LEWIS STL Wastewater Treatment Plant, Lewis, Iowa

LEWIS STL is a municipal wastewater treatment plant located in Lewis, Iowa, a small community in Cass County. The plant serves a population of 433 residents, reflecting the rural character of the area. It operates under the regulatory framework of the United States Clean Water Act, which governs wastewater discharges through the National Pollutant Discharge Elimination System (NPDES) permit program. The plant provides secondary treatment, a standard level for small communities in the U.S. that removes biodegradable organic matter and suspended solids. Its designed capacity is 227.12 cubic meters per day, and it currently discharges an average of 189.27 cubic meters per day, indicating operational headroom. Secondary treatment typically involves biological processes such as activated sludge or trickling filters. The treated effluent is discharged to a local water body, likely a stream or river within the Missouri River basin, as Lewis is situated in western Iowa. The plant's discharge contributes to the local hydrologic cycle and supports downstream aquatic ecosystems. Proper treatment helps protect water quality in the region's surface waters, which ultimately drain to the Missouri River and the Gulf of Mexico.

The plant's discharge enters a local watercourse within the Missouri River watershed, which flows into the Missouri River and eventually the Gulf of Mexico. The region's aquatic ecosystems support diverse fish and invertebrate populations, and maintaining water quality is essential for ecological health. The plant's secondary treatment reduces organic pollutants and suspended solids, mitigating impacts on downstream habitats.