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New Report: Public Health Crisis Unfolds as Tijuana River Sewage Contamination Escalates

The new report by SDSU researchers shows that the public health impact extends far further than beach closures, as toxic chemicals and microbes are also found in air and soil.

A new report released by San Diego State University’s (SDSU) School of Public Health researchers finds an escalating public health crisis due to Tijuana River contamination flowing from Mexico into South San Diego. This new paper, commissioned by Prebys Foundation at the request of Congressmember Scott Peters, brings to light how toxic chemicals and microbes in raw untreated sewage, industrial waste, and urban run-off, once thought to remain isolated to just the water, can also be airborne and linger in soils, which may have much larger and farther reaching health impacts. As part of the paper, researchers reviewed over 60 related studies and reports, examining environmental and public health concerns in the Tijuana River Valley and Estuary. 

The International Boundary and Water Commission has reported that over 100 billion gallons of untreated sewage, industrial waste, and urban runoff have spilled into the Tijuana Estuary and the Pacific Ocean via the Tijuana River and its tributaries over the last five years.

“This environmental catastrophe has hurt the region for many years, resulting in decades of adverse health consequences,” Congressmember Scott Peters said. “We must approach it as a health and national security concern, which is why I asked the Prebys Foundation to help me build the case that this crisis goes far beyond beach closures; the people of South Bay now endure constant toxic air pollution that damages their health and well-being.”

This ongoing contamination has resulted in over 700 consecutive days of beach closures, significantly impacting local residents, visitors, and economies. In addition, lifeguards, U.S. Navy personnel, first responders, and border patrol agents face dangerous occupational health exposures. The risk of acute infectious diseases and chronic conditions like cancer are potentially high but are not well understood, indicating a public health crisis with the possibility for long-term impacts on health, society, and the economy.

According to the SDSU report, the pollution is not only highly toxic, affecting water, air, and soil, but also poses severe health risks to vulnerable groups such as children, seniors, outdoor workers, and special populations including pregnant women. Antibiotic-resistant bacteria and other serious pathogens of public health concern, previously thought to be eradicated in California, have been found in the polluted waters. The alarming discovery prompted SDSU researchers to call for further investigations to better understand the public health risk in the impacted communities. The report also states that climate change and more intense storm events will only exacerbate these issues and further degrade the area infrastructure. 

“There needs to be more research done to fully understand the extent of the risks posed by exposure to these dangerous contaminants,” said Paula Stigler Granados, associate professor in SDSU’s School of Public Health and the paper’s lead author. “Urgent interventions are needed to help reduce and address both the immediate and long-term health repercussions of those living near this hazardous environment.”

Imperial Beach Mayor Paloma Aguirre has been calling for the involvement of San Diego County, the California Department of Health (CDPH) and Centers for Disease Control and Prevention (CDC) to actively monitor the issue and public health concerns related to transboundary sewage. In recent months, Aguirre has formed a task force in collaboration with SDSU’s School of Public Health and the University of California, San Diego School of Medicine.  

"The persistent health impacts greatly reduce the quality of life for the community,” said Imperial Beach Mayor Paloma Aguirre. “It's a challenging task, but now is the moment to ensure that our elderly, our children, and water enthusiasts are not exposed to heightened health hazards while simply trying to enjoy a sunny day. Tackling this problem promptly and effectively is essential, as it is closely linked to the health and well-being of South Bay communities. The residents of Imperial Beach are worthy of far more than what they have been handed down.”

The researchers say the problem is an environmental justice issue as well, as border communities, often with limited economic resources, already have an increased risk of chronic diseases, which put them at higher risk of complications due to these environmental hazards. These communities also already face increased pollution from other sources, such as from the vehicles idling at border crossings. These border communities have lost access to healthy outdoor spaces. It’s not only impossible to access the beach and ocean during pollution events, but some of the toxic waste could be airborne and affect people within the communities.

“This study confirms what should be obvious, which is that San Diego’s health and community well-being are being seriously and actively harmed by years of inaction on this issue,” said Prebys Foundation CEO Grant Oliphant. “The good news is that it is fixable, and that leaders like Representative Peters and Mayor Aguirre and organizations like SDSU’s School of Public Health are working to make that happen. Their efforts deserve broad support, because public health in our region depends on a robust shared commitment to protecting everyone in every one of our communities from these sorts of preventable harms.”




About San Diego State University

San Diego State University is a major public research institution that provides transformative experiences for its more than 36,000 students. SDSU offers bachelor’s degrees in 96 areas, master’s degrees in 84 fields and doctorates in 23 areas, with additional certificates and programs at regional microsites. SDSU ranks as the number 1 California State University in federal research support, as one of the top public research universities in California. In addition to academic offerings at SDSU, SDSU Imperial Valley and SDSU Georgia, SDSU Global Campus offers online training, certificates and degrees in areas of study designed to meet the needs of students everywhere. Students participate in transformational research, international experiences, sustainability and entrepreneurship initiatives, internships and mentoring, and a broad range of student life and leadership opportunities. SDSU is committed to inclusive excellence and is known for its efforts in advancing diversity and inclusion. SDSU is nationally recognized for its study abroad initiatives, veterans’ programs and support of LGBTQA+ students, as well as its powerhouse Division I Athletics Program. More than 50% of SDSU’s undergraduate and graduate students are students of color. The university resides on Kumeyaay land and was most recently recognized as an Asian American Native American Pacific Islander-Serving Institution (AANAPISI). SDSU is also a long-standing Hispanic-Serving Institution (HSI). The university’s rich campus life and location offers opportunities for students to lead and engage with the creative and performing arts, career and internship opportunities with SDSU’s more than 491,000 living alumni, and the vibrant cultural life of the greater San Diego and U.S.- Mexico region.


About Prebys Foundation 

Prebys Foundation is the largest independent private foundation in San Diego County and works to create an inclusive, equitable, and dynamic future for all San Diegans. The Foundation advances excellence and shared opportunity through investments in groundbreaking institutions, ideas, and people to ensure more San Diegans are financially secure, healthy, empowered, and connected. For more information, please visit

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