West Mifflin Thompson Run STP - Municipal Wastewater Treatment in West Mifflin, Pennsylvania

West Mifflin Thompson Run STP is a municipal wastewater treatment facility located in West Mifflin, Pennsylvania, serving a population of around 13,733. The plant is situated in Allegheny County, part of the Pittsburgh metropolitan area, and treats domestic wastewater from the community. As a US facility, the plant operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permitting, typically administered by the Pennsylvania Department of Environmental Protection. For a population of this scale, secondary treatment is the standard requirement under federal regulations, ensuring removal of organic matter and suspended solids. The plant discharges treated effluent into a local waterway, likely a tributary of the Monongahela River, which flows into the Ohio River and ultimately the Mississippi River system. This drainage supports aquatic habitats and is part of the larger Ohio River basin, which provides drinking water and recreational opportunities for millions.

The plant's treated effluent enters a tributary of the Monongahela River, which joins the Ohio River near Pittsburgh. The Ohio River flows into the Mississippi River, eventually reaching the Gulf of Mexico. This watershed supports diverse aquatic life, including fish species such as bass and catfish, and provides habitat for migratory birds. The region's industrial history means careful management of wastewater is important to maintain water quality and ecosystem health.