etangs aeres Regie Deux Montagnes Wastewater Treatment Plant, Sainte-Marthe-sur-le-Lac, Quebec

The etangs aeres Regie Deux Montagnes wastewater treatment plant is located in Sainte-Marthe-sur-le-Lac, Quebec, Canada, within the Deux-Montagnes regional county municipality. The facility serves a population of approximately 22,891 people, classifying it as a medium-sized agglomeration under Canadian wastewater management standards. As a plant in Quebec, it operates under provincial regulations that align with the Canadian Council of Ministers of the Environment (CCME) guidelines for wastewater treatment. For communities of this scale, secondary treatment is typically required to reduce organic matter and suspended solids before discharge. The plant uses aerated lagoons (etangs aeres) as its treatment process, a common technology in colder climates due to its reliability and low operational costs. The treated effluent is discharged into the local watershed, which ultimately drains into the Lake of Two Mountains (Lac des Deux Montagnes), a widening of the Ottawa River. This water body is part of the greater St. Lawrence River system, which flows into the Atlantic Ocean. The plant plays a key role in protecting the ecological health of these downstream waters from nutrient pollution and pathogens.

The plant discharges into the Lake of Two Mountains, an important water body that connects to the Ottawa River and eventually the St. Lawrence River. This watershed supports diverse aquatic life, including fish species such as walleye and northern pike, and serves as a migratory corridor for waterfowl. The area is ecologically sensitive due to its role in nutrient cycling and flood regulation, making effective wastewater treatment critical to preventing eutrophication and maintaining water quality.