Cassville STP - Secondary Wastewater Treatment Plant in Cassville, Wisconsin

Cassville STP is a municipal wastewater treatment facility located on Airport Street in Cassville, Grant County, Wisconsin. It serves a small community of approximately 1,073 residents, reflecting the rural character of the area along the Mississippi River. The plant provides secondary treatment, which is the standard level required under the US Clean Water Act for municipal facilities of this scale. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The plant has a designed capacity of 1,499.02 million gallons per day and reports an average discharge volume of 367.19 million gallons per day, indicating operational capacity well within design limits. Treated effluent from Cassville STP ultimately reaches the Mississippi River, a major waterway that drains into the Gulf of Mexico. The plant plays a key role in protecting local water quality in the Driftless Area, a region known for its unique topography and sensitive aquatic ecosystems. By reducing nutrient and pollutant loads, the facility helps maintain the ecological health of the Mississippi River and its tributaries.

Cassville STP discharges into the Mississippi River basin, which flows south to the Gulf of Mexico. The receiving waters support diverse aquatic life, including fish and migratory birds. The Driftless Area's steep topography and karst geology make groundwater and surface water particularly sensitive to pollution, so the plant's secondary treatment is critical for protecting downstream ecosystems.