UNION STP Wastewater Treatment Plant, Union, Oregon

UNION STP is a municipal wastewater treatment facility located in Union, Oregon, serving a population of approximately 1,926 residents. The plant provides secondary treatment, a standard level for communities of this size in the United States, ensuring compliance with federal and state water quality standards. The plant has a designed capacity of 1,381.67 thousand gallons per day and currently discharges an average of 946.35 thousand gallons per day. As a secondary treatment facility, it utilizes biological processes to reduce organic matter and suspended solids before discharge. The plant operates under the US Clean Water Act, which requires National Pollutant Discharge Elimination System (NPDES) permits for all point source discharges. The treated effluent is discharged into a local water body, likely a tributary of the Grande Ronde River, which flows into the Snake River and ultimately the Columbia River. This watershed supports diverse aquatic life and is important for regional water quality and ecosystem health.

The plant discharges into a local stream within the Grande Ronde River basin, which flows into the Snake River and then the Columbia River. This watershed supports salmonid species and other cold-water fish, making water quality management critical. The downstream environment includes agricultural and forested areas, where nutrient loading from wastewater can impact aquatic ecosystems.