OLYMPIA  – 

A new Washington regulation will help reduce emissions of methane, a potent greenhouse gas, from municipal solid waste landfills in the state.

Methane has more than 80 times the global warming potential of carbon dioxide over a 20-year period and is responsible for more than 25% of the temperature impacts coming from climate change today. In landfills, methane is produced by the decomposition of food, vegetation, and other organic materials. 

Reducing landfill methane emissions is part of a suite of climate policies Washington has been implementing to meet a state commitment to reduce greenhouse gas emissions by 95% below 1990 levels by 2050. 

Ecology estimates the new regulation will prevent the equivalent of about 1.6 million metric tons of carbon dioxide from escaping into the atmosphere every year, based on 20-year climate impacts for methane.

“Methane emissions are the second-largest contributor to climate change after carbon dioxide, and landfills are a significant source of this gas,” said Laura Watson, director of the Washington Department of Ecology. “Along with this new rule designed to limit methane emissions at landfills, we are working hard to reduce the amount of food waste and other organic material we throw away, so we can stop the problem before it starts.”

In 2022, the Washington Legislature set a target to reduce the amount of organic materials going into landfills 75% by 2030. The Legislature also directed Ecology to adopt regulations requiring municipal solid waste landfills to take steps to monitor and capture methane emissions. 

Landfill owners and operators affected by the new rule will be required to install gas collection and control equipment, energy recovery devices, and/or treatment and processing systems to reduce their methane emissions. Collecting and burning methane gas as it leaves a landfill limits its heat-trapping power, and the gas can be processed for electricity generation and vehicle fuel.

In addition, the rule requires quarterly monitoring of the landfill surface, quarterly monitoring of gas collection and control system equipment, and a timeline to ensure any methane leaks are quickly fixed. 

Owners and operators of about 26 affected landfills are eligible to apply for a portion of $15 million in grants funded by Washington’s Climate Commitment Act to help comply with the new requirements.

The U.S. Environmental Protection Agency estimates that municipal solid waste accounted for approximately 84% of landfill emissions nationwide in 2022. With this rulemaking, Washington has joined California, Oregon, and Maryland in implementing stronger standards for methane emissions from landfills.