Duncan PUA WWT Wastewater Treatment Plant, Duncan, Oklahoma

Duncan PUA WWT is a wastewater treatment facility located on Fuller Road in Duncan, Stephens County, Oklahoma. It serves an estimated population of 22,505, placing it in the medium-agglomeration category for US municipal plants. The facility is situated inland, more than 50 km from the coast. As a US-based plant, Duncan PUA WWT operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permitting, typically administered by the Oklahoma Department of Environmental Quality. For a plant serving over 20,000 people, secondary treatment is the minimum standard, with potential requirements for advanced treatment depending on the receiving water body's sensitivity. The plant discharges treated effluent into a local water body that ultimately drains into the Red River basin, which flows south to the Gulf of Mexico. The facility's operations contribute to protecting downstream water quality in the region's streams and rivers, supporting aquatic life and recreational uses.

The plant's discharge enters a tributary of the Red River, which flows through southern Oklahoma and into the Gulf of Mexico. The Red River basin supports diverse aquatic ecosystems, including fish species such as catfish and bass, and provides habitat for migratory birds. The watershed is influenced by agricultural and urban runoff, making proper wastewater treatment essential for maintaining water quality and ecological balance.