Chino Creek is a major stream of the

Pomona Valley The Pomona Valley is located in the Greater Los Angeles Area between the San Gabriel Valley and San Bernardino Valley in Southern California. The valley is approximately east of downtown Los Angeles. History The earliest inhabitants of Pomo ...

, in the western

Inland Empire The Inland Empire (commonly abbreviated as the IE) is a metropolitan area and region inland of and adjacent to coastal Southern California, centering around the cities of San Bernardino and Riverside, and bordering Los Angeles County and Or ...

region of Southern

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. It is a

tributary A tributary, or an ''affluent'', is a stream or river that flows into a larger stream (''main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which they ...

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 County, California, San Bernardino and Riversid ...

Geography

Although the

main stem In hydrology, a main stem or mainstem (also known as a trunk) is "the primary downstream segment of a river, as contrasted to its tributaries". The mainstem extends all the way from one specific headwater to the outlet of the river, although t ...

is short at about , it drains an extensive basin of 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 ...

to the

near

Corona Corona (from the Latin for 'crown') most commonly refers to: * Stellar corona, the outer atmosphere of the Sun or another star * Corona (beer), a Mexican beer * Corona, informal term for the coronavirus or disease responsible for the COVID-19 ...

. The creek's watershed spans three counties, with the majority in

San Bernardino County San Bernardino County ( ), officially the County of San Bernardino and sometimes abbreviated as S.B. County, 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 th ...

, and parts of seven incorporated cities. The

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 intensely developed for residential, industrial, and agricultural use. As a result, the creek and its tributaries are heavily polluted, and receive effluents from multiple wastewater treatment plants and drains.

Agricultural pollution Agricultural pollution refers to biotic and abiotic byproducts of farming practices that result in contamination or degradation of the environment and surrounding ecosystems, and/or cause injury to humans and their economic interests. The po ...

from the raising of livestock in the creek's lower basin is the largest source of contamination. There are efforts to control nuisance flows and pollutants in the lower part of the creek to protect the wetlands in the Prado Flood Control Basin, an important ecological area.

Course

Chino Creek rises from underground in a storm water channel flowing southwards from a subdivision in southern Pomona, eastern

Los Angeles County Los Angeles County, officially the County of Los Angeles and sometimes abbreviated as LA County, is the most populous county in the United States, with 9,663,345 residents estimated in 2023. Its population is greater than that of 40 individua ...

. The concrete channelized stream soon enters southwestern

and runs generally southeast across the Chino Valley between the Chino Hills to the south, and the city of Chino to the northeast. One of the creek's main tributaries, San Antonio Creek, comes in from the left about downstream of Pomona. San Antonio Creek originates in the

, and drains the northern part of the Chino basin, and its course is longer above their confluence than Chino Creek. From there the creek flows roughly parallel to the Chino Valley Freeway (State Route 71) southeast, through a predominantly industrial and agricultural area of Chino. About above the mouth, the streambed changes from a concrete culvert to an earthen channel. The river then enters the El Prado Golf Course and turns south. The last portion of the creek is predominantly marshland, situated within the Prado Flood Control Basin behind the Prado Dam, and mostly in

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

. The main affluent, Mill Creek, joins from the left within the Prado Basin. Chino Creek then runs south to its confluence with the Santa Ana River just north of the dam about east-northeast of

Geology

The creek runs along the southwest side of the gently sloping alluvial Cucamonga Plain comprising sediments deposited by erosion from the San Gabriel Mountains. It essentially follows the southern outline of the combined alluvial fans of San Antonio, Mill/Cucamonga, Deer, and other tributary streams flowing from the range across the Pomona Valley. Before urbanization Chino Creek was a

perennial stream A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long, large stream ...

, although most of its tributaries were

ephemeral Ephemerality (from the Greek word , meaning 'lasting only one day') is the concept of things being transitory, existing only briefly. Academically, the term ephemeral constitutionally describes a diverse assortment of things and experiences, fr ...

. The impermeable bedrock of the Chino Hills, which abut the southwest edge of the watershed, forced groundwater percolating southwards from the San Gabriels to rise to the surface, thus ensuring a stable year round flow even in years of drought. Historically, the waters of upper San Antonio Creek, Mill Creek, and other streams flowing from the San Gabriels disappeared into the ground about north of Chino Creek, only to reappear within a few miles of the main stream, providing most of its flow. The deposits by the San Gabriel streams are generally hundreds of feet deep and gradually decrease in coarseness in a southerly direction. These tributaries originally joined Chino only during extreme floods. Before channelization, San Antonio Creek was recognized as the upper section of Chino Creek, as the first water in the latter stream rose to the surface at their confluence.

Watershed

The

of Chino Creek spans in parts of Los Angeles, San Bernardino and Riverside Counties, with the vast majority within southwestern San Bernardino County. The broad, flat watershed comprises much of the southeastern slopes of the San Gabriel Mountains and alluvial plains that lie to the south of the range. Almost 55 percent of the basin is heavy urban development, and major cities include

Rancho Cucamonga Rancho Cucamonga was a Ranchos of California, Mexican land grant in present-day San Bernardino County, California, given in 1839 to the dedicated soldier, smuggler and politician Tiburcio Tapia by Mexican governor Juan Bautista Alvarado. The gra ...

Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...

Upland Upland or Uplands may refer to: Geography *Hill, an area of higher land, generally *Highland, an area of higher land divided into low and high points *Upland and lowland, conditional descriptions of a plain based on elevation above sea level *I ...

, Pomona and Chino. ~20% of the watershed is wild land, mostly in the mountainous north within the

Angeles National Forest The Angeles National Forest (ANF) of the United States Forest Service is located in the San Gabriel Mountains and Sierra Pelona Mountains, primarily within Los Angeles County in Southern California. The ANF manages a majority of the San Gabri ...

, and the remaining quarter in the south is used for agriculture, much for the raising of

livestock Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...

. The largest tributaries of Chino Creek are San Antonio Creek and Mill Creek (called Cucamonga Creek in San Bernardino County), both of which are longer than the main stem. Other tributaries include Little Chino Creek and an unnamed left fork that drains a large area south of Chino and north of the El Prado Golf Course. To the west the Chino Creek drainage basin borders on the San Gabriel River watershed, specifically the tributaries of that river, Coyote Creek, Walnut Creek, San Jose Creek and the East Fork San Gabriel River. To the east lies the basin of Etiwanda Creek, a tributary of the Santa Ana; to the northeast is Lytle Creek, another Santa Ana tributary stream. The Chino Creek watershed is notable for containing the heaviest concentration of dairy farms in the United States. A area of farmland in the southern part of the basin was found to have up to 400,000 cows in a study by the Regional Water Quality Control Board. Waste generated on these farms has led to severely raised nitrate and salinity levels in the creek. The Chino Creek Wetlands conservation area was established at the creek's mouth in 2008 in an effort to filter pollutants in the stream. The preserve comprises and includes artificial wetlands irrigated with water from the creek.

History and human usage

From the 1770s through the 1830s the creek's watershed in

was part of the grazing lands of the

Mission San Gabriel Arcángel Mission San Gabriel Arcángel () is a Californian mission and historic landmark in San Gabriel, California. It was founded by the Spanish Empire on the Nativity of Mary September 8, 1771, as the fourth of what would become twenty-one Spanish mi ...

herds. In 1841 much of the creek course became part of Rancho Santa Ana del Chino, a Mexican land grant in

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 ...

. In the late 1800s, the first American settlers arrived in the area and established small towns along the creek's confluence with the Santa Ana River, including Rincon (later changed to Prado). Agricultural development in the large, flat bowl of land adjoining the land between Chino Creek and the Santa Ana River, known as the Chino Basin, was heavy because of the region's rich soils, smooth topography and abundant water resources.

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 ...

alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial plant, perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, ...

and

sugar beet A sugar beet is a plant whose root contains a high concentration of sucrose and that is grown commercially for sugar production. In plant breeding, it is known as the Altissima cultivar group of the common beet (''Beta vulgaris''). Together with ...

s made up most of the agricultural production. Dams were constructed on Chino Creek and miles of irrigation laterals laid, but due to the stream's low flows and tendency for flash floods the system as a whole was not extremely efficient. By the 20th century steady urban development of the basin led to increased flooding risk because of

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 ...

problems, and floods were causing more damage to property adjoining streams. In the 1960s upper Chino Creek and most of its tributaries were channelized with concrete to allow faster passage of floodwaters, but this essentially caused the ecological devastation of the creek. Currently the channelized sections of lower Chino Creek have a design capacity of roughly . The San Antonio Dam was constructed in 1956 by the

U.S. Army Corps of Engineers The United States Army Corps of Engineers (USACE) is the military engineering branch of the United States Army. A direct reporting unit (DRU), it has three primary mission areas: Engineer Regiment, military construction, and civil wor ...

to control floods from upper San Antonio Creek.

Crossings

Crossings of the creek are listed going downstream. Tributary entry points are also included to clarify locations. *White Avenue *Philadelphia Street *Garey Avenue *Market Plaza *Towne Avenue *Riverside Drive *San Antonio Creek confluence (left) *Chino Avenue * State Route 71 *Grand Avenue *Pipeline Avenue * State Route 71 *Ramona Avenue *Little Chino Creek confluence (right) *Chino Hills Parkway *Central Avenue *Confluence of an unnamed tributary (left) *Pine Avenue * State Route 83/Euclid Avenue *Mill Creek confluence (left)

References

{{Authority control Rivers of Los Angeles County, California Rivers of Riverside County, California Rivers of San Bernardino County, California Tributaries of the Santa Ana River Chino, California Chino Hills (California) Chino Hills, California Pomona Valley Geography of Pomona, California Rancho Cucamonga, California Rivers of Southern California