ZEARING STL Wastewater Treatment Plant, Zearing, Iowa | Secondary Treatment

ZEARING STL is a municipal wastewater treatment plant located in Zearing, Iowa, United States. It serves a small population of 554 residents in the rural community of Story County. The plant operates under the regulatory framework of the U.S. Clean Water Act, which requires secondary treatment for municipal facilities discharging to surface waters. The plant provides secondary treatment, a standard biological process that removes organic matter and suspended solids. It has a designed capacity of 454.25 megaliters and currently discharges 227.13 megaliters annually, indicating it operates below its full capacity. As a small facility, it is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Iowa Department of Natural Resources, which set effluent limits to protect water quality. The treated effluent is discharged into a local water body that ultimately drains into the Mississippi River Basin. The plant plays a key role in protecting downstream ecosystems, including the Mississippi River, by reducing nutrient and pollutant loads. Its location in the agricultural Midwest means it helps mitigate impacts on regional water quality.

ZEARING STL discharges treated wastewater into a local stream that flows into the Iowa River, a tributary of the Mississippi River. The Mississippi River Basin supports diverse aquatic life and is a critical migratory corridor for fish and birds. The plant's secondary treatment reduces organic pollutants and suspended solids, helping to maintain water quality in downstream ecosystems. Its location in an agricultural region underscores its role in managing nutrient inputs to the watershed.