RIO WWTP - Secondary Wastewater Treatment Plant in Rio, Wisconsin

RIO WWTP is a municipal wastewater treatment plant located in Rio, Columbia County, Wisconsin, United States. The facility serves a small community of about 1,062 people, reflecting its role in managing local residential wastewater. The plant provides secondary treatment, which is the standard biological treatment process required under the U.S. Clean Water Act for most municipal facilities. With a designed capacity of 435.32 volume units and a current discharge volume of 264.98, the plant operates within its capacity. As a small agglomeration, it is subject to EPA NPDES permitting and state-level regulations administered by the Wisconsin Department of Natural Resources. The treated effluent is discharged into a local water body, contributing to the protection of downstream environments. The plant's operations help maintain water quality in the region, which ultimately drains into the Mississippi River basin and the Gulf of Mexico, supporting aquatic ecosystems and recreational uses.

The plant discharges into a local stream that is part of the Upper Mississippi River basin. This watershed supports diverse aquatic life and provides habitat for fish and macroinvertebrates. Downstream, the water flows into the Mississippi River and eventually reaches the Gulf of Mexico, where nutrient management is critical to mitigate hypoxic zones. The plant's secondary treatment helps reduce organic pollutants and protect local water quality.