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 drainage basin, watershed that encompasses parts of ...

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, Ne ...

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 the Car ...

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 in ...

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 d ...

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 Ca ...

in northwestern

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, between the

state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * ''The State'' (newspaper), a daily newspaper in Columbia, South Carolina, United States * ''Our S ...

s 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 Administrative divisions of Mexico, Federal Entities of Mexico. The state is d ...

. This north–south stretch of the Colorado River forms the border between the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

s of

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

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 Se ...

and

Lake Mead Lake Mead is a reservoir formed by the Hoover Dam on the Colorado River in the Southwestern United States. It is located in the states of Nevada and Arizona, east of Las Vegas. It is the largest reservoir in the US in terms of water capacity. ...

to its outlet at the northern

(Sea of Cortez); it includes the Colorado River proper, canyons, the valley, mountain ranges with

wilderness area Wilderness or wildlands (usually in the plural), are natural environments on Earth that have not been significantly modified by human activity or any nonurbanized land not under extensive agricultural cultivation. The term has traditionally re ...

s, and the floodplain and associated

riparian A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks ar ...

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 pleasur ...

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 wate ...

, 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

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...

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 to ...

, 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,

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 Reservation The Colorado River Indian Tribes (Mojave language 'Aha Havasuu, Navajo language: Tó Ntsʼósíkooh Bibąąhgi Bitsįʼ Yishtłizhii Bináhásdzo) is a federally recognized tribe consisting of the four distinct ethnic groups associated with the C ...

s; 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 the ...

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 Highest temperature recorded on Earth, hottest place on Earth. Death Valley's Badwater Basin is the ...

; 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 em ...

Lake Havasu City Lake Havasu City (, ) is a city in Mohave County, Arizona, United States. As of the 2020 census, the population of the city was 57,144, up from 52,527 in 2010. It is served by Lake Havasu City Airport. History The community first started as an ...

, 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 in ...

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 Arizona ...

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 De ...

. 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

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 Administrative divisions of Mexico, Federal Entities of Mexico. It is d ...

. The LCRV extends about from Hoover Dam to 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 ''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 t ...

'') 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 sma ...

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 ''Larrea tridentata'', called creosote bush and greasewood as a plant, chaparral as a medicinal herb, and ''gobernadora'' (Spanish language, Spanish for "governess") in Mexico, due to its ability to secure more water by inhibiting the growth of n ...

'' (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 t ...

, 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 ...

, ''

'', destruction of land by

offroad vehicle An off-road vehicle, sometimes referred to as an overland or adventure vehicle, is considered to be any type of vehicle which is capable of driving on and off paved or gravel surface. It is generally characterized by having large tires with dee ...

s, 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, fl ...

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 Clark County is located in the U.S. state of Nevada. As of the 2020 census, the population was 2,265,461. Most of the county population resides in the Las Vegas Census County Divisions, which hold 1,771,945 people as of the 2010 Census, across ...

* Needles, California in

San Bernardino County San Bernardino County (), officially the County of San Bernardino, is a county located in the southern portion of the U.S. state of California, and is located within the Inland Empire area. As of the 2020 U.S. Census, the population was 2,181, ...

, Arizona *

Mojave Valley Mojave or Mohave most often refers to: *Mojave Desert *Mojave River *Mohave people *Mojave language Mojave or Mohave may also refer to: Places * Fort Mojave Indian Reservation * Mohave County, Arizona * Mohave Valley, a valley in Arizona * Moh ...

, Arizona *

, Arizona * Silver Cliffs, Arizona/California *

Vidal Vidal (, , , ) is a Catalan, Aragonese, and possibly also Romansh surname, which also appears in French, Italian, Portuguese and English, and as a given name. Vidal may refer to: Surname * Maurice Vidal Portman (1850–1935), a British doct ...

, California *

Parker Parker may refer to: Persons * Parker (given name) * Parker (surname) Places Place names in the United States *Parker, Arizona *Parker, Colorado * Parker, Florida * Parker, Idaho * Parker, Kansas * Parker, Missouri * Parker, North Carolina *Park ...

, 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 tect ...

, Arizona * Winterhaven, California in

Imperial County, California Imperial County is a County (United States), county on the southeast border of the U.S. state of California. As of the 2020 United States Census, 2020 census, the population was 179,702, making it the least populous county in Southern Californi ...

* 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 bor ...

* 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 Lake Mohave is a reservoir on the Colorado River between the Hoover Dam and Davis Dam in Cottonwood Valley defining the border between Nevada and Arizona in the United States. This 67 mile stretch of the Colorado River flows past Boulder City, ...

* Laughlin–

* Needles– Mohave Valley, AZ *

Sacramento Mountains The Sacramento Mountains are a mountain range in the south-central part of the U.S. state of New Mexico, lying just east of Alamogordo in Otero County (small portions of the range lie in Lincoln County and Chaves County). From north to south, ...

Chemehuevi Mountains The Chemehuevi Mountains are found at the southeast border of San Bernardino County in southeastern California adjacent the Colorado River. Located south of Needles, California and northwest of the Whipple Mountains, the mountains lie in a nor ...

Chemehuevi Valley The Chemehuevi are an indigenous people of the Great Basin. They are the southernmost branch of Southern Paiute.Whipple Mountains The Whipple Mountains ( Mojave: Avii Kur'utat; Chemehuevi: Wiyaatuʷa̱) are located in eastern San Bernardino County, California. They are directly west of the Colorado River, Parker Dam, and Lake Havasu; south of Needles, California; north of ...

* Earp * Big River *

–Quartzsite * Winterhaven– Yuma *

Los Algodones Los Algodones is a city in Mexicali Municipality, Baja California. Located on the United States-Mexico border, Los Algodones is south of Andrade, California and west of Yuma, Arizona. It reported a population of 5,474 as of the 2010 Mexican census ...

, Baja California *

(at Gulf of California) Arizona–Sonora side * Willow Beach, Arizona *

* 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 St ...

* 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 refug ...

Bill Williams River The Bill Williams River is a river in west-central Arizona where it, along with one of its tributaries, the Santa Maria River (Arizona), Santa Maria River, form the boundary between Mohave County, Arizona, Mohave County to the north and La Paz C ...

* Earp–

Quartzsite Quartzsite is a town in La Paz County, Arizona, United States. According to the 2020 census, the population was 2,413. Interstate 10 runs directly through Quartzsite which is at the intersection of U.S. Route 95 and Arizona State Route 95 wi ...

, in

La Paz County, Arizona La Paz County is the 15th county in the U.S. state of Arizona, located in the western part of the state. As of the 2020 census, its population was 16,557, making it the second-least populous county in Arizona. The county seat is Parker. Th ...

* Ehrenberg * Cibola * Yuma in

, Sonora *

(at Gulf of California)

Feeder-valleys, or included small valleys

Nevada–California–Baja California side *

Eldorado Valley Eldorado Valley, or El Dorado Valley, is a Great Basin valley in the Mojave Desert southeast of Las Vegas and southwest of Boulder City, Nevada. The valley is endorheic, containing the Eldorado Dry Lake. The Great Basin Divide, transects ridgelines ...

–(

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 The Piute Valley is a north–south valley southeast of Las Vegas, Nevada, and northwest of Needles. The north of the valley is at Searchlight, with some of the valley extending northwest from Searchlight. At the center-north lies Cal-Nev-Ari, ...

* Laughlin–

* Needles– Mohave 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) *

Vidal Valley Vidal Valley is a 20-mile (32 km) long valley in the far eastern Colorado Desert bordering the Colorado River. Most of the valley is in eastern San Bernardino County, California, but the outfall on the Colorado River is in northeast Riverside ...

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 (Ca ...

–(included) *

Palo Verde Valley The Palo Verde Valley (Spanish: ''Valle de Palo Verde'') is located in the Lower Colorado River Valley, next to the eastern border of Southern California with Arizona, United States. It is located on the Colorado Desert within the Sonoran Desert ...

–(included) *

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 val ...

–(

Sacramento Wash The Sacramento Wash is a major drainage of northwest Arizona in Mohave County. The wash is east of the Black Canyon of the Colorado and drains into the south-flowing Colorado River 45 mi south of Lake Mohave, and 90 mi south of Hoover D ...

) *

–(included) * (east of Whipple Mtns

massif In geology, a massif ( or ) is a section of a planet's crust that is demarcated by faults or flexures. In the movement of the crust, a massif tends to retain its internal structure while being displaced as a whole. The term also refers to a ...

)–

–(Arizona) ** Maria fold and thrust belt Region *

–(included)—

La Posa Plain The La Posa Plain is a wide, generally flat plain in western Arizona near the Colorado River and is on the west and northwest border of the Kofa National Wildlife Refuge. The plain lies to the east of the Colorado River Indian Reservation and east ...

Ehrenberg, Arizona Ehrenberg, also historically spelled "Ehrenburg", is an unincorporated community and census-designated place (CDP) in La Paz County, Arizona, United States. The population was 1,470 at the 2010 census. Ehrenberg is named for its founder, Herman ...

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 southw ...

Yuma Valley Yuma can refer to: Places * Yuma Desert, desert in southwest U.S. and northwest Mexico ;United States * Yuma County, Arizona ** Yuma, Arizona ** Fortuna Foothills, Arizona ** Marine Corps Air Station Yuma ** United States Army Yuma Proving Ground ...

–(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 ...

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