DOON STL Wastewater Treatment Plant, Lyon County, Iowa

DOON STL is a municipal wastewater treatment plant located in Lyon County, Iowa, United States. The facility serves a small population of 476 residents, providing secondary treatment to meet state and federal water quality standards. As a small-scale plant, it plays a vital role in protecting local water resources in this rural agricultural region. The plant operates with a designed capacity of 189.27 cubic meters per day and currently discharges a similar volume, indicating full utilization. Secondary treatment, which typically involves biological processes, ensures that organic matter and suspended solids are reduced before effluent is released. Under the U.S. Clean Water Act, such facilities must comply with National Pollutant Discharge Elimination System (NPDES) permits, which set limits on pollutants to protect receiving waters. The treated effluent from DOON STL is discharged into local waterways that eventually drain into the Missouri River basin. This region is part of the larger Mississippi River watershed, which ultimately flows into the Gulf of Mexico. The plant's operation helps maintain water quality in local streams and contributes to the overall health of downstream aquatic ecosystems.

DOON STL discharges into tributaries of the Missouri River, which flows into the Mississippi River and eventually the Gulf of Mexico. The surrounding area is primarily agricultural, and the plant helps reduce nutrient and pollutant loads that could contribute to hypoxia in the Gulf. The local watershed supports diverse aquatic life and is important for regional water quality.