Johnsonville East STP - Florence County, South Carolina Wastewater Treatment Plant

Johnsonville East STP is a municipal wastewater treatment facility located in Florence County, South Carolina, serving a population of about 26,041. The plant is situated in the coastal plain region of the state, near the Lynches River watershed. As a US facility serving a medium-sized agglomeration, Johnsonville East STP is subject to the National Pollutant Discharge Elimination System (NPDES) permitting program under the Clean Water Act. This regulatory framework requires secondary treatment as a baseline for municipal plants, with more stringent limits for discharges to sensitive waters. The plant's treatment processes and capacity details are not publicly available, but typical plants of this scale employ activated sludge or lagoon systems. The plant's treated effluent ultimately drains into the Atlantic Ocean via the Pee Dee River basin. The receiving waters support diverse aquatic life and are part of an important migratory corridor for fish species. Proper treatment helps protect downstream ecosystems and recreational uses.

Johnsonville East STP discharges into the Lynches River, a tributary of the Pee Dee River, which flows into Winyah Bay and the Atlantic Ocean. The watershed supports diverse freshwater and estuarine habitats, including wetlands that provide flood control and water quality benefits. The coastal plain setting means the plant's nutrient discharges can influence downstream algal growth and estuarine health.