ELGIN STP Wastewater Treatment Plant, Elgin, Oregon | Secondary Treatment Facility

ELGIN STP is a municipal wastewater treatment facility located in Elgin, Union County, Oregon. The plant serves a population of approximately 2,035 residents, providing secondary treatment to meet state and federal water quality standards. As a small-scale facility, it plays a key role in managing the community's wastewater and protecting local water resources. The plant operates with a designed capacity of 1,362.74 thousand cubic meters per year and currently treats an average discharge volume of 677.59 thousand cubic meters annually. Under the U.S. Clean Water Act, secondary treatment is the minimum standard for municipal plants, ensuring removal of biodegradable organics and suspended solids. The facility is subject to National Pollutant Discharge Elimination System (NPDES) permitting, which sets effluent limits to protect receiving waters. Treated effluent from ELGIN STP is discharged into the Grande Ronde River watershed, which flows into the Snake River and ultimately the Columbia River. This drainage basin supports diverse aquatic life, including salmonid species, and is an important ecological corridor in northeastern Oregon. The plant's operations help maintain water quality in this sensitive inland system.

ELGIN STP discharges into the Grande Ronde River watershed, a tributary of the Snake River that flows into the Columbia River. This inland basin supports cold-water fisheries, including threatened salmon and steelhead populations. The plant's secondary treatment helps reduce nutrient and organic loading, protecting downstream aquatic habitats and recreational uses.