Pentwater STP - Secondary Wastewater Treatment Plant in Pentwater Township, Michigan

Pentwater STP is a municipal wastewater treatment facility located in Pentwater Township, Oceana County, Michigan, United States. The plant serves a small population of 948 residents and operates under the regulatory framework of the US Clean Water Act, which requires secondary treatment for municipal discharges to surface waters. The plant has a designed capacity of 492.10 m³/day and currently treats an average daily flow of 378.54 m³/day. As a secondary treatment facility, it provides biological treatment to reduce organic matter and suspended solids, meeting the national standards for secondary treatment under the National Pollutant Discharge Elimination System (NPDES) permit program. The treated effluent is discharged into the Lake Michigan watershed, which is part of the Great Lakes system. Lake Michigan supports diverse aquatic life and provides drinking water for millions. The plant's proximity to the coast (within 10 km) means its discharge has direct implications for the nearshore water quality and recreational uses of the lake.

The plant discharges into the Lake Michigan basin, which ultimately drains through the Great Lakes and the St. Lawrence River to the Atlantic Ocean. The nearshore zone of Lake Michigan is ecologically sensitive, supporting fish spawning habitats and migratory bird routes. The plant's secondary treatment helps protect water quality in this important freshwater resource.