The San Bernardino Mountains are a high and rugged

mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arise ...

Southern California Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most po ...

in the United States. Situated north and northeast of

San Bernardino San Bernardino (; Spanish for "Saint Bernardino") is a city and county seat of San Bernardino County, California, United States. Located in the Inland Empire region of Southern California, the city had a population of 222,101 in the 2020 cen ...

and spanning two California counties, the range tops out at at San Gorgonio Mountain – the tallest peak in all of Southern California. The San Bernardinos form a significant region of wilderness and are popular for hiking and

ski A ski is a narrow strip of semi-rigid material worn underfoot to glide over snow. Substantially longer than wide and characteristically employed in pairs, skis are attached to ski boots with ski bindings, with either a free, lockable, or partia ...

ing. The mountains were formed about eleven million years ago by tectonic activity along the

San Andreas Fault The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizonta ...

, and are still actively rising. Many local rivers originate in the range, which receives significantly more precipitation than the surrounding desert. The range's unique and varying environment allows it to maintain some of the greatest biodiversity in the state. For over 10,000 years, the San Bernardinos and their surroundings have been inhabited by indigenous peoples, who used the mountains as a summer hunting ground.

Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Can ...

explorers first encountered the San Bernardinos in the late 18th century, naming the eponymous

San Bernardino Valley The San Bernardino Valley ( es, Valle de San Bernardino) is a valley in Southern California located at the south base of the Transverse Ranges. It is bordered on the north by the eastern San Gabriel Mountains and the San Bernardino Mountains; ...

at its base. European settlement of the region progressed slowly until 1860, when the mountains became the focus of the largest gold rush ever to occur in Southern California. Waves of settlers brought in by the gold rush populated the lowlands around the San Bernardinos, and began to tap the mountains' rich timber and water resources on a large scale by the late 19th century. Recreational development of the range began in the early 20th century, when mountain resorts were built around new irrigation reservoirs. Since then, the mountains have been extensively engineered for transportation and water supply purposes. Four major

state highways A state highway, state road, or state route (and the equivalent provincial highway, provincial road, or provincial route) is usually a road that is either ''numbered'' or ''maintained'' by a sub-national state or province. A road numbered by a ...

and the

California Aqueduct The Governor Edmund G. Brown California Aqueduct is a system of canals, tunnels, and pipelines that conveys water collected from the Sierra Nevada Mountains and valleys of Northern and Central California to Southern California. Named after Califo ...

traverse the mountains today; these developments have all had significant impacts on area wildlife and plant communities.

Geography and climate

The San Bernardinos run for approximately from

Cajon Pass Cajon Pass (; Spanish: ''Puerto del Cajón'' or ''Paso del Cajón'') is a mountain pass between the San Bernardino Mountains to the east and the San Gabriel Mountains to the west in Southern California. Created by the movements of the San Andr ...

in the northwest – which separates them from the

San Gabriel Mountains The San Gabriel Mountains ( es, Sierra de San Gabriel) are a mountain range located in northern Los Angeles County, California, Los Angeles County and western San Bernardino County, California, United States. The mountain range is part of the Tr ...

– to

San Gorgonio Pass The San Gorgonio Pass, or Banning Pass, is a elevation gap on the rim of the Great Basin between the San Bernardino Mountains to the north and the San Jacinto Mountains to the south. The pass was formed by the San Andreas Fault, a major tra ...

, across which lie the

San Jacinto Mountains The San Jacinto Mountains (''Avii Hanupach''Munro, P., et al. ''A Mojave Dictionary''. Los Angeles: UCLA. 1992. in Mojave) are a mountain range in Riverside County, located east of Los Angeles in southern California in the United States. The mou ...

, in the southeast. The Morongo Valley in the southeast divides the range from the

Little San Bernardino Mountains 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 southeast from the San Bernardino Mountains through San Bernardino an ...

. Encompassing roughly , the mountains lie mostly 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, ...

, with a small southern portion reaching into

Riverside County Riverside County is a county located in the southern portion of the U.S. state of California. As of the 2020 census, the population was 2,418,185, making it the fourth-most populous county in California and the 10th-most populous in the Uni ...

. The range divides three major physiographic regions: the highly urbanized Inland Empire to the southwest, the Coachella Valley in the southeast, and 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 ...

to the north. Most of the range lies within the boundaries of the

San Bernardino National Forest The San Bernardino National Forest is a United States National Forest in Southern California encompassing of which are federal. The forest is made up of two main divisions, the eastern portion of the San Gabriel Mountains and the San Bernard ...

. From its northwestern end, the crest of the mountains rises steadily until they are interrupted by the gorge of Bear Creek. The northern part of the San Bernardinos is a large upland plateau characterized by a series of extensive subalpine basins, including Big Bear Valley, and is home to several large water supply reservoirs. South of the Big Bear area the range is cut by the Santa Ana Canyon, the broad valley of the

Santa Ana River The Santa Ana River is the largest river entirely within Southern California in the United States. It rises in the San Bernardino Mountains and flows for most of its length through San Bernardino and Riverside Counties, before cutting through ...

, and rises dramatically to culminate at Mount San Gorgonio and eleven other peaks that exceed in elevation. The mountains feature a steep drop into the Coachella Valley and San Gorgonio Pass – the latter of which is one of the deepest mountain passes in the United States, exceeding the

Grand Canyon The Grand Canyon (, yuf-x-yav, Wi:kaʼi:la, , Southern Paiute language: Paxa’uipi, ) is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is long, up to wide and attains a depth of over a m ...

's depth by over . Many cities lie at the base of the San Bernardino Mountains. These include San Bernardino, Redlands and Yucaipa in the south;

Yucca Valley Yucca Valley is an incorporated town in San Bernardino County, California, United States. The population was 20,700 as of the 2010 census. Yucca Valley lies west of Twentynine Palms, north of Palm Springs, south of Barstow via State Route ...

to the east; and Hesperia to the northwest. In addition, there are several mid-sized to large towns in the mountains themselves, including Big Bear Lake,

Big Bear City Big Bear City is an unincorporated community in San Bernardino County, California, United States along the east shore of Big Bear Lake and surrounded by the San Bernardino National Forest. It is northeast of the city of San Bernardino, and imme ...

, Crestline, Lake Arrowhead and Running Springs. Cities within the San Bernardino Mountains total a population of about 44,000, with this number sometimes increasing tenfold during peak tourist season. Several regional streams and rivers also have their

headwaters The headwaters of a river or stream is the farthest place in that river or stream from its estuary or downstream confluence with another river, as measured along the course of the river. It is also known as a river's source. Definition The ...

in the mountains. The principal drainage is provided by the Santa Ana River, which runs westwards into the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

Orange County Orange County most commonly refers to: *Orange County, California, part of the Los Angeles metropolitan area Orange County may also refer to: U.S. counties *Orange County, Florida, containing Orlando *Orange County, Indiana *Orange County, New ...

. Other streams flowing off the mountains include the Whitewater River, flowing southeast through the Coachella Valley into the

Salton Sea 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 ...

, and the

Mojave River The Mojave River is an intermittent river in the eastern San Bernardino Mountains and the Mojave Desert in San Bernardino County, California, United States. Most of its flow is underground, while its surface channels remain dry most of the time, ...

, which drains northwards into the Mojave Desert. The San Bernardino Mountains (along with the adjacent San Gabriel and San Jacinto Mountains) are a humid island in the mostly semi-arid southern California coastal plain. Parts of the San Bernardino Mountains have annual precipitation totals in excess of 40 inches (e.g. Lake Arrowhead and Barton Flats areas), and provide an important water resource for the coastal plain below. Most of the precipitation falls between November and March; summers are mostly dry except for infrequent thunderstorms during late summer. During the colder winter storms, snow can fall above 2,000 feet, but most usually falls above 3,500 feet. Ski resorts (mostly in the Big Bear area) capitalize on this snowfall, the most reliable south of the Sierra Nevada Mountains.

Geology

The San Bernardinos are part of the

Transverse Ranges The Transverse Ranges are a group of mountain ranges of southern California, in the Pacific Coast Ranges physiographic region in North America. The Transverse Ranges begin at the southern end of the California Coast Ranges and lie within Santa ...

of Southern California, a mountain chain formed by tectonic forces between the

North American 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 Ca ...

and

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

Plates along the

. An early version of the range rose in the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

, between eleven and five million years ago, but has largely eroded. The range was shaped into its present form during the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

epoch beginning approximately two million years ago, with regional uplift continuing to the present. The rocks that make up the mountains are much more ancient than the mountains themselves – ranging from 18 million years to 1.7 billion years old. The San Andreas Fault was also responsible for the formation of both major mountain passes that mark the east and west ends of the range. These mountains are shaped by several primary tectonic or fault blocks – the Big Bear block, which forms the large montane plateau that characterizes the northern portions of the range; and the more complex and fractured San Gorgonio, Wilson Creek and Yucaipa Ridge blocks, which form the rugged and heavily dissected southern parts of the mountains. Because of their large, steep rise above the surrounding terrain, the San Bernardinos have been subject to great amounts of erosion that have carved out numerous river gorges. Rocks and sediment from the mountains are deposited on the surrounding valley floors as massive

alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...

s. Regional alluvial deposits can reach depths of or more, and their permeable soils constitute several major

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...

basins.

History

Indigenous peoples

Archaeological discoveries in the San Bernardino Valley suggest that humans have populated the region for at least 10,000-12,000 years. Several Native American groups held the lands surrounding the San Bernardinos. These included the

Tongva The Tongva ( ) are an Indigenous people of California from the Los Angeles Basin and the Southern Channel Islands, an area covering approximately . Some descendants of the people prefer Kizh as an endonym that, they argue, is more historically ...

, who occupied the Inland Empire area southwest of the mountains; the

Cahuilla The Cahuilla , also known as ʔívil̃uqaletem or Ivilyuqaletem, are a Native American people of the various tribes of the Cahuilla Nation, living in the inland areas of southern California.Serrano and Chemehuevi peoples, whose territory comprised land north and northeast of the San Bernardinos, adjacent to the Mojave Desert. Most of these tribes did not have permanent settlements in the mountains, with the possible exception of a few groups of Serrano.Robinson and Harris, p. 32 Indigenous peoples traveled into the mountains in the summer to hunt deer and rabbits, gather acorns, berries and nuts, and seek refuge from the desert heat. They established well-traveled trade routes, some of which were later used by Europeans to explore and settle the region. The precipitous

Mojave Road The Mojave Road, also known as Old Government Road (formerly the Mohave Trail), is a historic route and present day dirt road across what is now the Mojave National Preserve in the Mojave Desert in the United States. This rough road stretched f ...

(or Mojave Trail) crested the San Bernardinos east of Cajon Pass and permitted trade between people of the Inland Empire basin and the Mojave Desert. San Gorgonio Pass, which forms the largest natural break in the Transverse Ranges, also allowed interaction between coastal and desert tribes. River canyons, especially those of the Mojave and Santa Ana, provided the major means of entry to the mountains. Many archaeological sites have been discovered along Deep Creek, a tributary of the Mojave River, in particular.

Explorers and early settlers

During the 17th and 18th centuries, various Spanish explorers passed through coastal Southern California and claimed the area for Spain. In 1769, the Spanish government began an effort to bring what they called Alta California under their control and introduce Christianity to native peoples through the construction of missions. It was not until 1772 when the military governor of Alta California, Pedro Fages, became the first European known to reach the San Bernardino Mountains. Although the original purpose of his expedition was to pursue deserters from the Spanish army, he ended up venturing into not just the San Bernardinos but also the San Jacinto Mountains, the Mojave Desert, and eventually north into the Central Valley. San Bernardino Valley

The San Bernardinos and their surrounds were sporadically explored throughout the next 50 years or so - first by

Francisco Garcés Francisco Hermenegildo Tomás Garcés (April 12, 1738 – July 18, 1781) was a Spanish Franciscan friar who served as a missionary and explorer in the colonial Viceroyalty of New Spain. He explored much of the southwestern region of North Am ...

, the first known European to use the Mojave Road, in 1776, followed by José Maria de Zalvidea, who surveyed the Mojave River area in 1806. In 1810,

Francisco Dumetz Francisco Dumetz (died 14 January 1811) was a Spanish Franciscan missionary. He gave the San Bernardino Valley in California its name, in 1810. Life He was a native of Majorca, Spain, where he entered the Franciscan Order. In May, 1770, he went t ...

led a small company to build a temporary chapel near what is now Redlands. On May 20, the Feast Day of

Bernardino of Siena Bernardino of Siena, OFM (8 September 138020 May 1444), also known as Bernardine, was an Italian priest and Franciscan missionary preacher in Italy. He was a systematizer of Scholastic economics. His preaching, his book burnings, and his " bon ...

, Dumetz named the San Bernardino Valley. This name was applied to San Bernardino Peak by 1835, and was in wide use for the entire range by 1849. In 1819,

San Bernardino de Sena Estancia The San Bernardino de Sena Estancia (also known as the San Bernardino Rancho or Asistencia) was a ranch outpost of Mission San Gabriel Arcángel in what is now in Redlands, California, United States. It was built to graze cattle, and for Indian ...

was created near present-day San Bernardino as an outpost of nearby Mission San Gabriel Arcángel. Although sometimes referred to as an ''asistencia'', or "a mission on a small scale with all the requisites for a mission, and with Divine Service held regularly on days of obligation, except that it lacked a resident priest", San Bernardino was really just an ''estancia'', or cattle ranch. In 1820, a -long irrigation ditch or "zanja" was dug using Native American labor to furnish water from Mill Creek, a major stream flowing out of the San Bernardinos, to the estancia and surrounding croplands. For the next twenty years, the Spanish – then the '' Californios'' under newly independent Mexico – practiced agriculture and ranching at the foot of the mountains. The high country of the San Bernardinos remained largely unexplored until 1845, when Benjamin D. Wilson led a party of 22 men from a rancho near present-day

Riverside Riverside may refer to: Places Australia * Riverside, Tasmania, a suburb of Launceston, Tasmania Canada * Riverside (electoral district), in the Yukon * Riverside, Calgary, a neighbourhood in Alberta * Riverside, Manitoba, a former rural m ...

to catch several Mohave cattle rustlers who had fled into the mountains. Wilson was the first recorded European to see the Big Bear Valley, and named Bear Lake (today's Baldwin Lake) for the abundance of

California grizzly The California grizzly bear (''Ursus arctos californicus'') is an extinct population or subspecies of the brown bear, generally known (together with other North American brown bear populations) as the grizzly bear. "Grizzly" could have meant "gri ...

in the area. The party captured and skinned more than twenty bears. Later, they found and arrested the rustlers, who were hiding along the Mojave River. Wilson's expedition opened the interior of the San Bernardinos to later exploration, and discouraged Native Americans such as the Mohave from staging similar raids over the mountains. Mill Creek drainage, San Bernardino National Forest

Mill Creek drainage, San Bernardino National Forest

Beginning in 1851,

Mormon Mormons are a religious and cultural group related to Mormonism, the principal branch of the Latter Day Saint movement started by Joseph Smith in upstate New York during the 1820s. After Smith's death in 1844, the movement split into several ...

colonists began emigrating to the San Bernardino Valley. The Mormons bought and subsequently split up

Rancho San Bernardino Rancho San Bernardino was a Mexican land grant in present-day San Bernardino County, California given in 1842 by Governor Juan B. Alvarado to José del Carmen Lugo, José María Lugo, Vicente Lugo, and Diego Sepulveda. The grant included a la ...

, and greatly improved the area's agricultural production by bringing in thousands of head of livestock and overhauling the local irrigation network. In order to obtain lumber for their settlements, they also began the first large-scale logging operations in the San Bernardino Mountains, starting in the Mill Creek valley. Luis Vignes built the first sawmill in the range sometime between 1851 and 1853. By 1854, six lumber mills were in operation in the mountains, some as high as the crest of the range three-quarters of a mile above San Bernardino, accessed by a twisting road through Waterman Canyon. Some of these mills were driven by waterwheels, although most were steam powered. Prospectors William F. Holcomb and Ben Choteau's 1860 discovery of gold on Holcomb Creek kicked off a flood of gold seekers to the San Bernardino Mountains. Mining boomtowns, including Belleville, Clapboard Town, Union Town, Bairdstown and Doble, were established almost overnight. Belleville even exceeded the population of San Bernardino itself for a short time and narrowly lost to the latter city for election as the county seat. Numerous mills and processing plants were constructed in the area, which became known as Holcomb Valley. In 1873, Eli "Lucky" Baldwin built California's largest stamp mill in Holcomb Valley. Although another major gold strike was made in that same year, area deposits petered out by the 1880s, and the mountains were quickly depopulated, with most of the miners settling down in the San Bernardino Valley and the Mojave Desert near present-day Hesperia. Many structures built by miners, including chutes, sluices and a few cabins, can still be found in the area today.

Reservoirs and recreation

In 1880, Frank Elwood Brown designed the first dam in the Big Bear Valley, forming Big Bear Lake – the world's largest artificial reservoir at the time – to supply water to citrus farms around San Bernardino. By 1910, a new dam had been built, increasing the size of the lake threefold. An unintended effect of the lake was to dramatically increase tourism in the San Bernardino Mountains, and its shores were developed with lodges and visitor facilities by the 1920s. The old logging camp of Big Bear Lake was expanded to accommodate increasing numbers of tourists from all over Southern California. Originally proposed in 1891 by the Arrowhead Reservoir and Power Company – and reportedly inspired by the success of the Big Bear Lake project – Lake Arrowhead was to be one of a series of three reservoirs that would divert water draining off the northwestern San Bernardino Mountains into the San Bernardino Valley, and furnish water to a 260 KW hydroelectric plant. Although the project was never completed to full extent, Arrowhead became one of the most popular fishing destinations in Southern California. In the early 20th century, John Baylis built the Pinecrest Resort on Lake Arrowhead. This was followed by several other tourist developments, including the Skyland Inn and Thousand Pines Camp. Most early tourists arrived by stagecoach, though in time the old Mormon logging road through Waterman Canyon was overhauled, allowing for the passage of automobiles. Lake Arrowhead 1

Development of resorts also proliferated on rivers and high mountain valleys. The Seven Oaks Camp was established on the banks of the Santa Ana River in 1890, and resorts also grew up at Crestline and Running Springs in higher regions of the San Bernardino Mountains. Snow in the San Bernardinos was seen as an obstacle before the 1920s and practically shut down recreation in the winter. However, more and more Southern Californians braved the dangers of winter travel in the mountains, and Lake Arrowhead became a sought-after winter destination by the 1930s. Skiing did not become a popular recreational activity in the mountains until a simple sling lift was built at Big Bear in 1938. By 1949, a -long chair lift was built, hugely increasing the amount of skiers the area's resorts could accommodate. Known as the Lynn Lift, it operated until 1970, but was demolished in 1981 due to its limited capacity. Tommi Tyndall, who founded ski schools at Big Bear, Mill Creek,

Snow Summit Snow Summit is a ski resort that was established in 1952 and is in the San Bernardino Mountains in Southern California. It is located by Big Bear Lake along with its sister resort Bear Mountain; these two resorts which operate under the same man ...

and

Sugarloaf Mountain Sugarloaf Mountain ( pt, Pão de Açúcar, ) is a peak situated in Rio de Janeiro, Brazil, at the mouth of Guanabara Bay on a peninsula that juts out into the Atlantic Ocean. Rising above the harbor, the peak is named for its resemblance to ...

, is widely credited for introducing and later advocating the sport in the San Bernardino Mountains, as well as for bringing

snowmaking Snowmaking is the production of snow by forcing water and pressurized air through a "snow gun", also known as a "snow cannon". Snowmaking is mainly used at ski resorts to supplement natural snow. This allows ski resorts to improve the reliabilit ...

technology, without which the present-day ski industry would be severely crippled during dry winters.

Infrastructure

Transportation

During the early 20th century, the roads that serviced the San Bernardino Mountains were steep and narrow, and conflicts occurred between those who believed that the automobile could provide fast and cheap transportation up the steep grades of the mountains, and those who worried that cars were dangerous and would cause accidents with the stagecoaches then in use. In 1908, W.C. Vaughan drove up the Waterman Canyon road to Lake Arrowhead in protest of county restrictions, with police in hot pursuit. In spite of a total ban on automobiles imposed by the county the following year, Jack Heyser took a car down the narrow stage roads around modern-day Crestline in 1910, proving that the mountains could be safely serviced by automobiles.Hatheway, p. 27 From hwy 38 sugarloaf mt

By 1911, cars had largely replaced horse-drawn carts as the primary mode of transport in the mountains, and new toll roads were constructed through the range to service them. Among the first were roads through Cajon Pass, City Creek Canyon ( SR 330), and Mill Creek and Santa Ana Canyons ( SR 38). The largest and most famous road through the San Bernardinos –

California State Route 18 State Route 18 (SR 18) is a state highway in the U.S. state of California. It serves as a primary route into the San Bernardino Mountains, both from the Riverside–San Bernardino metropolitan area from the south and the Mojave Desert from the n ...

, more popularly known as the Rim of the World Highway for as it winds through the mountains – was dedicated on July 18, 1915. Traveling from Crestline through Big Bear City and north into the Mojave Desert, the Rim of the World Highway is one of the most spectacular roads in Southern California, affording motorists wide views of the San Bernardino Valley, Santa Ana Canyon, and Big Bear Lake.

Water management

In the late 1950s, work began on the

, a massive system of canals and pipelines designed to bring water from Northern California to growing cities in the parched south. The East Branch of the aqueduct passes over the San Bernardino Mountains through a complex arrangement of pumping stations, reservoirs and power stations. The aqueduct feeds

Silverwood Lake Silverwood Lake is a large reservoir in San Bernardino County, California, United States, located on the West Fork Mojave River, a tributary of the Mojave River in the San Bernardino Mountains. It was created in 1971 as part of the State Water Pr ...

, a large reservoir created by the construction of a dam on the northern flank of the San Bernardinos in 1973. From Silverwood, the water passes through the mountains via the San Bernardino Tunnel, and drops down to the Devil Canyon Power Plant in the San Bernardino Valley, using the enormous hydraulic head afforded by the mountains to generate up to 276 MW of power. The streams of the San Bernardino Mountains are also prone to flash floods, a danger that has prompted the construction of numerous flood control dams throughout the range. The largest of these is Seven Oaks Dam – the sixth highest dam in the United States – on the Santa Ana River. In 1969, the

U.S. Army Corps of Engineers , colors = , anniversaries = 16 June (Organization Day) , battles = , battles_label = Wars , website = , commander1 = ...

deemed the Santa Ana the greatest flood threat in the United States west of the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...

because of its course through heavily developed areas. Completed in 1999, the dam is designed to completely contain a 350-year flood. Many other dams, including Mojave Forks Dam on the Mojave River and various

retention basin A retention basin, sometimes called a wet pond, wet detention basin, or stormwater management pond (SWMP), is an artificial pond with vegetation around the perimeter and a permanent pool of water in its design. It is used to manage stormwater r ...

s and

check dam A steel check dam A check dam is a small, sometimes temporary, dam constructed across a swale, drainage ditch, or waterway to counteract erosion by reducing water flow velocity. Check dams themselves are not a type of new technology; rather, th ...

s on smaller drainages, provide more localized flood and sediment control.

Ecology and wildlife

The San Bernardino Mountains, along with the nearby San Gabriel and San Jacinto ranges, is considered a

sky island Sky islands are topographic isolation, isolated mountains surrounded by radically different lowland environments. The term originally referred to those found on the Mexican Plateau, and has extended to similarly isolated montane ecosystems, hi ...

– a high mountain region whose plants and animals vary dramatically from those in the surrounding semi-arid lands. The San Bernardinos in particular comprise the largest forested region in Southern California, and support some 1,600 species of plants. Foothill regions are primarily composed of

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...

and evergreen oak woodland communities, with a transition to forests of deciduous oak,

yellow pine In ecology and forestry, yellow pine refers to a number of conifer species that tend to grow in similar plant communities and yield similar strong wood. In the Western United States, yellow pine refers to Jeffrey pine or ponderosa pine. In the ...

Jeffrey pine ''Pinus jeffreyi'', also known as Jeffrey pine, Jeffrey's pine, yellow pine and black pine, is a North American pine tree. It is mainly found in California, but also in the westernmost part of Nevada, southwestern Oregon, and northern Baja Califo ...

incense cedar ''Calocedrus'', the incense cedar (alternatively spelled incense-cedar), is a genus of coniferous trees in the cypress family Cupressaceae first described as a genus in 1873. It is native to eastern Asia and western North America. The generi ...

and several fir species at elevations above . Deeper within the mountains, perennial streams fed by springs and lakes nourish stands of

alder Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...

willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...

s and cottonwoods. About 440 species of wildlife inhabit the mountains, including many endangered species such as the San Bernardino flying squirrel,

California Spotted Owl The spotted owl (''Strix occidentalis'') is a species of true owl. It is a resident species of old-growth forests in western North America, where it nests in tree hollows, old bird of prey nests, or rock crevices. Nests can be between high and u ...

Mountain yellow-legged frog The mountain yellow-legged frog (''Rana muscosa''), also known as the southern mountain yellow-legged frog, is a species of true frog endemic to California in the United States. It occurs in the San Jacinto Mountains, San Bernardino Mountains, a ...

, Southern rubber boa, and Andrew's marbled butterfly. The mountains once had an abundant population of California grizzly, but hunting eliminated their populations by 1906.Keller, p. 9

Black bear Black bear or Blackbear may refer to: Animals * American black bear (''Ursus americanus''), a North American bear species * Asian black bear (''Ursus thibetanus''), an Asian bear species Music * Black Bear (band), a Canadian First Nations group ...

s roam the highlands today, but they are not native to the region: they were imported from the

Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily ...

by the

California Department of Fish and Game The California Department of Fish and Wildlife (CDFW), formerly known as the California Department of Fish and Game (CDFG), is a state agency under the California Natural Resources Agency. The Department of Fish and Wildlife manages and protec ...

in the 1930s, in part to attract tourists to the mountains.

References

Works cited

* * * * * * * * * * * * * * * * *

External links

Restoring the San Bernardino Mountains

San Bernardino Mountains at SummitPostSan Bernardino National ForestSan Gorgonio Wilderness Association
{{Authority control Transverse Ranges Mountain ranges of Southern California Mountain ranges of the Mojave Desert Mountain ranges of San Bernardino County, California