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57-587: Oso Creek is an approximately 13.5-mile (21.7 km) tributary of Arroyo Trabuco in southern Orange County in the U.S. state of California . Draining about 20 square miles (52 km) in a region north of the San Joaquin Hills and south of the Santa Ana Mountains , the creek is Trabuco Creek's largest tributary, and is part of the San Juan Creek drainage basin . Beginning in the foothills of

114-503: A toll road that follows the western foothills of the Santa Ana Mountains, and passes close to Lake Mission Viejo , a popular recreational lake in the city of Mission Viejo . Still steadily bending southwards, Arroyo Trabuco is joined by Tijeras Canyon Creek from the left bank , then passes under a high bridge for Oso Parkway and leaves the southern boundary of the regional park. After passing Saddleback College , located near

171-501: A "nuisance flow". This dry-season flow, which has an average minimum of 1 cubic foot per second (0.03 m/s), has created erosion problems in the few unlined reaches of the creek, as the creek is mostly channelized. A structure exists on Oso Creek that is designed to divert a portion of the flow into the Galivan Basin depending on the specific level of a high inflow. Amounts diverted include 350 cubic feet per second (10 m/s) during

228-408: A fire road. The trail, however, does not extend to the creek's mouth, as the creek flows through privately owned farmland to its mouth. Arroyo Trabuco Acjachemen and Payómkawichum people lived along the perennial stream in settlements and hunting camps for 8,000 years before the invasion of Spanish colonization . Villages along the creek included Alauna and Putiidhem . Trabuco

285-505: A flow of 4,000 cubic feet per second (110 m/s), and 4,800 cubic feet per second (140 m/s) during a flow of 29,000 cubic feet per second (820 m/s). In 1991, the continuing erosion along Oso Creek, due to upstream development, had carved a 50-foot (15 m) deep canyon from a creek channel that originally "was about 6 feet deep and 6 feet wide". The canyon was threatening to swallow large portions of citrus groves. It begins less than 1 mile (1.6 km) downstream of

342-456: A larger area. The Trabuco watershed covers 54 square miles (140 km ) in the northern and far eastern parts of the San Juan Creek watershed. Located in an arid coastal basin in southern Orange County, the creek's watershed comprises 40.3% of the 133.9-square-mile (347 km ) San Juan Creek watershed. It makes a wide bend from northeast to southwest, bounded by the Santa Ana Mountains to

399-664: A tributary from San Juan Canyon. Crossing under Niguel Road, it flows south through a natural channel in the Salt Corridor Regional Park. The Salt Creek Trail parallels the creek from here until the mouth. The creek crosses beneath Camino del Avion in a culvert, and enters the Monarch Beach Golf Links in Dana Point. It is joined from the right by the Arroyo Salada Storm Channel, which drains from

456-509: Is Spanish for a Blunderbuss , a type of shotgun. Local legend attributes a Franciscan missionary friar traveling with the Gaspar de Portolà Expedition in 1769 for the story that a blunderbuss was lost in the upper canyon by the creek, and so the naming of the area. John "Don Juan" Forster received a Mexican land grant in 1846 for the canyon lands and creek and established Rancho Trabuco here. In its natural state, Arroyo Trabuco supported one of

513-492: Is joined by its largest tributary, Oso Creek , from the right. The creek flows south through orchards until it is forced into a concrete channel, passes by Mission San Juan Capistrano , and joins with San Juan Creek in downtown San Juan Capistrano. On Arroyo Trabuco, the USGS operated two stream gauges, one from 1932 to 1981, and the second from 1973 to 2008, both near its mouth. The USGS refers to this creek as "Arroyo Trabuco". For

570-509: Is now the Arroyo Salada channel into Salt Creek, but at some point in geologic time was captured to the north and resultantly makes a sharp turn north of what is now Crown Valley Parkway and Niguel Road. A low divide about 80 feet (24 m) high now divides the two drainage basins . Like other Orange County creeks south of Aliso Creek and north of San Mateo Creek, the Salt Creek watershed

627-653: The Interstate 5 / California State Route 73 interchange, where Oso Creek spills out of its concrete channel onto bare ground, and continues downstream to where the creek meets Trabuco Creek. In early 1993, severe storm erosion damage along Oso Creek threatened sewer lines and a church. On 15 March 2000, 21,000 U.S. gallons (80 m) overflowed into Oso Creek from a broken sewage pipeline in Mission Viejo. The USGS operated one stream gauge for ten years from 1971 to 1981 near Mission Viejo, California , specifically near

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684-515: The Pacific Coast Highway . Due to channelization during urban development, the source of Salt Creek, once a small marshy wetland, is no longer where it was before the area was developed in the 1990s. Between the original source and Salt Corridor Regional Park, water flows are channeled into storm drain K01P07. The Orange County Department of Public Works manages the storm channels and considers

741-608: The Pacific coast of Orange County, created a physical barrier for these streams flowing off the Santa Ana Mountains. But by the Wisconsinian Glaciation , an enormous climate change helped solve that problem. During the Wisconsinian Glaciation, a period of time that lasted from about 70,000 to 10,000 years ago, glaciers and ice sheets moved south from northern Canada into the northern United States, radically altering

798-521: The Santa Ana Mountains border it to the north and northeast. The drainage divide between Oso Creek and the Aliso Creek watershed is quite pronounced, connecting the San Joaquin Hills to the Santa Ana Mountains in a northeasterly direction. The creek was formerly ephemeral , but significant amounts of urban runoff that flow uncontrolled into the creek have created a perennial flow, known also as

855-548: The 600-to-1,000-foot (180 to 300 m) high San Joaquin Hills. The Trabuco/San Juan Creek canyon is one of the less prominent ones, and is the last canyon before the San Joaquin Hills continue south into San Diego County . Because of the enormous erosion channels carved out by the Wisconsinian-era rivers, the creeks now flow on broad and deep beds of sediment that have filled these canyons. The Arroyo Trabuco watershed, especially

912-791: The Arroyo Trabuco watershed. Conversely, steelhead were sighted in 2003 and 2005 along the creek. A project was proposed in 2005 to build a fish ladder into a concrete drop structure in Arroyo Trabuco that blocks steelhead passage. $ 1.2 million was allocated by the California State Wildlife Conservation Board in 2005 to fund the project, but it has not been begun. The canyon is in the California chaparral and woodlands Ecoregion , with California oak woodland and Chaparral plant communities of California native plants , with invasive plant species of Noxious weeds in

969-467: The Crown Valley Parkway crossing, approximately 5 miles (8.0 km) above the confluence with Trabuco Creek and in total 8 miles (13 km) above where the water joins San Juan. This gauge recorded an average annual flow of 5.3 cubic feet per second (0.15 m/s), or 3,800 acre⋅ft (4,700,000 m) per year, with most of the flow occurring between December and March. The highest peak flow

1026-512: The O'Neill Ranch out of the Rancho Trabuco. The name stayed and most of the ranch is now the site of O'Neill Regional Park, which was dedicated on October 5, 1982. Salt Creek (Orange County) Salt Creek is a small coastal stream in southern Orange County, California in the United States. About 4 miles (6.4 km) long, the creek drains 6.1 square miles (16 km ) in parts of

1083-597: The Oso Creek subwatershed, has been severely affected by suburban development. Lower riparian areas along the creek have been damaged by channelization and contaminated runoff from the creek contributes to pollution problems in Capistrano Bight at the mouth of San Juan Creek at Dana Point . Such pollutants include urban runoff , fertilizers , heavy metals and oils. There is one dam on Arroyo Trabuco, located inside Trabuco Canyon. There are also many drop structures on

1140-466: The Salt Creek Canyon remained relatively undeveloped, except for a golf course - the Monarch Beach Golf Links - at its southern end, and a golf course surrounding the Arroyo Salada Storm Channel's mainstem. As recently as the 1970s, the lowermost stretch of the Salt Creek Canyon was still in existence. This part of the canyon was also destroyed by landfill for the purpose of building more houses and

1197-560: The Santa Ana Mountains near the city of Mission Viejo , the creek is dammed twice to form Upper Oso Reservoir and Lake Mission Viejo . The creek is channelized and polluted along much of its length. "Oso", meaning bear in the Spanish language , was likely the name given to the creek by Spanish conquistadors . Up to the 1970s, the Oso Creek watershed was mostly undeveloped and the creek ephemeral . The watershed lies close to two major wilderness areas - Aliso and Wood Canyons Wilderness Park to

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1254-473: The Santa Ana foothills are Paleogene -age (66-2.59 MYA) sandstone. As the Santa Ana Mountains rose, Arroyo Trabuco first formed as a canyon cut into the southeastern part of the range. Many of the creeks draining the range—including Santiago Creek , San Diego Creek , Bell Canyon and San Juan Creek—first formed in the same way. The uplift of the San Joaquin Hills , a coastal mountain range generally following

1311-696: The Trabuco Ranger District of the Cleveland National Forest , just west of the Orange–Riverside County border, at an elevation of 4,310 feet (1,310 m). The headwaters of the creek are in the large and deep Trabuco Canyon just north of 4,400-foot (1,300 m) Los Pinos Peak and south of 4,604-foot (1,403 m) Trabuco Peak . The creek flows in this 2,000-foot (610 m) deep gorge for its first 4 miles (6.4 km), receiving Holy Jim and Falls Canyon creeks before it passes

1368-514: The cities of Laguna Niguel and Dana Point . The creek begins in Laguna Niguel and flows west and south through a narrow canyon, partly in the Salt Corridor Regional Park. It empties into the Pacific Ocean at Salt Creek County Beach in Dana Point. According to U.S. Geological Survey (USGS) topographic maps, Salt Creek historically began in the southern San Joaquin Hills near what is now

1425-424: The cities of Mission Viejo , Laguna Niguel , and San Juan Capistrano . Most of the watershed is used for residential, commercial, and agricultural purposes. Oso Creek runs parallel to Trabuco Creek, while Salt Creek is to the southwest, Sulphur Creek to the west, and Aliso Creek to the northwest. The southernmost portions of the San Joaquin Hills lie to the west and southwest of the Oso Creek watershed, and

1482-441: The city of Dana Point completed the $ 6.7 million Salt Creek Ozone Treatment Plant, located near Pacific Coast Highway just above Salt Creek's ocean outlet. Dry weather runoff from the creek is captured, filtered for garbage and coarse solids, then treated with filtration and ozonation to reduce bacterial levels. The plant is designed to treat 1,000 US gallons (3.8 m ) per minute and was originally intended to function only during

1539-522: The climate of the entire continent. The arid Southern California climate was supplanted by a temperate rainforest climate that would receive rainfall in excess of 80 to 90 inches (2,000 to 2,300 mm) per year. Arroyo Trabuco and other streams along the Orange County coast became powerful rivers that cut their way through the San Joaquin Hills. This changed climate did not last, and by the time it had ended, several enormous canyons had been cut through

1596-439: The convergence of Interstate 5 and California State Route 73 , within the city limits of Laguna Niguel . Near this area, Oso Creek enters a concrete flood control channel with sloping sides, 5 miles (8.0 km) from the mouth. It then flows through a riprap lined channel before entering a concrete box culvert, which runs south under the state route. The creek then spills out into a natural channel, 1.2 miles (1.9 km) from

1653-399: The creek provided a small but stable year round flow. The creek was labeled "Cañada Salada" (Salt Canyon) or "Cañada Niguel" in a map dating to 1858. From the 1960s to the 1990s, residential development filled most of the available land within the Salt Creek watershed. Mountaintops were flattened and dumped into small canyons to create level land for tract housing and roads. Despite that,

1710-408: The creek was once a productive habitat for steelhead trout . Its upper portions, which include numerous gravel beds and bars, stream pools, and cascades, are suitable habitat for the anadromous fish, which still exist as rainbow trout in upper Arroyo Trabuco. Because of extensive modifications—affecting the stability and water quality of the creek—steelhead no longer migrate to the upper reaches of

1767-413: The creek, fed by three small seasonal streams. After leaving the reservoir, Oso Creek crosses under California State Route 241 and for the next mile (1.6 km) of its course, it flows through a narrow riparian corridor surrounded by residential areas in the city of Mission Viejo. The creek enters an underground culvert , bends east and south, and enters Lake Mission Viejo , 12 miles (19 km) from

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1824-525: The end of the most recent Ice Age . The Santa Ana Mountains, forming the northern, eastern and southeastern boundaries of the entire San Juan Creek watershed, did not begin to form until roughly 5.5 million years ago (MYA). The Santa Ana Mountains at the headwaters of San Juan Creek are composed primarily of Jurassic -age (196.6-145.5 MYA) igneous and sedimentary rock overlain by Cretaceous -age (145.5-66 MYA) granite , gabbro , tolamite , siltstone , sandstone and conglomerates . The underlying rock of

1881-605: The first of which is the second longest tributary of San Juan Creek. On the west of the Arroyo Trabuco watershed is the Aliso Creek drainage basin, on the north the Santiago Creek , and on the northeast streams draining into the Lake Elsinore area. There are between 140,000 and 145,000 people living in the major cities in the Arroyo Trabuco watershed. Geologically the present-day Arroyo Trabuco basin did not exist as early as

1938-441: The former gauge, the average flow was 6.22 cubic feet per second (0.176 m /s) or 4,500 acre-feet (5,600,000 m ) per year, and the highest recorded flow was on February 6, 1937, water flow 9,240 cubic feet per second (262 m /s), with a stage of 6.8 feet (2.1 m). For the latter gauge, the average discharge was 17.4 cubic feet per second (0.49 m /s), 12,600 acre-feet (15,500,000 m ) per year. The largest flow

1995-462: The gun, and they named the creek Arroyo Trabuco as a memorial. Mission San Juan Capistrano was established in 1776 at the confluence of San Juan Creek and Arroyo Trabuco. Rancho Trabuco was a Mexican land grant that covered most of the upper Arroyo Trabuco watershed. Created in 1841, its boundaries were changed in both 1843 and 1846. In 1880, the land was sold to F.L.S. Pioche and the final owners were James L. Flood and Jerome O'Neill, who created

2052-493: The highway and Camino Capistrano through a series of freshwater marshes. The La Paz Channel, its largest tributary, joins here on the right. It passes the Galivan Basin, which functions to capture floodwaters from Oso Creek, on the right bank, and receives from the right a second unnamed tributary, 7.5 miles (12.1 km) from the mouth. This tributary actually flows through the Galivan Basin before meeting Oso Creek. The creek then bends southwest around several shopping centers near

2109-425: The historic landscape encountered by the Spanish conquistadors when they began expeditions to the area in the 18th century. In 1769 Gaspar de Portolà led an expedition to the canyons of the Santa Ana Mountains. They camped on a bluff east of Arroyo Trabuco on the night of July 24–25, and the next day, one of the soldiers found his trabuco , or blunderbuss (the type of gun), missing. The expedition never found

2166-404: The intersection of Golden Lantern and Marina Hills Drive in Laguna Niguel. The upper half of the creek, now filled in and graded over with suburban residential development, ran southwest through a small valley along present-day Marina Hills Drive then south along Niguel Road. It emerges from an underground culvert at the intersection of Niguel Road and Club House Drive and is joined from the east by

2223-499: The lower creek. The climate of the Arroyo Trabuco watershed is almost entirely semi-arid. Scrubland and chaparral make up most of the vegetation in the hilly and sometimes mountainous watershed. 16 different vegetation "bands", or zones, have been identified in the San Juan Creek watershed as a whole, and most of these also exist in the Arroyo Trabuco watershed. These range from riparian to chaparral, coastal sage scrub and rocky outcroppings where little to no vegetation grows. In

2280-643: The modern "Salt Creek Channel" to start from the area of Chapparosa Park in Laguna Niguel, including part of what the USGS labels as San Juan Canyon. The tributary entering within Monarch Beach golf course is now K01P01, the Niguel Shores Storm Drain, and the Arroyo Salada is now K01S02, the Arroyo Salada Storm Channel. The dry season flow of the stream is almost entirely composed of urban runoff . The creek carries pollutants and bacteria into coastal waters off

2337-421: The most significant steelhead trout runs in Orange County, and birds, large mammals, and amphibians still flourish in riparian zones along its undeveloped portions. Trabuco Canyon along upper Arroyo Trabuco, and long, narrow O'Neill Regional Park , formed from the original land grant of Rancho Trabuco in 1982, are popular off-roading, hiking, fishing and camping areas in the watershed. Arroyo Trabuco begins in

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2394-508: The mouth, which it has incised to depths of 50 feet (15 m) or more, as the interstate bends southeast. Flowing through an agricultural area, the creek bends east to join Trabuco Creek inside San Juan Capistrano . Occupying the west and northwest portions of the San Juan Creek watershed, the 25-square-mile (65 km) Oso Creek watershed comprises about 18% of the 133-square-mile (340 km) San Juan Creek watershed. It includes parts of

2451-447: The mouth. Downstream of the artificial lake, Oso Creek flows through a golf course , then after flowing through another narrow canyon, receives an unnamed tributary from the left, 10.5 miles (16.9 km) from the mouth. It then bends slightly to flow southwest and enters a culvert under Marguerite Parkway, emptying into another golf course, 8 miles (13 km) from the mouth. The creek then crosses under Interstate 5 and flows between

2508-669: The north, the foothills of the Santa Anas to the west, and a drainage divide within the San Juan watershed itself on the south and east. Although much of the Arroyo Trabuco watershed is bounded by the San Juan Creek basin it also borders on several other major Orange and Riverside County watersheds. Listed from east to west, the major San Juan Creek subwatersheds it bounds are Bell Canyon , Cañada Gobernadora , Cañada Chiquita and El Horno Creek . Arroyo Trabuco's headwaters are actually not physically far from that of Bell Canyon and San Juan Creek,

2565-644: The people in the Southern Orange County/Northern San Diego County area settled down in semi-permanent villages, and this area became part of the Acjachemen tribal territory. There were two Acjachemen villages on the main stem of the Trabuco and one on Oso Creek, as well as numerous settlements at the confluence of San Juan Creek and Arroyo Trabuco all the way downstream to the Pacific. This was

2622-417: The popular recreational areas of Salt Creek Beach and Monarch Beach. In 2007 this was estimated at 500 to 900 US gallons (1.9 to 3.4 m ) per minute. Both Laguna Niguel and Dana Point implemented measures to reduce pollution from urban runoff, including stream and wetland restoration, drain filters, and irrigation runoff reduction. However, the beaches continued to experience water quality issues. In 2004,

2679-507: The riparian and ' bunch grass ' grasslands . It is hypothesized that Hokan -speaking Native Americans of Shoshone origin occupied a 12-mile (19 km)-long, 8-mile (13 km)-wide strip of land along much of central Arroyo Trabuco and most of Oso Creek , its major tributary, beginning at an unknown date. The Shoshoneans centered around the Trabuco/Oso Creek confluence and had a primarily hunter-gatherer way of life. Eventually,

2736-446: The southern junction of California State Route 73 and Interstate 5 , the creek flows through a residential community and is diverted into twin culverts underneath the interstate. The creek flows over two large man-made drop structures , the first of which marks the beginning of a small canyon that it flows through almost until it reaches downtown San Juan Capistrano. Passing into the northernmost extreme of San Juan Capistrano, it

2793-414: The southwest and O'Neill Regional Park to the west, on Trabuco Creek - but has no major parks within its boundaries. Interstate 5 parallels the creek for over half of its length. The original headwaters of Oso Creek were in a small canyon in the south-central part of the Santa Ana Mountains. A dam was built across this canyon, flooding it to create Upper Oso Reservoir , which now forms the headwaters of

2850-407: The undeveloped Plano Trabuco, there are grasslands , while most of the middle section of the Arroyo Trabuco valley is urbanized. Riparian zones, consisting of small to medium-sized trees and a variety of other streambank flora, line Arroyo Trabuco, Tijeras Canyon Creek, and the upper tributaries including Live Oak Canyon, Falls Canyon and Holy Jim Canyon. These riparian habitats are now only found in

2907-480: The unincorporated community of Trabuco Canyon , where Live Oak Canyon Creek joins from the right . Once out of the mountains, Arroyo Trabuco changes from a swift mountain torrent to a meandering, braided stream crossing a wide sandy bed known as the "Plano Trabuco". After entering the city limits of Rancho Santa Margarita , the creek flows southwest through the long, narrow wilderness preserve of O'Neill Regional Park . It crosses under California State Route 241 ,

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2964-425: The upper watershed. Oso Creek is heavily developed, and has little to no riparian vegetation. Lower Arroyo Trabuco still supports some riparian zones, but they have decreased in health because of the introduction of urban and agricultural runoff. Aside from the large mammals including mountain lions , coyotes , and bobcats (the last California grizzly bear in the Santa Ana Mountains was shot near Trabuco Canyon)

3021-454: The vicinity of Crown Valley Parkway and Hillhurst Drive in Laguna Niguel. In the golf course, it is joined from the left by an unnamed tributary that drains much of western Dana Point. It then enters a long underground culvert beneath Pacific Coast Highway, emerging at a concrete spillway near the north end of Salt Creek Beach. Salt Creek drains one of the smallest watersheds in the county, at 6.1 square miles (16 km ). About two-thirds of

3078-447: The watershed is in Laguna Niguel, with the remainder in Dana Point. Situated within the southern San Joaquin Hills, the Salt Creek watershed is located east of the Aliso Creek watershed and west of the San Juan Creek watershed. The Salt Creek watershed was shaped by seismic uplift of the San Joaquin Hills starting about 1.2 million years ago. Sulphur Creek , which now flows northwest into Aliso Creek, may have once flowed down what

3135-454: Was 10,000 cubic feet per second (280 m /s) (estimated) on 23 February 1998, with a peak stage of 19.81 feet (6.04 m). The USGS states that "All or part of the record affected by Urbanization, Mining, Agricultural changes, Channelization, or other", explaining the large discrepancy in average flows between early and more recent records. Above their confluence, Arroyo Trabuco actually is longer than San Juan Creek, but San Juan Creek drains

3192-465: Was 5,150 cubic feet per second (146 m/s) on 16 February 1980, with a gauge height of 7.6 feet (2.3 m). The second highest flow was the preceding year, which saw a flow of 2,445 cubic feet per second (69.2 m/s). The Oso Creek Trail follows the creek for a notable portion of its length, and is said to be the "backbone" of the trail system of the City of Mission Viejo . The paved trail mostly follows

3249-464: Was once part of the territory of the nomadic Acjachemen Native American group, which was later renamed the Juaneño by Spanish missionaries when they founded Mission San Juan Capistrano at the confluence of San Juan and Trabuco Creeks farther south, close to the group's main population center. It is possible that Juaneño villages once were located along the lower channel of Salt Creek, as springs feeding

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