PETERSON STP Wastewater Treatment Plant, Clay County, Iowa

PETERSON STP is a municipal wastewater treatment facility located in Clay County, Iowa, United States. The plant serves a small population of 372 residents and operates under secondary treatment standards, which are typical for smaller communities in the region. The facility is situated inland, far from coastal areas, and its operations are regulated under the U.S. Clean Water Act through the National Pollutant Discharge Elimination System (NPDES) permit program. As a secondary treatment plant, it provides biological treatment to remove organic matter and suspended solids before discharge. The plant has a designed capacity of 246.05 million gallons per year and currently discharges 113.56 million gallons per year, indicating it operates below its full capacity. The treated effluent is discharged into local waterways that drain into the Missouri River basin, ultimately reaching the Mississippi River and the Gulf of Mexico. The plant plays a key role in protecting local water quality and supporting the ecological health of the surrounding watershed.

The treated effluent from PETERSON STP enters local streams that flow into the Little Sioux River, a tributary of the Missouri River. The Missouri River then joins the Mississippi River, which empties into the Gulf of Mexico. This watershed supports diverse aquatic life and is an important migratory corridor for fish and birds. The plant's secondary treatment helps reduce nutrient loads that could contribute to hypoxia in the Gulf of Mexico.