San Diego County officials are escalating their fight against a decades-old environmental crisis by commissioning a major scientific study of the Tijuana River Valley. Following a unanimous vote, the county’s Board of Supervisors will formally request $1.4 million in state funding for a comprehensive analysis of soil and water contamination, a direct effort to overcome a previous federal rejection and secure one of the nation’s most powerful tools for environmental cleanup.
The goal is to provide the U.S. Environmental Protection Agency with incontrovertible evidence that the region should be designated a federal Superfund site. Such a listing would place the Tijuana River Valley on the National Priorities List, potentially unlocking immense federal funding and technical resources to address a cross-border pollution problem that has evolved from a chronic water quality issue into a severe public health emergency impacting the air, land, and economic vitality of southern San Diego County.
Decades of Cross-Border Contamination
The pollution crisis is not new, with its origins tracing back to the 1930s as the population of Tijuana, Mexico, began to outpace its sanitation infrastructure. By the 1950s, millions of gallons of raw sewage were flowing across the border daily. The problem intensified through the decades, reaching an estimated 10 million gallons per day in the 1970s. A turning point occurred in 1983, when the once-intermittent river began to flow year-round, its current now consisting primarily of untreated human and industrial waste.
Despite numerous binational agreements and the construction of wastewater treatment facilities on both sides of the border, the system is consistently overwhelmed. Aging and inadequate infrastructure in Mexico frequently fails, particularly during periods of heavy rain, sending torrents of contaminated water northward. The scale of the issue has reached staggering levels; since October 2023 alone, an estimated 31 billion gallons of sewage, polluted stormwater, and trash have flowed into the Tijuana River Valley and the Pacific Ocean. The discharge is a toxic mix of pathogens, heavy metals like hexavalent chromium, banned pesticides such as DDT, plastics, and industrial chemicals.
A Crisis Escalating from Water to Air
For years, the most visible consequence of the pollution was the contamination of local waterways and beaches. However, recent scientific studies have revealed a more insidious and pervasive threat: the pollution has become airborne. Research has confirmed that toxic compounds from the river are being aerosolized, meaning they are carried into the atmosphere and inhaled by residents far from the water’s edge. This has transformed the crisis from an environmental issue to a direct and constant public health danger.
A 2025 study found that the polluted river releases enormous quantities of hydrogen sulfide, a toxic gas commonly known as “sewer gas.” At its peak, concentrations were measured at 4,500 times the level typical for an urban environment. South Bay residents have long reported symptoms consistent with exposure, including persistent headaches, nausea, respiratory distress, and irritation of the eyes, nose, and throat. A survey conducted by the Centers for Disease Control and Prevention found that 97% of residents were concerned about air quality and 64% had experienced new or worsening physical symptoms they attributed to the pollution. The findings have validated community fears that simply closing a beach is not enough to protect public health when the threat is in the air they breathe.
Economic and Environmental Toll
The relentless flow of contamination has inflicted profound damage on the region’s economy, community life, and natural habitats. The persistent pollution has crippled the local economies of coastal communities that depend heavily on tourism and recreation.
Community and Commerce
The city of Imperial Beach has endured more than 1,300 consecutive days of beach closures, rendering its coastline unusable for residents and visitors alike. Businesses that rely on beach traffic have suffered, and the closures have diminished the quality of life for residents who can no longer access their primary recreational areas. The pollution also impacts national security, as frequent contamination of coastal waters disrupts critical training exercises for U.S. Navy special warfare operators stationed in Coronado. A survey found that 80% of residents have been forced to make lifestyle changes to avoid exposure, with many parents reporting their children have missed school due to related health symptoms.
An Ecosystem Under Threat
The environmental damage centers on the Tijuana River Estuary, one of Southern California’s last remaining coastal wetland ecosystems. This vital area, designated a “Wetland of Global Importance,” serves as a critical habitat for hundreds of bird species and other wildlife, including several threatened and endangered species. The estuary is being systematically degraded by the constant influx of sewage, sediment, chemicals, and trash, which smother habitats, kill vegetation, and poison the food web. The long-term ecological viability of this protected natural treasure is in jeopardy.
The Renewed Push for Superfund Status
The supervisors’ decision to fund a new study is a strategic response to the EPA’s rejection of a similar request in January 2025. At the time, the agency stated there was insufficient evidence of hazardous waste contamination, noting that the Superfund program is not typically intended to address human waste. Local leaders, led by Supervisors Terra Lawson-Remer and Paloma Aguirre, argued the EPA’s decision was based on outdated data and failed to consider the complex mix of industrial and chemical contaminants present in the river flow.
The proposed $1.4 million, two-year study aims to fill that evidentiary gap. It would be the first comprehensive analysis of soil contamination in the valley, testing for a wide array of hazardous substances, including heavy metals, pesticides, pharmaceuticals, and PFAS, also known as “forever chemicals.” The objective is to build an undeniable, science-based case that the contamination meets the technical threshold for federal intervention. This hard data, officials believe, will compel the EPA to authorize a full investigation and ultimately grant the Superfund designation.
Understanding the Superfund Program
The Superfund program was established in 1980 by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). It grants the EPA the authority and funding to clean up the nation’s most contaminated land and respond to environmental emergencies. Sites are placed on the National Priorities List (NPL) through a formal process that begins with assessment and scoring using the Hazard Ranking System, which evaluates the relative risk a site poses to public health and the environment.
If the Tijuana River Valley were added to the NPL, it would become eligible for long-term remedial action managed and funded by the federal government. This would provide a level of financial investment and technical expertise that has been unattainable through past efforts. For a region exhausted by decades of broken promises and failed infrastructure projects, a Superfund designation represents what many now see as the only viable path toward a comprehensive, lasting solution to an environmental disaster.
