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The Lower Colorado River Valley (LCRV) is the river region of the lower
Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid watershed that encompasses parts of seven U.S. s ...
of the
southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that generally includes Arizona, New Mexico, and adjacent portions of California, Colorado, N ...
in
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
that rises in the
Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...
and has its outlet at the
Colorado River Delta The Colorado River Delta is the region where the Colorado River flows into the Gulf of California (also known as the Sea of Cortez) in eastern Mexicali Municipality in the north of the state of Baja California in northwesternmost Mexico. The ...
in the northern
Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...
in northwestern
Mexico Mexico (Spanish language, Spanish: México), officially the United Mexican States, is a List of sovereign states, country in the southern portion of North America. It is borders of Mexico, bordered to the north by the United States; to the so ...
, between the states of
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 ...
and
Sonora Sonora (), officially Estado Libre y Soberano de Sonora ( en, Free and Sovereign State of Sonora), is one of the 31 states which, along with Mexico City, comprise the Federal Entities of Mexico. The state is divided into 72 municipalities; the ...
. This north–south stretch of the Colorado River forms the border between the U.S. states of
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
/
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
and
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
/Arizona, and between the Mexican states of Baja California/Sonora. It is commonly defined as the region from below
Hoover Dam Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on S ...
and Lake Mead to its outlet at the northern
Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...
(Sea of Cortez); it includes the Colorado River proper, canyons, the valley, mountain ranges with wilderness areas, and the floodplain and associated riparian environments. It is home to
recreation Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or plea ...
activities from the
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of ...
, the
lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...
s created by dams,
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
, and the home of various cities, communities, and towns along the river, or associated with the valley region. Five Indian reservations are located in the LCRV: the
Chemehuevi The Chemehuevi are an indigenous people of the Great Basin. They are the southernmost branch of Southern Paiute.Fort Mojave Fort Mohave was originally named Camp Colorado when it was established on April 19, 1859 by Lieutenant Colonel William Hoffman during the Mohave War. It was located on the east bank of the Colorado River, at Beale's Crossing, near the head of t ...
and Colorado River Indian Reservations; at Yuma are the
Quechan The Quechan (or Yuma) ( Quechan: ''Kwatsáan'' 'those who descended') are a Native American tribe who live on the Fort Yuma Indian Reservation on the lower Colorado River in Arizona and California just north of the Mexican border. Despite t ...
and Cocopah reservations.


Ecology

Some of the highest absolute air temperatures (of North America) are recorded in the LCRV, rivaling
Death Valley Death Valley is a desert valley in Eastern California, in the northern Mojave Desert, bordering the Great Basin Desert. During summer, it is the hottest place on Earth. Death Valley's Badwater Basin is the point of lowest elevation in Nort ...
; specifically
Bullhead City Bullhead City is a city located on the Colorado River in Mohave County, Arizona, United States, south of Las Vegas, Nevada, and directly across the Colorado River from Laughlin, Nevada, whose casinos and ancillary services supply much of the e ...
, Lake Havasu City, Laughlin, Needles, Yuma, or the southeastern deserts of California, west of the Colorado River where extreme heat is the main summertime weather feature. Worldwide, only some deserts found in
Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
and in the
Middle East The Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolitical region commonly encompassing Arabian Peninsula, Arabia (including the Arabian Peninsula and Bahrain), Anatolia, Asia Minor (Asian part of Turkey except Hatay Pro ...
stand up with an even hotter summer climate on average. The LCRV is defined by three deserts. The
Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily ...
is in southeast California, southern Nevada, and northwest Arizona. South of the Mojave the
Sonoran Desert The Sonoran Desert ( es, Desierto de Sonora) 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 (in Ariz ...
spans both sides of the Colorado River. The Lower Colorado River Valley is in the western part of the Sonoran Desert, which is called the
Colorado Desert California's Colorado Desert is a part of the larger Sonoran Desert. It encompasses approximately , including the heavily irrigated Coachella and Imperial valleys. It is home to many unique flora and fauna. Geography and geology The Colorado D ...
. the Sonoran Desert region proper extends from areas west of the river, and then southeastwards to southeast Arizona, south along the eastern side of the Baja Peninsula cordillera to
Baja California Sur Baja California Sur (; 'South Lower California'), officially the Free and Sovereign State of Baja California Sur ( es, Estado Libre y Soberano de Baja California Sur), is the least populated state and the 31st admitted state of the 32 federal ent ...
, and southeast
Sonora Sonora (), officially Estado Libre y Soberano de Sonora ( en, Free and Sovereign State of Sonora), is one of the 31 states which, along with Mexico City, comprise the Federal Entities of Mexico. The state is divided into 72 municipalities; the ...
state, Mexico to the northern border of neighboring
Sinaloa Sinaloa (), officially the Estado Libre y Soberano de Sinaloa ( en, Free and Sovereign State of Sinaloa), is one of the 31 states which, along with Mexico City, comprise the Federal Entities of Mexico. It is divided into 18 municipalities and ...
. The LCRV extends about from Hoover Dam to the
Colorado River Delta The Colorado River Delta is the region where the Colorado River flows into the Gulf of California (also known as the Sea of Cortez) in eastern Mexicali Municipality in the north of the state of Baja California in northwesternmost Mexico. The ...
. The Sonoran Desert itself is more than twice as extensive north-to-south, and about in width. Two species,
Desert Ironwood ''Olneya tesota'' is a perennial flowering tree of the family Fabaceae, legumes (peas, beans, etc.), which is commonly known as ironwood, desert ironwood, or palo fierro in Spanish. It is the only species in the monotypic genus ''Olneya''. This ...
–('' Olneya tesota'') and the Lesser Long-nosed Bat, have geographic ranges identical to the Sonoran Desert, and are
indicator species A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sm ...
of the ''Sonoran Desert region''. The spring flowering of ironwood, and the bat species migration arrivals also become indicators of annual or multi-year climate trends for regions of the Sonoran Desert.


Fauna


Flora

The Lower Colorado River Valley has unique plant communities because it is the most arid part of the desert and it has the highest temperatures, in excess of during the summer. The low humidity means that most plants must have mechanisms that deal with severe water loss through evaporation. The soils tend to be typical desert soils, coarse and without well-developed organic horizons, and plants can only obtain soil water during and very soon after the infrequent rains. Dominant plants in the valleys are low shrubs such as ''
Ambrosia dumosa ''Ambrosia dumosa'', the burro-weed or white bursage, a North American species of plants in the family Asteraceae. It is a common constituent of the creosote-bush scrub community throughout the Mojave desert of California, Nevada, and Utah and ...
'' (white bursage) and '' Larrea tridentata'' (creosote bush). Over half of the floral diversity comprises annual species, with even higher percentages in drier habitats. Vulnerable species and plant communities include saltbush/wolfberry flats, saguaro, nightblooming cereus cacti, tamarisks, barrel cactus, Sonoran panicgrass, and Acuna cactus.


Threats

The Lower Colorado River Valley subregion of the Sonoran Desert bioregion has multiple threats. Some major threats include
urbanization Urbanization (or urbanisation) refers to the population shift from rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. It is predominantly th ...
, clearing of land for agriculture, human occupancy – especially as a result of imported external resources, and camping and camptrailers on BLM land. Other threats include harvesting for fuelwood, campfires, etc. of
desert ironwood ''Olneya tesota'' is a perennial flowering tree of the family Fabaceae, legumes (peas, beans, etc.), which is commonly known as ironwood, desert ironwood, or palo fierro in Spanish. It is the only species in the monotypic genus ''Olneya''. This ...
, '' Olneya tesota'', destruction of land by offroad vehicles, especially in
sand dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...
s, and harvesting and manipulation of groundwater.Ecological threats, ''Lower Colorado River Valley''
/ref>


List of major cities and communities

* Laughlin, Nevada in Clark County, Nevada * Needles, California in San Bernardino County *
Bullhead City Bullhead City is a city located on the Colorado River in Mohave County, Arizona, United States, south of Las Vegas, Nevada, and directly across the Colorado River from Laughlin, Nevada, whose casinos and ancillary services supply much of the e ...
, Arizona * Mojave Valley, Arizona * Lake Havasu City, Arizona * Silver Cliffs, Arizona/California * Vidal, California * Parker, Arizona *
Blythe The name Blythe ( or ) derives from Old English ''bliþe'' ("joyous, kind, cheerful, pleasant"; modern ''blithe''), and further back from Proto-Germanic ''*blithiz'' ("gentle, kind"). People *Blythe (given name), including a list of people named ...
, California *
Quartzite Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tec ...
, Arizona * Winterhaven, California in
Imperial County, California Imperial County is a county 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 th ...
* Yuma, Arizona in
Yuma County, Arizona Yuma County is a county in the southwestern corner of the U.S. state of Arizona. As of the 2020 census, its population was 203,881. The county seat is Yuma. Yuma County includes the Yuma, Arizona Metropolitan Statistical Area. The county bo ...
* San Luis, Arizona *
San Luis Río Colorado San Luis Río Colorado is a city and also the name of its surrounding municipality in the state of Sonora, Mexico. In the 2020 census, the city had a population of 176,685. The city is the fourth-largest community in the state, and the municip ...
, Sonora


Complete list of towns, areas, etc, north to south

Nevada–California–Baja California side * Cottonwood Cove, Nevada * Lake Mohave * Laughlin
Bullhead City Bullhead City is a city located on the Colorado River in Mohave County, Arizona, United States, south of Las Vegas, Nevada, and directly across the Colorado River from Laughlin, Nevada, whose casinos and ancillary services supply much of the e ...
* NeedlesMohave Valley, AZ * Sacramento Mountains * Chemehuevi Mountains *
Chemehuevi Valley The Chemehuevi are an indigenous people of the Great Basin. They are the southernmost branch of Southern Paiute.
–(Lake Havasu City) * Whipple Mountains * Earp * Big River *
Blythe The name Blythe ( or ) derives from Old English ''bliþe'' ("joyous, kind, cheerful, pleasant"; modern ''blithe''), and further back from Proto-Germanic ''*blithiz'' ("gentle, kind"). People *Blythe (given name), including a list of people named ...
–Quartzsite * WinterhavenYuma * Los Algodones, Baja California *
Colorado River Delta The Colorado River Delta is the region where the Colorado River flows into the Gulf of California (also known as the Sea of Cortez) in eastern Mexicali Municipality in the north of the state of Baja California in northwesternmost Mexico. The ...
(at Gulf of California) Arizona–Sonora side * Willow Beach, Arizona * Lake Mohave *
Bullhead City Bullhead City is a city located on the Colorado River in Mohave County, Arizona, United States, south of Las Vegas, Nevada, and directly across the Colorado River from Laughlin, Nevada, whose casinos and ancillary services supply much of the e ...
* Mohave Valley, AZ, in
Mohave County, Arizona Mohave County is in the northwestern corner of the U.S. state of Arizona. As of the 2020 census, its population was 213,267. The county seat is Kingman, and the largest city is Lake Havasu City. It is the fifth largest county in the United S ...
* Topock
Topock Marsh Havasu National Wildlife Refuge is a U.S. National Wildlife Refuge on the lower Colorado River in Arizona and California. It preserves habitat for desert bighorn sheep, the endangered southwestern willow flycatcher, and other animals. The refu ...
* Lake Havasu City * Bill Williams River * EarpParker * Quartzsite, in
La Paz County, Arizona La Paz County is the 15th County (United States), county in the U.S. state of Arizona, located in the western part of the state. As of the 2020 United States census, 2020 census, its population was 16,557, making it the second-least populous ...
* Ehrenberg * Cibola * Yuma in
Yuma County, Arizona Yuma County is a county in the southwestern corner of the U.S. state of Arizona. As of the 2020 census, its population was 203,881. The county seat is Yuma. Yuma County includes the Yuma, Arizona Metropolitan Statistical Area. The county bo ...
*
San Luis Río Colorado San Luis Río Colorado is a city and also the name of its surrounding municipality in the state of Sonora, Mexico. In the 2020 census, the city had a population of 176,685. The city is the fourth-largest community in the state, and the municip ...
, Sonora *
Colorado River Delta The Colorado River Delta is the region where the Colorado River flows into the Gulf of California (also known as the Sea of Cortez) in eastern Mexicali Municipality in the north of the state of Baja California in northwesternmost Mexico. The ...
(at Gulf of California)


Feeder-valleys, or included small valleys

Nevada–California–Baja California side * Eldorado Valley–(
endorheic An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into lakes ...
) * Piute Valley * Laughlin
Bullhead City Bullhead City is a city located on the Colorado River in Mohave County, Arizona, United States, south of Las Vegas, Nevada, and directly across the Colorado River from Laughlin, Nevada, whose casinos and ancillary services supply much of the e ...
* NeedlesMohave Valley, AZ *
Mohave Valley The Mohave Valley is a valley located mostly on the east shore of the south-flowing Colorado River in northwest Arizona. The valley extends into California's San Bernardino County; the northern side of the valley extends into extreme southeast ...
–(included) * Sacramento Mountains *
Mohave Valley The Mohave Valley is a valley located mostly on the east shore of the south-flowing Colorado River in northwest Arizona. The valley extends into California's San Bernardino County; the northern side of the valley extends into extreme southeast ...
–(included) * Chemehuevi Mountains *
Chemehuevi Valley The Chemehuevi are an indigenous people of the Great Basin. They are the southernmost branch of Southern Paiute.
–(Lake Havasu City) * Whipple Mountains * Vidal Valley *
Parker Valley The Parker Valley is located along the Lower Colorado River within the Lower Colorado River Valley region, in southwestern Arizona and southeastern California. Its natural habitats are within the Sonoran Desert (Arizona) and Colorado Desert (C ...
–(included) * Palo Verde Valley–(included) *
Colorado River Delta The Colorado River Delta is the region where the Colorado River flows into the Gulf of California (also known as the Sea of Cortez) in eastern Mexicali Municipality in the north of the state of Baja California in northwesternmost Mexico. The ...
Arizona–Sonora side *
Sacramento Valley (Arizona) The Sacramento Valley of northwestern Arizona is a north–south trending valley west and southwest of Kingman in Mohave County. The valley lies just east of the southern section of the Black Mountains. Interstate 40 in Arizona traverses the va ...
–( Sacramento Wash) *
Mohave Valley The Mohave Valley is a valley located mostly on the east shore of the south-flowing Colorado River in northwest Arizona. The valley extends into California's San Bernardino County; the northern side of the valley extends into extreme southeast ...
–(included) * (east of Whipple Mtns massif)– Bill Williams River–(Arizona) ** Maria fold and thrust belt Region *
Parker Valley The Parker Valley is located along the Lower Colorado River within the Lower Colorado River Valley region, in southwestern Arizona and southeastern California. Its natural habitats are within the Sonoran Desert (Arizona) and Colorado Desert (C ...
–(included)— La Posa Plain * Ehrenberg, Arizona *
Cibola, Arizona Cibola is a census-designated place (CDP) in La Paz County, Arizona, United States. The population was 250 at the 2010 census, up from 172 in 2000. It is named for the famed city of gold of the same name. Geography Cibola is located in south ...
* Yuma Valley–(included)-
Yuma, Arizona Yuma ( coc, Yuum) is a city in and the county seat of Yuma County, Arizona, United States. The city's population was 93,064 at the 2010 census, up from the 2000 census population of 77,515. Yuma is the principal city of the Yuma, Arizona, M ...
*
Colorado River Delta The Colorado River Delta is the region where the Colorado River flows into the Gulf of California (also known as the Sea of Cortez) in eastern Mexicali Municipality in the north of the state of Baja California in northwesternmost Mexico. The ...


References

{{Reflist, refs= {{cite web, url=http://www.desertmuseumdigitallibrary.org/public/detail.php?id=ASDM13685&sp=Sonoran+Desertscrub+-+Lower+Colorado+River+Valley, title=Sonoran Desertscrub – Lower Colorado River Valley by Mark A. Dimmitt :: ASDM Sonoran Desert Digital Library, website=Desertmuseumdigitallibrary.org, access-date=15 September 2018