Harlowton Lagoon Wastewater Treatment Plant, Wheatland County, Montana

Harlowton Lagoon is a municipal wastewater treatment facility located in Wheatland County, Montana, United States. The plant serves a small population of around 1,017 residents and operates as a lagoon system providing secondary treatment. Its location in the rural plains of central Montana places it within the Upper Missouri River Basin, an area characterized by agricultural land use and semi-arid climate. As a secondary treatment facility, Harlowton Lagoon meets the standard requirements under the U.S. Clean Water Act for municipal wastewater treatment. The plant has a designed capacity of 938.78 volume units and processes an average daily discharge of 545.10 volume units, indicating it operates below its full capacity. Such lagoon systems are common in small communities across the Great Plains due to their cost-effectiveness and low operational complexity. The treated effluent from Harlowton Lagoon is discharged into local waterways that eventually drain into the Musselshell River, a tributary of the Missouri River. The Missouri River system supports diverse aquatic life and provides critical habitat for species such as the pallid sturgeon and piping plover. Proper treatment helps protect downstream water quality in this ecologically significant river basin.

The plant discharges into the Musselshell River watershed, which flows into the Missouri River and ultimately the Mississippi River system. This basin supports a variety of fish species and migratory birds. The semi-arid climate means that maintaining water quality is crucial for both ecological health and agricultural uses downstream.