Where the Tijuana River passes through old culverts under Saturn Boulevard, sewage-filled water churns and releases hydrogen sulfide into nearby neighborhoods.
Why it matters
Research traced most of the valley's airborne pollution to this one crossing. Readings nearby have reached 4,500 parts per billion, against a California standard of 30. The crossing was never meant to carry the river: the river shifted into this channel in 1993, and culverts were added in an emergency.
Where it stands (as of September 2026)
- In January 2026, San Diego County, the City of San Diego, and the U.S. Navy completed a feasibility study for the crossing.
- A $2.5 million interim pipe extension, which carries low flows under the road and releases them below the water surface so they stop churning, is underway, with construction expected in 2027.
- In September 2026 the county approved $4 million to design and permit the permanent fix, estimated at about $25 million. Construction of the permanent fix is not yet funded.
Who's responsible
San Diego County, with the City of San Diego and the Navy, which own land and infrastructure nearby.
What to watch
Whether the interim fix is built before the rainy season, and funding for the full fix.
Related
The Tijuana River Valley. Health.
Sources
- KPBS, supervisors propose immediate fix at Tijuana River pollution hot spot, January 2026
- San Diego County Parks, Tijuana River Valley improvements
- California Coastal Commission, June 2026 correspondence, on the crossing's history
- Science, heavily polluted Tijuana River drives a regional air quality crisis, the primary source for the 4,500 ppb reading
- NBC San Diego, supervisors vote to build Tijuana River sewage treatment in the U.S.
- The Spokesman-Review, county greenlights the Saturn Boulevard plan, September 2026
- CalMatters, the Saturn Boulevard fix, May 2026