SUMPTER STP Wastewater Treatment Plant, Baker County, Oregon

SUMPTER STP is a wastewater treatment facility located in Baker County, Oregon, United States. It serves a small community of 175 people, reflecting its role as a local-scale treatment plant in a rural area of the Pacific Northwest. The plant provides secondary treatment, which is the standard biological treatment process for removing organic matter and suspended solids. With a designed capacity of 151.42 units and a current discharge volume of 37.85 units, the facility operates well below its capacity, indicating ample headroom for future growth. As a US plant, it operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permitting, which sets effluent limits to protect water quality. The treated effluent is discharged into a local waterway within the Powder River basin, which ultimately drains into the Snake River and then the Columbia River system. This watershed supports diverse aquatic life and is important for regional water resources. The plant's location inland and away from the coast reduces direct marine impact, but its discharge contributes to the overall health of the river ecosystem.

The plant discharges into a tributary of the Powder River, which flows into the Snake River and then the Columbia River before reaching the Pacific Ocean. This inland watershed supports cold-water fisheries, including salmon and trout, and provides habitat for migratory birds. The plant's secondary treatment helps protect these downstream ecosystems from nutrient pollution and organic loading.