Saco WWTP - Secondary Treatment Plant in Saco, Montana

Saco WWTP is a municipal wastewater treatment facility located in Saco, Phillips County, Montana, serving a small population of 250 residents. The plant provides secondary treatment, a standard level for communities of this size in the United States. The plant has a designed capacity of 113.56 cubic meters per day and currently treats an average daily flow of 94.64 cubic meters, indicating operational headroom. As a US facility, it operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Montana Department of Environmental Quality, which set effluent limits to protect water quality. The treated effluent is discharged to local surface waters, likely tributaries of the Milk River, which flows into the Missouri River and ultimately the Mississippi River system. This watershed supports agricultural irrigation and aquatic habitats in the northern Great Plains region.

The plant's discharge enters a small stream in the Milk River basin, part of the Missouri River watershed. This semi-arid region relies on surface water for irrigation and livestock, making effluent quality critical for downstream uses. The Milk River supports diverse fish species and migratory birds along the Missouri River corridor.