(Image Credit: IMAGN) A sign along the Arroyo Simi in Moorpark warns of possible sewage contamination on Thursday, May 4, 2023. County officials recently detected a sewer line break that has sent millions of gallons of raw sewage into the channel.
San Diego, California – For years, yellow warning signs have lined the shoreline of southern San Diego County, urging beachgoers to “Keep Out of the Water” due to dangerous levels of pollution. Now, there may be a glimmer of hope — though a cautious one.
An International Boundary and Water Commission (IBWC) spokesperson confirmed Monday that Mexico’s San Antonio de los Buenos wastewater treatment plant is once again operational, treating upward of 18 million gallons of raw sewage daily. The news comes after years of inaction, during which the failing facility discharged untreated sewage directly into the Pacific Ocean, impacting beaches from Tijuana to Coronado.
Shuttered in 2020 due to disrepair and poor maintenance, the plant’s failure worsened an already dire cross-border pollution problem. Repairs began in early 2024, with officials initially promising completion by September of that year. But delays due to construction setbacks, weather, and supply shortages pushed the timeline back — first to February, then March, then April.
“It’s frustrating to know that we were promised this in September,” said Bethany Case, spokeswoman for the Surfrider Foundation. Still, she welcomed the progress. “That’s a good thing. It’s great. We’re excited about that.”
The IBWC said the plant is now complete and running, though still in the “stabilization” phase to meet Mexican environmental standards. Once that process is finished, responsibility will shift to local operators who must ensure the plant continues to function — and doesn’t again become a source of raw sewage flowing into the ocean.
While the plant’s return to operation is encouraging, it doesn’t spell the end of the region’s long-standing sewage crisis. Polluted runoff — an estimated 20 to 40 million gallons daily — still flows north via the Tijuana River, making its way through the Tijuana River Valley and out to the Pacific, continuing to contaminate U.S. waters.
The United States, for its part, still faces its own infrastructural challenges. Plans to repair and expand the U.S. side’s wastewater treatment plant remain critical to any long-term solution.
Though details remain unclear — including exactly when the Mexican plant resumed treatment and whether it’s operating at full capacity — officials and environmental advocates alike are cautiously optimistic that a major source of pollution is finally being addressed.
