U.S., Mexico Sign New Agreement to Address Tijuana River Sewage Crisis

By Emmanuel Bobby

The Trump administration has signed a new binational agreement with Mexico aimed at resolving a decades-long sewage crisis affecting communities on both sides of the U.S.–Mexico border along the Tijuana River.

On Dec. 15, the U.S. Environmental Protection Agency (EPA) announced that the two countries finalized a new agreement known as *Minute 333*, describing it as a historic step toward permanently and urgently ending chronic sewage flows into the Tijuana River watershed.

The Tijuana River stretches approximately 120 miles, with most of its length in Mexico’s Baja California state. Only the final five miles run through the United States before flowing through San Diego and into the Pacific Ocean. Pollution from raw sewage, trash, and industrial runoff prompted the San Diego City Council to declare a state of emergency in 1993.

Under Minute 333, Mexico has committed to developing a comprehensive water infrastructure plan for Tijuana within six months. The agreement also calls for plans to ensure proper operation and maintenance of critical systems, an assessment of a new ocean outfall for the San Antonio de los Buenos Wastewater Treatment Plant, and an expansion of that facility by at least 25 million gallons per day (MGD).

The San Antonio de los Buenos plant, which was shut down from 2015 until early 2025 due to long-term disrepair, is now operational but remains severely overburdened. While its current capacity is 18 MGD, it receives an estimated 40–45 MGD, resulting in frequent sewage overflows, according to the EPA.

All new plans are required to account for Tijuana’s future population growth—an element the EPA said was missing from earlier agreements.

Additional measures include Mexico’s commitment to construct a sediment basin near the international boundary at Matadero Canyon, also known as Smuggler’s Gulch, before the 2026–2027 rainy season. Mexico will also build the Tecolote–La Gloria Wastewater Treatment Plant, located five miles south of the border, by December 2028. That facility will have a capacity of 3 MGD and will treat wastewater that currently flows untreated into the Pacific Ocean, contributing to cross-border pollution.

Deteriorating infrastructure combined with rapid population growth in Tijuana has created a significant public health crisis. The breakdown of the San Antonio de los Buenos facility in 2015 led to the daily discharge of millions of gallons of untreated sewage and industrial waste into the river.

Communities in the San Diego region have experienced beach closures, suspended naval training, and exposure to hazardous gases such as hydrogen sulfide and hydrogen cyanide. Residents in affected areas have been advised to use air purifiers and filtration systems due to poor air quality.

Mexico’s Ministry of Foreign Affairs said the agreement establishes technical, financial, and governance measures to carry out sanitation projects in Tijuana that will improve public health, environmental conditions, and coastal areas in both Tijuana and San Diego. The ministry added that the United States will share financial responsibility through the North American Development Bank (NADB) to support the operation and maintenance of Mexican-side infrastructure and prevent future deterioration.

The EPA emphasized that Minute 333 does not obligate any additional U.S. taxpayer funding beyond existing appropriations. U.S. contributions to the NADB’s Border Water Infrastructure Program are allocated annually by Congress and are contingent on Mexico meeting construction milestones outlined in the agreement.

EPA Administrator Lee Zeldin said the agreement establishes a framework for significant progress and allows both countries to move quickly on implementation.

“I saw the frustration of San Diego area residents firsthand when I visited in April,” Zeldin said. “I promised them a 100 percent solution to this issue, and the EPA is doing its part to deliver.”

Minute 333 builds on a memorandum of understanding signed in July by Zeldin and Mexican Environment Minister Alicia Bárcena, in which Mexico agreed to accelerate the use of $93 million for improvements to Tijuana’s sewage system. The new agreement formalizes those commitments, including provisions designed to accommodate future population growth and ensure long-term system maintenance.