Mesillas Wastewater Treatment Plant, Sinaloa, Mexico

Mesillas is a wastewater treatment plant located in the town of Mesillas, within the municipality of Concordia, Sinaloa, Mexico. The facility serves a population of approximately 2,829 residents, providing secondary treatment to manage municipal wastewater. It is situated inland, away from coastal zones, and operates as part of the local sanitation infrastructure. The plant applies secondary treatment processes, which typically involve biological degradation of organic matter. With a designed capacity of 302.40 cubic meters per day and an actual discharge volume of 267.84 cubic meters per day, the facility operates below its maximum capacity. Mexican 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 ultimately drain into the Pacific Ocean via the Presidio River basin. The surrounding region supports diverse ecosystems, including tropical dry forests and agricultural lands. Proper treatment helps protect downstream water quality and aquatic habitats.

The plant discharges into local waterways that flow into the Presidio River, which drains into the Pacific Ocean near Mazatlan. The downstream environment includes estuarine and coastal habitats that support fish, crustaceans, and migratory birds. Secondary treatment reduces organic load and suspended solids, mitigating eutrophication risks in receiving waters.