Mon Valley STP - Donora, Pennsylvania Wastewater Treatment Plant

Mon Valley STP is a municipal wastewater treatment plant located in Donora, Pennsylvania, serving a population of about 21,600. The plant is situated in the Monongahela River valley, an area with a history of industrial activity. As a facility in the United States, it operates under the Clean Water Act, with National Pollutant Discharge Elimination System (NPDES) permits issued by the Pennsylvania Department of Environmental Protection. For a community of this size, secondary treatment is typically required, and the plant likely meets federal and state effluent guidelines. The treated effluent is discharged into the Monongahela River, which flows north to join the Allegheny River at Pittsburgh, forming the Ohio River. The Ohio River then drains into the Mississippi River and ultimately the Gulf of Mexico. The plant plays a key role in protecting water quality in the Monongahela watershed, supporting aquatic life and downstream uses.

The Monongahela River flows through southwestern Pennsylvania, joining the Allegheny River to form the Ohio River. The watershed supports diverse aquatic species and is an important migratory corridor. Downstream, the Ohio River provides drinking water and recreation for millions. The plant's discharge contributes to the river's flow and must meet standards to protect these ecological and human uses.