Tijuana River sewage pollution raises San Diego health concerns as US Mexico cleanup deal advances

Residents living near the Tijuana River in Southern California reported daily exposure to foul air and health troubles. The International Boundary and Water Commission said more than 100 billion gallons, or 378 billion litres, of raw sewage flowed into the river since 2018. The river then emptied into the Pacific Ocean. Officials in the US and Mexico agreed to upgrades last year.

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Steve Egger, 72, said rotten-egg odours filled the home most nights, often worse after dark. Egger said Egger and a spouse faced headaches, congestion, coughing, and thick phlegm. A hospital-grade filtration system cycled the air every 15 minutes. "Despite those measures, most nights we breathe in a horrible stench,\" Egger said.

Tijuana River sewage and hydrogen sulfide health risks

Raw sewage released hydrogen sulfide, a toxic gas linked to serious health harm. The Centres for Disease Control and Prevention said exposure could trigger asthma attacks and damage nose neurons. The agency also listed headaches, nausea, delirium, tremors, cough, breathlessness, skin and eye irritation, and death. Long-term effects were still being studied by researchers.

There was no federal safety limit for hydrogen sulfide for the public. Existing federal rules focused on high-risk workplaces, like wastewater plants or manure pits. Some states set limits decades ago, but experts called them outdated. California considered updating its 56-year-old standard. Texas lawmakers also discussed changes to its related law.

\"I think when you look back when the standard was first established and then it was reviewed, it was all about nuisance - basically it was all about odour,\" said the California bills author, Democratic Sen Steve Padilla, who represents the Tijuana River Valley. \"I dont think we had the understanding scientifically of what the health impacts were here, and now we do.\"

Even if Californias bill passed, a revised standard would likely not arrive until 2030. Environmental Protection Agency Administrator Lee Zeldin said during a February visit to San Diego that a fix may take about two years. Zeldin described the situation as one of the nation’s longest-running environmental crises. The problem affected a largely poor, Latino population in the area.

Tijuana River sewage scale and community exposure

The 195 km-long Tijuana River began in the Mexican city of Tijuana. It crossed into California and then reached the ocean. San Diego County beaches nearby stayed closed for years. Navy SEALs who trained in local waters also fell ill. A \"Stop the Stink\" sign on Eggers fence backed a Citizens for Coastal Conservancy campaign.

International Water and Boundary Commission data said the river carried 10 billion gallons, or 38 billion litres, since January. The flow included mostly raw sewage and industrial waste crossing into the US. Industrial chemicals and trash were also part of the mixture. Many factories in the region were owned by US companies, according to the report.

By contrast, a major January pipe rupture sent 244 million gallons, or 924 million litres, of untreated sewage into the Potomac River. That spill affected affluent, largely white communities. Federal intervention followed within weeks. In San Diego County, tens of thousands faced ongoing exposure while longer-term work continued.

A 2024 sampling by San Diego County and the CDC focused on about 40,000 households near the river. It found 71 per cent could smell sewage inside homes. It also found 69 per cent had a household member who got sick after exposure. The EPA said it worked with local and state officials on ways to reduce the odour.

San Diego County distributed over 10,000 air filters to homes during 2026. Still, residents said the air remained difficult to escape indoors. Observers also said the river’s foam was visible from space. Complaints often rose at night, when river flow and smells increased in nearby neighbourhoods.

Tijuana River sewage monitoring and hydrogen sulfide spikes

In September 2024, Kimberly Prather, a chemistry professor at the University of California, San Diego, installed air monitors near Eggers neighbourhood. The findings surprised the team during night-time flow peaks. Hydrogen sulfide reached 4,500 times typical urban levels. It also measured 150 times higher than California’s air standards.

Residents said the monitoring results matched what they experienced for years. Prather said officials had downplayed the issue as only an odour problem. \"Theyd been being more or less gaslit and told, Theres gas. Its a nuisance. It smells, but its not bad,\" Prather said. Prather added the team detected thousands of other gases too.

Ryan Sinclair, an associate professor at Loma Linda University School of Public Health, said symptoms could start even at low exposure levels. \"Even at low levels, youre going to feel like its in your sinuses. You cant get rid of the smell. Its going to be a constant irritation,\" Sinclair said. Residents linked these effects to repeated river surges.

Tijuana River sewage hotspots and medical observations

Less than half a mile from Eggers home, the odour intensified near Saturn Boulevard. The river shot out from pipes after running underground for a short stretch. Scientists called the area the Saturn hot spot. Drivers said the smell entered cars even with windows closed. Some said the stench stayed inside vehicles for days.

Dr Matthew Dickson and Dr Kimberly Dickson ran a clinic about a mile from the hot spot. Patients reported migraines, nausea, wheezing, eye infections, and brain fog. Asthma patients said inhaler use rose when the smell returned. \"Theyd say, You know, I feel better when it doesnt smell outside,\" Dr Kimberly Dickson said.

In August 2023, a tropical storm pushed the river over banks and onto streets. The doctors said the patient load tripled within days. Electronic health records supported their observations. When river flows jumped, respiratory cases treated by the clinic increased by 130 per cent. \"Every day that this isnt fixed,\" Dr Matthew Dickson said, \"more people are getting sick.\"

Egger said doctors advised moving, but no written diagnosis confirmed hydrogen sulfide exposure. Egger said family ties made relocation hard. \"This is where Ive lived all my life, with my family, my parents, my grandparents,\" Egger said. \"This is home.\" Egger said the river once flowed only in rainy months.

Egger said the river now ran year-round and carried sewage and industrial waste instead of rainwater. Egger said the river should return to its historical route, closer to the border. Egger believed that shift could reduce pooling and gas hotspots near homes and schools. For now, residents continued reporting odours, illness, and slow-moving cleanup plans.

With inputs from PTI