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Cedar Hills Regional Landfill
Learn about King County’s only remaining active landfill. Find information on landfill operations, community meetings, the gas-to-energy facility, and more.
Cedar Hills Regional Landfill
About the Cedar Hills Regional Landfill
The Cedar Hills Regional Landfill is the only active landfill in the county. Located on a 920-acre site in Maple Valley, Cedar Hills has been in operation since 1965. It provides safe and efficient waste disposal for all of King County, except for the cities of Seattle and Milton.
Over 800,000 tons of waste goes to Cedar Hills each year. Most of that waste comes from King County businesses and households. Commercial companies or self-haulers collects and transports waste to a King County transfer station or rural drop box. From these locations, we consolidate the waste for efficiency, then truck it to Cedar Hills for final disposal.
Operations and monitoring
Visit Cedar Hills Regional Landfill Monitoring to read our most recent annual reports and environmental monitoring reports.
Landfill gas-to-energy facility
When waste is buried in the landfill it decomposes and produces landfill gas. At Cedar Hills a network of pipes captures the gas and routes it to an on-site gas-to-energy facility. The plant processes landfill gas into pipeline quality biogas and electric power.
In 2025, King County acquired the gas-to-energy facility from Bio Energy Washington, which previously operated the plant. The County’s Solid Waste Division is working with industry experts to improve collection of landfill gas and optimize production of biogas.
Planning for the future
The 2019 Comprehensive Solid Waste Management Plan sets strategies for managing solid waste over the next six to 20 years in King County. The plan recommends further development of Cedar Hills to maximize capacity and meet regional disposal needs. Visit the Cedar Hills development project to learn more about our plans for landfill development.
Community meetings
We host two community meetings a year as part of our ongoing communication with households living near the landfill. Visit Cedar Hills Regional Landfill community meetings to learn more.
Odor management
Our staff are trained and certified in industry best practices for mitigating landfill odors. To effectively prevent odors, we use strategies such as covering active parts of the landfill at the end of each working day. We also perform regular odor checks. Read more about Cedar Hills odor management and reporting: