El Saucito Wastewater Treatment Plant, Durango, Mexico

El Saucito wastewater treatment plant is located in the town of El Saucito, within the municipality of San Juan del Río, Durango, Mexico. The facility serves a small population of 134 residents, reflecting its role in a rural or semi-rural community. As a secondary treatment plant, it provides biological treatment to reduce organic matter and suspended solids before discharge. The plant has a designed capacity of 235.87 m³/day and currently discharges 203.90 m³/day of treated wastewater. Under Mexico's federal water law (Ley de Aguas Nacionales) and NOM-001-SEMARNAT standards, secondary treatment is the minimum required for municipal wastewater to protect receiving water bodies. The plant's operation is subject to oversight by the National Water Commission (CONAGUA), which issues discharge permits and monitors compliance. The treated effluent from El Saucito likely discharges into a local arroyo or stream that drains into the San Juan River, part of the larger Nazas-Aguanaval basin. This basin is ecologically important in the arid region of northern Mexico, supporting agriculture and wildlife. Proper treatment helps prevent contamination of groundwater and surface water, which are critical for local communities and ecosystems.

The plant's discharge enters the San Juan River watershed, which flows into the Nazas River and ultimately contributes to the Laguna de Mayrán, an endorheic basin in the Chihuahuan Desert. This arid region relies on limited surface water and groundwater, making wastewater treatment essential for protecting water quality. The surrounding ecosystem supports desert-adapted species and migratory birds, and treated effluent can help sustain base flows in dry periods.