Environmental groups on both sides of the border want Tijuana River pollution on the agenda when the United States, Mexico, and Canada sit down on July 20 to review their shared trade agreement. Organizations including Wildcoast are pressing negotiators to attach enforceable environmental provisions to the T-MEC (the trade pact that replaced NAFTA in 2020), arguing that decades of infrastructure promises have failed to stop sewage, industrial chemicals, and trash from flowing through the Tijuana River Valley into the Pacific Ocean.
Serge Dedina, Wildcoast’s executive director and a former mayor of Imperial Beach, California, confirmed that the San Antonio de los Buenos wastewater treatment plant (known by its Spanish acronym PTAR SAB), rehabilitated in 2025, is still underperforming. “Our sources tell us that plant is not working,” Dedina said. “There are days when the smell in Imperial Beach is horrible and it comes from the Tijuana River.”
Three Decades of Broken Infrastructure Promises on the Tijuana River
The contamination crisis is not new. The International Boundary and Water Commission (IBWC), the binational body responsible for managing shared waterways, has overseen multiple repair and expansion cycles at the South Bay International Wastewater Treatment Plant on the U.S. side since the 1990s. On the Mexican side, the PTAR SAB plant in the San Antonio de los Buenos canyon south of Playas de Tijuana was designed to treat a significant share of Tijuana’s municipal wastewater before it reached the ocean. That plant fell into disrepair by the early 2020s, and Mexico’s federal government completed a rehabilitation in 2025.
But Tijuana has grown faster than its infrastructure. The city’s population now exceeds 2 million, and sewer collection systems in many colonias remain incomplete. During heavy rains, the Tijuana River carries untreated sewage, tire fragments, plastics, and industrial waste downstream. In 2024, the U.S. Environmental Protection Agency allocated $630 million for new infrastructure to address transboundary flows on the American side, the largest single federal investment in the problem’s history. Construction on expanded U.S. treatment capacity is underway but not expected to be fully operational for several years.
On the Mexican side, CONAGUA (Mexico’s national water commission) and state authorities have announced multiple remediation plans over the past decade. Activists say most have stalled or underdelivered. The PTAR SAB rehabilitation was the highest-profile completion, and Dedina’s claim that it still falls short of its design capacity is central to the argument that voluntary infrastructure commitments are not enough.
Beach Closures and Health Warnings Hit Playas de Tijuana and South Bay
The practical effects of the contamination are measurable on both sides of the border. Imperial Beach, Coronado, and other South Bay communities in San Diego County have experienced recurring beach closures tied to sewage-contaminated water flowing from the Tijuana River mouth. In some years, Imperial Beach’s shoreline has been closed for more than 300 days.
On the Baja side, Playas de Tijuana and Rosarito Beach face similar conditions. Swimmers and surfers along this stretch of coast regularly encounter water quality advisories. Property listings in Playas de Tijuana and the coastal corridor south of the border have reflected the issue for years: oceanfront units that should command premium prices often sell below expectations when buyers learn about water quality data.
Health risks extend beyond the beach. Residents of colonias near the riverbed report respiratory problems linked to airborne contaminants, and waterborne disease outbreaks have been documented in low-lying neighborhoods during flood events. Tijuana’s rapid urbanization has pushed informal settlements into flood-prone areas along the river, increasing exposure for some of the city’s most vulnerable populations.
T-MEC Dispute Mechanisms Could Create Enforceable Accountability
What makes the T-MEC angle different from past approaches is enforcement. The trade agreement includes a chapter on environmental cooperation and, critically, a dispute resolution process that can carry economic penalties. Under NAFTA, the environmental side agreement (the North American Agreement on Environmental Cooperation) had no real teeth. The T-MEC, at least on paper, allows one country to file complaints against another for failing to enforce its own environmental laws, and a successful complaint can result in tariff consequences.
Activists argue that this mechanism gives communities something they have never had: legal standing to demand action backed by economic leverage. If the July 20 review results in specific language linking Tijuana River remediation to trade compliance, both the U.S. and Mexican governments would face structured accountability timelines rather than open-ended promises.
The idea has precedent elsewhere in the agreement. T-MEC’s labor provisions have already been used to challenge conditions at specific factories in Mexico, resulting in concrete changes. Environmental groups want the same template applied to transboundary pollution.
Whether negotiators will prioritize the river remains uncertain. Both governments face competing demands in the review, from auto manufacturing rules to agricultural tariffs. Wildcoast and allied organizations plan to submit formal proposals before the July 20 start date and coordinate public pressure campaigns in border communities on both sides. The story was first reported by La Jornada Baja California.