Coldwater WWTP and Sewer System - Municipal Wastewater Treatment in Coldwater, Ohio

Coldwater WWTP and Sewer System is a municipal wastewater treatment facility located in Coldwater, Mercer County, Ohio. The plant serves a population of about 4,482 residents, placing it in the small-to-medium agglomeration category under U.S. regulatory frameworks. As a publicly owned treatment works (POTW), it operates under the Clean Water Act, which requires secondary treatment as a baseline for municipal plants of this scale. Under the U.S. EPA National Pollutant Discharge Elimination System (NPDES) program, the plant holds a permit issued by the Ohio Environmental Protection Agency. For a facility serving fewer than 10,000 people, typical treatment includes secondary biological processes such as activated sludge or trickling filters, followed by disinfection. The plant's design capacity and treatment level are consistent with standard practices for small Ohio communities. The treated effluent is discharged to a receiving stream that flows into the Wabash River basin, ultimately reaching the Ohio River and then the Mississippi River. The local watershed supports agricultural drainage and provides habitat for fish and aquatic invertebrates. Proper nutrient removal helps protect downstream water quality in the Wabash River, which is a major tributary of the Ohio River.

The plant discharges into a tributary of the Wabash River, which flows southwest through Indiana to the Ohio River. The Wabash River basin supports diverse aquatic life, including freshwater mussels and game fish. As an agricultural region, the watershed faces challenges from nutrient runoff, making the plant's nutrient removal important for preventing algal blooms downstream.