Washington Compost Market Study

Providing statewide projections to guide composting infrastructure and policy planning under Washington’s new organics management laws

When Washington set an ambitious goal to reduce organic material in landfills by 75%, the Department of Ecology needed to understand how this would impact composting capacity and market demand. Recent organics management laws established Business Organics Management Areas (BOMAs), which require more businesses to participate in organics collection, and Organics Recycling Collection Areas (ORCAs), setting thresholds for mandatory residential collection. These new requirements are expected to significantly increase the volume of organic material collected statewide, creating a planning challenge for counties, municipalities, and compost operators.

To address this, Ecology engaged Greene Economics to forecast the volumes of incoming feedstocks and finished compost through 2035. Using historical data, facility reports, and waste characterization studies, our team developed a state- and county-level forecasting model that accounts for phased ORCA and BOMA implementation, regional processing differences, and feedstock-to-compost conversion rates. Interviews with facility operators and Ecology staff informed assumptions about capacity limits, market demand, and use of bulking agents and compostable food-service products.

The analysis projects organic material collected for composting will grow from roughly 805,000 tons in 2023 to more than 3 million tons by 2035—nearly a fourfold increase. King County is expected to remain the state’s largest producer, while Spokane and south-central counties such as Benton and Franklin will see the fastest percentage growth. Finished compost production from Washington-sourced feedstock is projected to rise about 30%, reaching nearly 2 million cubic yards by 2035.

For compost operators, these projections highlight new opportunities. Facilities can plan for rising feedstock volumes, optimize operations, and generate new revenue through tipping fees and the sale of compost products. For counties and municipalities, the forecast provides a roadmap to expand collection and processing capacity where and when it's needed.

This study will help local governments and compost facilities plan for growth, divert organic waste from landfills, and reduce greenhouse gas emissions.

View the full report for county-level projections, maps, and insights.

Compost Market Study_Ecology.pdf

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