
The Santa Ana River is the largest river entirely within
Southern California
Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural List of regions of California, region that generally comprises the southern portion of the U.S. state of California. Its densely populated coastal reg ...
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 the northern
Santa Ana Mountains
The Santa Ana Mountains are a short peninsular mountain range along the coast of Southern California in the United States. They extend for approximately southeast of the Los Angeles Basin largely along the border between Orange and Riversid ...
via
Santa Ana Canyon and flowing southwest through urban
Orange County to drain into the Pacific Ocean. The Santa Ana River is long,
[U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data]
The National Map
accessed March 16, 2011 and its
drainage basin
A drainage basin is an area of land in which all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...
is in size.
The Santa Ana drainage basin has a diversity of terrain, ranging from high peaks of inland mountains in the north and east, to the hot, dry interior and semidesert basins of the
Inland Empire, to the flat coastal plain of Orange County. Although it includes areas of
alpine and highland forest, the majority of the watershed consists of arid desert and
chaparral
Chaparral ( ) is a shrubland plant plant community, community found primarily in California, southern Oregon, and northern Baja California. It is shaped by a Mediterranean climate (mild wet winters and hot dry summers) and infrequent, high-intens ...
environments. Due to low regional rainfall, the river carries only a small flow except during the brief winter season, when it is prone to massive
flash floods. The
San Jacinto River, which drains the southern half of the watershed, rarely reaches the Santa Ana except in extremely wet years. A wide variety of animal and plant communities depend on the
riparian zone
A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripari ...
s and remnant wetlands along the Santa Ana River.
Humans have lived on the Santa Ana River for at least 9,000 years. The villages of
Lupukngna,
Genga,
Pajbenga,
Totpavit, and
Hutuknga were located along the river.
The river was first seen by Europeans in 1769, when it received its name from members of the Spanish
Portola expedition. Because it was one of the only reliable sources of water in a wide region, many large
ranchos developed along the river and one of its major tributaries,
Santiago Creek. After the area became part of the United States, the economy transitioned to agriculture, before urbanizing in the 20th century. Many cities established during this time including
Santa Ana,
Riverside and
Anaheim derived their names from the river. In order to protect urban areas from the river's flood threat, major
channelization and
damming projects were undertaken, resulting in the loss of much of the natural river channel.
Course
The Santa Ana River rises in the southern
San Bernardino Mountains, at the
confluence
In geography, a confluence (also ''conflux'') occurs where two or more watercourses join to form a single channel (geography), channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river (main ...
of two tiny streams, Heart Bar Creek and Coon Creek, at an elevation of . Its highest
sources
Source may refer to:
Research
* Historical document
* Historical source
* Source (intelligence) or sub source, typically a confidential provider of non open-source intelligence
* Source (journalism), a person, publication, publishing institute ...
are Dollar Lake, at , and Dry Lake, at , both on the northern flank of
San Gorgonio Mountain, at the headwaters of the South Fork Santa Ana River. The river flows west through a wide, deep and heavily forested mountain valley. About from its headwaters, it receives its first major tributary,
Bear Creek, which enters from the north. Bear Creek receives its water from
Big Bear Lake, a popular recreational mountain lake. The river turns south, passing through the
Seven Oaks Dam, and reaches the arid Inland Empire lowland covering large parts of
San Bernardino County and
Riverside County. It receives
Mill Creek from the south and passes to the south of
San Bernardino, then receives
City Creek from the north and
San Timoteo Creek from the south. Due to water diversions for
groundwater recharge, the river bed is usually dry in this stretch between Mill Creek and the outlet of the Veolia water treatment plant north of
Riverside, which restores a year-round flow. From there to
Prado Dam the river supports a
riparian zone
A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripari ...
with considerable greenery.
Not far below the confluence with San Timoteo Creek,
Lytle Creek enters from the north. Lytle Creek is one of the largest tributaries of the Santa Ana river, rising from three forks in the San Gabriel Mountains and flowing southeast, before emptying into the Santa Ana River as Lytle Creek Wash. From there, the river turns southwest, and after passing through western
Riverside, it discharges into the normally dry
flood control
Flood management or flood control are methods used to reduce or prevent the detrimental effects of flood waters. Flooding can be caused by a mix of both natural processes, such as extreme weather upstream, and human changes to waterbodies and ru ...
reservoir formed by
Prado Dam. Two major tributaries of the river join in the reservoir area:
Chino Creek from the north, and
Temescal Creek from the south.
Temescal Creek drains the largest area of all the tributaries, because it provides the outflow from
Lake Elsinore, into which the
San Jacinto River flows. It is also one of the longest, at in length. Except during the wettest years when Lake Elsinore fills high enough to overflow, Temescal Creek contributes little to no water into the Santa Ana River.
Below Prado Dam, the Santa Ana River crosses into
Orange County, and cuts between the Santa Ana Mountains and
Chino Hills via the narrow
Santa Ana Canyon. The river roughly bisects the county as it flows southwest towards the ocean. In
Anaheim, the entire flow of the river (except during wet seasons) is diverted into
spreading grounds for
groundwater recharge of the north Orange County
aquifer
An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...
, providing about half of the county's municipal water supply. Downstream of there, the river is mostly confined to a concrete channel, serving only for flood control and
urban runoff
Urban runoff is surface runoff of rainwater, landscape irrigation, and car washing created by urbanization. Impervious surfaces (roads, parking lots and sidewalks) are constructed during land development. During rain, storms, and other Precipitati ...
drainage, and is usually dry or a small trickle. At
Orange it receives
Santiago Creek from the east before entering
Santa Ana. After crossing under
Interstate 5
Interstate 5 (I-5) is the main north–south Interstate Highway System, Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels thro ...
it passes through the River View Golf Course, one of its few non-concreted sections within Orange County, and then becomes a concrete channel again through most of Santa Ana and
Fountain Valley to a point below the 405 Freeway, where the river bed becomes natural (though the banks remain concrete). The mouth of the river is located in a small tidal lagoon between
Huntington State Beach in
Huntington Beach and
Newport Beach.
Watershed
The Santa Ana River drains the largest watershed of California's South Coast region,
covering in parts of San Bernardino, Riverside, Orange and Los Angeles Counties. Although the river does not pass through Los Angeles County, some of its tributaries, including
San Antonio Creek extend into it. The watershed consists mainly of high mountain ranges that surround and divide large, dry alluvial valleys. The San Gabriel, San Bernardino and San Jacinto Mountains encircle the arid
Inland Empire lowland on the north and east. The Santa Ana Mountains and Chino Hills divide the Inland Empire from the Orange County coastal plain; the Santa Ana Canyon is the only natural break in the range between the two lowlands.
The southern part of the watershed, drained by the
San Jacinto River into
Lake Elsinore and via
Temescal Creek into the Santa Ana River, constitutes some 45% of the total area and extend its boundaries as far south as the
Colorado Desert at
Anza-Borrego Desert State Park. The river has over 50 named tributaries, most of which are intermittent streams.
As of 2000, about 4.8 million people lived in the Santa Ana River watershed.
Most of the population is concentrated close to the river in urban centers such as San Bernardino, Riverside, Anaheim and Santa Ana. The Inland Empire still has large areas dedicated to
agriculture
Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...
and
ranching, although it is rapidly urbanizing. In Orange County, nearly all the valley lands are urbanized. Some major bodies of water in the watershed include
Irvine Lake,
Lake Mathews,
Lake Perris,
Diamond Valley Lake,
Lake Skinner, and
Big Bear Lake. All of these are water supply reservoirs constructed by county or state water agencies, and with the exception of Big Bear, much of the water is imported from other parts of California due to the arid local climate.
Diamond Valley Lake, with a storage capacity of , is the largest and most recently constructed. Lake Elsinore is the only major natural lake in the watershed.

The Santa Ana River watershed shares boundaries with many adjacent river basins. In the northwest is the
San Gabriel River, which empties into the Pacific at
Long Beach. In Orange County, the
San Diego Creek,
Aliso Creek, and
San Juan Creek watersheds border the Santa Ana watershed on the south. Further south, in San Diego County, the watershed is bordered by those of
San Mateo Creek, the
Santa Margarita River, and the
San Luis Rey River. On the east the watershed shares borders with those of the
Whitewater River and the
Coachella Valley, flowing into the
Salton Sea,
and on the north with the
Mojave River, which flows into the
endorheic basin
An endorheic basin ( ; also endoreic basin and endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water (e.g. rivers and oceans); instead, the water drainage flows into permanent ...
of the
Mojave Desert
The Mojave Desert (; ; ) is a desert in the rain shadow of the southern Sierra Nevada mountains and Transverse Ranges in the Southwestern United States. Named for the Indigenous peoples of the Americas, indigenous Mohave people, it is located pr ...
.
In Orange County, the river flows across a vast, gently sloping
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 Semi-arid climate, semiar ...
created from its own sediments therefor its
drainage basin
A drainage basin is an area of land in which all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...
is extremely narrow because the surrounding land slopes away from the river bed. In its natural state the river would frequently change course into one of many intermittent channels that fan out across the plain. Today, these auxiliary river-beds have been artificially disconnected from the Santa Ana River and converted into flood control channels, including the Talbert and Huntington Beach channels, which empty into the Pacific very near the mouth of the Santa Ana River. The combined Talbert-Huntington Beach watershed drains of mostly suburbanized land. The river originally had many different outlets to the Pacific, one of which even extended as far north as the San Gabriel River. The original mouth of the river was located at
Newport Bay, which drained into the Pacific Ocean, at what is today the entrance to
Newport Harbor. Based on a U.S. Coastal Survey from 1878, Newport Bay was predominantly a river estuary with few open channels. The river flowed into the bay bringing with it heavy silt and making boating difficult. To eventually create Newport Harbor, sand deposited by the Santa Ana River had to be constantly dredged away. In 1920, the Bitter Point Dam was built to divert the river away from the bay and on its current course to the ocean at Huntington Beach. Stone jetties were built to form the new river mouth. All of the Islands in Newport Harbor are the product of dredging and man made forming from the sands and silt deposited over time by the Santa Ana River.
Geology
Ancient
igneous,
metamorphic and
sedimentary rock
Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or de ...
underlie and form the geologic base of the Santa Ana River watershed. Most of the
strata
In geology and related fields, a stratum (: strata) is a layer of Rock (geology), rock or sediment characterized by certain Lithology, lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by v ...
in the flat valleys and basins of the watershed are underlain by thousands of feet of sediment deposited by shallow seas that covered parts of Southern California in ancient times.
[.] Most of the mountains in and around the basin consist of
granite
Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...
batholiths about 75 million years old.
However, above elevations of ancient metamorphic rock up to 1.7 billion years old is exposed.
[.] This rock originally formed at the bottom of the ancestral Pacific Ocean and was uplifted to the highest peaks of the mountains by tectonic action. Even during the
ice age
An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and g ...
s, Southern California mountains were not subjected to extensive
glaciation
A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate be ...
, so the rock has remained for tens of millions of years without significant erosion.
Diverse and complex
faulting and geologic instability have shaped the Santa Ana River watershed. The
San Andreas Fault runs across the northern section of the watershed and is responsible for the formation of the San Bernardino and San Gabriel Mountains, part of the
Transverse Ranges of Southern California.
The
Elsinore–
Whittier Fault Zone crosses the Santa Ana River further downstream, near the Orange/Riverside County line.
Tectonic action along this fault created the Santa Ana Mountains, Puente Hills, East Orange Hills, Chino Hills, Loma Ridge, and the other mountain ranges and ridges that run northwest–southeast across the lower section of the watershed – the coastal
Peninsular Ranges. While the Transverse Ranges rise above in many places, the highest peaks of the Peninsular Ranges reach less than half that elevation.
The cutting of Santa Ana Canyon across the Peninsular Ranges is attributed to the wetter Southern California climate during the
Wisconsinian Glaciation and earlier ice ages, during which rivers in Southern California were substantially bigger in volume. The Santa Ana River, which existed prior to the creation of the Peninsular Ranges, maintained its course as an
antecedent stream due to its increased erosive power.
The canyon was eroded through bedrock that today divides the groundwater basins of the Inland Empire and the coastal plain. Because groundwater in the watershed generally flows from east to west, it is forced to the surface at the bedrock "sill" of Santa Ana Canyon, resulting in a perennial stream that prior to development flowed freely across the coastal plain to the Pacific. During this period, the Santa Ana changed course multiple times, eroding now-dry
wind gaps in the Peninsular Range and the coastal mesas around Huntington Beach and Newport Beach.
Ecology
Hundreds of species of animals and plants characterize the Santa Ana River's diversity of climates and vegetation zones. There are over ten of these vegetation zones in the watershed—including the sparsely vegetated
alpine and
subalpine zones in the mountains, mid-elevation forests of
pine
A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae.
''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as cu ...
,
lodgepole and
oak,
chaparral
Chaparral ( ) is a shrubland plant plant community, community found primarily in California, southern Oregon, and northern Baja California. It is shaped by a Mediterranean climate (mild wet winters and hot dry summers) and infrequent, high-intens ...
,
coastal sage scrub, the increasingly rare
riparian forest
A riparian forest or riparian woodland is a forested or wooded area of land adjacent to a body of water such as a river, stream, pond, lake, marshland, estuary, canal, Sink (geography), sink, or reservoir. Due to the broad nature of the definitio ...
and
marsh
In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...
es along the river bed, lined with trees and rushes, and the thinly vegetated coastal areas virtually flush with
sea level
Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical ...
. The watershed supports up to 200 bird species, 50
mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
species, 13
reptile
Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...
species, 7
amphibian
Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
species, and 15
fish
A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...
species, including
steelhead trout.
The largest portion of the watershed, the Inland Empire portion, is dominated by a hot, dry
desert
A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...
climate that supports sparse wildlife, while the climate and vegetation of the
San Jacinto River and
Temescal Creek watershed is similar to that of the southern
Central Valley.
Downstream of the desert was once the
coastal sage scrub and dry
grassland
A grassland is an area where the vegetation is dominance (ecology), dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes such as clover, and other Herbaceo ...
community of the Orange County coastal plain, but that region has been almost entirely lost to urbanization. Rimming the arid portions of the watershed are the
chaparral
Chaparral ( ) is a shrubland plant plant community, community found primarily in California, southern Oregon, and northern Baja California. It is shaped by a Mediterranean climate (mild wet winters and hot dry summers) and infrequent, high-intens ...
zones, consisting of
sclerophyllous, thick, low bushes and small trees. The chaparral generally is found between elevations of , and occurs mainly closer to the coast on the windward side of the Peninsular Ranges. The
scrub oak is one of the most common plants in chaparral regions, forming a dense groundcover that makes it difficult for humans and large animals such as
mountain lion
The cougar (''Puma concolor'') (, ''Help:Pronunciation respelling key, KOO-gər''), also called puma, mountain lion, catamount and panther is a large small cat native to the Americas. It inhabits North America, North, Central America, Cent ...
s,
coyotes, and
bobcats to traverse. Chaparral growth is determined by
wildfire
A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a ...
s and droughts, and depends on the semi-arid climate of the region.
Perennial and seasonal streams often are lined with
live oak and
sycamore, which transition into the
riparian zone
A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripari ...
s of the main stem Santa Ana River. The largest unbroken riparian corridor is the stretch between Riverside and Prado Dam, where the river has been largely left in its natural state despite pollution from urban runoff. In addition, the flood control basin behind Prado Dam contains of seasonal wetlands. The
Santa Ana sucker, a small bottom-dwelling fish, was once found along most of the Santa Ana River, but is now rarely seen.
Near the mouth, the river was once abundant in
salt marsh
A salt marsh, saltmarsh or salting, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. I ...
es, which stretched for miles on either side of the river, even near
Upper Newport Bay, which has also served as an alternate mouth of the river.
The alpine and subalpine zones, despite their high elevation (above ) and significant rainfall (at least per year, except in drought years), are sparsely vegetated. The windswept terrain of the alpine zone is primarily small brush and weeds, while trees—mostly small gnarled
pine
A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae.
''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as cu ...
s and
junipers—occur in canyons and shielded depressions in the subalpine zone. Inland elevations above support much denser forest.
Jeffrey pine,
ponderosa pine,
black oak,
lodgepole pine, and willow constitute most of the forested lands. The mountain habitats of the watershed support many animals typical of Californian mountain regions, including
squirrels,
chipmunks,
black bears,
mule deer
The mule deer (''Odocoileus hemionus'') is a deer indigenous to western North America; it is named for its ears, which are large like those of the mule. Two subspecies of mule deer are grouped into the black-tailed deer.
Unlike the related whit ...
, and many species of migratory birds. In the canyons of the San Bernardinos, the river is abundant in
rainbow trout
The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributary, tributaries of the Pacific Ocean in North America and Asia. The steelhead (sometimes called steelhead trout) is an Fish migration#Classification, ...
and is lined with
alder
Alders are trees of the genus ''Alnus'' in the birch family Betulaceae. The genus includes about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few species ex ...
s, willow and cottonwoods. Where the river and its large upper tributaries empty out of the mountain canyons into the Inland Empire basin, they are surrounded by the alluvial scrub zone, a mix of desert and upper riparian vegetation. Along the main stem, this zone begins at the base of
Seven Oaks Dam and ends at the
Lytle Creek confluence.

Historically, the Santa Ana was named "the best stream in Southern California
or steelhead trout habitat.
The steelhead is an
anadromous fish, similar to
salmon
Salmon (; : salmon) are any of several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the genera ''Salmo'' and ''Oncorhynchus'' of the family (biology), family Salmonidae, native ...
, that migrates up rivers and streams to spawn. Unlike salmon, which usually only reproduce once, steelhead may reproduce multiple times and have a much longer life span. Steelhead was once found along the entire main stem of the Santa Ana River, as well as on some of its main tributaries—
Santiago Creek, San Antonio and Chino Creeks, Cucamonga Creek,
Lytle Creek, City Creek, and
Mill Creek. Few, if any, steelhead were present in Temescal Creek (although one of its tributaries was stocked in the 1930s
) and none inhabited the
San Jacinto River, because it is disconnected from most of the Santa Ana River system.
Up to the 1950s, significant numbers of steelhead trout still migrated in from the ocean.
Because of pollution and modifications to the river, very few steelhead still use the river. There is a population of wild stream resident coastal rainbow trout upstream of Seven Oaks Dam and in the upper reaches of a few tributaries.
Despite the rarity of steelhead, in recent years fin samples from 13 trout were collected from Harding Canyon in the
Santiago Creek tributary of the Santa Ana River and genetic analysis has shown them to be of native and not hatchery stocks.
Invasive species—those that are not native to the region—have caused problems in the watershed for many years. One of the most troublesome invasive species is the
giant reed, which plagues many coastal Southern California waterways. The giant reed is similar to a tall grass or thin
bamboo
Bamboos are a diverse group of mostly evergreen perennial plant, perennial flowering plants making up the subfamily (biology), subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family, in th ...
, but grows quickly and can take over native stands of vegetation, block the streambed, hurts the habitat of native animals, and increases the hazard of
wildfire
A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a ...
s.
Perhaps the largest effect that giant reed has is its usage of water. To support its fast growth rate, the giant reed population in the Santa Ana River watershed can consume of water per year.
Other invasive species also have affected the Santa Ana River. One of the most prominent is the
brown-headed cowbird, which feeds off parasites and insects identified with
cattle
Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...
, which were brought to Southern California during the Spanish Rancho period. The brown-headed cowbird is a "brood parasite", or a bird that lays its eggs in another bird's nest. One of the most afflicted birds is the
least Bell's vireo, whose population also suffers from the loss of riparian habitat. The least Bell's vireo is considered an endangered species, as is the
southwestern willow flycatcher, whose habitat is often shared with the other bird.
The
saltcedar is another invasive large weed that also, like the giant reed, uses large amounts of water. Unlike giant reed, the saltcedar has deeper roots, not only making it more difficult to remove but allowing it to access and use up deep
groundwater
Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...
. However, the saltcedar is similar in that it also provides little usable habitat for native animals.
History
First peoples
Human habitation on the Santa Ana River dates back 9,000 to 12,000 years ago, close to the early stages of the
Holocene
The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...
period. The first Native Americans to live in the area were
nomadic tribes that traveled from place to place, grazing animals on fertile grasslands and gathering fruits and seeds for food. The ancestors of these early people originated from the
Shoshone and
Uto-Aztecan people of the northwestern United States. Eventually, the human population of the watershed reached a peak of about 15,000. About 8,000 years ago, the climate experienced a change becoming more arid and the originally nomadic tribes began to stay in individual places longer, becoming semi-nomadic. However, they did not establish
agriculture
Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...
, nor did they raise animals or live in villages.
Like many Native American tribes in California,
acorn
The acorn is the nut (fruit), nut of the oaks and their close relatives (genera ''Quercus'', ''Notholithocarpus'' and ''Lithocarpus'', in the family Fagaceae). It usually contains a seedling surrounded by two cotyledons (seedling leaves), en ...
s were a staple food of many of the inland valley people. People closer to the ocean often fished and hunted small animals, often from
tide pools and coastal stream areas, for food.
Several major premodern Native American groups eventually gained control of lands along the river: the
Yuhaviatam or Yuharetum people in the upper basin, the
Payomkowishum in the southeastern basin, the
Cahuilla in the desert areas of the watershed, and the
Tongva people in the lower basin.
[.] The Yuhaviatam generally lived in the mountain headwaters of the Santa Ana River and its tributaries rimming the present-day Inland Empire basin, in present-day San Bernardino County, as well as in the
foothills
Foothills or piedmont are geography, geographically defined as gradual increases in elevation at the base of a mountain range, higher hill range or an highland, upland area. They are a transition zone between plains and low terrain, relief hill ...
of the San Bernardino Mountains.
The Tongva lived on the flat
coastal plains of present-day Orange County south of the Santa Ana Mountains. They were also the larger of the two groups, controlling all the coastal lands from the
San Gabriel Mountains
The San Gabriel Mountains () are a mountain range located in Los Angeles and San Bernardino counties, California, United States. The mountain range is part of the Transverse Ranges and lies between the Los Angeles Basin and the Mojave Desert ...
in the north to
Aliso Creek in the south, including all of the
Los Angeles Basin.
These peoples established villages, some of which were multiethnic and multilingual, including
Lupukngna,
Genga,
Pajbenga,
Totpavit, and
Hutuknga.
Spanish period

When
Spanish explorer
Juan Rodriguez Cabrillo sailed along the Southern California coast on his voyage of 1542, he passed the mouth of the Santa Ana River without noting it.
Neither did any of the subsequent Spanish sea-borne explorers leave any written notice of the river mouth.
It was not until 1769 that
Gaspar de Portolà led the first overland expedition northwards through coastal Southern California—still a largely unexplored part of the
Alta California
Alta California (, ), also known as Nueva California () among other names, was a province of New Spain formally established in 1804. Along with the Baja California peninsula, it had previously comprised the province of , but was made a separat ...
province of
New Spain
New Spain, officially the Viceroyalty of New Spain ( ; Nahuatl: ''Yankwik Kaxtillan Birreiyotl''), originally the Kingdom of New Spain, was an integral territorial entity of the Spanish Empire, established by Habsburg Spain. It was one of several ...
—and gave the river its name.
On July 28, the party camped "about three leagues" from where the Santa Ana River exits the canyon through the northern Santa Ana Mountains, near present-day
Olive
The olive, botanical name ''Olea europaea'' ("European olive"), is a species of Subtropics, subtropical evergreen tree in the Family (biology), family Oleaceae. Originating in Anatolia, Asia Minor, it is abundant throughout the Mediterranean ...
. Fray
Juan Crespí
Juan Crespí, OFM (Catalan language, Catalan: ''Joan Crespí''; 1 March 1721 – 1 January 1782) was a Franciscan missionary and explorer of The Californias, Las Californias.
Biography
A native of Majorca, Crespí entered the Franciscan ord ...
, one of the members of the expedition, wrote in his diary that he called the spot "Jesus de los Temblores", referring to an
earthquake
An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...
that struck while they were camped alongside there.
Crespi also noted that the soldiers were calling the river "Rio de Santa Ana", probably because they had recently celebrated
Saint Anne's Day. That name remains today (the second oldest place name in Orange County, after
Santiago Creek), and the name of the mountain range and city were derived from the river.
Although no missions were actually located along the Santa Ana River or within the watershed, the river basin was nearly depleted of native people because the Spanish forced them to work at nearby missions, including
Mission San Gabriel Arcangel and
Mission San Luis Rey. The affected tribes were usually renamed after the missions, resulting in tribal names such as
Gabrieliño and
Luiseño. Difficult working and living conditions and European diseases such as
smallpox
Smallpox was an infectious disease caused by Variola virus (often called Smallpox virus), which belongs to the genus '' Orthopoxvirus''. The last naturally occurring case was diagnosed in October 1977, and the World Health Organization (W ...
killed much of the native population during the roughly 50-year-long Mission Period. The
Secularization Act of 1833, passed by the newly independent country of
Mexico
Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
, eventually brought an end to the Mission Period.
The post-Mission Period native population was almost entirely devastated. The population was very little, their native religions were nearly lost, and most of their land had been taken by Spanish settlers.
Although the Mexican government's original intention with the Secularization Act was to provide the Native Americans with their own land and property, most of the provisions made by the act never actually happened. Spanish settlers continued to press into the remaining tribal lands, and eventually, the tribes were forced into the surrounding desert lands or into the high mountains.
Following the Mission Period came the
Rancho Period. This occurred when the enormous land holdings of the missions were subdivided into
ranchos owned by individuals. Some of the new private ranchos were merely converted mission ranchos. The first private rancho along the Santa Ana River was
Rancho Santiago de Santa Ana, a rancho on the left bank of the lower Santa Ana River. This rancho was acquired by Don Juan Pablo Grijalva as early as 1801. Other ranchos on the river followed, including ones in inland areas that had not been exploited in the Mission Period.
The ranchos (beginning with the missions) established the tradition of raising
cattle
Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...
in coastal Southern California, a custom upheld until the late 19th century.
Agriculture, however, although established, was not yet a major industry.
A flood that raged down the Santa Ana in 1825 caused the river's course to change temporarily to an outlet at
Newport Bay, depositing sediment that partially created
Balboa Island.
Spread throughout the ranchos on the Santa Ana River were a few towns, military outposts and trading posts. The Santa Ana River valley was one of the most prosperous regions in Southern California for many decades.
American settlement
In the late 1840s, California fought for its independence from Mexico in the
Mexican–American War
The Mexican–American War (Spanish language, Spanish: ''guerra de Estados Unidos-México, guerra mexicano-estadounidense''), also known in the United States as the Mexican War, and in Mexico as the United States intervention in Mexico, ...
. The Santa Ana river played an important part in the victory of the Americans over the Mexican army. In 1847, one year after the
Bear Flag Revolt, a Mexican military force set out northwards to attack a smaller American force in the
Los Angeles
Los Angeles, often referred to by its initials L.A., is the List of municipalities in California, most populous city in the U.S. state of California, and the commercial, Financial District, Los Angeles, financial, and Culture of Los Angeles, ...
area. However, the Santa Ana River flooded, preventing the Mexicans from crossing the river to attack the Americans. When the river's flow finally subsided, the American forces had been reinforced enough to drive the Mexicans out of the region.
[.]

When the
California Republic was assimilated into the United States in 1848, American settlers began to move into the Santa Ana River region in great numbers. The Mexican ranchos were divided into smaller individual properties, and irrigated agriculture began on a large scale. The city of
Santa Ana Viejo, the original location of Santa Ana, was founded in this period. In 1854,
Mormons settled in the upper Inland Empire area and started the city of
San Bernardino, gaining prosperity by using water from the river, as well as
Lytle Creek and
Mill Creek, to irrigate crops.
The cattle industry began to decline as farms began to replace ranches. Soon, white settlers in the region were more numerous than Hispanics as well. The
California Gold Rush
The California gold rush (1848–1855) began on January 24, 1848, when gold was found by James W. Marshall at Sutter's Mill in Coloma, California. The news of gold brought approximately 300,000 people to California from the rest of the U ...
around this time was responsible for attracting many of these people to the state, but many remained in Southern California afterwards.
In 1860, a much closer gold rush occurred in the San Bernardino Mountains when prospector William Holcomb discovered significant deposits, just over the northern drainage divide of the Santa Ana River. This discovery exploded into a full-scale gold mining operation in days.
The Santa Ana River served as a conduit for miners traveling to the region and many of the forests in the upper basin experienced
clearcutting
Clearcutting, clearfelling or clearcut logging is a forestry/logging practice in which most or all trees in an area are uniformly cut down. Along with Shelterwood cutting, shelterwood and Seed tree, seed tree harvests, it is used by foresters t ...
as a result of the high resource demands of the boom. Gold was also discovered in Lytle Creek in that same year.
Following the gold rush, the cultivation of
citrus
''Citrus'' is a genus of flowering trees and shrubs in the family Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, mandarins, lemons, grapefruits, pomelos, and limes.
''Citrus'' is nativ ...
became the mainstay of the economy of the lower Santa Ana River area.
Through the late 19th century, citrus fields covered much of the coastal plain and led to the naming of Orange County.
Floods, droughts and legacy
Notwithstanding the increased prosperity in the 1860s, this decade was also the scene of a series of natural disasters. In the
Great Flood of 1862, heavy rains dropped by a series of winter storms caused the Santa Ana to burst its banks, flooding thousands of acres of land and killing 20 to 40 people in the greatest flood it had experienced in recorded history.
The
levees along the river burst in many places, flooding part of the Inland Empire into a continuous body of water several miles wide stretching from the mouth of Santa Ana Canyon to where the river cuts through the Santa Ana Mountains. Downstream in Orange County, the river overwhelmed nearly all the existing floodworks and transformed the coastal plain into a transient inland sea. The flow, now calculated as a 1,000-year flood, peaked at roughly , over half the average flow of the
Mississippi River
The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...
.
[.] Even after the flood, detrimental conditions continued in the region. For the two years following the flood, an intense
drought
A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...
caused the deaths of tens of thousands of head of livestock. Despite all of the hardships experienced in the three years, after conditions finally returned to normal, the Santa Ana River watershed again became a prospering agricultural region.
The cities of
Santa Ana and
Riverside were established in 1869 and 1870, respectively.
1934 and 1938 saw a further pair of devastating floods that in part brought an end to the area's citrus industry.
In the
Los Angeles flood of 1938, the Santa Ana again burst its banks and flooded
Anaheim and
Orange in up to of water, stripping away thousands of acres of rich topsoil and destroying many of the citrus groves. Almost 60 people were killed in the disaster and about of land were flooded,
despite the fact that the flow in the river was only one-third of that of the 1862 flood. With the extreme damage from the floods, the
U.S. Army Corps of Engineers made the decision to dam and concrete the river beginning in the 1940s, and declared it as the greatest flood hazard in the U.S. west of the
Mississippi River
The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...
.
Prado Dam, built in 1941, was designed to capture floodwaters from the Inland Empire about upstream from the river's mouth. The dam's impoundment,
Prado Flood Control Basin, was designed to handle a 70-year flood.

With the increased flood protection afforded by the Prado Dam, major industrial development migrating south from the Los Angeles Basin, and the Southern California housing boom in the 1950s and 1960s, the Santa Ana River watershed began its third and final transition—from agricultural to
urban.
The population of the Santa Ana River basin increased dramatically, but brought with it the threat of greater damage from floods, somewhat compromising the protection afforded by Prado Dam. Because housing and urban areas encroached on the river's historic
floodplain
A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high Discharge (hydrolog ...
—an area once occupied by farms—and the river became confined to a narrow channel—a flood similar to the ones surrounding the turn of the 20th century would cause much more damage. The construction of roads and buildings also heightened the runoff that would flow into the river during rainfall, a process known as
urban runoff
Urban runoff is surface runoff of rainwater, landscape irrigation, and car washing created by urbanization. Impervious surfaces (roads, parking lots and sidewalks) are constructed during land development. During rain, storms, and other Precipitati ...
.
In fact, the river flooded again in 1969, and while much of the runoff from the Inland Empire was captured behind Prado Dam—probably saving Orange County from an even greater flood—Santiago Creek, a large tributary flowing from the Santa Ana Mountains, eroded its banks until it swept away portions of residential communities in the cities of
Tustin and
Orange.
In 1964, the Santa Ana River Mainstem Project, which involved concreting the lower of the river, was first proposed. Construction work began in 1989, and today, through much of Orange County, the river's channel is essentially an enormous box
culvert
A culvert is a structure that channels water past an obstacle or to a subterranean waterway. Typically embedded so as to be surrounded by soil, a culvert may be made from a pipe (fluid conveyance), pipe, reinforced concrete or other materia ...
. The second dam, Seven Oaks Dam, was completed in 1999. This dam captures flood runoff from Santa Ana Canyon before it can enter the Inland Empire.
The dam was designed to withstand a 350-year flood. Today, the river lies mainly between levees and concrete channels, and especially in its lower course, functions only as a flood drainage channel.
Pollution and restoration

As with many Southern California rivers, the Santa Ana is heavily polluted and used. The main stem above
Seven Oaks Dam is free-flowing, as are many of its upper tributaries. Once the river enters the Inland Empire basin, however, much of its flow is diverted for
municipal and
agricultural
Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created f ...
water use. Most of the flow in the river below the city of San Bernardino consists of effluent from 45
wastewater treatment plants and dry season
urban runoff
Urban runoff is surface runoff of rainwater, landscape irrigation, and car washing created by urbanization. Impervious surfaces (roads, parking lots and sidewalks) are constructed during land development. During rain, storms, and other Precipitati ...
, which is collected behind
Prado Dam.
[''New strategies for America's watersheds'', p. 102.] Any flow that makes it downstream to Orange County is diverted by another pair of dams into approximately of
groundwater
Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...
recharge basins, providing approximately of municipal water for the county every year, or one-third of its water supply. Downstream of that dam, the river gathers further urban runoff before finally making it into the Pacific.
The Santa Ana River is included on the
U.S. Environmental Protection Agency's (EPA) list of "304 (l) 'toxic hot spots' list of impaired waterways".
In Orange County, the
Orange County Water District, formed in 1932 to manage the county's groundwater, uses the treated water from upstream to recharge a massive reservoir, or aquifer, that runs roughly nine miles from Lakeview Avenue to Ball Road. The water percolates through layers of sand and gravel, which work to scrub, or purify it. There, it joins treated wastewater pumped from the Orange County Sanitation Department's state-of-the-art plant in Fountain Valley. Those two types of water account for 60 to 70 percent of the aquifer, which can hold 500,000 acre feet. Combined with water imported from Northern California and the Colorado River, the OCWD maintains that the aquifer could serve the water needs of all its clients for a year.
A number of organizations have been formed to try to gain public interest in restoring the river. One of the most prominent is the Santa Ana Watershed Project Authority (SAWPA), formed by five municipal water districts in the Santa Ana River area. A second one is the Santa Ana River Dischargers Association. Both have conducted studies as to what beneficial uses the Santa Ana River would have aside from water supply and flood control, as well as the removal of some of the concreted sections of the lower river. This set of studies is known as the "Use-Attainability Analysis", which was submitted to the state Congress, which approved it. However, upon submission to the EPA, it was rejected. As a result, little work has been done to repair the ecological damage that has been caused by urbanization along the river.
[''New strategies for America's watersheds'', p. 103.] Other projects include the Santa Ana Watershed Planning Advisory Committee,
and the Santa Ana River Watershed Alliance (SARWA).
Recreation

There are many recreational opportunities along the Santa Ana River. The Santa Ana River watershed includes parts of the
Cleveland National Forest
Cleveland National Forest is a National forest (United States), U.S. national forest in Southern California that encompasses 460,000 acres/ of inland Montane ecosystems, montane regions. It is approximately 60 miles from the Pacific Ocean, withi ...
,
San Bernardino National Forest,
Angeles National Forest,
Mount San Jacinto State Wilderness Area,
Chino Hills State Park, and Lake Perris State Recreation Area.
Big Bear Lake,
Lake Elsinore, and
Lake Irvine are popular recreational lakes in the watershed. The river never actually flows through any of these lakes, but they each have drainage to the river via tributaries.
The
Santa Ana River bicycle path which, when complete, will run from the river's mouth at Huntington Beach to near the San Bernardino Mountains, currently extends about along the river to Prado Dam. The proposed distance along the trail is over . In Riverside County, the Hidden Valley Wildlife Area also has of recreational paths.
Some entities have been opting for a Santa Ana River Park, which would encompass a strip of land on either side of the river for its entire course. The
city of Redlands would like to develop riverside green space near the historic downtown district.
[ The Santa Ana River Lakes, located near Anaheim, are a popular recreational fish farm fed with water from the river. Ultimately, the trail could link a network of river-bottom parks. In 2014, naturalists navigated the stretch of river flanked by Chino Hills State Park on the north and the Cleveland National Forest on the south. The rafts made it before the vegetation was impenetrable but they were convinced there were possibilities of improving public access and recreational opportunities.][Sahagun, Louis (October 27, 2014]
"How California is turning drainage canals back to rivers"
''Los Angeles Times
The ''Los Angeles Times'' is an American Newspaper#Daily, daily newspaper that began publishing in Los Angeles, California, in 1881. Based in the Greater Los Angeles city of El Segundo, California, El Segundo since 2018, it is the List of new ...
''
Crossings
The Santa Ana River has 70 significant crossings, bridges and dams. This list places them from mouth to source.
Orange County
*
State Route 1 (Pacific Coast Highway) (Newport Beach/Huntington Beach)
* Victoria Street/Hamilton Avenue (Costa Mesa/Huntington Beach)
* Santa Ana River bicycle path (Costa Mesa/Huntington Beach)
* Adams Avenue (Costa Mesa/Huntington Beach)
* Interstate 405 ( San Diego Freeway) (Costa Mesa/Fountain Valley)
* Talbert Avenue/MacArthur Boulevard (Santa Ana/Fountain Valley)
* Slater Avenue/West Segerstrom Avenue (Santa Ana/Fountain Valley)
* Warner Avenue (Santa Ana/Fountain Valley)
* Harbor Boulevard (Santa Ana)
* Edinger Avenue (Santa Ana)
* McFadden Avenue (Santa Ana)
* Bolsa Avenue/1st Street (Santa Ana)
* 5th Street (Santa Ana)
* Former Pacific Electric Railway Railway Bridge (future OC Streetcar)
* Fairview Street (Santa Ana)
* Westminster Avenue/17th Street (Santa Ana)
* Santa Ana River bicycle path (Santa Ana)
* Garden Grove Boulevard/Memory Lane (Orange/Santa Ana)
*
State Route 22 ( Garden Grove Freeway) (Orange)
* Interstate 5
Interstate 5 (I-5) is the main north–south Interstate Highway System, Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels thro ...
( Santa Ana Freeway) (Orange)
* Chapman Avenue (Orange/Anaheim)
* Orangewood Avenue (Orange/Anaheim)
*
State Route 57 ( Orange Freeway) (Orange/Anaheim)
* Metrolink Orange County Line & Amtrak
The National Railroad Passenger Corporation, Trade name, doing business as Amtrak (; ), is the national Passenger train, passenger railroad company of the United States. It operates intercity rail service in 46 of the 48 contiguous United Stat ...
'' Pacific Surfliner'' (Orange/Anaheim)
* Katella Avenue (Orange/Anaheim)
* Railroad Bridge (Orange/Anaheim)
* Taft Avenue/Ball Road (Orange/Anaheim)
* Lincoln Avenue (Orange/Anaheim)
* Glassell Street/Kraemer Boulevard (Orange/Anaheim)
* Metrolink Inland Empire–Orange County Line (Anaheim)
* Tustin Avenue (Anaheim)
*
State Route 91 ( Riverside Freeway) (Anaheim)
* Lakeview Avenue (Anaheim)
*
State Route 90 ( Imperial Highway) (Anaheim)
* Santa Ana River bicycle path (Anaheim)
* Weir Canyon Road (Anaheim/Yorba Linda)
* Gypsum Canyon Road (Yorba Linda)
Riverside County
* Green River Road (Corona)
* Metrolink 91/Perris Valley & Inland Empire-Orange County lines (Corona)
*
State Route 71 ( Corona Freeway)
* Prado Dam
* River Road (Norco/Eastvale)
* Hamner Avenue (Norco)
* Interstate 15 ( Ontario Freeway) (Norco)
* Van Buren Boulevard (Jurupa Valley)
* Metrolink Riverside Line (Jurupa Valley/Riverside)
* Mission Boulevard/Buena Vista Avenue (Jurupa Valley/Riverside)
*
State Route 60 ( Pomona Freeway) (Jurupa Valley/Riverside)
* Market Street (Jurupa Valley/Riverside)
San Bernardino County
* Riverside Avenue (Colton)
* La Cadena Drive (Colton)
* Metrolink Inland Empire-Orange County Line (Colton)
* Railroad Bridge (Colton)
* Mount Vernon Avenue (Colton)
* Amtrak Sunset Limited & Texas Eagle (Colton)
* Interstate 10 ( San Bernardino/ Redlands Freeway) (Colton)
* Interstate 215 ( San Bernardino/ Riverside Freeway) (San Bernardino)
* E Street (San Bernardino)
* Waterman Avenue (San Bernardino)
* Arrow
An arrow is a fin-stabilized projectile launched by a bow. A typical arrow usually consists of a long, stiff, straight shaft with a weighty (and usually sharp and pointed) arrowhead attached to the front end, multiple fin-like stabilizers c ...
commuter rail service (San Bernardino)
* Orange Show Road (San Bernardino)
* Tippecanoe Avenue (San Bernardino)
* Alabama Street (Redlands)
*
State Route 210 ( Foothill Freeway) (Redlands)
* Orange Street (Redlands)
* Greenspot Road (Highland)
* Santa Ana Canyon Road
* Seven Oaks Dam
*
State Route 38
See also
* List of rivers of Orange County, California
* List of tributaries of the Santa Ana River
* Populated places on the Santa Ana River
* List of rivers of California
* List of watershed topics
References
External links
Archival collections
Guide to the Santa Ana River Report.
Special Collections and Archives, The UC Irvine Libraries, Irvine, California.
Other
Santa Ana Watershed Association
{{Authority control
Rivers of Orange County, California
Rivers of Riverside County, California
Rivers of San Bernardino County, California
San Bernardino Mountains
Santa Ana Mountains
Geography of Santa Ana, California
Rivers of Southern California
Watersheds of California