On Thursday, July 24, 2025, the United States and Mexico took a significant step forward in addressing a decades-old environmental and public health crisis by signing a new agreement to tackle the persistent sewage pollution flowing from Tijuana into Southern California. This accord lays out specific actions and a fresh timetable aimed at cleaning up the Tijuana River, whose contaminated waters have long plagued the border region, closing beaches and endangering residents and military personnel alike.
The Tijuana River, stretching 120 miles (195 kilometers) near the coast of Mexico before crossing into Southern California, has become a conduit for billions of gallons of raw sewage and industrial pollutants. Since 2018, more than 100 billion gallons of untreated sewage, laden with toxic chemicals and trash, have flowed into San Diego County and the Pacific Ocean, causing repeated beach closures and health hazards. Navy SEALs training in the waters have fallen ill, and the contamination has affected swimmers, surfers, lifeguards, schoolchildren, Border Patrol agents, and others who may never even enter the water. Scientists warn that the foaming sewage vaporizes, releasing harmful substances into the air that residents breathe.
Despite numerous efforts and millions of dollars invested over the years—including initiatives launched during the first Trump administration—the problem has persisted. The aging wastewater treatment infrastructure in Tijuana has struggled to keep pace with the city's rapid population growth and industrial expansion, notably the maquiladoras, manufacturing plants producing goods for the U.S. market. This has led to increased toxins entering the river and crossing the border, exacerbating the pollution crisis.
Environmental Protection Agency (EPA) Administrator Lee Zeldin, who visited San Diego in April 2025 to meet with Mexican officials and observe the border conditions firsthand, described his experience as eye-opening. "I smelled what a lot of residents in the community lived through and have to deal with," Zeldin recounted during the signing ceremony in Mexico City. "I saw the degradation of the Tijuana River valley. I heard about the beaches that were closed. I met with the Navy SEALs, who have had their training impacted. It was a powerful visit all around for me." His visit underscored the urgency of renewed binational cooperation.
Mexico's Environmental Secretary Alicia Bárcena echoed this sentiment, emphasizing the strong commitment from both countries to enhance collaboration. "There is a great commitment by the two countries to strengthen cooperation," she said after meeting with Zeldin to sign the memorandum of understanding. The accord commits Mexico to completing its allocation of $93 million toward critical infrastructure projects, with a detailed schedule of priority initiatives extending through 2027.
Mexican President Claudia Sheinbaum, who assumed office in October 2024, has been praised by Zeldin for her administration's proactive approach to the crisis. Sheinbaum announced plans to expand a wastewater treatment plant aimed at reducing contamination reaching the coast. "There are other actions that were signed that we have to complete, that we’re going to get done in the next year for the entire Tijuana sanitation system, for the entire metropolitan Tijuana area," she said. She also highlighted the importance of U.S. investment in addressing this binational challenge and pointed to the Tijuana River agreement as a prime example of how technical cooperation can solve seemingly intractable problems. Referring to a separate agreement to send more water to the U.S. to reduce Mexico’s water debt in the Rio Grande, she remarked, "It is a good example of how when our technical teams sit down, they can resolve a problem that seemed unsolvable."
On the U.S. side, officials have committed to completing the expansion of the South Bay International Wastewater Treatment Plant by August 2025. The agreement also stipulates that Mexico will divert 10 million gallons per day of treated sewage away from the shore within this year, a vital step in mitigating the flow of pollutants into the ocean.
Since 2020, over $653 million has been allocated to tackle the Tijuana River pollution issue. However, progress has been hampered by delays in implementation, particularly on the Mexican side. Kristan Culbert, associate director of California river conservation at American Rivers, underscored the human toll of the crisis, stating, "The communities along the Tijuana River have suffered this public health crisis for far too long." The frequent closure of California beaches near the border over the past four years has disrupted local economies and limited recreational opportunities, while the health risks persist.
Environmental experts and local stakeholders view the new agreement as a hopeful turning point. Zeldin noted that the accord takes into account factors such as population growth, operation and maintenance costs, and other variables to ensure that the solutions put in place will be durable and long-lasting. The memorandum of understanding signals a renewed commitment to shared responsibility and action between the two nations.
While the Tijuana River sewage crisis has been a thorny, binational issue for decades, this latest accord offers a concrete roadmap to mitigate the pollution, safeguard public health, and restore the vitality of the border region’s waterways and beaches. With coordinated efforts, increased funding, and political will on both sides, the long-suffering communities along the Tijuana River may finally see relief from the chronic contamination that has overshadowed their lives.
As the clock ticks toward the deadlines set in this agreement, eyes will remain on the progress made in the coming months and years. The stakes are high not only for environmental preservation but for the wellbeing of countless individuals who live, work, and play near the Tijuana River and its polluted waters.
