McCallsburg STL Wastewater Treatment Plant, McCallsburg, Iowa

McCallsburg STL is a municipal wastewater treatment facility located in McCallsburg, Iowa, United States. The plant serves a small population of 292 residents, reflecting the rural character of the community in Story County. As a secondary treatment plant, it provides biological treatment to remove organic matter and suspended solids from wastewater. The plant operates under the regulatory framework of the U.S. Clean Water Act, which requires secondary treatment for municipal wastewater discharges. The National Pollutant Discharge Elimination System (NPDES) permit program governs the plant's discharge limits and monitoring requirements. With a designed capacity of 151.42 megaliters per year and an actual discharge volume of 113.56 megaliters per year, the plant operates below its capacity. The treated effluent from McCallsburg STL is discharged into local waterways that are part of the Mississippi River basin. The plant's location in inland Iowa means its discharge ultimately contributes to the Mississippi River system, which supports diverse aquatic life and provides drinking water for millions downstream. Proper treatment helps protect water quality in the region's streams and rivers.

The plant discharges into local tributaries that flow into the South Skunk River, a major waterway in central Iowa. The South Skunk River joins the Skunk River, which eventually empties into the Mississippi River. This watershed supports agricultural drainage and provides habitat for fish and wildlife. The Mississippi River downstream is a critical migratory corridor for birds and supports a diverse aquatic ecosystem. Effective wastewater treatment at McCallsburg STL helps reduce nutrient and pollutant loads to these waters.