San Antonio del Mar Wastewater Treatment Plant, Tijuana, Baja California

San Antonio del Mar is a wastewater treatment plant located in the Zona Río district of Tijuana, Baja California, Mexico. It serves a population of approximately 4,107 people, classifying it as a small-scale municipal facility within the Tijuana metropolitan area. The plant provides secondary treatment, which is the standard biological treatment level required under Mexican regulations (NOM-001-SEMARNAT) for municipal wastewater. With a designed capacity of 216.00 thousand cubic meters per year and an actual discharge volume of 388.80 thousand cubic meters, the plant operates above its nominal capacity, reflecting the demands of the growing urban area. The treated effluent is discharged into the Tijuana River basin, which flows into the Pacific Ocean near the US-Mexico border. This coastal discharge point is ecologically significant as it affects nearshore water quality and marine habitats in the Southern California Bight, a region known for its biodiversity and migratory species.

The plant discharges into the Tijuana River watershed, which drains into the Pacific Ocean at the Tijuana Estuary, a critical coastal wetland that supports migratory birds and marine life. The discharge enters the Southern California Bight, a region influenced by the California Current, where nutrient inputs can affect algal blooms and nearshore ecosystems. The proximity to the coast (within 10 km) increases the potential for direct marine impact.