Stoughton STP Wastewater Treatment Plant, Stoughton, Wisconsin

Stoughton STP is a municipal wastewater treatment facility located in Stoughton, Dane County, Wisconsin, United States. The plant serves a population of approximately 12,800 residents, placing it in the medium-agglomeration category for US wastewater systems. As part of the state's wastewater infrastructure, it plays a key role in managing domestic sewage from the community. The plant operates under the regulatory framework of the US Clean Water Act, which requires National Pollutant Discharge Elimination System (NPDES) permits for all discharges to surface waters. For a facility of this scale, typical treatment includes secondary biological processes to meet effluent limits set by the Wisconsin Department of Natural Resources. The plant's design and operation must comply with state and federal standards to protect water quality. The treated effluent is discharged into a local water body that ultimately drains into the Yahara River, then into the Rock River, and eventually reaches the Mississippi River basin. This downstream chain supports diverse aquatic life and provides water for agricultural and recreational uses. The plant's location in the Yahara River watershed means its performance directly affects the health of local lakes and rivers, including the nearby Lake Kegonsa and Lake Waubesa.

The plant discharges into the Yahara River watershed, which flows through the Rock River basin and eventually into the Mississippi River. This system supports a variety of fish and wildlife, including migratory waterfowl and game fish. The Yahara River chain of lakes (Mendota, Monona, Waubesa, and Kegonsa) is ecologically sensitive to nutrient loading, making effective wastewater treatment critical for preventing algal blooms and maintaining water quality for recreation and habitat.