- Source: Lower Colorado River Valley
The Lower Colorado River Valley (LCRV) is the river region of the lower Colorado River of the southwestern United States in North America that rises in the Rocky Mountains and has its outlet at the Colorado River Delta in the northern Gulf of California in northwestern Mexico, between the states of Baja California and Sonora. This north–south stretch of the Colorado River forms the border between the U.S. states of California/Arizona and Nevada/Arizona, and between the Mexican states of Baja California/Sonora.
It is commonly defined as the region from below Hoover Dam and Lake Mead to its outlet at the northern Gulf of California (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 activities from the river, the lakes created by dams, agriculture, 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 and Colorado River Indian Reservations; at Yuma are the Quechan and Cocopah reservations.
Ecology
Some of the highest air temperatures in North America are recorded in the LCRV, rivaling Death Valley; specifically Bullhead City, 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 deserts in Africa and in the Middle East are hotter. The LCRV is defined by three deserts. The Mojave Desert is in southeast California, southern Nevada, and northwest Arizona. South of the Mojave the Sonoran Desert 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. 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, and southeast Sonora state, Mexico to the northern border of neighboring Sinaloa.
The LCRV extends about 350 miles (563 km) from Hoover Dam to the Colorado River Delta. The Sonoran Desert itself is more than twice as extensive north-to-south, and about 450 miles (724 km) in width. Two species, desert ironwood and the lesser long-nosed bat, have geographic ranges identical to the Sonoran Desert, and are indicator species 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 120 °F (49 °C) 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 (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 (a subspecies of Sclerocactus johnsonii).
= Threats
=The Lower Colorado River Valley subregion of the Sonoran Desert bioregion has multiple threats. Some major threats include urbanization, 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, destruction of land by offroad vehicles, especially in sand dunes, and harvesting and manipulation of groundwater.
List of major cities and communities
Laughlin, Nevada in Clark County, Nevada
Needles, California in San Bernardino County
Bullhead City, Arizona
Mojave Valley, Arizona
Lake Havasu City, Arizona
Silver Cliffs, Arizona/California
Vidal, California
Parker, Arizona
Blythe, California
Quartzite, Arizona
Winterhaven, California in Imperial County, California
Yuma, Arizona in Yuma County, Arizona
San Luis, Arizona
San Luis Río Colorado, Sonora
Complete list of towns, areas, etc, north to south
= Feeder-valleys, or included small valleys
=References
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- Lower Colorado River Valley
- Colorado River
- Colorado River Indian Tribes
- Imperial Valley
- List of valleys of the Lower Colorado River Valley
- Course of the Colorado River
- Blythe, California
- Green River (Colorado River tributary)
- Colorado River Delta
- List of fauna of the Lower Colorado River Valley
