CARLTON STP Wastewater Treatment Plant, Yamhill County, Oregon

CARLTON STP is a municipal wastewater treatment facility located in Yamhill County, Oregon, United States. The plant serves a population of approximately 1,514 residents, classifying it as a small-scale treatment facility within the region. The plant provides secondary treatment, which is the standard level required by the U.S. Clean Water Act for municipal wastewater facilities. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The plant's designed capacity is 1,389.24 units, with an average daily discharge volume of 643.52 units, indicating operational capacity below its design limit. The treated effluent from CARLTON STP is discharged into a local waterway that ultimately drains into the Willamette River basin. The Willamette River flows north through Oregon's agricultural and urban areas before joining the Columbia River, which empties into the Pacific Ocean. The plant's operations help protect downstream water quality and aquatic ecosystems in the region.

CARLTON STP discharges into a tributary of the Willamette River, which flows through the fertile Willamette Valley and supports diverse aquatic life, including salmon and steelhead. The river is a critical water source for agriculture and communities before joining the Columbia River and reaching the Pacific Ocean. The plant's secondary treatment helps reduce nutrient and pollutant loads that could otherwise contribute to eutrophication or harm downstream habitats.