South Bay International Wastewater Treatment Plant completes 10 MGD expansion

The U.S. Environmental Protection Agency (EPA) and the U.S. International Boundary and Water Commission (USIBWC) announced the completion of a 10 million-gallon-per-day expansion at the South Bay International Wastewater Treatment Plant (SBIWTP) in San Diego. The project boosts the facility’s capacity from 25 to 35 mgd, a 40% increase aimed at reducing cross-border sewage flows from Tijuana into the Tijuana River Valley.

Originally planned as a two-year project, the expansion was completed in just 100 days. “Just four months after I personally surveyed the environmental devastation in San Diego, we've delivered this critical expansion years ahead of schedule,” said EPA Administrator Lee Zeldin in a press release.

Commissioner Chad McIntosh of the USIBWC called the project “a key part of a durable, comprehensive solution to the Tijuana River pollution crisis.”

Local officials also pointed to the impact on communities. “For decades politicians ignored the sewage crisis that poisoned our beaches, threatened our health and harmed our U.S. Navy Seals,” said San Diego County Supervisor Jim Desmond in a press release. “In just 100 days we’ve seen action instead of excuses.”

The expansion fulfills a major element of the U.S.–Mexico Memorandum of Understanding signed in July, which sets out binational commitments to accelerate infrastructure projects, secure funding, and establish long-term monitoring and maintenance mechanisms. EPA officials also noted that further expansion to 50 mgd or more is under consideration for completion by 2027.