The United States and Mexico have signed a memorandum of understanding aimed at ending decades of untreated sewage flowing from the Tijuana River into the Pacific Ocean and fouling beaches in San Diego. The pact was signed in Mexico City by U.S. Environmental Protection Agency Administrator Lee Zeldin and Mexican Environment Minister Alicia Bárcena, with American ambassador Ronald Johnson as witness, marking the first major environmental accord under the administrations of President Claudia Sheinbaum and President Donald Trump. Under the agreement Washington will release roughly US$600 million to finish expanding the South Bay International Wastewater Treatment Plant and related works on the U.S. side of the border. Mexico will accelerate US$93 million in spending to double the capacity of the San Antonio de los Buenos plant and rehabilitate key collectors, interceptors and pumping stations in Tijuana. In all, the US$693 million package finances 13 priority projects slated for completion between 2025 and 2027. Officials say the accelerated schedule could cut project timelines by up to four years. The International Boundary and Water Commission estimates that as much as 50 million gallons of contaminated water a day currently reach Imperial Beach, leading to frequent closures that have hurt tourism and public health. Zeldin called the deal “a huge win” for border communities, while Bárcena said it provides a definitive path to resolve the river’s wastewater problem.