The Alamo River is a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 flowing west and north from the Mexicali Valley

Municipality of Mexicali

Mexicali Municipality is a municipality in the Mexican state of Baja California. Its municipal seat is located in the city of Mexicali. According to the 2010 census, it had a population of 956,826 inhabitants, and according to the 2000 census, it had 764,602 inhabitants, which means an increase...

 (Baja California

Baja California

Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...

) across the Imperial Valley (California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

). The river drains into the Salton Sea

Salton Sea

The Salton Sea is a shallow, saline, endorheic rift lake located directly on the San Andreas Fault, predominantly in California's Imperial Valley. The lake occupies the lowest elevations of the Salton Sink in the Colorado Desert of Imperial and Riverside counties in Southern California. Like Death...

.

The creation of the New River

New River (California)

The New River flows north from near Cerro Prieto, through the city of Mexicali, Baja California, Mexico, into the United States through the city of Calexico, California towards the Salton Sea...

, Alamo River, and Salton Sea

Salton Sea

The Salton Sea is a shallow, saline, endorheic rift lake located directly on the San Andreas Fault, predominantly in California's Imperial Valley. The lake occupies the lowest elevations of the Salton Sink in the Colorado Desert of Imperial and Riverside counties in Southern California. Like Death...

 of today started in the autumn of 1904, when heavy rainfall and snow-melt caused the Colorado River

Colorado River

The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

 to swell, overrunning a set of headgates for the Alamo Canal

Alamo Canal

The Alamo Canal was a long waterway that connected the Colorado River to the head of the Alamo River. The canal was constructed to provide irrigation to the Imperial Valley. A small portion of the canal was located in the United States but the majority of the canal was located in Mexico...

. The resulting flood poured down the canal and breached an Imperial Valley dike. The sudden influx of water and the lack of any drainage from the basin resulted in the formation of the Salton Sea; the rivers had re-created a great inland sea in an area that it had frequently inundated before, the Salton Sink

Salton Sink

The Salton Sink is a geographic sink in the Coachella and Imperial valleys of southeastern California. It is in the Colorado Desert subregion of the Sonoran Desert ecoregion...

. It took nearly two years to control the Colorado River’s flow and stop the flooding, but it was effectively dammed in the early part of 1907 and returned to its normal course. The Alamo and New Rivers continued to flow, but at a lesser rate.

In most places, the river is a vegetation-choked ravine with a small watercourse at the bottom.