Opinion: U.S.-Mexico sewage deal proves that diplomacy can pay off

In an era when headlines about U.S.-Mexico relations are dominated by tensions over migration, tariffs and security, it’s easy to lose sight of what the two countries can achieve when they sit down, negotiate and commit to solutions. Last month’s agreement to accelerate tackling the long‑running sewage crisis in the Tijuana River Valley is proof that — even now — quiet, institutional diplomacy can deliver.

On July 24, EPA Administrator Lee Zeldin and Mexican Environment Minister Alicia Bárcena Ibarra signed a memorandum of understanding in Mexico City to address one of the most stubborn environmental and public health challenges along the border. For decades, untreated wastewater from Tijuana has flowed north into Southern California, fouling beaches, harming marine life, and triggering respiratory and gastrointestinal illnesses among residents and even U.S. Navy and Border Patrol personnel. Meanwhile, Tijuana’s population boomed, its sewage systems buckled due to lack of investment, and Southern California communities paid the price.

Since the 1983 La Paz Agreement, the United States and Mexico have built a structured framework for environmental cooperation, with programs emphasizing joint planning, community engagement and environmental protection. In 2022, this collaboration deepened with a memorandum of understanding and a commitment from Mexico to invest $144 million in wastewater infrastructure in the Tijuana River Watershed by 2027, underscoring the importance of treaty‑based institutions like the International Boundary and Water Commission for closing infrastructure gaps and moving toward proactive, binational operations and maintenance.

The new agreement reinforces this prior commitment by prioritizing the remaining $93 million and accelerating timelines, reflecting a shared understanding that expanded infrastructure and sustained operations are vital to protect public health and ecosystems. This is deadline‑driven, technically grounded diplomacy that avoids zero‑sum politics. The negotiation is part of a continuum, building on past agreements to address urgent needs while embedding long‑term resilience. Geography ensures the Tijuana River Watershed will remain a shared responsibility; sustained progress will require trust, transparency, technical integrity and mutual accountability.

Central to this breakthrough is Bárcena’s leadership. A biologist by training and a proven diplomat, she previously served as Mexico’s secretary of foreign affairs. Her deep understanding of both environmental systems and international negotiation made her the ideal figure to bridge political divides. She avoided theatrics, focusing instead on institutional credibility, technical rigor and mutual respect — creating the space for both sides to deliver without inflaming domestic political sensitivities.

The significance of this deal extends far beyond sewage treatment. It offers a template for how to address other persistent challenges — whether on water sharing, cross‑border air pollution, trade enforcement or security coordination. The formula is clear: anchor negotiations in trusted institutions; define measurable outcomes, timelines, and funding commitments; empower technical experts to design solutions and diplomats to safeguard the process; and keep politics to a minimum.

For U.S. communities like Imperial Beach, the immediate benefit will be cleaner water, fewer beach closures and improved public health. For Mexico, the agreement is a visible demonstration of environmental responsibility and state capacity — an investment in the quality of life for Tijuana’s residents and the preservation of the city’s natural resources. Crucially, it reinforces the reality that shared ecosystems demand shared governance. The Tijuana River does not recognize the international boundary; neither should the solutions. And most importantly, it shows that Mexico can make progress on tricky issues with the Trump administration by sticking to an institutional approach supported by knowledgeable, steady leaders.

The work is far from done. By Dec. 31, 2027, the U.S. must deliver its promised upgrades, and the IBWC must negotiate a new “minute” agreement (a formal treaty addendum) to incorporate additional resilience measures. Execution will require sustained political will on both sides, as well as transparent reporting to ensure commitments are met. The history of this issue shows how easily momentum can be lost when attention shifts elsewhere.

In today’s political climate, it can be tempting to view U.S.-Mexico relations as a ledger of grievances and disputes. This agreement is a reminder that the ledger can also record successes — especially when both nations commit to solving problems through structured, rules‑based cooperation. The Tijuana River will not be clean overnight, but the path is now clear. More importantly, the process that delivered this breakthrough — quiet negotiation, respect for sovereignty, reliance on technical expertise — can and should guide work on other pressing bilateral issues.

If two nations can finally end decades of finger‑pointing over sewage and turn it into a plan for clean water, then perhaps there’s hope that the same disciplined diplomacy can be brought to trade, migration, climate resilience and security. Sometimes the best progress is not announced with fanfare — it’s built step by step, through institutions that endure beyond electoral cycles. The Tijuana River agreement is one such step, and it’s worth celebrating.

Wood, Ph.D. is CEO of Hurst International Consulting in Washington, D.C., and former president of the Pacific Council and vice president at the Wilson Center. Giner, Ph.D. is based in Austin, Texas, and is the former commissioner for the International Boundary and Water Commission and former general manager for the Border Environment Cooperation Commission.