Croswell STP - Wastewater Treatment Plant in Croswell, Michigan

Croswell STP is a municipal wastewater treatment facility located in Croswell, Sanilac County, Michigan. The plant serves a population of approximately 2,497 people, classifying it as a small-scale treatment facility within the state's wastewater infrastructure. As a U.S. facility, Croswell STP operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Michigan Department of Environment, Great Lakes, and Energy (EGLE). For small agglomerations like this, secondary treatment is typically required to meet effluent standards before discharge. The plant's treated effluent ultimately drains into the Lake Huron watershed, a major freshwater resource and part of the Great Lakes system. The receiving waters support diverse aquatic life and provide drinking water for millions. Protecting this ecosystem through effective wastewater treatment is critical for maintaining water quality in the region.

Croswell STP discharges into local streams that flow into the Lake Huron basin, part of the Great Lakes system. Lake Huron is a large freshwater lake supporting diverse fish populations and serving as a vital water source. The watershed includes sensitive coastal wetlands and spawning grounds, making proper nutrient and pathogen removal essential to prevent eutrophication and protect aquatic habitats.