Main St Outfall Wastewater Treatment Plant, Humber Arm South, Newfoundland and Labrador

Main St Outfall is a municipal wastewater treatment facility located in Humber Arm South, Newfoundland and Labrador, Canada. The plant serves a small community of 557 residents and operates with secondary treatment, meeting Canadian federal and provincial standards for wastewater effluent quality. The plant's treatment process is secondary, which typically involves biological treatment to reduce organic matter and suspended solids. Under Canadian regulations, such facilities are required to meet the Wastewater Systems Effluent Regulations (WSER), which set national standards for effluent quality. The treated effluent is discharged into the local coastal environment, as the plant is located within 10 km of the coast. The receiving waters ultimately flow into the Gulf of St. Lawrence, a vital marine ecosystem supporting fisheries and diverse aquatic life. The plant plays a key role in protecting this sensitive coastal area from untreated sewage pollution.

The plant discharges treated wastewater into the coastal waters of Newfoundland and Labrador, which drain into the Gulf of St. Lawrence. This marine environment supports important fisheries, including cod and lobster, and provides habitat for migratory seabirds. The secondary treatment helps reduce nutrient loading and pathogen levels, protecting water quality in this ecologically sensitive region.