Oso Nuevo y Oso Viejo Wastewater Treatment Plant, Oso Viejo, Sinaloa

Oso Nuevo y Oso Viejo is a municipal wastewater treatment plant located in Oso Viejo, a locality within the municipality of Culiacán, Sinaloa, Mexico. The plant serves a population of approximately 3,081 residents, reflecting its role in managing domestic wastewater for a small community in northwestern Mexico. The plant provides secondary treatment, which is the standard biological treatment process that removes organic matter and suspended solids. With a designed capacity of 673.92 cubic meters per day and a current discharge volume of 552.96 cubic meters per day, the facility operates below its maximum capacity. In Mexico, wastewater treatment plants are regulated under the National Water Law and NOM-001-SEMARNAT-1996, which sets discharge limits for pollutants into national waters. The treated effluent is discharged into local water bodies that eventually drain into the Pacific Ocean via the Culiacán River basin. The plant's location within 50 kilometers of the coast means its discharge can influence coastal water quality. Proper secondary treatment helps protect downstream aquatic ecosystems and supports the ecological health of the region's rivers and coastal areas.

The plant discharges into the Culiacán River basin, which flows into the Pacific Ocean near the city of Culiacán. This coastal watershed supports diverse aquatic life, including fish and migratory birds. The region's agricultural and urban runoff also contributes to the water quality dynamics, making effective treatment essential for maintaining the ecological balance of the river and its estuary.