Aumsville STP - Secondary Wastewater Treatment in Marion County, Oregon

Aumsville STP is a municipal wastewater treatment facility located in Marion County, Oregon, along the North Santiam Highway. The plant serves a population of approximately 3,730 residents, classifying it as a small-scale treatment facility within the state's wastewater infrastructure. The plant provides secondary treatment, a standard level required by the US Clean Water Act for municipal wastewater. With a designed capacity of 1,268.11 thousand cubic meters and an annual discharge volume of 870.65 thousand cubic meters, the facility operates under the National Pollutant Discharge Elimination System (NPDES) permit program, which sets effluent limits to protect water quality. The treated effluent is discharged into the local watershed, which ultimately drains into the Santiam River system and then the Willamette River. The Willamette River flows north to the Columbia River, which empties into the Pacific Ocean. The plant's operations help protect the aquatic ecosystems of the Santiam and Willamette rivers, supporting fish habitat and water quality for downstream communities.

The plant discharges into the Santiam River watershed, a tributary of the Willamette River. The Willamette River is a major waterway in Oregon that supports diverse aquatic life, including salmon and steelhead. The plant's secondary treatment helps reduce nutrient and pollutant loads, protecting downstream water quality and ecological health in the Columbia River basin.