MANHATTAN WWTP - Secondary Treatment Plant in Gallatin County, Montana

MANHATTAN WWTP is a municipal wastewater treatment facility located in Gallatin County, Montana, serving a population of 1,380. The plant provides secondary treatment, a standard level for small communities in the United States, ensuring compliance with Clean Water Act requirements. The plant has a designed capacity of 757.08 thousand cubic meters and handles an annual discharge volume of 957.71 thousand cubic meters. As a US facility, it operates under the National Pollutant Discharge Elimination System (NPDES) permit program, which sets effluent limits to protect water quality. The treated effluent is discharged into local streams that drain into the Missouri River watershed, ultimately reaching the Mississippi River and the Gulf of Mexico. The plant plays a key role in protecting the Gallatin Valley's aquatic ecosystems and downstream water resources.

The plant discharges into tributaries of the Missouri River, which flows through Montana and joins the Mississippi River system. The Gallatin Valley supports diverse aquatic life, including trout populations, and the plant's secondary treatment helps maintain water quality in this sensitive watershed. Downstream, the Missouri River provides habitat for numerous fish species and supports agricultural and recreational uses.