The Parallel Gravity Line is a major sewer main that carries Tijuana's wastewater toward the coastal treatment plant. It's old, and it breaks.
Why it matters
Two sections collapsed within about two weeks in May 2026, on May 14 and May 31. Both times, sewage was diverted and the South Bay plant took more than 40 million gallons a day, well past its capacity, to keep it out of the river. Nearby, hydrogen sulfide spiked to levels that triggered county health guidance. EPA says the rehabilitation will prevent future ruptures and spills that reach the U.S. through border canyons.
Where it stands (as of October 2026)
- Mexico secured $8.9 million, and construction began in November 2025.
- Completion was estimated for July 2026, then August 2026.
- Both May collapses were repaired.
- EPA's September 2026 update says the rehabilitation was completed in August 2026.
Who's responsible
CESPT, with Mexican state and federal funding.
What to watch
Whether spills from this line stop in the coming rainy season.
Related
The map: Pump Station 1 and the coastal line. Why it keeps happening.
Sources
- U.S. EPA, Tijuana River watershed public updates, quarterly updates from November 2025 to September 2026
- San Diego County News Center, public health guidance after the broken sewage pipe, June 2026