The Tijuana River is one of the most polluted rivers in the world. What’s your plan to clean it up?

Written by Deborah Brennan, CalMatters

Sewage and chemicals create a layer of foam bubbling along parts of the Tijuana River after a rainy day in San Diego, Nov. 21, 2025. Cinematography: Adriana Heldiz, Calmaters

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San Diego leaders are trying to speed up a solution to Tijuana River sewage pollution while examining the scope of the problem.

On Thursday, community activists, medical experts and environmental experts from the Tijuana River Coalition provided an update on the toxic pollution plaguing south San Diego. And they outlined efforts to solve the problem, including state legislation, cleanup funding, and studies on health and economic impacts.

“As many of us know, this is one of the longest-standing public health issues facing the United States,” said Courtney Baltisky, vice president of public policy and advocacy at the YMCA of San Diego County. “This is a unique problem because this region is located on the Mexico-U.S. border, where there is a lot of commerce, a very unique ecosystem, and natural resources. But we know that the threats to our communities are dire, and they are worse than ever.”

Sewage pollution from Mexico is entering the Tijuana River, sickening swimmers and surfers, forcing beach closures and endangering Navy SEALs training in Coronado. The river also emits airborne toxins such as foul-smelling hydrogen sulfide gas, causing respiratory and other illnesses in nearby communities. Speakers said air pollution has worsened in recent months, leading to an increase in hazardous air warnings.

County officials are quick to send out information when air quality deteriorates. Previously, parents received hydrogen sulfide alerts long after their children left for school. Stephanie Sekich, special adviser to San Diego County Supervisor Paloma Aguirre, said the county is now giving notice much earlier.

“They were getting updates at 8 a.m.,” she said. “When you’re walking to school, that’s not enough. You don’t want to get text updates that your child is breathing hydrogen sulfide. So our office worked with the county to make sure that…the county is making people wake up at 5 a.m. and sending out alerts.”

San Diego County officials distributed 12,000 air purifiers to households near the Tijuana River, Sekich said. They point out that health officials recommend one for every bedroom and that many families near the Tijuana River live in multigenerational homes to raise more funds.

The county has set aside $2.5 million for initial work to remediate a contamination “hotspot” on Saturn Boulevard in southern San Diego County. There, contaminated water flows through culverts, aerosolizing hydrogen sulfide and other pollutants. Reconfiguring the structure may slow the flow of water and prevent toxins from becoming airborne. Officials are also requesting at least $25 million from the state for its improvements.

A series of state laws are aimed at tightening air quality standards and creating funding to reduce pollution emitted from rivers.

State Sens. Steve Padilla and Catherine Breakspear, Democrats from San Diego and Encinitas, have introduced a bill to overhaul the standards for hydrogen sulfide gas. The bill would require the state Office of Environmental Health Hazard Assessment to develop health-based threshold levels for hydrogen sulfide by January 2030, which could lower state standards for safe levels of the toxic gas. The bill passed the state Senate and awaits a vote in the Assembly.

A companion bill would require the state Occupational Safety and Health Administration to set standards to protect the health and safety of employees whose outdoor work exposes them to cross-border pollution, such as lifeguards and park rangers who work near the Tijuana River. Breakspear said at a Senate committee hearing last month that some workers have reported “headaches, fatigue, nausea, and nosebleeds after exposure.” The bill awaits a final vote in the Senate Appropriations Committee.

Rep. David Alvarez, D-Chula Vista, also proposed a bill to accelerate spending on California’s 2024 Climate Change Bond (Prop. 4). Funds from the bond measure are slated to repair hot spots on Saturn Boulevard and reduce air pollution from the river.

County officials are conducting an economic impact study on how sewage contamination will affect local schools and businesses. Baltisky said an initial study conducted in 2023 by the county and the San Diego Regional Chamber of Commerce found that 74% of local businesses were negatively impacted and 50% experienced significant revenue losses.

The next study will be more comprehensive, Sekic said. “This is going to be looked at for two years and everything, and we’re going to look at how many kids missed school? How has that affected school funding? What’s going to happen to property values?”

Health-related research is also underway. Virginia Castellanos, a school nurse at Bayside STEAM Academy near the mouth of the Tijuana River, said a U.S. Environmental Protection Agency study found that pollution can increase lung inflammation and worsen asthma symptoms in children, and a Stanford University study showed that exposure to air pollution can alter immune function.

A San Diego County epidemiological study will examine how Tijuana River pollution affects residents’ health by retrospectively examining exposure to toxic substances through hair samples, blood samples, and other tissues.

Dr. Vi Nguyen, a San Diego pediatrician, has established a network of hundreds of local doctors to diagnose and document health problems related to pollution, including ear infections, allergic rhinitis, skin rashes, and gastrointestinal issues such as diarrhea. We’re also seeing an increase in serious illnesses such as kidney disease and drug-resistant urinary tract infections in teenage girls.

“San Diego will not be left behind. The South Bay will not be forgotten,” Nguyen said. “My patients, especially our little ones at Imperial Beach, San Ysidro, Nestor Elementary School, and Berry Elementary School, deserve better care. That’s why I’m here to continue to show up as a community pediatrician. And California and other Californians really need to do the same.”

This article was originally published on CalMatters and is republished under the Creative Commons Attribution-NonCommercial-NoDerivatives License.

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