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fir tree branch with blurred background and the text BIOSOLIDS over the top of the photo

The Biosolids Program oversees agriculture and forestry projects and new product development for Loop®, our nutrient-rich organic fertilizer alternative, and a natural soil builder created from King County’s wastewater. As the longest running biosolids program in Washington state, we manage Loop from when it leaves our wastewater treatment plants to when used on farmland and forest floors.

Every ton of Loop is tracked from start to finish, including transportation and delivery, regulatory requirements, monitoring, and public outreach. Our program has a long, successful history of partnering with customers and researchers to ensure 100% of Loop is distributed for beneficial use.

For more information about Loop biosolids, please contact us at: