25-700: Pacoima Wash , 33 miles (53 km) long, is a major tributary of the Tujunga Wash , itself a tributary of the Los Angeles River , in the San Fernando Valley of Los Angeles County , California . The stream begins at Mount Gleason, 6,502 ft (1,982 m), in the western San Gabriel Mountains of the Angeles National Forest . The upper reaches, sometimes known as Pacoima Creek, flow through Pacoima Canyon as
50-434: A navigational context, if one were floating on a raft or other vessel in the main stream, this would be the side the tributary enters from as one floats past; alternately, if one were floating down the tributary, the main stream meets it on the opposite bank of the tributary. This information may be used to avoid turbulent water by moving towards the opposite bank before approaching the confluence. An early tributary
75-700: A capacity of 3,777 acre⋅ft (4,659,000 m ) Built by the Los Angeles County Flood Control District, which became part of the Department of Public Works, it was completed in 1928. At the time, the 371 foot (113m) high dam was the tallest arch dam in the U.S. The dam is situated approximately 1 mile (1.6 km) northeast of Sylmar , above the San Fernando Valley . As a flood control structure, district routinely compensates for hydraulic deficiencies in downstream areas by restraining flows of stormwater released from
100-735: A greenway along the Wash connecting the communities of the Northeast San Fernando Valley. In 2004 the Pacoima Wash Greenway Master Plan was created by Department of Landscape Architecture at Cal Poly Pomona which focuses on the portion of the Wash within the City of San Fernando. In 2008, environmental non-profit Pacoima Beautiful started the Pacoima Wash initiative. The goal of this project
125-447: 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 flow, drain the surrounding drainage basin of its surface water and groundwater , leading the water out into an ocean. The Irtysh is a chief tributary of the Ob river and is also the longest tributary river in
150-414: A left tributary which is called Right Fork Steer Creek. These naming conventions are reflective of the circumstances of a particular river's identification and charting: people living along the banks of a river, with a name known to them, may then float down the river in exploration, and each tributary joining it as they pass by appears as a new river, to be given its own name, perhaps one already known to
175-485: A rapid mountain stream. It then reaches the Pacoima Dam Reservoir in the western San Gabriel Mountains of the Angeles National Forest and proceeds south in a free-flowing stream alongside Pacoima Trail Road. Below the dam, it is generally known as the Pacoima Wash. From there, it joins several other unnamed streams that drain the nearby mountains, collecting at Lopez Dam. South of that dam, Pacoima Wash
200-410: A third stream entering between two others is designated the middle fork; or the streams are distinguished by the relative height of one to the other, as one stream descending over a cataract into another becomes the upper fork, and the one it descends into, the lower ; or by relative volume: the smaller stream designated the little fork, the larger either retaining its name unmodified, or receives
225-514: Is a tributary that joins the main stem river closer to its source than its mouth, that is, before the river's midpoint ; a late tributary joins the main stem further downstream, closer to its mouth than to its source, that is, after the midpoint. In the United States, where tributaries sometimes have the same name as the river into which they feed, they are called forks . These are typically designated by compass direction. For example,
250-598: Is encased in a concrete flood control channel , and travels south from Kagel Canyon in Sylmar though San Fernando , Pacoima , Mission Hills , Panorama City , and Van Nuys . In 1911, the developers of the Van Nuys townsite altered the Pacoima Wash from Sherman Way to the Los Angeles River, for 3 miles by adding a 50’ wide street/flood channel. Years of flooding downstream followed, and Van Nuys flooded in
275-689: Is to create a linear greenway composed of bike lanes and a walking path along a 12-mile stretch of the Wash between the Pacoima Dam in Sylmar and the Tujunga Wash in Arleta . The Pacoima Wash Vision Plan, which covers the Sylmar and Pacoima portions of the Wash was produced in 2011. An addendum to the plan focusing on the Arleta portion of the Wash is currently being produced. Several new parks along
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#1732786767279300-648: The American River in California receives flow from its North, Middle, and South forks. The Chicago River 's North Branch has the East, West, and Middle Fork; the South Branch has its South Fork, and used to have a West Fork as well (now filled in). Forks are sometimes designated as right or left. Here, the handedness is from the point of view of an observer facing upstream. For instance, Steer Creek has
325-465: The San Fernando Valley to be made a concrete channel. In 2007, the wash was cleaned up after being cited as a fertile breeding ground for mosquitoes carrying the West Nile virus . Pacoima Wash has been the site of several rescues of people, mostly of children and teenagers trapped in the spring runoff. Incidents occurred in 1985, 1993, 1995, 1996, 1998, and 2006. There have been efforts to create
350-494: The Pacoima Diversion Channel took the stream east from Laurel Canyon and the I 5-CA 118 interchange to the Tujunga Wash. several miles of Pacoima Wash remained, drained by several miles of adjoining storm drains. And from Vanowen to the Los Angeles River, the historic Pacoima Wash disappears. In 1991, the section between Lassen Street and Parthenia Street was one of the last sections of natural stream beds in
375-424: The Wash are in various stages of completion. 8th Street Park is a 4.75 acre park in the City of San Fernando which will be completed in spring of 2014. The city of Los Angeles is creating preliminary designs for a park along the Wash between El Dorado and Telfair Street. From mouth to source (year built in parentheses): Tributary A tributary , or an affluent , is a stream or river that flows into
400-513: The dam. As construction of Pacoima Dam began, the County of Los Angeles hired Roy W. Carlson as their concrete and soil testing engineer. He developed the world's first strain meter which could be embedded in concrete. He also developed an adiabatic calorimeter and electrical-resistance thermometers to find why the temperature of concrete increased during curing and how best to avoid cracking caused by these stresses. The Pacoima Dam withstood, but
425-416: The designation big . Tributaries are sometimes listed starting with those nearest to the source of the river and ending with those nearest to the mouth of the river . The Strahler stream order examines the arrangement of tributaries in a hierarchy of first, second, third and higher orders, with the first-order tributary being typically the least in size. For example, a second-order tributary would be
450-465: The great Los Angeles Flood of 1938 . In the 1950’s many drastic efforts were made to protect residents along the Pacoima Wash. Just after flowing below Interstate 5 , the stream is diverted to the Pacoima Diversion Channel, joining Tujunga Wash further upstream. The Pacoima Wash Headworks were created where the Interstate 5 interchange is for settling of high flood volumes. The threat of flooding
475-463: The great 1938 Los Angeles rains and flood, many parts of Van Nuys flooded severely. Through the 1960’s, Van Nuys Elementary School kept a pontoon bridge for students to cross the flood channel when it flooded. Parts of the original streambed disappeared and can be traced behind the YMCA. The Knights of Columbus is shoehorned in a 100 foot wide channel. The flooding issues remained until the 1950’s when
500-403: The main stream. Distributaries are most often found in river deltas . Right tributary , or right-bank tributary , and left tributary , or left-bank tributary , describe the orientation of the tributary relative to the flow of the main stem river. These terms are defined from the perspective of looking downstream, that is, facing the direction the water current of the main stem is going. In
525-464: The people who live upon its banks. Conversely, explorers approaching a new land from the sea encounter its rivers at their mouths, where they name them on their charts, then, following a river upstream, encounter each tributary as a forking of the stream to the right and to the left, which then appear on their charts as such; or the streams are seen to diverge by the cardinal direction (north, south, east, or west) in which they proceed upstream, sometimes
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#1732786767279550-570: The result of two or more first-order tributaries combining to form the second-order tributary. Another method is to list tributaries from mouth to source, in the form of a tree structure , stored as a tree data structure . Pacoima Dam Pacoima Dam is a concrete arch dam on Pacoima Creek in the San Gabriel Mountains , in Los Angeles County, California . The reservoir it creates, Pacoima Reservoir, has
575-433: The world with a length of 4,248 km (2,640 mi). The Madeira River is the largest tributary river by volume in the world with an average discharge of 31,200 m /s (1.1 million cu ft/s). A confluence , where two or more bodies of water meet, usually refers to the joining of tributaries. The opposite to a tributary is a distributary , a river or stream that branches off from and flows away from
600-450: Was damaged by the very strong (>1 g ) ground movement which occurred during both the 1971 San Fernando and 1994 Northridge earthquakes . Because of concerns about the stability of the dam and especially its response to potential future earthquakes, the County of Los Angeles, with the technical support of the USGS, began monitoring the dam using continuous GPS. This article about
625-480: Was diminished greatly. 41 years later, Congressman Tony Cardenas won funding to turn the headworks, bare ground used only to settle flood volumes, into parkland. The earlier attempts to channelize the wash from the Pacoima Headworks south were left alone, and the channel was redirected closer to Van Nuys Bl. Because of the flash floods in the Pacoima Wash, flooding in Van Nuys was an issue every year. In
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