Au Gres WWSL Wastewater Treatment Plant, Au Gres, Michigan

Au Gres WWSL is a municipal wastewater treatment facility located in Au Gres, Michigan, along the Au Gres River Drive. The plant serves a small community of 976 residents in Arenac County, situated on the eastern coast of Michigan's Lower Peninsula. Its location near the Saginaw Bay places it within a sensitive coastal environment. The plant provides secondary treatment, a standard level for small US communities under the Clean Water Act. With a designed capacity of 757.08 cubic meters per day and a discharge volume of 416.40 cubic meters per day, the facility operates at about 55% capacity. As a US plant, it is regulated under the National Pollutant Discharge Elimination System (NPDES) permit program, which sets effluent limits to protect water quality. The treated effluent is discharged into the Au Gres River, which flows into Saginaw Bay of Lake Huron. This watershed supports diverse aquatic life and is part of the larger Great Lakes ecosystem. The plant's coastal proximity requires careful management to prevent nutrient loading and protect the bay's recreational and ecological value.

The plant discharges into the Au Gres River, a tributary of Saginaw Bay, which is part of Lake Huron in the Great Lakes system. This watershed supports diverse fish populations and migratory birds. The coastal location near Saginaw Bay means effluent must meet strict phosphorus and pathogen limits to prevent algal blooms and protect drinking water intakes downstream.