CAIRO WWTP - Secondary Treatment Plant in Cairo, West Virginia

CAIRO WWTP is a municipal wastewater treatment facility located in Cairo, Ritchie County, West Virginia, along the North Bend Rail Trail. The plant serves a small population of 373 residents, reflecting the rural character of the area. It operates under the regulatory framework of the U.S. Clean Water Act, which requires secondary treatment for municipal discharges. The plant provides secondary treatment, a standard level for small communities in the United States. With a designed capacity of 151.42 m³/day and an average daily discharge of 75.71 m³/day, the facility operates at approximately 50% capacity, indicating room for future growth. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The treated effluent is discharged into a local waterway that ultimately drains into the Ohio River basin, contributing to the Mississippi River system. The plant's location inland and away from coastal areas reduces direct marine impact. The surrounding watershed supports diverse aquatic life and is part of the broader Appalachian region's ecological network.

The plant discharges into a tributary of the Ohio River, which flows into the Mississippi River and eventually the Gulf of Mexico. The local watershed is part of the Appalachian mixed mesophytic forests ecoregion, supporting diverse aquatic species including freshwater mussels and fish. The small population served and secondary treatment help maintain water quality in this rural, inland setting.