Eaux usees Wastewater Treatment Plant, Sainte-Agathe-de-Lotbinière, Québec

Eaux usees is a municipal wastewater treatment plant located in Sainte-Agathe-de-Lotbinière, a small community in the Chaudière-Appalaches region of Québec, Canada. The plant serves a population of 757 residents and operates under secondary treatment standards, which involve biological processes to reduce organic matter and suspended solids. The plant's treatment process is classified as secondary, meeting the typical requirements for small Canadian municipalities. Under the Canadian Environmental Protection Act and provincial regulations in Québec, secondary treatment is the baseline for wastewater facilities to protect receiving water bodies. The plant's discharge volume is 340 cubic meters per day, reflecting its small scale. The treated effluent is released into the local watershed, which ultimately drains into the St. Lawrence River via the Chaudière River system. This river is a major tributary of the St. Lawrence, supporting diverse aquatic life and serving as a critical migratory corridor for fish species. The plant's operation helps maintain water quality in this ecologically sensitive region.

The plant discharges into the Chaudière River basin, which flows northward into the St. Lawrence River near Québec City. The St. Lawrence River is a major waterway that empties into the Gulf of St. Lawrence, a vast estuary supporting rich marine biodiversity. The local watershed includes agricultural and forested areas, and the plant's secondary treatment helps reduce nutrient loading that could otherwise contribute to eutrophication in downstream waters.