CROMWELL STP Wastewater Treatment Plant, North Carlton, Minnesota

CROMWELL STP is a wastewater treatment facility located in North Carlton, Minnesota, United States. It serves a small population of 252 residents in the rural community of Cromwell, within Carlton County. The plant is situated inland, away from coastal areas, and operates under the regulatory framework of the US Clean Water Act. The plant provides secondary treatment, a standard level for small communities in the US, which typically involves biological processes to remove organic matter and suspended solids. With a designed capacity of 181.70 units and an average daily discharge of 75.71 units, the plant operates well below its capacity, indicating room for future growth. The facility is likely permitted under the National Pollutant Discharge Elimination System (NPDES) administered by the Minnesota Pollution Control Agency. The treated effluent is discharged into a local water body, which ultimately drains into the Lake Superior watershed via the St. Louis River system. This region is ecologically sensitive, supporting diverse aquatic life and serving as a critical habitat for fish species. The plant's secondary treatment helps protect downstream water quality in this important Great Lakes basin.

The plant discharges into a local water body that flows into the St. Louis River, which empties into Lake Superior, the largest of the Great Lakes. Lake Superior is a vital freshwater resource with significant ecological value, supporting cold-water fish species and providing drinking water for millions. The surrounding watershed includes forests and wetlands that filter runoff and maintain water quality. Secondary treatment at this plant reduces nutrient and pollutant loads, helping to prevent eutrophication and protect the lake's sensitive ecosystem.