Bancroft Sewage Lagoon - Secondary Treatment Facility in Bancroft, Idaho

Bancroft Sewage Lagoon is a municipal wastewater treatment facility located on Cemetery Road in Bancroft, Caribou County, Idaho. The plant serves a small population of 377 residents, reflecting the rural character of the surrounding area in southeastern Idaho. The facility provides secondary treatment, a standard level required by the US Clean Water Act for municipal plants of this scale. With a designed capacity of 181.70 megaliters and an annual discharge volume of 143.85 megaliters, the plant operates within its capacity. As a US facility, it is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Idaho Department of Environmental Quality, ensuring compliance with water quality standards. The treated effluent is discharged into local waterways that ultimately drain into the Bear River watershed, which flows into the Great Salt Lake. This connection to a terminal lake ecosystem underscores the importance of effective nutrient removal to prevent eutrophication in downstream waters.

The plant discharges into the Bear River basin, which flows through southeastern Idaho and northern Utah before terminating in the Great Salt Lake. This terminal lake ecosystem is highly sensitive to nutrient loading, as it supports brine shrimp and migratory bird populations. Effective secondary treatment helps reduce organic pollutants and nutrients, protecting water quality in the river and the lake's unique hypersaline environment.