Tijuana River
The Tijuana River is an intermittent river that flows 120 miles through the Mexican state of Baja California, then crosses the U.S.-Mexico border into southern California for 5 miles before flowing into the Tijuana River Estuary and ends where it connects to the Pacific Ocean near San Diego. The river is home to the Kumeyaay Nation and over 2.8 million residents on both sides of the border. The river’s watershed covers 1,750-square-miles and mostly lies within northwestern Mexico where there has been extensive development around the river. The lower Tijuana watershed is located in the Southwest United States and is largely undeveloped.
Unfortunately, decades of mismanagement and under-investment in wastewater infrastructure have led to long-running Clean Water Act violations, impacting communities in Imperial Beach and south San Diego, hurting ecosystems, forcing beach closures, and causing widespread illnesses. Southern San Diego County’s beautiful, world-class beaches once drew families, swimmers, and surfers, and are now choked with pollution, limiting coastal access and sickening communities exposed to airborne pollutants and sewage.
Frontline communities have advocated for solutions for decades, and advocates have been successful in forming a coalition of over 50 local organizations, policymakers, and government agencies. After American Rivers named the Tijuana River as one of America’s Most Endangered Rivers in 2024, this coalition secured millions of dollars in funding to implement the Comprehensive Infrastructure Solution (CIS), a plan to fix failing wastewater treatment plants and stop pollution discharges into the Tijuana River. While this plan has been vetted by the U.S. Environmental Protection Agency, communities impacted by the crisis, and local governments, millions of dollars are still needed to maintain broken wastewater treatment plants discharging into the river to prevent recurring crises and divert pollution from flowing into the main river channel near residential neighborhoods and schools.
Where is the Tijuana River?
The Tijuana River flows from Mexico into California.
What Direction does the Tijuana River flow?
The Tijuana River flows South to North from Mexico into California.
The Tijuana Estuary is a National Estuarine Research Reserve that protects the largest remaining natural coastal wetland in southern California. The Reserve contains one of California’s few remaining salt marshes and is home to over 370 birds and other endangered species. The Tijuana River flows into a marine protected area and a world-renowned surf break known as “The Sloughs.” With unparalleled beauty and world-class waves, surfers used to flock to this break, but as of January 2025, health officials have closed local beaches. citing a mounting public health crisis from exposure to sewage-laden waters.
America’s Most Endangered Rivers®
The Tijuana River was named as one of America’s Most Endangered Rivers® of 2025. Listed for the second year in a row, the Tijuana River is known for its communities on both sides of the U.S./Mexico border as well as stunning beaches, world-class surf breaks and diverse wildlife. This region, however, has been plagued with severe pollution for decades. Every day, millions of gallons of contaminated stormwater, sewage, harmful chemicals, and trash flow down the river into the Pacific Ocean. Protecting our communities and ensuring clean water is a non-partisan issue—it’s a matter of basic governance and national responsibility. The Trump administration must act decisively to declare a federal emergency to address this public health crisis.
Protect the Tijuana River
Join American Rivers and the American Rivers Action Fund in urging the Trump administration to declare a national emergency for the water pollution and public health crisis on the Tijuana River.
2024 Listing
What about the Tijuana river is making people and wildlife sick?
The polluted water in the Tijuana River aerosolizes as sea spray, polluting air quality. Doctors and researchers often note correlations between urgent care visits with coastal pollution events. Researchers have installed air quality monitors in coastal communities to track air quality and public health impacts in south San Diego County. Sadly, lifeguards, emergency responders, Navy Seals, and Border Patrol agents who operate in the region are often training on contaminated coastlines. “An entire generation of children is growing up in South San Diego County having only experienced polluted beaches,” wrote Imperial Beach Mayor Aguirre in her June 6, 2024 letter to the Biden administration. This is a grave public health crisis and an environmental justice emergency.
In 2024 the Tijuana River was listed on the America’s Most Endangered Rivers® list by American Rivers due to pollution, limiting coastal access and causing serious threats to public health. American Rivers along with partners called on the Federal Government to take decisive and immediate action to address the crisis in the Tijuana River Watershed by fully funding the solutions needed to restore a clean and safe environment for the affected communities.
Since the first listing in 2024, we have had the immense honor of joining our Tijuana River partners, Surfrider and Un Mar de Colores, at a rally in Imperial Beach, California –Unite to Heal our Coast. The rally allowed folks to gather, connect, strengthen community, and have their voices heard. Above all, it celebrated the people who continue to fight for justice for the Tijuana River.
Issues facing the river
For over a century, toxic waste and raw sewage have flowed into the Tijuana River Watershed and out into the Pacific Ocean, sickening people and wildlife. These year-round transboundary flows measure 35-50 million gallons per day. These flows carry trash from Tijuana’s urban area, untreated wastewater from failing treatment systems and sub-standard sewage disposal, and toxic industrial waste from factories upstream. When it rains, high water flows and pollution overwhelm the region’s wastewater treatment plants, creating hazardous conditions for coastal communities and ecosystems at the U.S.-Mexico border. The volume of water and pollution overwhelms regional infrastructure and creates dangerous conditions for the natural environment and local communities in the U.S. and Mexico.
Wastewater treatment plants on both sides of the border regularly fail and are severely under-capacity due to decades of under-investment and deferred maintenance. The resulting sewage discharges into the Pacific Ocean do not meet U.S. or Mexican regulations and travel up the coast with summer currents, impacting visitors, residents, and ecosystems. A 2017 study by the Scripps Institute of Oceanography linked 34,000 illnesses to water pollution at Imperial Beach’s coastline.
River Radius Podcast | Part 1 Tijuana River, Binational Flow
This episode is on site where a beautiful desert mountain river flows through an estuary and into the Pacific Ocean. Before the Tijuana River meets the ocean, it navigates through a dense urban border region with 5 million people. The outcome is a river that is carrying toxic sewage and pollution to the ocean, closing beaches and creating illness in the river and beach communities. This is the first episode in a series about this beautiful place, the epic pollution, and the incredible people who are engaged in the work to clean up this river and ocean.
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