DUMONT STL Wastewater Treatment Plant, Dumont, Iowa | Secondary Treatment

DUMONT STL is a municipal wastewater treatment plant located in Dumont, Butler County, Iowa. Serving a small population of 637 residents, the facility provides secondary treatment to meet Clean Water Act standards. The plant is situated inland, far from coastal zones, and its operations are regulated under the US EPA National Pollutant Discharge Elimination System (NPDES) program. The plant has a designed capacity of 946.35 cubic meters per day and currently treats an average daily flow of 492.10 cubic meters, indicating ample reserve capacity. Secondary treatment, which includes biological processes to remove organic matter and suspended solids, is the standard for small communities in the United States. The facility's permit and operator details are managed through state-level environmental agencies. The treated effluent is discharged into local streams that drain into the Iowa River watershed, ultimately flowing to the Mississippi River and the Gulf of Mexico. This discharge contributes to the nutrient load in the Mississippi River basin, which is a key concern for downstream hypoxia zones in the Gulf. The plant's secondary treatment helps reduce organic pollutants but does not specifically target nutrient removal.

The plant discharges into tributaries of the Iowa River, which flows into the Mississippi River and eventually the Gulf of Mexico. The Mississippi River basin is a major agricultural region, and nutrient runoff from wastewater and farms contributes to seasonal hypoxia in the Gulf. Secondary treatment at this plant reduces biochemical oxygen demand and suspended solids but does not include advanced nutrient removal, which is typical for small plants in inland areas.