San Pedro Wastewater Treatment Plant, Tijuana, Baja California, Mexico

San Pedro is a wastewater treatment plant located in Tijuana, Baja California, Mexico. It serves a population of approximately 8,762 people, classifying it as a small to medium agglomeration. The plant is situated in the Zona Río district, near the Tijuana River, and lies within 10 km of the Pacific coast. The plant provides secondary treatment, which is the standard level required under Mexican regulations (NOM-001-SEMARNAT) for municipal wastewater before discharge. Its designed capacity is 5,788.80 m³/day, with an actual discharge volume of 829.44 m³/day, indicating it operates well below capacity. As a coastal plant, it must meet stringent effluent quality standards to protect marine environments. The treated effluent likely discharges into the Tijuana River or directly into the Pacific Ocean via the river's estuary. The Tijuana River flows into the Pacific Ocean near the US-Mexico border, an area of ecological importance for coastal wetlands and migratory birds. The plant plays a key role in reducing pollution in this transboundary watershed.

The plant's discharge enters the Tijuana River watershed, which flows into the Pacific Ocean at the Tijuana River Estuary. This estuary is a critical habitat for fish, birds, and other wildlife, and supports a diverse aquatic ecosystem. The coastal location means that treated wastewater must meet strict standards to prevent nutrient loading and protect marine life in the nearshore environment.