ELMA WWTP - Secondary Treatment Plant in Elma, Iowa, United States

ELMA WWTP is a municipal wastewater treatment facility located on Maple Street in Elma, Howard County, Iowa. The plant serves a small population of 653 residents, typical of rural communities in the Midwestern United States. The plant provides secondary treatment, which is the standard level required by the US Clean Water Act for municipal wastewater. With a designed capacity of 264.98 thousand cubic meters per year and an annual discharge volume of 227.13 thousand cubic meters, the facility operates within its capacity. As a US plant, it operates under an EPA NPDES permit issued by the Iowa Department of Natural Resources, ensuring compliance with effluent limits. The treated effluent is discharged into a local waterway that ultimately drains into the Upper Mississippi River basin. The plant plays a key role in protecting local water quality and downstream ecosystems, including the Mississippi River and the Gulf of Mexico.

The plant discharges into a tributary of the Upper Mississippi River basin, which flows into the Mississippi River and eventually the Gulf of Mexico. The region's agricultural landscape means the plant helps reduce nutrient loading that could contribute to the Gulf of Mexico hypoxic zone. The local watershed supports diverse aquatic life and is part of a critical migratory corridor for waterfowl.