streams, some of which may be subject to specific requirements under the Colorado Solid Waste Regulations and the Colorado Hazardous Waste Regulations. It is up to each facility to comply with these regulations and to determine appropriate waste management strategies including making hazardous waste determinations for each waste stream.

Hazardous wastes generated by these facilities may include, but are not limited to, spent organic solvents and refining chemicals, used reactants, compressed gases or aerosols, bulk or residual fertilizers, cleaning solutions, and universal wastes (mercury-containing lighting, ballasts, batteries, etc.).

​Marijuana and marijuana-related waste disposal

• Compliance Bulletin - waste guidance policy​

Hemp and hemp-related waste disposal

Effective 1/1/21- Summary of New Marijuana Waste Handling Rules

• Recorded webinar on Marijuana Composting Regulations March 2021 

Most cannabis is grown indoors and grow facilities rely on the municipal water distribution system for influent irrigation and wastewater collection system for effluent discharge. Influent filtration and treatment can be necessary for crop optimization which results in energy consumption and waste generation.

If wastewater is sent through a sanitary sewer system, the sewer provider needs to know the type of discharge coming from the grow facility to ensure that they can handle treating that contaminant.

If wastewater is not sent through a wastewater treatment plant via a sanitary sewer system, other options of wastewater treatment must be evaluated. For the domestic portion (e.g., toilets, sinks, showers, laundry), an on-site wastewater treatment system (OWTS) may be appropriate. An OWTS might be permitted either under the local OWTS program (if design capacity is 2,000 gpd or less) or the Water Quality Control Division through the site application/discharge permit process (if design capacity is greater than 2,000 gpd).

For non-domestic wastewater (e.g., hydroponic water, wastewater with plant food or fertilizers), there are several options depending on the type and quantity of wastewater generated, but the permitting entity is dependent on the selected method of discharge or waste handling. Here is a summary of options for industrial (non-domestic) wastewater discharges and the appropriate entity for coordination:

• Discharge to sanitary sewer (Contact the specific sanitation district).
• Discharge to surface water (Contact the Water Quality Control Division, Permits Section).
• Discharge to impoundment (Contact the Hazardous Materials Waste Management Division, Solid Waste Permitting). This option includes evaporation only or settling impoundments before a discharge to surface water, with the discharge permitted by the Water Quality Control Division.
• Discharge to containers/vault and then pump and haul to a facility for discharge (Contact the receiving facility. Note: There may be waste generator and/or tank issues depending on the wastes so should also coordinate with Hazardous Materials Waste Management Division through the technical assistance line at 303-692-3320.)
• Discharge using beneficial use (Contact the Hazardous Materials Waste Management Division, Materials Management) – this includes sludges that are land applied.
• Composting materials (Contact the Hazardous Materials Waste Management Division, Materials Management).
• Disposal at a landfill after mixing with soil or other absorbent material (Contact the receiving landfill to confirm the resulting mixture can meet its waste acceptance criteria prior to disposal at the landfill.)
• Discharge to a septic system or other underground injection if approved by the U.S. Environmental Protection Agency, Underground Injection Control program (Contact Omar Sierra-Lopez at EPA Region 8 regarding permitting). Note: This includes a septic system that combines the industrial (non-domestic) wastewater with domestic wastewater. If there is a non-domestic OWTS at the site, EPA may also evaluate the domestic OWTS during their review/permitting. Please note that OWTS is appropriate for easily digested organic material and settleable solids - similar to household domestic wastewater. OWTS consisting of a tank and soil treatment area without additional treatment is not appropriate treatment for high strength and many other wastes. EPA will require appropriate treatment for the particular wastewater.

Regarding cannabis grow facilities specifically, the discharge and appropriate permitting also depends on the type of operation. For example, a discharge permit is not needed for a greenhouse situation with gravel floors where water is applied to plants in a single use and minimal water drips from the plants to the gravel. In contrast, a hydroponic operation trying to waste a water solution concentrated with nutrients and other constituents would definitely be non-domestic and handled consistent with the list above.

Please coordinate with the local public health agency and the permitting entities identified above when considering options.

There are also water quality considerations other than specific discharges. Inefficient use of water is not only wasteful, but can cause facility damage by encouraging fungal growth, create worker air quality safety hazards and add extra load to the HVAC system, wasting energy.

To contribute towards a greener industry, please use the resources below. To discuss innovative strategies and collaboration, contact Kaitlin Urso.

20 min Video on CDPHE Cannabis Environmental Assistance and the Environmental Leadership Program

Media links and outreach materials

• North American Cannabis Summit - CDPHE presentation.
• Sustainable Cannabis - Podcast
• Navigating Environmental Requirements- Magazine article.
• Air Pollution From Pot Farms - Magazine article.

Environmental Leadership Program

• Cannabis companies are now eligible for State environmental awards 

Food safety requirements for hemp facilities

Marijuana occupational safety and health

Cannabis Consumer Protection - Denver DPHE

• Sanitation guidance for centers, stores, manufacturers and cultivators.
• Inspection process overview.

Cannabis Sustainability- Denver DPHE

• Current best practices.
• Cannabis Environmental Best Management Practices Guide.​