Skip to Main Content



Tri-City Service District recycles 1,000 dry tons of biosolids per year.

What are Biosolids?
Biosolids are an organic by-product generated from wastewater treatment. They are rich in nutrients such as nitrogen and phosphorus and are used by farmers as a soil amendment. All municipal wastewater treatment plants produce biosolids, a highly treated product resulting from the processed solids separated from wastewater. These processed solids are treated to substantially reduce pathogens (disease-causing organisms) and vector attraction, which allows the solids to be reused.

Why Biosolids?
As our population grows, resource conservation has become essential.  The biosolids program is the very essence of “reduce, reuse, recycle.” By reclaiming biosolids from wastewater, Tri-City is doing its part to save money and resources by reducing dependence on petroleum-based fertilizers.  Resource recycling through biosolids land application puts nutrients back into the soil, instead of creating more solid waste going to landfills.
For farmers, the use of biosolids improves soil condition and provides useful soil additives to pastures, providing cost savings to farmers by eliminating the need for expensive fertilizers.
What are Biosolids good for?
Biosolids are applied to a wide range of crops; for example, grass, pasture, hay, dryland wheat, nursery stock, grass/sod or Christmas tree farmland. Other beneficiaries include: improving soil condition, feeding plants a diet rich in nitrogen, phosphorus and sulfur, provide food for earthworms that, in turn, keep soil healthy and reduce runoff that can clog water bodies making them better for fish.
Are Biosolids regulated?
The Tri-City biosolids program is required to meet strict state and federal regulations designed to protect public health and the environment.  The fields chosen for biosolids application are first approved by the State of Oregon’s Department of Environmental Quality (DEQ) who applies strict criteria established by the Environmental Protection Agency (EPA) for each wastewater treatment facility and application site. Tri-City prides itself on producing quality biosolids for land application resulting in a cleaner environment, a useful soil amendment, and cost savings.

Curious? Check out these pages: