MT GRETNA AUTH STP - Secondary Wastewater Treatment in South Londonderry Township, Pennsylvania

MT GRETNA AUTH STP is a municipal wastewater treatment facility located in South Londonderry Township, Lebanon County, Pennsylvania. The plant serves a population of around 6,145 residents, classifying it as a small to medium-sized agglomeration under US regulatory frameworks. Its location in the Susquehanna River basin places it within a region characterized by mixed agricultural and residential land use. The plant provides secondary treatment, a standard level required by the US Clean Water Act for facilities of this scale. With a designed capacity of 757.08 megaliters per year and an actual discharge volume of 454.25 megaliters annually, the plant operates below its 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 local waterways that ultimately drain into the Susquehanna River and then to the Chesapeake Bay. The Chesapeake Bay is a major estuary of ecological and economic importance, and nutrient removal from wastewater is critical to reducing eutrophication. The plant's performance contributes to regional water quality goals under the Chesapeake Bay Total Maximum Daily Load (TMDL) program.

The plant discharges into streams within the Susquehanna River basin, which flows into the Chesapeake Bay. The Chesapeake Bay is the largest estuary in the United States and supports diverse aquatic life, including blue crabs, oysters, and migratory fish. Nutrient pollution from wastewater and agriculture has historically caused hypoxia and algal blooms, making advanced treatment and nutrient management essential for bay restoration.