County official demands state of emergency to address toxic river

The pollution is a transnational problem, poisoning residents in South San Diego.

Apr. 15, 2026 at 5:38pm

Got story updates? Submit your updates here. ›

A ghostly, translucent X-ray photograph showing the internal structures of a polluted river, with glowing veins of toxic waste and debris flowing through the water, conceptually illustrating the environmental and public health crisis.An X-ray view reveals the toxic pollution poisoning the Tijuana River, a transnational environmental crisis impacting vulnerable communities.San Diego Today

The San Diego County Board of Supervisors has declared the pollution in the Tijuana River an emergency 22 times and sent a letter to California Governor Gavin Newsom asking him to follow suit. Newsom has declared 52 other states of emergency, and the county supervisor is urging him to take action on this issue as well. The pollution, which includes toxic hydrogen sulfide gas, has caused serious health problems for the predominantly Hispanic and low-income residents living near the river valley. Several gubernatorial candidates have agreed to declare a state of emergency if elected, and the county is giving Newsom one more chance to respond before he potentially runs for president in 2028.

Why it matters

The pollution in the Tijuana River has become a major environmental and public health crisis for the South San Diego community. Residents are suffering from a range of health issues, including migraines, respiratory problems, heart problems, and neurological issues. The pollution has also forced small businesses to close and families to move out of the area, leaving behind properties that real estate agents can't sell. This is an environmental justice issue, as the affected residents are predominantly Hispanic and living in poverty.

The details

Researchers at the University of California San Diego Airborne Institute found that the toxic hydrogen sulfide gas in San Diego's South Bay region had peaked at 4,500 parts per billion for at least one minute and had averaged 2,100 parts per billion over an hour — well over the state-regulated one-hour standard of 30 parts per billion. The lead scientist on the study, Kimberly Prather, blamed the pollution on U.S. companies that have set up factories across the border in Mexico to skirt U.S. regulations and dump toxic waste.

  • The San Diego County Board of Supervisors has declared this an emergency 22 times.
  • Newsom visited the South Bay International Wastewater Treatment Plant in 2024.
  • Researchers at the University of California San Diego Airborne Institute published a study on the pollution last year.

The players

Nora Aguirre

A San Diego County supervisor who has been advocating for Newsom to declare a state of emergency to address the pollution in the Tijuana River.

Gavin Newsom

The governor of California who has the power to declare a state of emergency for San Diego County to address the pollution crisis.

Kimberly Prather

The lead scientist and researcher at the University of California San Diego Airborne Institute who published a study on the toxic hydrogen sulfide gas levels in the South Bay region.

Got photos? Submit your photos here. ›

What they’re saying

“The San Diego County Board of Supervisors has declared this an emergency 22 times and sent a letter to our governor asking him to follow suit. Governor [Gavin Newsom] it is time. We can't keep passing the buck to another country even if they're the source.”

— Nora Aguirre, San Diego County Supervisor

“People are really sick. They have migraines, respiratory problems, heart problems, neurological problems. The biggest one I hear the most about is lack of sleep, migraines, depression. I mean, it's just crushing this community. And there's not one fish that's alive in the river — it's a complete dead zone.”

— Kimberly Prather, Lead Scientist and Researcher, University of California San Diego Airborne Institute

What’s next

Aguirre has invited several gubernatorial candidates, including Katie Porter, Tom Steyer, Matt Mahan and Betty Yee, to visit the area — all of whom have agreed to declare a state of emergency if elected. Newsom is being given 'one more chance' to respond to the crisis before he potentially runs for president in 2028.

The takeaway

This pollution crisis in the Tijuana River Valley highlights the urgent need for cross-border environmental cooperation and action to address transnational issues that disproportionately impact low-income and minority communities. Declaring a state of emergency could unlock critical resources and regulatory flexibility to mitigate the public health and environmental damage.