Merrimac STP - Advanced Wastewater Treatment in Merrimac, Wisconsin

Merrimac STP is a municipal wastewater treatment facility located in Merrimac, Sauk County, Wisconsin. Serving a small population of 424, the plant provides advanced treatment to protect local water quality. As a community-scale facility, it plays a vital role in managing wastewater for this rural village. The plant employs advanced treatment processes, ensuring high-quality effluent before discharge. With a designed capacity of 287.69 thousand cubic meters per year and an actual discharge volume of 155.20 thousand cubic meters per year, it operates well within its capacity. Under the U.S. Clean Water Act, such facilities are regulated through National Pollutant Discharge Elimination System (NPDES) permits, which set strict effluent limits to safeguard receiving waters. The treated wastewater is discharged into nearby streams that flow into the Wisconsin River, a major tributary of the Mississippi River. This connection to the Mississippi River basin means the plant's operations contribute to the ecological health of a vast watershed that supports diverse aquatic life and provides water for communities downstream.

The plant discharges into local streams that drain into the Wisconsin River, which flows south to join the Mississippi River. The Mississippi River basin is one of the largest in North America, supporting a wide range of fish, birds, and other wildlife. The advanced treatment at Merrimac STP helps reduce nutrient and pollutant loads, protecting downstream ecosystems from eutrophication and other water quality issues.