SULLY STL Wastewater Treatment Plant, Jasper County, Iowa

SULLY STL is a municipal wastewater treatment plant located in Jasper County, Iowa, serving a small community of 841 residents. The plant provides secondary treatment, a standard level for facilities of this scale in the United States, ensuring removal of organic matter and suspended solids before discharge. The plant has a designed capacity of 416.39 volume units and a current discharge volume of 264.98, indicating operational headroom. As a US facility, it operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Iowa Department of Natural Resources, which set effluent limits to protect water quality. The treated effluent is discharged into local streams that drain into the broader Mississippi River basin. This watershed supports diverse aquatic life and provides water for downstream communities. The plant's secondary treatment helps reduce nutrient loading and protects the ecological health of receiving waters in the region.

The plant discharges into local tributaries of the Mississippi River basin, which ultimately flows into the Gulf of Mexico. This watershed supports diverse aquatic species and is an important migratory corridor for birds. The secondary treatment process reduces organic pollutants and helps mitigate downstream eutrophication risks in the Mississippi River and Gulf of Mexico hypoxic zone.