Pomeroy STL Wastewater Treatment Plant | Pomeroy, Iowa

Pomeroy STL is a municipal wastewater treatment facility located in Pomeroy, Iowa, serving a population of 662. The plant provides secondary treatment, a standard level required by the US Clean Water Act for communities of this size. It processes an average daily flow of approximately 0.62 million gallons per day, based on its designed capacity of 227.12 megaliters per year. As a secondary treatment plant, Pomeroy STL uses biological processes to remove organic matter and suspended solids. The facility operates under the National Pollutant Discharge Elimination System (NPDES) permit program, which sets effluent limits to protect water quality. Plants of this scale in Iowa are typically regulated by the Iowa Department of Natural Resources. The treated effluent is discharged into a local waterway, likely a tributary of the Des Moines River, which flows south to the Mississippi River and eventually to the Gulf of Mexico. The plant plays a key role in protecting local streams from nutrient pollution and pathogens, supporting aquatic life and downstream water quality.

The plant discharges into a local stream within the Des Moines River basin, which drains into the Mississippi River and ultimately the Gulf of Mexico. This watershed supports diverse aquatic habitats and is part of the larger Mississippi River system, a critical migratory corridor for birds and fish. Nutrient loading from wastewater can contribute to hypoxia in the Gulf, making effective treatment important for regional water quality.