ELK HORN WWTP - Secondary Treatment Plant in Shelby County, Iowa

ELK HORN WWTP is a municipal wastewater treatment plant located in Clay Township, Shelby County, Iowa, United States. The facility serves a small population of 669 residents and operates with secondary treatment, which is the standard level for domestic wastewater in the region. The plant's designed capacity is 378.54 million gallons, and it discharges approximately 529.96 million gallons of treated effluent annually. Under the U.S. Clean Water Act, such facilities are regulated through the National Pollutant Discharge Elimination System (NPDES) permit program, which sets effluent limits to protect water quality. The treated wastewater is discharged into local waterways that eventually drain into the Missouri River basin. The plant plays a key role in protecting downstream aquatic ecosystems by reducing organic pollutants and suspended solids before discharge.

The plant discharges into tributaries of the Missouri River, which flows into the Mississippi River and ultimately the Gulf of Mexico. The local watershed supports diverse aquatic life and is part of an important migratory corridor for birds. Proper treatment helps prevent nutrient loading that could contribute to hypoxia in the Gulf.