The Tijuana River Estuary, located on the U.S. side of the Tijuana River, is the last 10% of California’s wetland that remains. According to the Tijuana Estuary National Park, it serves as a stop for migratory birds to feed and reproduce. The site also serves as a local attraction with guided tours offered by the park.
In recent years, the city of Tijuana in Mexico has caused runoff that gets into the water and flows to the American part of the river, according to a ResearchGate study. According to the study, the rise in migration to the city contributes to the Tijuana River pollution because the city’s infrastructure isn’t equipped to handle all these migrants.
The runoff has had a devastating impact on the ecology of the Tijuana estuary, as the water is full of sewage, creating filthy water and foul odors. Jeff Crooks, a researcher at the Tijuana Estuary, expressed his concerns about the environmental impact affecting residents of San Diego, including SDSU students.
“Just from my own experience, it certainly affects well-being in general,” Crooks said.
Crooks also emphasized that the Tijuana sewage crisis is a long-standing issue, saying that it existed when he first started working at the reserve roughly 35 years ago.
Both the United States and Mexico have signed agreements and funded projects aimed at improving wastewater treatment, but untreated sewage still enters the Tijuana River and flows north into San Diego County. The discharges have led to repeated beach closures and public health advisories from local agencies, as stated by the City of Imperial Beach.
According to a study by the San Diego State University School of Public Health, this unregulated sewage load can overwhelm existing treatment plants, sending “over 40 million gallons of raw sewage” into the estuary on peak days. This threatens the safety of nearby residents and anyone visiting beaches including Imperial Beach and Coronado.
Rhiannon Rannochio, a graduate student at SDSU, said that she is worried about pollution in the ocean.
“It makes me a bit nervous to go into the water, truthfully, at all,” Rannochio said. “I shouldn’t have to be afraid to go in the water because it’s dangerously dirty.”
In a survey conducted by San Diego County in 2024, 64.6% of households in South Bay reported at least one member who believed their health had been affected because of the pollution. Among the most common issues were skin rashes, gastrointestinal illness, persistent coughing, headaches, nausea and eye irritation.
“I got a rash on my leg from swimming in Coronado,” said SDSU junior John Yokoyama. “There weren’t even signs up saying I couldn’t swim, but sure enough, I checked the water contamination levels later on, and it said high.”
The issue has fluctuated over the past two decades, largely due to inconsistent funding, as reported in San Diego Coastkeeper. In December 2024, President Joe Biden signed a stopgap budget bill that allocated $250 million to address operational challenges at the South Bay International Wastewater Treatment Plant, which oversees shared water resources between the United States and Mexico. Combined with $400 million previously approved by Congress, the commission’s total 2024 funding reached about $650 million, still short of what officials say is needed for a long-term solution.
Dr. Paula Stigler Granados, SDSU’s division head of the Environmental Health department, has been working closely with Dr. Kimberly Prather of the University of California, San Diego, to conduct research and surveys as to how this is affecting South Bay residents. She and her team of researchers and students have been working to bring awareness to this issue.
“What’s happening in the Tijuana River Valley is a reminder that public health isn’t just in textbooks; it’s right here in our backyard,” Granados said. “Our research gives students the chance to be part of real solutions for one of San Diego’s biggest environmental justice challenges.”
On July 24, 2025, the U.S. and Mexico signed a Memorandum of Understanding in Mexico City designed to expedite improvements to Tijuana’s failing sewage infrastructure.
Serge Dedina, the former mayor of Imperial Beach said, “So, it’s good that the United States government signed an agreement with Mexico to talk about fixing this, horrendous crisis, but I think many of us who’ve been involved in this issue for a long time, have been very clear that until the beaches are open 365 days a year, we’re not going to be celebrating.”
San Diego, in conjunction with its beaches, has a large surfing population. Due to the sewage, however, surfing competitions have had to be delayed or postponed. One competition, Surf the Border, organized by Surfrider San Diego and Surfrider Baja, was designed to raise awareness of ocean pollution and highlight the shared coastline.
However, organizers said unsafe bacteria levels in the water made it impossible to hold the event, according to the Surfrider website.
“I once tried to surf around Imperial Beach, but soon realized how gross the water really is,” said San Diego surfer, Sol Vashez. “I was annoyed, ya know, because I had driven 20 or 30 minutes to get there, and now I couldn’t even go in the water.”
For local San Diego residents, the crisis means more than missed surf sessions; it’s a daily reminder that the environmental neglect at the border can wash up on their own shores. It’s crucial to public health, recreation, and, not to mention, the lasting environmental effects. Until the sewage stops, the ocean will remain unsafe for use.
