Sag Harbor V WWTP - Secondary Treatment Plant in Village of Sag Harbor, New York

Sag Harbor V WWTP is a municipal wastewater treatment facility located at 51 Bay Street in the Village of Sag Harbor, Suffolk County, New York. The plant serves a population of approximately 4,340 residents and has a designed capacity of 946.35 thousand cubic meters per day, with an average discharge volume of 329.33 thousand cubic meters per day. The plant provides secondary treatment, which is the standard level required under the US Clean Water Act for municipal wastewater facilities. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. As a plant serving a small community, it operates under the National Pollutant Discharge Elimination System (NPDES) permit program, administered by the New York State Department of Environmental Conservation. The treated effluent is discharged into local waters that ultimately flow into Gardiners Bay and the Atlantic Ocean. The plant's coastal location means its discharge can affect nearby marine habitats, including shellfish beds and fish spawning areas. Proper treatment is essential to protect water quality in the ecologically sensitive Peconic Estuary system.

The plant discharges into a watershed that drains to Gardiners Bay, part of the Peconic Estuary, which is a designated estuary of national significance. This coastal ecosystem supports diverse marine life, including shellfish, finfish, and migratory birds. The estuary connects to Block Island Sound and the Atlantic Ocean, making water quality management critical for both local recreation and regional marine health.