U.S. and Mexico Finalize Historic Deal to End Tijuana River Sewage Crisis

EPA Administrator Lee Zeldin and Mexican officials signed a binding MOU to expedite infrastructure projects and deliver a permanent, binational solution to the decades-long pollution of the Tijuana River Valley.

• By Stasia DeMarco
• July 25, 2025

The United States and Mexico signed a historic Memorandum of Understanding (MOU) this week aimed at permanently ending the decades-long flow of untreated sewage from Tijuana into Southern California, marking what U.S. officials called a “100% solution” to a persistent cross-border environmental crisis.

The agreement, signed by U.S. Environmental Protection Agency (EPA) Administrator Lee Zeldin and Mexico’s Secretary of the Environment and Natural Resources Alicia Bárcena Ibarra, outlines a fast-tracked strategy to complete all infrastructure projects under Minute 328 of the U.S.-Mexico Water Treaty by December 31, 2027, including new provisions to address future growth and system maintenance.

For far too long, raw sewage has polluted the Tijuana River Valley, closed beaches, harmed public health, and hurt the economy on both sides of the border,” said Zeldin, calling the new MOU “a massive environmental and national security win.”

Key Components of the Agreement

• Mexico will obligate the remaining $93 million of its Minute 328 funding and accelerate the timeline for project completion—some by as much as four years.
• Mexico agreed to launch construction immediately on two priority projects: diverting 10 million gallons per day (MGD) of treated effluent and rehabilitating the Parallel Gravity Line—both set to be completed by December 31, 2025.
• The United States, in turn, will release EPA Border Water Infrastructure Program (BWIP) funds to complete upgrades to Pump Station 1 and the Tijuana River collection system.
• Mexico also committed to entering into a new Minute with the U.S. by the end of 2025 that will include a dozen new actions deemed necessary to reach a permanent resolution.

The U.S. International Boundary and Water Commission (IBWC) pledged to complete expansion of the South Bay International Wastewater Treatment Plant (SBIWTP)—increasing capacity from 25 to 35 MGD—by August 28, 2025, in what officials described as a record 100-day construction timeline.

A Long-Awaited Breakthrough

The MOU follows renewed diplomatic engagement after Administrator Zeldin’s April visit to San Diego and Tijuana, where he toured the affected area by helicopter and met with local officials and military personnel. The effort was coordinated in part with the U.S. Department of State, the National Security Council, and Mexican leadership, including President Claudia Sheinbaum and Secretary Bárcena.

EPA officials emphasized the MOU is designed not only to address the current crisis but to ensure long-term durability through infrastructure modernization and binational collaboration.
“Millions of Americans and Mexicans have demanded a solution,” said Zeldin. “Today, we delivered it.”

For more information and the full text of the agreement, visit: EPA.gov