View source for Colorado Desert

{{Short description|Subdivision of the Sonoran Desert, California}}
{{about-distinguish-text|the desert in California|the arid [[Colorado Plateau]] in parts of Colorado, New Mexico, Utah, and Arizona}}
[[File:Coloradodesert.jpg|thumb|250px|Colorado Desert landscape]]

The '''Colorado Desert''' is a part of the larger [[Sonoran Desert]] located in [[California]], United States, and [[Baja California]], Mexico. It encompasses approximately {{convert|7|e6acre|ha km2}}, including the heavily [[irrigation|irrigated]] [[Coachella Valley|Coachella]], [[Imperial Valley|Imperial]] and [[Mexicali]] valleys. It is home to many unique flora and fauna.

==Geography and geology==
[[File:Imperial sand dunes.jpg|thumb|The [[Algodones Dunes]]]]

The Colorado Desert is a [[subregion]] of the larger [[Sonoran Desert]],<ref>{{cite web |url=https://calwil.wordpress.com/category/california-colorado-desert |title=California Colorado Desert - CDFW Wildlife Investigations Lab Blog |website=calwil.wordpress.com}}</ref> covering about {{convert|7|e6acre|e6ha km2 |abbr=unit}}.<ref>{{cite web |url=https://borregospringschamber.com/abdsp/documents/ch08_colorado.pdf |title=Archived copy |access-date=2015-07-25 |archive-url=https://web.archive.org/web/20150725204127/http://www.borregospringschamber.com/abdsp/documents/ch08_colorado.pdf |archive-date=2015-07-25 |url-status=dead}}</ref> The desert occupies [[Imperial County, California|Imperial County]], parts of [[San Diego County, California|San Diego]] and [[Riverside County, California|Riverside]] counties, and a small part of [[San Bernardino County, California|San Bernardino County]] in [[California]], United States,<ref>{{cite web |url=https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=79062 |title=Poster- Colorado Desert Ecoregion (ER_322C) |access-date=2017-10-31}}</ref> as well as the northern part of [[Mexicali Municipality]] in [[Baja California]], Mexico.

Most of the Colorado Desert lies at a relatively low elevation, below {{cvt|1,000|ft|m|0}}, with the lowest point of the desert floor at {{cvt|275|ft|m|0}} [[height above mean sea level|below sea level]], at the [[Salton Sea]]. Although the highest peaks of the [[Peninsular Ranges]] reach elevations of nearly {{cvt|10,000|ft|m|0}}, most of the region's mountains do not exceed {{cvt|3,000|ft|m|0}}.

In this region, the [[geology]] is dominated by the transition of the [[tectonic plate]] boundary from [[rift]] to [[fault (geology)|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 [[earthquake]]s, and the crust is being stretched, which will result in a sinking of the terrain over time.

==Climate==
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.<ref name="CAdfg">{{cite web|url=https://www.britannica.com/place/Colorado-Desert|title=Colorado Desert|access-date=2009-08-06}}</ref><ref>[[Allen A. Schoenherr]], ''A Natural History of California'', 1992</ref>

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.<ref name="CAdfg"/> 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 [[monsoon]]s. These include remnants of Pacific hurricanes, storms from the southern tropical [[jetstream]], and the northern [[Intertropical Convergence Zone]].

==Flora and fauna==
{{See also|Flora of the Colorado Desert|List of flora of the Sonoran Desert Region by common name}}
{{category see also|Flora of the California desert regions|Fauna of the Colorado Desert|Fauna of the Sonoran Desert}}
[[File:Cholla Anza Borrego.jpg|thumb|Blooming cholla cactus with bird's nest in [[Anza Borrego Desert State Park]]]]
[[File:Bighorns.jpg|thumb|200px|[[Bighorn sheep]] at [[Palm Canyon]] in [[Anza-Borrego State Park]]]]

The region's terrestrial habitats include [[creosote bush]] scrub; mixed [[scrubland|scrub]], including [[yucca]] and [[cholla cactus]]; desert [[saltbush]]; sandy soil [[grasslands]]; and desert [[dunes]]. Higher elevations are dominated by [[pinyon pine]] and [[Juniperus californica|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 (Psorothamnus)|smoketree]], [[Desert Ironwood|ironwood]], and [[Parkinsonia florida|palo verde]] trees.

Common desert wildlife include [[mule deer]], [[bobcat]], desert [[kangaroo rat]], [[cactus mouse]], [[black-tailed jackrabbit]], [[Gambel's quail]], and [[Crotalus ruber|red-diamond rattlesnake]]. Among sensitive species are [[flat-tailed horned lizard]], Coachella Valley fringe-toed lizard, [[desert tortoise]], [[prairie falcon]], [[Pseudocotalpa andrewsi|Andrews' dune scarab beetle]], peninsular [[bighorn sheep]], and [[California leaf-nosed bat]].<ref name="CAdfg"/>  The best place to spot wildlife is at the wetland refuges along the Colorado River, [[Cibola National Wildlife Refuge]] and [[Imperial National Wildlife Refuge]].<ref name="CRL2015">{{cite web|url=http://www.californiaresortlife.com/imperialvalley/nwr_cibola.htm|title=Tour Cibola Wildlife Refuge|work=CaliforniaResortLife|access-date=2015-12-24|url-status=usurped|archive-url=https://web.archive.org/web/20151227033439/http://www.californiaresortlife.com/imperialvalley/nwr_cibola.htm|archive-date=2015-12-27}}</ref>

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 [[Arroyo (watercourse)|arroyos]], desert fan palm [[oasis|oases]], freshwater [[marshes]], brine lakes, desert washes, ephemeral and perennial streams, and [[desert riparian]] vegetation communities dominated by [[Populus sect. Aegiros|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]], [[Ridgway's rail|Yuma rail]], and [[willow flycatcher|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]].

[[File:Washingtonia filifera Anza-Borrego.jpg|thumb|''[[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]].<ref name="CAdfg"/> The only palm native to California, ''[[Washingtonia filifera]]'' (desert fan palm), grows at the oases.<ref>{{cite web|url=http://www.nps.gov/jotr/planyourvisit/desertpark.htm|archive-url=https://web.archive.org/web/20061011085214/http://www.nps.gov/jotr/planyourvisit/desertpark.htm|url-status=dead|archive-date=October 11, 2006|title=A Desert Park|publisher=National Park Service|access-date=2009-05-06}}</ref>

===Endemic flora===
Some sub-regions of the Colorado Desert contain [[endemism|endemic]] flora. Along the [[Lower Colorado River Valley]], in-flow side canyons, flatlands, or low-to-higher level elevations, at least one such plants occur: ''[[Salvia greatae]]'' (Orocopia sage).

==National and State Parks==
* [[Joshua Tree National Park]]
* [[Chuckwalla National Monument]]
* [[Imperial National Wildlife Refuge|Imperial NWR]]
* [[Sonny Bono Salton Sea National Wildlife Refuge|Sonny Bono Salton Sea NWR]]
* [[Indio Hills Palms]]
* [[Anza-Borrego Desert State Park]]
* [[Ocotillo Wells State Vehicular Recreation Area]]
* [[Picacho State Recreation Area]]
* [[Heber Dunes State Vehicular Recreation Area]]
* [[Salton Sea State Recreation Area]]

==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.<ref name="CAdfg"/>

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, California|Los Angeles]] and [[San Diego, California|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]].<ref name="CAdfg"/>

==See also==
{{Div col|colwidth=30em}}
* [[Yuma Desert]]
* [[Chihuahuan Desert]]
* The [[Low Desert]] region
* [[Deserts of California]]
* [[List of North American deserts]]
* [[List of lakes of the Colorado Desert]]
{{div col end}}

==References==
{{Reflist}}

==External links==
{{Commons category|Colorado Desert}}
* [https://web.archive.org/web/20060220121901/http://www.dfg.ca.gov/habitats/wdp/region-colorado/overview.html Colorado Desert – Overview] from [https://web.archive.org/web/20060220104510/http://www.dfg.ca.gov/habitats/wdp/index.html California Wildlife Action Plan] site
* {{Cite NIE|wstitle=Colorado Desert|short=x}}

{{Colorado Desert Region}}
{{Deserts}}

{{Authority control}}
[[Category:Colorado Desert| ]]
[[Category:Deserts and xeric shrublands in the United States]]
[[Category:Ecoregions of California]]
[[Category:Sonoran Desert]]
[[Category:Deserts of California]]
[[Category:Deserts of the Lower Colorado River Valley]]
[[Category:Coachella Valley]]
[[Category:Imperial Valley]]
[[Category:Geography of Riverside County, California]]
[[Category:Geography of San Bernardino County, California]]
[[Category:Geography of Southern California]]