New Castle STP Wastewater Treatment Plant, Pennsylvania

New Castle STP is a municipal wastewater treatment facility located in New Castle, Pennsylvania, serving a population of about 40,102. The plant is situated inland, more than 50 km from the coast, and operates under the regulatory framework of the United States Clean Water Act, which requires NPDES permits for discharges to surface waters. As a medium-sized agglomeration, the plant is expected to provide at least secondary treatment under federal standards. Typical facilities of this scale employ biological treatment followed by disinfection to meet permit limits. The plant's treated effluent is discharged to a receiving water body within the Ohio River basin, which ultimately drains to the Mississippi River and the Gulf of Mexico. The local watershed supports diverse aquatic life and is important for regional water quality.

The plant discharges into a tributary of the Ohio River, part of the larger Mississippi River basin that drains to the Gulf of Mexico. The local watershed supports diverse aquatic ecosystems, including fish and macroinvertebrate communities. Downstream waters are used for recreation and drinking water supply, making nutrient and pathogen control important for ecological and public health.