ALGONAC STP - Wastewater Treatment Plant in Algonac, Michigan, United States

ALGONAC STP is a municipal wastewater treatment plant serving the community of Algonac in St. Clair County, Michigan. The facility handles wastewater from a population of about 11,209, placing it in the small-to-medium agglomeration category under US regulatory frameworks. Its designed capacity is 1.00 million gallons per day, reflecting the scale of the local service area. As a US-based plant, ALGONAC 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 plants of this size, secondary treatment is typically required, with possible additional nutrient controls due to the Great Lakes watershed's sensitivity to phosphorus loading. The plant's treated effluent discharges into the St. Clair River system, which flows south into Lake St. Clair and then via the Detroit River into Lake Erie. This water body chain is part of the Great Lakes Basin, one of the largest freshwater ecosystems in the world. The plant plays a key role in protecting downstream water quality, including recreational and drinking water uses.

ALGONAC STP discharges into the St. Clair River, which connects Lake Huron to Lake St. Clair and ultimately the Detroit River and Lake Erie. This watershed is part of the Great Lakes Basin, a globally significant freshwater system. The area supports diverse aquatic life, including fish species such as walleye and perch, and is an important migratory corridor for birds. Nutrient management is critical here to prevent algal blooms in the lower Great Lakes.