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Hydrogen Sulfide Readings Rise in South Bay Near Tijuana River
Hydrogen sulfide levels near the U.S.-Mexico border exceeded county safety standards more than 10 percent of the time this year, up from under 2 percent in 2024. The pollutant originates from sewage flowing through the Tijuana River.
Jul 20, 5:24 PM·1m read1 source
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Hydrogen sulfide concentrations at a monitoring station near an elementary school in the Nestor neighborhood exceeded county safety standards more than 10 percent of hourly readings this year, according to San Diego County Air Pollution Control District data.
The same station recorded exceedances in fewer than 2 percent of readings during 2024. Researchers traced the source to the Saturn hotspot section of the Tijuana River near Saturn Boulevard.
Up to 30 million gallons of sewage-contaminated water have entered the Pacific Ocean daily from Tijuana this year. Several beaches in Coronado have posted warning signs and health officials have advised residents to avoid ocean contact.
Steve Padilla has introduced legislation directing the California Air Resources Board to create a statewide hydrogen sulfide response plan and review air quality standards last updated in 1969.
