U.S-Mexico Border Water Quality
- On April 10, the United States section of the International Boundary and Water Commission (USIBWC) reported that authorities in Mexico began discharging approximately 5 million gallons per day (MGD) of wastewater to the Tijuana River as they repair a critical junction box related to the rehabilitation of the International Collector. Authorities in Mexico were able to limit the discharge to the river to 5 MGD, from a potential of approximately 25 MGD. The remaining wastewater is pumped to a shoreline discharge at Punta Bandera, approximately 5 miles south of the international border. Mexican authorities reported that the discharge is expected to last for five days.
- Planning is underway for Phase 2 of the rehabilitation of the International Collector in Tijuana. During this phase of construction, the South Bay International Wastewater Treatment Plant (SBIWTP) will undergo a period of 6 days with no flow. USIBWC and the operator of the SBIWTP, Veolia, are coordinating closely with authorities in Mexico to ensure the plant remains in compliance with its NPDES permit as it resumes operations after Phase 2.
- Construction of a new wastewater treatment plant at San Antonio de los Buenos in Mexico was completed on January 31. Testing, corrective actions, and stabilization efforts are currently underway, with full operation at 18 MGD and compliance with Mexican effluent standards expected in early May.
- On March 13 the United States Environmental Protection Agency (USEPA) formally accepted the Lower Tijuana River Indicator Bacteria and Trash Advance Restoration Plan (ARP). USEPA acknowledges that the ARP fulfills California’s obligation under the Clean Water Act’s 303(d) Program to develop a plan to restore water quality in the lower Tijuana River. For more details, please visit the ARP’s website.
- Non-profits Alter Terra and Rural Community Assistance Corporation (RCAC), have reported that the Tijuana River Trash Boom is functioning as expected, intercepting trash generated in Mexico, and preventing it from reaching the Tijuana River Estuary and Pacific Ocean. This $4.7 million pilot project was funded by the State Water Resources Control Board to study the most effective mechanism for trash interception and disposal and to inform a more permanent solution in accordance with Project J in the June 2023 USIBWC-USEPA Joint Record of Decision for the Final Programmatic Environmental Impact Statement for the United States-Mexico-Canada Agreement Mitigation of Contaminated Transboundary Flows Project.
- On February 18, the San Diego Water Board issued Investigative Order No. R9-2025-0022 to USIBWC. The investigative order requires USIBWC to submit technical information related to discharges of waste from multi-day Spill Events at the Hollister Street Pump Station and at the Goat Canyon and Smuggler’s Gulch canyon collectors.
- The South Bay International Wastewater Treatment Plant (SBIWTP) continues to be in compliance with secondary treatment effluent limitations. On February 10, San Diego Water Board staff conducted the annual compliance evaluation inspection of the SBIWTP. No new violations were identified.
- The U.S. Section of the International Boundary and Water Commission (USIBWC) reports that the Comisión Internacional de Límites y Aguas pump station (PBCILA) in Tijuana has not been in operation since January 26 due to high flows in the Tijuana River during January and February storm events and following the storm events. Therefore, transboundary flows are reaching the Tijuana River Valley, Tijuana River Estuary, and Pacific Ocean. USIBWC flow gauge data for the Tijuana River is available on the USIBWC Water Data Portal. USIBWC Water Data Portal.
Interested parties can sign up for the following San Diego Water Board email notifications at http://www.waterboards.ca.gov/resources/email_subscriptions/reg9_subscribe.html:
- South Bay International Wastewater Treatment Plant – NPDES
- Tijuana River Valley Recovery