Circle Lagoon Wastewater Treatment Plant - Circle, Montana

Circle Lagoon is a municipal wastewater treatment facility located on Harms Street in Circle, McCone County, Montana. The plant serves a population of approximately 644 residents, reflecting a small community in the rural Great Plains region of the United States. The facility provides secondary treatment, which is the standard level required by the U.S. Clean Water Act for municipal wastewater before discharge. With a designed capacity of 605.66 units and an average daily discharge of 276.34 units, the plant operates well within its capacity, indicating room for future growth or seasonal variations. The treated effluent is discharged into local waterways that ultimately drain into the Missouri River basin, a major tributary of the Mississippi River system. The plant's inland location, over 50 km from the coast, reduces direct marine impact, but its discharge contributes to the overall water quality of the region's freshwater ecosystems.

The plant's discharge enters the local watershed, which is part of the Missouri River basin. This river system flows eastward through the Great Plains, eventually joining the Mississippi River and draining into the Gulf of Mexico. The surrounding semi-arid climate and agricultural land use mean that maintaining water quality in receiving streams is critical for downstream aquatic life and irrigation uses.