Oakfield STP - Advanced Wastewater Treatment in Oakfield, Wisconsin

Oakfield STP is a municipal wastewater treatment facility located at 375 North Main Street in Oakfield, Fond du Lac County, Wisconsin. The plant serves a population of approximately 1,240 residents, placing it in the small-agglomeration category typical of rural communities in the Upper Midwest. The plant employs advanced treatment processes, which go beyond secondary treatment to remove nutrients and other pollutants. With a designed capacity of 1,154.55 units and an average daily discharge of 745.73 units, the facility operates well within its capacity. Under the U.S. Clean Water Act, such plants must comply with National Pollutant Discharge Elimination System (NPDES) permits issued by the Wisconsin Department of Natural Resources, ensuring effluent quality protects receiving waters. The treated effluent is discharged into a local water body that ultimately drains into the Lake Michigan basin via the Fond du Lac River and Lake Winnebago system. Lake Michigan is a critical freshwater resource supporting diverse aquatic life, recreational activities, and municipal water supplies for millions. The plant's advanced treatment helps minimize nutrient loading, protecting downstream ecosystems from eutrophication.

The plant discharges into a tributary of the Fond du Lac River, which flows into Lake Winnebago and then via the Fox River to Lake Michigan. Lake Michigan is a major freshwater ecosystem supporting diverse fish populations, migratory birds, and aquatic plants. The advanced treatment reduces phosphorus and nitrogen loads, helping to prevent harmful algal blooms in downstream lakes and estuaries.