The Colorado Air Quality Control Commission has approved a new regulation aimed at reducing methane emissions from municipal solid waste landfills. The move is intended to help the state reach its target of net-zero greenhouse gas emissions by 2050.
Michael Ogletree, senior director of the state’s air quality programs, said, “Colorado prides itself on sustainable regulations, and this progress reflects the extensive collaboration and commitment of our partners in advancing state climate goals. This new standard will significantly reduce methane emissions using proven technologies and climate-smart practices. Strong actions like this help address climate change while protecting our environment, public health, and state economy.”
The newly adopted Colorado Air Quality Control Commission Regulation 31 introduces emission control and monitoring requirements for municipal solid waste landfills. These landfills emit methane as organic matter breaks down. The standard also targets pollutants such as benzene and hydrogen sulfide.
According to the Colorado Department of Public Health and Environment (CDPHE) Air Pollution Control Division, the new measures are expected to cut up to 12.53 million metric tons of carbon dioxide equivalent by 2050—comparable to the emissions from burning nearly 1.41 billion gallons of gasoline.
The regulation will affect up to 32 out of Colorado’s 82 municipal solid waste landfills based on their size and emission levels. Eleven of these sites are already under similar federal rules that have helped lower greenhouse gas emissions over the past five years.
Key elements of Regulation Number 31 include a stricter threshold for emissions controls than required by federal standards, requiring more landfills to install gas collection systems; mandates for closed landfills with combustion devices like flares to add biofilters when those devices are removed; expanded methane monitoring using tools such as satellite imaging; permission for landfill operators to use alternative monitoring technologies; and a phased ban on open flares in favor of enclosed ones that allow performance testing.
These steps follow an October 2024 rulemaking that broadened greenhouse gas reporting requirements for state landfills. The data collected through that process will support tracking reductions in methane as Regulation Number 31 is put into effect.
Development of the rule involved more than a year of input from community members, environmental organizations, industry representatives, and technical experts. Community meetings began in December 2024, with further discussions held through November 2025 before final adoption in December 2025. Ongoing stakeholder engagement is planned during implementation.
For more information about these changes or upcoming public participation opportunities regarding air quality regulations in Colorado, visit the division’s landfill methane reductions web page or contact cdphe.commentsapcd@state.co.us.
