During yesterday’s pounding rains, the South Bay International Wastewater Treatment Plant at the U.S.–Mexico border took on an extraordinary surge, handling more than 50 million gallons in a single day. Officials say the flow was loaded with stormwater, heavy sediment and trash, and that a Mexican pump station was briefly shut down to protect its equipment. The plant reports no structural damage, and binational agencies are now watching river runoff as the region dries out.
What officials reported
The U.S. Section of the International Boundary and Water Commission said in a post, shared by San Diego County HHSA, that Mexico’s PBCILA pumps were taken offline at 3:11 PM PDT on April 13 to safeguard the system. According to the commission, the South Bay plant “took on over 50 million gallons per day” at peak flow, with the incoming water laced with stormwater, heavy sediment and trash. The post added that “no damage is reported to the plant” and that USIBWC will keep coordinating with Mexican water authorities and share further updates as conditions evolve.
The #USIBWC reports the following regarding the South Bay International Wastewater Treatment Plant (SBIWTP) in #SanDiegoCA :@cilamexico advises PBCILA operations were suspended at 3:11 pm PDT to protect equipment on April 13, 2026 due to heavy rain fall in the region.
— U.S. International Boundary and Water Commission (@usibwc) April 13, 2026
CILA…
How the plant handled the surge
The SBIWTP is a federal facility typically sized to treat about 25 million gallons per day, but it was built with room to grow and is currently in the middle of phased upgrades intended to boost capacity. Official materials note that the plant can be expanded, and recent work has focused on increasing interim throughput. Industry coverage earlier this month detailed the restart of key Mexican pump operations that had previously constrained cross-border flows. For background on the upgrade program and ongoing binational coordination, see the IBWC wastewater treatment plant page, Wastewater Digest, and earlier Hoodline coverage of the rehabilitation contract in USIBWC awards $42.4 million.
Why it matters for beaches and public health
Transboundary flows that blend sewage, stormwater and sediment are a familiar trigger for South Bay beach closures and public health warnings, especially during and immediately after big storms. The EPA’s Tijuana River watershed overview notes that wet-weather events can routinely push tens of millions of gallons per day of mixed wastewater and runoff north into U.S. waters, and local governments often shut down or limit recreation until water sampling shows conditions are safe. County health officials and state regulators continue to track water quality in the days following a surge like this to decide when signs or closures are warranted.
What to watch
Binational agencies are keeping an eye on river levels and pump operations. As the USIBWC noted in its update shared by San Diego County HHSA, it plans to release more information if circumstances change. Local health officials advise staying out of river water after storms and following county advisories for beaches and nearby trails while runoff remains high.
