The San Antonio de los Buenos treatment plant at Punta Bandera, about five miles south of the border, receives roughly twice what it can treat. The rest goes onto the shoreline and drifts north to Imperial Beach.
Why it matters
This is the biggest source of dry-season beach closures. Two fixes are on the table: an ocean outfall to carry discharges offshore instead of onto the beach, and expanding the plant from 18.26 to 43.37 million gallons a day.
Where it stands (as of October 2026)
- Proposed, not funded. Minute 333 created a binational work group to assess an outfall and the technical and financial feasibility of the expansion.
- The work group reviewed existing engineering and financial studies, which build on earlier work by the North American Development Bank and CESPT, and prepared a scope of work for a full analysis of water flowing through Tijuana's system.
- Mexico expects to hire a firm for that flow analysis by the end of 2026, with the study finished by the end of 2027.
- Mexico was also to produce a Tijuana water infrastructure master plan within six months of Minute 333. That date has slipped: in September 2026, EPA said only the plan's scope of work would be finalized, in December 2026.
Who's responsible
The Minute 333 work group (both IBWC sections, EPA, and Mexican agencies). Construction would fall to Mexico, likely with international financing.
What to watch
The work group's recommendations, a funding plan, and the master plan. Until one of these moves, dry-season closures are unlikely to end.
Related
The map: San Antonio de los Buenos plant. What reaches the ocean.
Sources
- U.S. EPA, Minute No. 333
- U.S. EPA, announcement of Minute 333, December 2025
- U.S. EPA, Tijuana River watershed public updates, quarterly updates from November 2025 to September 2026