Three binational environmental organizations called on U.S. trade officials to include cross-border sewage pollution in the upcoming USMCA trade treaty review, set to begin July 20. Costa Salvaje, Pronatura Noroeste, and the Sierra Club San Diego Chapter held a press conference at El Faro de Playas de Tijuana on July 9 to announce they had sent a formal letter to U.S. Trade Representative Jamieson Greer. The groups argue that years of failed bilateral agreements justify embedding Tijuana beach pollution fixes in binding trade language.
Decades of Binational Sewage Agreements Have Failed
The cross-border sewage crisis is not new. Tijuana and San Diego have shared contaminated coastal waters for decades, and each round of diplomatic promises has produced limited results. In 1944, a U.S.-Mexico water treaty established the International Boundary and Water Commission (IBWC) to manage shared waterways, but enforcement on sewage flows has remained weak.
In 2020, the U.S. Congress approved the bipartisan USMCA trade agreement, which replaced NAFTA. That deal included an environmental chapter but no specific provisions for transborder sewage. The same year, Congress also passed a $300 million authorization through the EPA to upgrade the South Bay International Wastewater Treatment Plant on the U.S. side. Construction on those upgrades has been slow, and completion timelines have shifted repeatedly.
On the Mexican side, CONAGUA, Mexico’s national water commission, and CESPT, Tijuana’s municipal water utility, inaugurated an expansion of the San Antonio de los Buenos wastewater treatment plant roughly a year ago. But Serge Dedina, executive director of Costa Salvaje and former mayor of Imperial Beach, California, said the plant treats only 30 percent of Tijuana’s sewage. The remaining 70 percent flows untreated into the Pacific Ocean.
“It is important that governments take the environmental issue seriously, not just sign papers and agreements, but actually invest in infrastructure that stops toxic discharge, trash, and sewage spills,” Dedina said at the press conference.
Imperial Beach, located just north of the border, has been closed to swimmers for more than three years due to high levels of enterococcus bacteria from human waste. On the Tijuana side, Playas de Tijuana has faced recurring advisories and closures over the same period. Rosario Norzagaray, Costa Salvaje’s marine debris program manager, said the contamination discourages visitors and damages the coastal ecosystem.
“Everything that arrives, sewage and trash, hits and harms the delicate environmental services this biodiversity-rich ecosystem provides,” Norzagaray said. “With these odors, people avoid the beaches.”
USMCA Review Creates a Rare Window for Binding Commitments
The USMCA includes a built-in review mechanism. On July 20, the three signatory nations will begin the formal six-year review process. This is the first such review since the treaty took effect on July 1, 2020. Any party can propose amendments, and if the three countries do not agree to extend the deal, it expires in 2036.
Environmental advocates see this review as their strongest leverage point in years. Previous commitments on cross-border sewage, including memoranda of understanding signed between IBWC and CONAGUA, lacked enforcement mechanisms. A provision within the USMCA could, in theory, carry trade consequences for noncompliance. The treaty’s environmental chapter already includes dispute resolution procedures that allow one country to challenge another’s failure to enforce its own environmental laws.
The groups’ letter to Greer was backed by California’s two U.S. senators and San Diego-area members of Congress, according to Dedina. The coalition is asking for verifiable commitments from both governments to reduce transborder contamination, develop infrastructure to control polluted runoff from the Tijuana River, and strengthen enforcement against illegal sewage discharges.
Beachfront Businesses and Coastal Residents Bear the Cost
The economic toll on both sides of the border has been significant. Norzagaray said reduced beach attendance has hurt established businesses in Tijuana’s coastal zones. On the U.S. side, Imperial Beach and Coronado have reported losses in tourism revenue tied directly to years of beach closures.
Playas de Tijuana, one of the city’s most popular coastal neighborhoods, draws both local families and cross-border visitors on weekends. Beachfront restaurants and vendors depend on foot traffic that drops sharply when contamination warnings are posted. CESPT, which is responsible for Tijuana’s wastewater collection and treatment, has faced chronic underfunding and aging infrastructure that contributes to frequent sewage spills into the Tijuana River and storm drains leading to the coast.
The environmental groups also called on CONAGUA and CESPT to guarantee wastewater treatment capacity and monitor treatment plant operations more effectively. Among their proposals: new infrastructure to capture contaminated runoff from the Tijuana River before it reaches the ocean, and public awareness campaigns to reduce illegal sewage discharges.
The formal USMCA review process opens on July 20, giving the three governments until 2026’s end to negotiate any amendments. This story was first reported by Punto Norte.