Feds find Tijuana River pollution poses public health hazard in San Diego

"Polluted water becomes polluted air, and air reaches everyone who breathes it, far beyond anyone who touches the water," one UC San Diego researcher said.SAN DIEGO (CN) — A report on the Tijuana River pollution crisis from the U.S. Department of Health on Wednesday confirmed what many people living in San Diego County have long suspected: Air pollution from the river has reached levels capable of harming their health.The federal health assessment from the department’s Agency for Toxic Substances and Disease Registry found residents may experience headaches, nausea and respiratory congestion, among other symptoms, as a result of a high concentration of hydrogen sulfide coming from the Tijuana River.Residents in San Diego’s South Bay have complained of sulfurous odor in the area for years, which has worsened as the city of Tijuana’s infrastructure has been unable to match its unprecedented growth.The agency found hydrogen sulfide levels exceeded the odor threshold of .5 parts per billion at all four Tijuana River Valley air quality monitoring sites in 93% of its 30-minute samples. In one instance, a 30-minute average of hydrogen sulfide at its Leon Avenue monitoring station reached a high of 3,021 ppb in September 2024, far above the 2,000-ppb level associated with health effects in humans.“Hydrogen sulfide in outdoor air at the Leon Avenue monitoring site, and likely the Berry Elementary monitoring site, has reached a level for short periods of time that could harm people’s health,” the report concluded. “Exposure to hydrogen sulfide at this level is a public health hazard.”But leaders in San Diego were unsurprised by the news.“For two years, families in Nestor, San Ysidro, Imperial Beach and Coronado have said the air was making them sick,” San Diego County Supervisor Paloma Aguirre, who represents the South Bay communities, said in a statement. “Headaches. Burning eyes. Kids who couldn’t sleep. Constant stress and anxiety from living with air that didn’t feel safe to breathe … Today, a federal public health agency put it in the record: Hydrogen sulfide in our air reached levels that can harm people’s health and well-being.”The report relied in part on data collected from the UC San Diego Scripps Institution of Oceanography in the South Bay.“Families in the local communities pointed us to the smelliest stretch of the river, at Saturn Boulevard,” Kimberly Prather, a professor of atmospheric chemistry at UC San Diego, said in a statement. “That is the community where we placed our instruments, and today a federal health agency has reached the same conclusion from the same data. Polluted water becomes polluted air, and air reaches everyone who breathes it, far beyond anyone who touches the water.”The agency recommended preventing transboundary sewage flows into the Tijuana River Valley so that hydrogen sulfide levels remain below .5 ppb — a major decrease from some of the measured levels.The report also concluded that long-term exposure near the monitoring stations was not expected to cause other health effects in addition to those linked with short-term exposure, but that odors could still cause symptoms of illness.Despite the longstanding complaints of residents over the years, the agency could not conclude if hydrogen sulfide exposure before September 2024 harmed residents because data was not available for that period.Aguirre, who has described the issue as the biggest health and environmental crisis in the Western Hemisphere, said that the report’s findings are belated, after the Board of Supervisors voted earlier this month to fund its own solution to the problem.“This community has waited decades for Mexico City and the administration to stop the sewage, and it’s still flowing,” Aguirre said. “If they won’t fix it, San Diego County will. We’re not waiting for permission to protect our own kids.”The county Board of Supervisors approved its Capture and Clean Initiative earlier this month, which would build a sewage treatment system on the U.S. side of the border and replace failing infrastructure in the Tijuana River Valley, including plans to replace a box culvert underneath Saturn Boulevard, which has been described as a Tijuana River pollution hot spot.The county has also issued 14,500 free air purifiers to residents in the area to help address the issue.A 60-day public comment period on the report will remain open until Nov. 21.The Tijuana River dumps an estimated 35 to 50 million gallons of sewage into the Pacific Ocean every day, which has caused widespread and prolonged beach closures in San Diego County for years.Subscribe to our free newslettersOur weekly newsletter Closing Arguments offers the latest about ongoing trials, major litigation and rulings in courthouses around the U.S. and the world, while the monthly Under the Lights dishes the legal dirt from Hollywood, sports, Big Tech and the arts.Additional Reads