The Tijuana River Estuary is an

intertidal The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...

coastal wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The p ...

at the mouth of the

Tijuana River , name_etymology = , image = Presa Tij 1.jpg , image_size = , image_caption = Dam on the Tijuana River in Mexico. , map = Tijuana River Basin.svg , map_size = 250 , map_caption ...

San Diego County San Diego County (), officially the County of San Diego, is a county in the southwestern corner of the U.S. state of California. As of the 2020 census, the population was 3,298,634, making it California's second-most populous county and the f ...

, California, in the United States bordering

Tijuana Tijuana ( ,"Tijuana"
(US) and < ...

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

, Mexico. It is the location of the

Tijuana River National Estuarine Research Reserve Tijuana River National Estuarine Research Reserve is a natural reserve in Imperial Beach, California and San Ysidro, San Diego. It encompasses the Tijuana River Estuary, located on the Mexico–United States border. It is divided into two part ...

Tijuana Slough National Wildlife Refuge Tijuana Slough National Wildlife Refuge is located in the most southwestern corner of the contiguous United States. As a National Wildlife Refuge, it is administered by the U.S. Fish and Wildlife Service. It was established in 1980. The refuge for ...

Border Field State Park Border Field State Park is a state park of California, United States, containing beach and coastal habitat on the Mexico–United States border. The park is within the city limits of Imperial Beach in San Diego County, next to the suburb of Pla ...

, and Tijuana River Valley Regional Park. The

estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

is a shallow water habitat. Often termed an intermittent estuary since its volume is subject to the discharge controlled by the seasons of the year, the volume of the estuary fluctuates and at times there is dry land, or flooded areas. It was designated a

National Natural Landmark The National Natural Landmarks (NNL) Program recognizes and encourages the conservation of outstanding examples of the natural history of the United States. It is the only national natural areas program that identifies and recognizes the best ...

in 1973.

Ecology

The estuary is one of the few remaining salt marshes on the

South Coast South Coast is a name often given to coastal areas to the south of a geographical region or major metropolitan area. Geographical Australia *South Coast (New South Wales), the coast of New South Wales, Australia, south of Sydney * South Coast (Q ...

. Its location positions it under the path of the

Pacific Flyway The Pacific Flyway is a major north-south flyway for migratory birds in the Americas, extending from Alaska to Patagonia. Every year, migratory birds travel some or all of this distance both in spring and in fall, following food sources, heading ...

, where it serves as a stopover point. It is the largest remaining natural coastal area between

Santa Barbara, California Santa Barbara ( es, Santa Bárbara, meaning " Saint Barbara") is a coastal city in Santa Barbara County, California, of which it is also the county seat. Situated on a south-facing section of coastline, the longest such section on the West ...

and San Quintín, Baja California. Three times the size of

Central Park Central Park is an urban park in New York City located between the Upper West and Upper East Sides of Manhattan. It is the fifth-largest park in the city, covering . It is the most visited urban park in the United States, with an estimated ...

, the estuary covers about 2,500 acres. Many species of migratory and native species rely on the estuary as an essential breeding, feeding, and nesting habitat. The estuary lies within the southernmost part of San Diego County within the city limits of the South Bay city of Imperial Beach. Prior to 1994, foot traffic by

illegal immigration Illegal immigration is the migration of people into a country in violation of the immigration laws of that country or the continued residence without the legal right to live in that country. Illegal immigration tends to be financially upwar ...

was a major source of top soil erosion. After 1994, off-road vehicle usage for

policing The police are a constituted body of persons empowered by a state, with the aim to enforce the law, to ensure the safety, health and possessions of citizens, and to prevent crime and civil disorder. Their lawful powers include arrest and t ...

has become a major cause of soil loss. Beginning in 2010, a re-vegetation effort along the Border Infrastructure System has occurred.

Ecology

References

Further reading