Colstrip WWTP - Secondary Treatment Plant Serving Colstrip, Montana

Colstrip WWTP is a municipal wastewater treatment facility located in Colstrip, Rosebud County, Montana, United States. The plant serves a population of approximately 2,300 residents and operates under the regulatory framework of the US Clean Water Act, which requires secondary treatment for municipal discharges. The plant provides secondary treatment, a standard biological process that removes organic matter and suspended solids. With a designed capacity of 2,271.24 thousand cubic meters per year and an actual discharge volume of 567.81 thousand cubic meters, the facility operates well below its capacity, indicating room for future growth. The treated effluent is discharged into a local water body that eventually drains into the Yellowstone River basin, a major tributary of the Missouri River. This watershed supports diverse aquatic life and agricultural activities, making proper treatment essential for protecting downstream water quality and ecosystem health.

The plant discharges into a receiving water body within the Yellowstone River basin, which flows into the Missouri River and ultimately the Mississippi River system. This watershed supports a variety of fish species and provides irrigation water for agriculture. The secondary treatment process helps reduce nutrient and organic loads, protecting downstream aquatic habitats and recreational uses.