South Bay WRP, San Diego, California: Wastewater Treatment Plant Overview

South Bay WRP is a municipal wastewater treatment plant located in San Diego, California, serving a population of approximately 134,433. The facility is situated near the US-Mexico border in the San Ysidro neighborhood, providing essential wastewater services to a densely populated urban area. As a large-scale treatment plant in the United States, South Bay WRP operates under the regulatory framework of the Clean Water Act, administered through the EPA's National Pollutant Discharge Elimination System (NPDES) permits. For agglomerations of this size, secondary treatment is typically required, with additional nutrient removal in sensitive watersheds. The plant's designed capacity is 1.00 million gallons per day, indicating a substantial infrastructure footprint. The plant's treated effluent is discharged into the local watershed, which ultimately drains to the Pacific Ocean via the Tijuana River estuary and coastal waters. This region supports diverse marine life and is an important migratory corridor for birds and aquatic species. The plant plays a critical role in protecting downstream water quality and public health in the San Diego Bay and adjacent coastal ecosystems.

South Bay WRP discharges into the Tijuana River watershed, which flows into the Pacific Ocean near the US-Mexico border. The receiving waters include the Tijuana River estuary, a sensitive coastal habitat that supports diverse aquatic life and migratory birds. Downstream, the effluent enters the Southern California Bight, a marine region known for its rich biodiversity and proximity to protected marine areas. The plant's operations are critical to preventing untreated wastewater from impacting these ecologically important coastal waters.