MONROE STP - Secondary Wastewater Treatment Plant in Monroe, Oregon

MONROE STP is a municipal wastewater treatment facility located in Monroe, Benton County, Oregon, serving a small population of 610 residents. The plant provides secondary treatment, a standard level for communities of this size in the United States. As a secondary treatment plant, MONROE STP utilizes biological processes to remove organic matter and suspended solids, meeting the requirements of the U.S. Clean Water Act. The plant has a designed capacity of 681.37 and currently discharges 446.68, indicating operational headroom. Facilities of this scale are typically regulated under the National Pollutant Discharge Elimination System (NPDES) permit program, administered by the Oregon Department of Environmental Quality. The treated effluent from MONROE STP is discharged into a local water body that ultimately drains into the Willamette River basin, a major tributary of the Columbia River. The Willamette River supports diverse aquatic life, including salmon and steelhead runs, and is an important ecological corridor in the Pacific Northwest. The plant's secondary treatment helps protect downstream water quality and aquatic habitats.

MONROE STP discharges into a local watercourse within the Willamette River watershed, which flows northward to join the Columbia River near Portland. The Willamette River supports critical salmonid populations and is a key migratory corridor for fish and wildlife. The plant's secondary treatment reduces organic pollutants and suspended solids, helping maintain water quality in this ecologically sensitive river system.