Emergency repairs to a collapsed wastewater pipeline in Tijuana are complete, sharply reducing the sewage flows that overwhelmed the U.S.-Mexico border region over the past several days, officials confirmed on June 4.
The Tijuana Parallel Gravity Line, a roughly 10-mile pipeline that transports wastewater to the San Antonio de los Buenos treatment plant south of Tijuana, collapsed on the night of Friday, May 30. The break sent an estimated 40 to 50 million gallons of raw sewage into the Tijuana River, according to Chris Helmer, Environmental and Natural Resources Director for the city of Imperial Beach.
Treatment Plant Pushed Past Capacity
The collapse overwhelmed the South Bay International Wastewater Treatment Plant (SBIWTP) on the U.S. side. The plant is designed to process 35 million gallons per day (MGD). During the crisis, it sustained flows above 45 MGD for 13 hours and peaks above 60 MGD for nine hours, according to the U.S. International Boundary and Water Commission (USIBWC).
Hydrogen sulfide gas levels in the Tijuana River Valley spiked above safe thresholds during the rupture, triggering health alerts for residents on both sides of the border. Communities in southern San Diego County, including Imperial Beach, bore the brunt of the odors and contamination.
Pump Stations Back at Full Capacity
With the repairs now finished, pump stations are operating at full capacity, and flows into the Tijuana River and the surrounding canyon collector system have dropped significantly. The SBIWTP has returned to normal operations, processing up to 35 MGD.
Residents near the Tijuana River may still notice lingering odors despite the reduced flows. Officials warned that the smell could persist for some time as residual sewage clears the system.
Aging Infrastructure Remains a Concern
The San Antonio de los Buenos plant, which receives wastewater through the repaired Parallel Gravity Line, is designed to treat 18 million gallons per day before discharging into the Pacific Ocean. The pipeline collapse was just the latest in a series of breaks in Tijuana’s aging sewage infrastructure. An earlier rupture in January 2026 sent an estimated 11.5 million additional gallons of sewage per day across the border.
Imperial Beach Mayor and other local leaders requested a state of emergency declaration from the governor’s office but were denied. Long-term improvements are in the works, including expansion of the SBIWTP and renewed agreements with Mexico to accelerate infrastructure projects. For residents of the Tijuana, Rosarito, and Playas de Tijuana coastal corridor, the fix offers temporary relief, but officials caution that the underlying infrastructure remains fragile.
This story was first reported by FOX 5 San Diego and Border Report.