Contemplate the Tijuana River a waterway straddling two nations. It embodies both ecological richness and environmental concern. The Tijuana River is an intermittent river. It stretches 120 miles. It flows near the Pacific coast. The river begins in northern Baja California Mexico. It ends in Southern California United States.
For most of its journey the Tijuana River flows through Mexico. Then it crosses into Southern California. Here the river travels its final 5 miles. It empties into the Pacific Ocean. This meeting happens at the Tijuana River Estuary. This lies on San Diego’s southern edge.
The region around the Tijuana River experiences both Mediterranean and semi-arid climates. Because of this the river often dries up during droughts. The Tijuana River has two primary tributaries. One is the Arroyo de Alamar also known as Cottonwood Creek. The other tributary is the Arroyo de las Palmas. The Arroyo de las Palmas is the main tributary.
The Tijuana River’s waters flow through Tijuana in a concrete channel. This channel leads to the international border. From there the river flows west. It crosses the Tijuana River Valley. The journey ends at the estuary. Then it continues into the Pacific Ocean.
Its lower reaches are significant. They provide San Diego County’s last undeveloped coastal wetlands. This exists amid a highly urbanized area. This location is at Imperial Beach’s southern city limits.
The Tijuana River rises in the Sierra de Juárez. This is in northern Baja California. It flows WNW through Tijuana. The river crosses the border about 5 miles from the Pacific. Its mouth is a broad mud flat estuary. This estuary is a rich habitat. It supports over 370 bird species. The Ridgway’s rail is one such species. It is Southern California’s largest coastal wetland.
Flooding has been a significant concern for the Tijuana River. It can cause sewage runoff and property damage. The United States-Mexico Water Treaty was signed in 1944. It addressed water usage in the Colorado and Tijuana rivers. The International Boundary and Water Commission was appointed. It handles issues like border sanitation. The IBWC then created the Tijuana River Flood Control Project in 1966. This was to build flood control channels along the river.
The Tijuana River National Estuarine Research Reserve protects 2293 acres. It studies the Tijuana River Estuary. It was established as part of the National Estuarine Research Reserve system. San Diego State University manages part of the reserve. They do this as a Biological Field Station. They protect part of the estuary near the ocean.
Since the early 20th century the Tijuana River has conveyed wastewater. Sewage in the Tijuana River predates other border issues. Raw sewage overflows from Mexico are a recurring problem. These overflows are the main source of pollution. Trash is also carried downstream. This damages vegetation and contributes to flooding.
In 1980 Imperial Beach dammed the river to block sewage flow. Partial progress occurred in the 1980s. A Clean Water Grant helped improve wastewater treatment. This created the San Diego-Tijuana Wastewater Treatment Plant.
In 1988 the Tijuana River was the most polluted river on the Mexico-United States border. In 1990 the EPA found lead and mercury in the river. These exceeded U.S. standards. Fears of malaria and encephalitis outbreaks rose.
Since 1993 San Diego has had a state of emergency for the Tijuana River Valley. The river remains one of San Diego’s most polluted areas. Beaches near the river’s mouth often close. Even when the flow is low toxins and sewage become dust. This dust can cause medical problems.
Since 2018 more than 100 billion US gallons of wastewater have flowed from Mexico into the United States via the Tijuana River. Lawsuits have been filed. These seek solutions to the Tijuana River’s ongoing pollution issues. The United States-Mexico-Canada Agreement was ratified in 2020. It provided $300 million to abate water pollution in the Tijuana River.
The Tijuana River Valley Regional Park protects over 1800 acres. It includes dense riparian forests along the river. The mouth of the river is home to the Tijuana Sloughs. This is a big-wave surfing break. Sewage impacts water quality. It often makes the area unsurfable. The Tijuana River’s story is complex. It involves ecology pollution international relations and recreation.