Communities near the sewage-laced Tijuana River in South County say the stench of raw sewage has been exceptionally bad over the last few weeks.
Data from the San Diego County Air Pollution Control District, the agency monitoring hydrogen sulfide emissions in the region, and from The Airborne Institute, confirm what they are smelling.
Levels of hydrogen sulfide, a byproduct of raw sewage, detected in the air in Nestor, exceeded the state’s standard multiple times per day nearly every day in March, thus far.
The direct cause of the recent rise in concentrations is unclear, but San Diego County public health officials said excess heat, like last week’s heat wave, can increase emissions.
In mid-March, a critical pumping station in Mexico failed, sending several tens of thousands of gallons of untreated wastewater to a canyon collector in the river valley. The U.S. International Boundary and Water Commission, which manages a treatment plant in the area, said it believed those flows were not responsible for the increased hydrogen sulfide odors, and did not explain what might be causing them.
One thing is clear: the strong, rotten-egg odors are persistent and affecting residents’ health.
“It’s been for years, many years and sometimes it’s worse than other days,” said Mario Pacheco, who said he has lived in Imperial Beach for about 50 years. “It does affect you because sometimes you get a headache, you get nauseated. In the long run, I don’t know, especially if you’re older, it could hurt you.”
Residents can sign up to receive email or text alerts from the district when elevated levels of hydrogen sulfide are detected. They advise people to limit their time outdoors or to see a doctor when they should.
But the alerts are not sent in real time.
Since the district first began sending alerts in 2024, those who had signed up for notifications would receive a morning report, typically around 7 a.m., that summarized when levels surpassed the state threshold the night before.
“Receiving word that the pollution is above safe levels when we can clearly smell that they are is way too late,” said Bethany Case, an Imperial Beach resident who works at a middle school in Nestor.
Case said the lack of real-time notifications shows a gap in the existing alert system and is a disservice to the community.
“We need a better, faster, more immediate notification system so that not only are residents quickly notified, but schools know how to keep their students safe as well,” she said.
Case is also a part of the Tijuana River Coalition. The group, which consists of residents, environmental advocates, scientists and doctors, said it had recently met with county and district officials to raise concerns and ask for potential improvements.
Case said it seems like they listened.
“Immediately, they made sure that staff was going to be there earlier and later so that we would get alerts, families get alerts before kids go to school,” she said.
The district did not respond to a request for comment. As of Friday, the agency has begun sending alerts as early as 5 a.m. and as late as 10 p.m.
Case said it’s a step in the right direction, but a real-time system would be more effective. It will especially be needed as summer approaches, she said. For nearly a year, another group of local medical professionals has also asked the county to use its main emergency alert system to send out notifications for elevated levels of hydrogen sulfide in the affected ZIP codes. The county has repeatedly said, however, that alerts related to the sewage crisis remain within the district’s purview.
Several other gaps in keeping the public informed about exposure to elevated levels of the sewer gas still exist, according to the Coalition. They have proposed ensuring that all school administrators, nurses and local health care providers are enrolled in the district’s alert system, holding public forums to keep people better informed about increases in emissions, and improving outreach to non-English speaking communities.
In a statement, County Public Health Officer Sayone Thihalolipavan said the county would “continue to coordinate to expand resources and find long-term solutions to the unacceptable conditions in the Tijuana River Valley."
Later this year, the county is expected to build a temporary pipe extension at a hot spot for airborne sewage pollution in the river valley. The work is designed to mitigate the contaminants and help reduce odors.
To sign up for alerts and to apply for a free air purifier, the district encourages the public to visit its website at sdapcd.org/TJRiver.
