Gravois Arm SD Phase II Wastewater Treatment Plant, Gravois Mills, Missouri

Gravois Arm SD Phase II is a municipal wastewater treatment plant located in Gravois Mills, Missouri, a small community in Morgan County. The plant serves a population of approximately 650 residents and operates under the regulatory framework of the U.S. Clean Water Act, which governs wastewater discharges through National Pollutant Discharge Elimination System (NPDES) permits issued by the Missouri Department of Natural Resources. The plant provides secondary treatment, a standard biological process that removes organic matter and suspended solids. With a designed capacity of 711.66 megaliters per year, the facility currently treats an annual discharge volume of 151.42 megaliters, indicating significant reserve capacity for future growth. The treatment process aligns with federal requirements for secondary treatment, ensuring compliance with water quality standards. The treated effluent is discharged into the Lake of the Ozarks watershed, a major reservoir on the Osage River that supports recreational activities and aquatic habitats. The plant's inland location, over 50 kilometers from the coast, minimizes direct marine impacts. Its operations contribute to protecting local water quality in a region known for tourism and fishing.

The plant discharges into the Lake of the Ozarks, a large reservoir formed by the Osage River, which ultimately flows into the Missouri River and then the Mississippi River. The lake is a popular recreational destination and supports diverse aquatic life, including game fish species. The plant's secondary treatment helps reduce nutrient loads that could otherwise contribute to algal blooms in the reservoir.