DELMAR STL Wastewater Treatment Plant, Clinton County, Iowa

DELMAR STL is a municipal wastewater treatment plant located in Clinton County, Iowa, United States. The facility serves a small population of 517 residents, providing secondary treatment to meet state and federal water quality standards. The plant operates under the U.S. Clean Water Act, which requires secondary treatment for municipal wastewater. With a designed capacity of 264.98 megaliters and an annual discharge volume of 227.13 megaliters, the plant operates within its capacity. The treatment process is secondary, typically involving biological treatment to reduce organic matter and suspended solids. The treated effluent is discharged into local waterways, contributing to the Mississippi River basin. The plant plays a role in protecting downstream water quality in the region, which supports diverse aquatic life and recreational uses. Its inland location reduces direct marine impact.

The plant discharges into the Mississippi River basin, which drains into the Gulf of Mexico. The watershed supports a variety of aquatic species and is an important migratory corridor for birds. Downstream ecosystems include wetlands and floodplains that provide natural water filtration and habitat. The plant's secondary treatment helps reduce nutrient loading, which is critical for preventing hypoxic zones in the Gulf.