CARLISLE WWTP - Secondary Treatment Plant in Sullivan County, Indiana

CARLISLE WWTP is a municipal wastewater treatment facility located on Gill Road in Sullivan County, Indiana, United States. The plant serves a population of approximately 907 residents, classifying it as a small community system within the state's wastewater infrastructure. The facility provides secondary treatment, which is the standard biological treatment process required by the US Clean Water Act for most municipal plants. This level of treatment significantly reduces organic matter and suspended solids before discharge. The plant has a designed capacity of 302.83 volume units and operates at full capacity based on reported discharge volume. The treated effluent from CARLISLE WWTP is discharged into local waterways that ultimately drain into the Wabash River basin, a major tributary of the Ohio River. The plant's operations are subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Indiana Department of Environmental Management, ensuring compliance with water quality standards to protect downstream aquatic ecosystems.

The plant discharges into receiving waters within the Wabash River watershed, which flows into the Ohio River and eventually the Mississippi River. This region supports diverse aquatic life, including fish species such as bass and catfish, and provides habitat for migratory birds. The Wabash River is ecologically significant as one of the longest free-flowing rivers in the eastern United States, and maintaining water quality is critical for its ecological health.