Madison MSD STP - Major Wastewater Treatment Plant in Madison, Wisconsin

Madison MSD STP is a major wastewater treatment facility serving the city of Madison, Wisconsin, and surrounding areas in Dane County. With a population served of around 358,612, it is classified as a large agglomeration under U. S. regulatory frameworks. The plant is located near the Capital City State Trail and operates as part of the region's municipal wastewater infrastructure. As a large-scale facility in the United States, Madison MSD STP operates under the Clean Water Act, which requires National Pollutant Discharge Elimination System (NPDES) permits for discharges into surface waters. Such permits typically mandate secondary treatment as a minimum, with additional nutrient removal requirements for sensitive water bodies. The plant's treatment processes are designed to meet these federal and state standards, ensuring compliance with Wisconsin Department of Natural Resources regulations. The treated effluent from Madison MSD STP is discharged into a receiving water body that flows into the Yahara River, then into the Rock River, and ultimately into the Mississippi River. This downstream chain supports diverse aquatic life and provides water for communities and agriculture. The plant plays a critical role in protecting water quality in the Yahara River watershed and the larger Mississippi River basin.

Madison MSD STP discharges into the Yahara River, which flows into the Rock River and then the Mississippi River. The Mississippi River is a major ecological corridor supporting diverse fish, bird, and plant species. The plant's operations help maintain water quality in this sensitive watershed, which is subject to nutrient pollution concerns from agricultural and urban runoff.