GREENFIELD STP | Hancock County, Indiana Wastewater Treatment Plant

GREENFIELD STP is a municipal wastewater treatment plant serving Hancock County, Indiana, United States. The facility handles wastewater from a population of about 18,400, placing it in the small-to-medium agglomeration category. As a US-based plant, GREENFIELD STP operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Indiana Department of Environmental Management. These permits set effluent limits to protect water quality. For a plant of this scale, secondary treatment is typically required, with possible additional nutrient removal depending on the receiving water body's sensitivity. The plant discharges treated wastewater into local streams that are part of the Mississippi River basin, ultimately draining into the Gulf of Mexico. The surrounding area is predominantly agricultural and rural, making the plant's role in controlling nutrient loads important for downstream water quality and aquatic ecosystems.

The plant's discharge enters local tributaries within the Upper Mississippi River basin, which flows into the Gulf of Mexico. This region is part of the Mississippi River watershed, a critical ecological corridor supporting diverse aquatic life and migratory birds. Nutrient loading from wastewater and agricultural runoff contributes to the Gulf of Mexico's hypoxic zone, making effective treatment at plants like GREENFIELD STP important for downstream environmental health.