Sauz de Los Vallin Wastewater Treatment Plant, Calvillo, Aguascalientes, Mexico

Sauz de Los Vallin is a wastewater treatment plant located in the community of El Sauz, within the municipality of Calvillo, Aguascalientes, Mexico. The plant serves a small population of 91 residents, reflecting its role in a rural or peri-urban setting. It is situated inland, more than 10 km from the coast, and operates under Mexico's national water regulatory framework. The plant provides secondary treatment, which is the standard level required for municipal wastewater in Mexico under the Federal Water Rights Law (Ley de Aguas Nacionales) and NOM-001-SEMARNAT-1996, which sets discharge limits for pollutants. The designed capacity is 86.40 cubic meters per day, and the current discharge volume is 8.64 cubic meters per day, indicating a utilization rate of about 10%. Secondary treatment typically involves biological processes to reduce organic matter and suspended solids. The treated effluent is discharged into a local water body, likely a stream or arroyo that drains into the Rio Calvillo or the Rio Aguascalientes, eventually reaching the Rio Verde and the Rio Grande de Santiago, which flows into the Pacific Ocean. The plant helps protect the local watershed from untreated sewage, supporting water quality for downstream communities and ecosystems in the semi-arid region of Aguascalientes.

The plant discharges into a local watercourse that is part of the Rio Verde basin, a tributary of the Rio Grande de Santiago, which ultimately drains into the Pacific Ocean. The region is semi-arid, and water resources are critical for agriculture and domestic use. The plant's secondary treatment reduces organic pollution, helping to maintain water quality in downstream rivers and reservoirs that support diverse aquatic life and migratory birds.