Morning Sun STL Wastewater Treatment Plant, Louisa County, Iowa

Morning Sun STL is a municipal wastewater treatment plant located on 173rd Avenue in Louisa County, Iowa, United States. The plant serves a population of 872, placing it in the small community category under US EPA guidelines. As a US facility, the plant operates under the Clean Water Act's National Pollutant Discharge Elimination System (NPDES) permit program, which sets discharge limits and monitoring requirements. For small communities in Iowa, treatment typically involves secondary treatment or equivalent, as mandated by federal standards. The plant's treated effluent is discharged into a local waterway that ultimately drains into the Mississippi River basin, supporting regional aquatic ecosystems and downstream water quality. The plant plays a key role in protecting local streams and the broader watershed.

The plant discharges into a tributary of the Mississippi River, which flows into the Gulf of Mexico. The local watershed supports diverse aquatic life and is part of the larger Mississippi River basin, an ecologically significant corridor for migratory fish and birds. Proper treatment helps reduce nutrient loading that can contribute to hypoxia in the Gulf.