Colorado Desert

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Colorado Desert landscape Coloradodesert.jpg
Colorado Desert landscape

California's Colorado Desert is a part of the larger Sonoran Desert. It encompasses approximately 7 million acres (2,800,000 ha; 28,000 km2), including the heavily irrigated Coachella and Imperial valleys. It is home to many unique flora and fauna.


Geography and geology

The Algodones Dunes Imperial sand dunes.jpg
The Algodones Dunes

The Colorado Desert is a subdivision of the larger Sonoran Desert [1] encompassing approximately 7 million acres (2,800,000 ha; 28,000 km2). [2] The desert encompasses Imperial County and includes parts of San Diego County, Riverside County, and a small part of San Bernardino County, California, United States. [3]

Most of the Colorado Desert lies at a relatively low elevation, below 1,000 feet (305 m), with the lowest point of the desert floor at 275 feet (84 m) below sea level, at the Salton Sea. Although the highest peaks of the Peninsular Ranges reach elevations of nearly 10,000 feet (3,048 m), most of the region's mountains do not exceed 3,000 feet (914 m).

In this region, the geology is dominated by the transition of the tectonic plate boundary from rift to fault. The southernmost strands of the San Andreas Fault connect to the northernmost extensions of the East Pacific Rise. Consequently, the region is subject to earthquakes, and the crust is being stretched, which will result in a sinking of the terrain over time.


The Colorado Desert's climate distinguishes it from other deserts. The region experiences greater summer daytime temperatures than higher-elevation deserts and almost never experiences frost. In addition, the Colorado Desert experiences two rainy seasons per year (in the winter and late summer), especially toward the southern portion of the region; the more northerly Mojave Desert usually has only winter rains. [4] [5]

The west coast Peninsular Ranges, or other west ranges, of Southern California–northern Baja California, block most eastern Pacific coastal air and rains, producing an arid climate. [4] Other short or longer-term weather events can move in from the Gulf of California to the south, and are often active in the summer monsoons. These include remnants of Pacific hurricanes, storms from the southern tropical jetstream, and the northern intertropical convergence zone.

Flora and fauna

Blooming cholla cactus with bird's nest in Anza Borrego Desert State Park Cholla Anza Borrego.jpg
Blooming cholla cactus with bird's nest in Anza Borrego Desert State Park
Bighorn sheep at Palm Canyon in Anza-Borrego State Park. Bighorns.jpg
Bighorn sheep at Palm Canyon in Anza-Borrego State Park.

The region's terrestrial habitats include creosote bush scrub; mixed scrub, including yucca and cholla cactus; desert saltbush; sandy soil grasslands; and desert dunes. Higher elevations are dominated by pinyon pine and California juniper, with areas of manzanita and Coulter pine. In addition to hardy perennials, more than half of the desert's plant species are herbaceous annuals, and appropriately timed winter rains produce abundant early spring wildflowers. In the southern portion of the region, the additional moisture supplied by summer rainfall fosters the germination of summer annual plants and supports smoketree, ironwood, and palo verde trees.

Common desert wildlife include mule deer, bobcat, desert kangaroo rat, cactus mouse, black-tailed jackrabbit, Gambel's quail, and red-diamond rattlesnake. Among sensitive species are flat-tailed horned lizard, Coachella Valley fringe-toed lizard, desert tortoise, prairie falcon, Andrews' dune scarab beetle, peninsular bighorn sheep, and California leaf-nosed bat. [4] The best place to spot wildlife is at the wetland refuges along the Colorado River, Cibola National Wildlife Refuge and Imperial National Wildlife Refuge. [6]

In the Colorado Desert's arid environment, aquatic and wetland habitats are limited in extent but are critically important to wildlife. Runoff from seasonal rains and groundwater springs forms desert arroyos, desert fan palm oases, freshwater marshes, brine lakes, desert washes, ephemeral and perennial streams, and desert riparian vegetation communities dominated by cottonwood, willow, and non-native tamarisk. Two of the region's most significant aquatic systems are the Salton Sea and the Colorado River. While most desert wildlife depend on aquatic habitats as water sources, a number of species, such as the arroyo toad, desert pupfish, Yuma rail, and southwestern willow flycatcher, are restricted to these habitats. In some places, summer rains produce short-lived seasonal pools that host uncommon species like Couch's spadefoot toad.

Washingtonia filifera in Anza Borrego Desert State Park Washingtonia filifera Anza-Borrego.jpg
Washingtonia filifera in Anza Borrego Desert State Park

Desert fan palm oases are rare ecological communities found only in the Colorado Desert. They occur only where permanent water sources are available, such as at springs or along fault lines, where groundwater is forced to the surface by the movement of hard impermeable rock, and can be found in the San Jacinto, Santa Rosa, and Little San Bernardino mountains, in the canyons of Anza-Borrego Desert State Park, and along the San Andreas Fault in the Coachella Valley. [4] The only palm native to California, Washingtonia filifera (desert fan palm), grows at the oases. [7]

Endemic flora

Some sub-regions of the Colorado Desert contain endemic flora. Along the Lower Colorado River Valley, in-flow side canyons, flatlands, or low-to-higher level elevations, at least three such flora occur: Hesperocallis undulata (desert lily), Nolina bigelovii (Bigelow's nolina), and Peucephyllum schottii (desert fir).

National and State Parks

Environmental issues

The Colorado Desert is one of the least-populous regions in California, but human activities have had substantial impacts on the region's habitats and wildlife. Many unique communities, particularly aquatic and dune systems, are limited in distribution and separated by vast expanses of inhospitable, arid desert terrain. Even limited human disturbances can have markedly deleterious effects on the endemic and sensitive species supported by these unique regional systems. [4]

Some of the greatest human-caused effects on the region have resulted from the water diversions and flood control measures along the Colorado River. These measures have dramatically altered the region's hydrology by redistributing the region's water supply to large expanses of irrigated agriculture and metropolitan coastal areas such as Los Angeles and San Diego. The once-dynamic Salton Sea and Colorado River ecosystems are now controlled by human water management. Because of the scarcity of water resources in the desert environment, these alterations have had substantial impacts on regional wildlife and habitats. In addition, portions of the region are experiencing substantial growth and development pressures, most notably the Coachella Valley. [4]

See also

Related Research Articles

<span class="mw-page-title-main">Geography of California</span> Overview of the geography of California

California is a U.S. state on the western coast of North America. Covering an area of 163,696 sq mi (423,970 km2), California is among the most geographically diverse states. The Sierra Nevada, the fertile farmlands of the Central Valley, and the arid Mojave Desert of the south are some of the major geographic features of this U.S. state. It is home to some of the world's most exceptional trees: the tallest, most massive, and oldest. It is also home to both the highest and lowest points in the 48 contiguous states. The state is generally divided into Northern and Southern California, although the boundary between the two is not well defined. San Francisco is decidedly a Northern California city and Los Angeles likewise a Southern California one, but areas in between do not often share their confidence in geographic identity. The US Geological Survey defines the geographic center of the state at a point near North Fork, California.

<span class="mw-page-title-main">Imperial County, California</span> County in California, United States

Imperial County is a county located on the southeast border of the U.S. state of California. As of the 2020 census, the population was 179,702, making it the least populous county in Southern California. The county seat is El Centro. Imperial is the most recent California county to be established, as it was created in 1907 out of portions of San Diego County.

<span class="mw-page-title-main">Sonoran Desert</span> Desert in northwestern Mexico and the southwestern United States

The Sonoran Desert is a desert in North America and ecoregion that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the southwestern United States. It is the hottest desert in both Mexico and the United States. It has an area of 260,000 square kilometers (100,000 sq mi).

<span class="mw-page-title-main">Salton Sea</span> Shallow saline lake in southern California

The Salton Sea is a shallow, landlocked, highly saline body of water in Riverside and Imperial counties at the southern end of the U.S. state of California. It lies on the San Andreas Fault within the Salton Trough that stretches to the Gulf of California in Mexico. Over millions of years, the Colorado River has flowed into the Imperial Valley and deposited alluvium (soil), creating fertile farmland, building up the terrain, and constantly moving its main course and river delta. For thousands of years, the river has alternately flowed into the valley, or diverted around it, creating either a saline lake called Lake Cahuilla, or a dry desert basin, respectively. When the Colorado River flows into the valley, the lake level depends on river flows and the balance between inflow and evaporative loss. When the river diverts around the valley, the lake dries completely, as it did around 1580. Hundreds of archaeological sites have been found in this region, indicating possibly long-term Native American villages and temporary camps.

<span class="mw-page-title-main">Imperial Valley, California</span> Valley in California, United States

The Imperial Valley of Southern California lies in Imperial and Riverside counties, with an urban area centered on the city of El Centro. The Valley is bordered by the Colorado River to the east and, in part, the Salton Sea to the west. Farther west lies the San Diego and Imperial County border. To the north is the Coachella Valley region of Riverside County, which together with Imperial Valley form the Salton Trough, or the Cahuilla Basin, also the county line of Imperial and Riverside counties, and to the south the international boundary with Mexico.

<span class="mw-page-title-main">Anza-Borrego Desert State Park</span> State park in California, United States

Anza-Borrego Desert State Park is a California State Park located within the Colorado Desert of southern California, United States. The park takes its name from 18th century Spanish explorer Juan Bautista de Anza and borrego, a Spanish word for sheep. With 585,930 acres (237,120 ha) that includes one-fifth of San Diego County, it is the largest state park in California.

<span class="mw-page-title-main">Low Desert</span>

The Low Desert is a common name for any desert in California that is under 2,000 feet in altitude. These areas include, but are not exclusive to, the Colorado Desert and Yuha Desert, in the Southern California portion of the Sonoran Desert. These areas are distinguished in biogeography from the adjacent northern High Desert or Mojave Desert by latitude, elevation, animal life, climate, and native plant communities.

<span class="mw-page-title-main">San Jacinto Mountains</span> Mountain range in Riverside County, in southern California

The San Jacinto Mountains are a mountain range in Riverside County, located east of Los Angeles in southern California in the United States. The mountains are named for one of the first Black Friars, Saint Hyacinth, who is a popular patron in Latin America.

<span class="mw-page-title-main">Santa Rosa Mountains (California)</span> Mountain range in California

The Santa Rosa Mountains are a short mountain range in the Peninsular Ranges system, located east of the Los Angeles Basin and northeast of the San Diego metropolitan area of southern California, in the southwestern United States.

<span class="mw-page-title-main">Little San Bernardino Mountains</span> Mountain range of the Transverse Ranges in California, United States

The Little San Bernardino Mountains are a short mountain range of the Transverse Ranges, located in southern California in the United States. They extend for approximately 40 mi (64 km) southeast from the San Bernardino Mountains through San Bernardino and Riverside Counties to near the northeast edge of the Salton Sink and Salton Sea.

Indio Hills Palms Park Property and the Coachella Valley Preserve, located in the Indio Hills, contain the Thousand Palms Oasis and are a protected area in the Coachella Valley, located east of Palm Springs near Palm Desert, California. The Coachella Valley National Wildlife Refuge is contained within the Coachella Valley Preserve, and all are in the Colorado Desert section of the Sonoran Desert and adjacent to the Lower Colorado River Valley region.

<span class="mw-page-title-main">Santa Rosa and San Jacinto Mountains National Monument</span> Protected area in California

The Santa Rosa and San Jacinto Mountains National Monument is a National Monument in southern California. It includes portions of the Santa Rosa and San Jacinto mountain ranges, the northernmost ones of the Peninsular Ranges system. The national monument covers portions of Riverside County, west of the Coachella Valley, approximately 100 miles (160 km) southeast of downtown Los Angeles.

<span class="mw-page-title-main">Deserts of California</span> Region of California

The Deserts of California, collectively known as the California Deserts, are a region of California made up of distinct deserts that each have unique ecosystems and habitats. The region is home to a sociocultural and historical "Old West" collection of legends, districts, and communities, and they also form a popular tourism region of dramatic natural features and recreational development.

<span class="mw-page-title-main">Santa Rosa Wilderness</span> Protected wilderness area in California, United States

The Santa Rosa Wilderness is a 72,259-acre (292.42 km2) wilderness area in Southern California, in the Santa Rosa Mountains of Riverside and San Diego counties, California. It is in the Colorado Desert section of the Sonoran Desert, above the Coachella Valley and Lower Colorado River Valley regions in a Peninsular Range, between La Quinta to the north and Anza Borrego Desert State Park to the south. The United States Congress established the wilderness in 1984 with the passage of the California Wilderness Act, managed by both the US Forest Service and the Bureau of Land Management. In 2009, the Omnibus Public Land Management Act was signed into law which added more than 2,000 acres (8.1 km2). Most of the Santa Rosa Wilderness is within the Santa Rosa and San Jacinto Mountains National Monument.

<span class="mw-page-title-main">Sonny Bono Salton Sea National Wildlife Refuge</span> Protected area in Imperial Valley, California

The Sonny Bono Salton Sea National Wildlife Refuge is located in the Imperial Valley of California, 40 miles (64 km) north of the Mexican border. Situated at the southern end of the Salton Sea, the refuge protects one of the most important nesting sites and stopovers along the Pacific Flyway. Despite its location in the Colorado Desert, a subdivision of the larger Sonoran Desert, the refuge contains marine, freshwater, wetland, and agricultural habitats which provide sanctuary for hundreds of birds and wetland species, including several that have been listed as endangered or sensitive by the U.S. Fish and Wildlife Service.

<span class="mw-page-title-main">Coachella Valley National Wildlife Refuge</span> Protected area located near Palm Desert, California

Coachella Valley National Wildlife Refuge is a 3,709-acre (15.01 km2) protected area in Riverside County, California's Coachella Valley. It lies within the unincorporated community of Thousand Palms, just north of Palm Desert. The refuge contains the majority of critical habitat for the Coachella Valley Fringe-toed Lizard within the Coachella Valley Preserve and Indio Hills Palms State Reserve.

The Coachella Valley Water District is an independent special district formed in 1918, specifically to protect and conserve local water sources in the Coachella Valley. Since then, the district has grown into a multi-faceted agency that delivers irrigation and domestic (drinking) water, collects and recycles wastewater, provides regional storm water protection, replenishes the groundwater basin and promotes water conservation.

<span class="mw-page-title-main">Flora of the Colorado Desert</span>

Flora of the Colorado Desert, located in Southern California. The Colorado Desert is a sub-region in the Sonoran Desert ecoregion of southwestern North America. It is also known as the Low Desert, in contrast to the higher elevation Mojave Desert or High Desert, to its north.

<span class="mw-page-title-main">Sand to Snow National Monument</span> National monument in California, United States

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  2. "Archived copy" (PDF). Archived from the original (PDF) on 2015-07-25. Retrieved 2015-07-25.{{cite web}}: CS1 maint: archived copy as title (link)
  3. "Poster- Colorado Desert Ecoregion (ER_322C)" . Retrieved 2017-10-31.
  4. 1 2 3 4 5 6 "Colorado Desert" . Retrieved 2009-08-06.
  5. Allen A. Schoenherr, A Natural History of California, 1992
  6. "Tour Cibola Wildlife Refuge". CaliforniaResortLife. Archived from the original on 2015-12-27. Retrieved 2015-12-24.
  7. "A Desert Park". National Park Service. Retrieved 2009-05-06.