The Rio San Bernardino, or San Bernardino River, begins in extreme southeastern

Cochise County, Arizona Cochise County ( ) is a county in the southeastern corner of the U.S. state of Arizona. It is named after Cochise, a Chiricahua Apache who was a key war leader during the Apache Wars. The population was 125,447 at the 2020 census. The count ...

, and is a tributary of the Bavispe River, in

Sonora Sonora (), officially Estado Libre y Soberano de Sonora (), is one of the 31 states which, along with Mexico City, comprise the Administrative divisions of Mexico, Federal Entities of Mexico. The state is divided into Municipalities of Sonora, 72 ...

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

Watershed

The Rio San Bernardino has two major tributaries, the Rio de Agua Prieta and the Arroyo Cajón Bonito. The river's headwaters are in extreme southeastern Cochise County, Arizona as Black Draw. From here the Rio San Bernardino flows south, crossing into Mexico east of

Douglas, Arizona Douglas is a city in Cochise County, Arizona, United States, that lies in the north-west to south-east running Sulphur Springs Valley. Douglas has a Douglas, Arizona Port of Entry, border crossing with Mexico at Agua Prieta and a history of min ...

. In northern

, the Cajón Bonito River joins the San Bernardino River in the

San Bernardino Valley The San Bernardino Valley () is a valley in Southern California located at the south base of the Transverse Ranges. It is bordered on the north by the eastern San Gabriel Mountains and the San Bernardino Mountains; on the east by the San Jacin ...

after draining the Sierra San Luis and northern end of the

Sierra Madre Occidental The Sierra Madre Occidental is a major mountain range system of the North American Cordillera, that runs northwest–southeast through northwestern and western Mexico, and along the Gulf of California. The Sierra Madre is part of the American C ...

. Next the Rio San Bernardino is joined by the Agua Prieta River which also begins in Cochise County, crossing south as Whitewater Draw into Mexico at Douglas and

Agua Prieta Agua Prieta ("dark water") is a town in the Agua Prieta Municipality in the northeastern corner of the Mexican state of Sonora. It stands on the Mexico–U.S. border, adjacent to the town of Douglas, Arizona, Douglas, Arizona. The municipality c ...

. The Agua Prieta River flows south and east to join the Rio San Bernardino, shortly after the Rio Agua Prieta has its confluence with the Rio Fronteras, the latter flowing north from near Nacozari de Garcia, Sonora. The San Bernardino River joins the Bavispe River at Morelos, Sonora at the northern end of the Sierra del Tigre. The Bavispe River flows south by southwest to the

Yaqui River The Yaqui River (Río Yaqui in Spanish) (Hiak Vatwe in the Yaqui or Yoreme language) is a river in the state of Sonora in northwestern Mexico. It was formerly known as the Rio del Norte. Being the largest river system in the state of Sonora, th ...

and eventually to the

Gulf of California The Gulf of California (), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Vermejo''), is a marginal sea of the Pacific Ocean that separates the Baja California peninsula from ...

at Ciudad Obregon, Sonora.

Ecology

North American beaver The North American beaver (''Castor canadensis'') is one of two Extant taxon, extant beaver species, along with the Eurasian beaver (''Castor fiber''). It is native to North America and has been introduced in South America (Patagonia) and Europe ...

(''Castor canadensis'') were documented by Leopold in 1977 in northern Mexico, and a 2000 survey found five breeding pairs of beavers on the Cajón Bonito River mostly in remote ranches without livestock. The authors of the latter study reported that local ranchers kill beavers because they fear felled trees will block roads. However, beavers are considered keystone species and ecosystem engineers, as their dams raise the water table and turn seasonal stretches of streams into perennial reaches, producing highly beneficial impacts on

species abundance In ecology, local abundance is the relative representation of a species in a particular ecosystem. It is usually measured as the number of individuals found per sample. The ratio of abundance of one species to one or multiple other species livin ...

and diversity in the riparian zone. Beavers were also documented by Hendrickson et al. in 1978 on the Cajón Bonito.

References

{{authority control Rivers of Arizona Rivers of Cochise County, Arizona Rivers of Sonora

Watershed

Ecology

See also

References