DELOIT STL Wastewater Treatment Plant, Crawford County, Iowa

DELOIT STL is a municipal wastewater treatment plant located in Crawford County, Iowa, United States. It serves a small population of 264 residents in the rural community of Deloit and surrounding areas. The plant is situated in the Midwestern region of the country, characterized by agricultural land use and a continental climate with cold winters and warm summers. The plant provides secondary treatment, which is the standard level required under the U.S. Clean Water Act for municipal wastewater facilities. Secondary treatment typically involves biological processes to remove organic matter and suspended solids. The plant has a designed capacity of 151.42 million gallons per year and currently discharges 211.98 million gallons per year, indicating operation above its nominal capacity. As a small facility, it is likely subject to state-level NPDES permits issued by the Iowa Department of Natural Resources, which set effluent limits to protect water quality. The treated effluent from DELOIT STL is discharged into local waterways that ultimately drain into the Missouri River watershed. The Missouri River flows southward to join the Mississippi River, which empties into the Gulf of Mexico. The plant's discharge contributes to the overall nutrient load in the basin, which is a concern for downstream water quality and the hypoxic zone in the Gulf. The local streams support aquatic life and are used for recreation and irrigation.

The plant discharges into tributaries of the Missouri River, which flows into the Mississippi River and eventually the Gulf of Mexico. The watershed is predominantly agricultural, contributing to nutrient runoff concerns. Downstream ecosystems include the Missouri River's diverse fish and bird populations, and the Gulf's marine environment faces seasonal hypoxia due to nutrient enrichment. The plant's secondary treatment helps reduce organic pollutants but may not fully address nutrient removal.