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105-802: Coordinates : 44°56′42″N 123°02′36″W  /  44.94500°N 123.04333°W  / 44.94500; -123.04333 Bridge in Salem, Oregon Center Street Bridge [REDACTED] Coordinates 44°56′42″N 123°02′36″W  /  44.94500°N 123.04333°W  / 44.94500; -123.04333 Carries [REDACTED] OR 22 (Center Street) Crosses Willamette River Locale Salem, Oregon Maintained by Marion County Characteristics Design Plate girder History Opened July 30, 1918 (replaced 1891 steel bridge) Location [REDACTED] The Center Street Bridge

210-505: A tan ⁡ ϕ {\displaystyle \textstyle {\tan \beta ={\frac {b}{a}}\tan \phi }\,\!} ; for the GRS   80 and WGS   84 spheroids, b a = 0.99664719 {\textstyle {\tfrac {b}{a}}=0.99664719} . ( β {\displaystyle \textstyle {\beta }\,\!} is known as the reduced (or parametric) latitude ). Aside from rounding, this

315-460: A datum transformation such as a Helmert transformation , although in certain situations a simple translation may be sufficient. Datums may be global, meaning that they represent the whole Earth, or they may be local, meaning that they represent an ellipsoid best-fit to only a portion of the Earth. Examples of global datums include World Geodetic System (WGS   84, also known as EPSG:4326 ),

420-562: A flood in 1861 . This and many other large flows preceded the Flood Control Act of 1936 and dam construction on the Willamette's major tributaries. The river below Willamette Falls, 26.5 miles (42.6 km) from the mouth, is affected by semidiurnal tides , and gauges have detected reverse flows (backwards river flows) below Ross Island at RM 15 (RK 24). The National Weather Service issues tide forecasts for

525-470: A plan to improve fish passage and take other actions to help native fish recover in 2008. Since then, work has proceeded slowly, and the Corps of Engineers, citing engineering difficulties and cost, may not meet the original agreed-upon deadline of 2023 for a system of effective remedies. Other major dams in the Willamette watershed are owned by other interests; for example, several hydroelectric facilities on

630-608: A point on Earth's surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses (often called great circles ), which converge at the North and South Poles. The meridian of the British Royal Observatory in Greenwich , in southeast London, England, is the international prime meridian , although some organizations—such as

735-404: A power plant. The locks at Willamette Falls were completed in 1873. Elsewhere on the main stem, numerous minor flow-regulation structures force the river into a narrower and deeper channel to facilitate navigation and flood control . The dams on the Willamette's major tributaries are primarily large flood-control, water-storage, and power-generating dams. Thirteen of these dams were built from

840-473: A region of the surface of the Earth. Some newer datums are bound to the center of mass of the Earth. This combination of mathematical model and physical binding mean that anyone using the same datum will obtain the same location measurement for the same physical location. However, two different datums will usually yield different location measurements for the same physical location, which may appear to differ by as much as several hundred meters; this not because

945-523: A system of parks, trails, and wildlife refuges along the river. In 1998, the Willamette became one of 14 rivers designated an American Heritage River by U.S. President Bill Clinton . By 2007 the Greenway had grown to include more than 170 separate land parcels, including 10 state parks. Public uses of the river and land along its shores include camping, swimming, fishing, boating, hiking, bicycling, and wildlife viewing. In 2008, government agencies and

1050-467: A temporary lake, Lake Allison , that stretched from Lake Oswego to near Eugene. The ancestral Tualatin Valley, part of the Willamette basin, flooded as well; water depths ranged from 200 feet (61 m) at Lake Oswego to 100 feet (30 m) as far upstream (west) as Forest Grove . Flood deposits of silt and clay, ranging in thickness from 115 feet (35 m) in the north to about 15 feet (4.6 m) in

1155-411: Is 6,367,449 m . Since the Earth is an oblate spheroid , not spherical, that result can be off by several tenths of a percent; a better approximation of a longitudinal degree at latitude ϕ {\displaystyle \phi } is where Earth's equatorial radius a {\displaystyle a} equals 6,378,137 m and tan ⁡ β = b

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1260-480: Is 110.6 km. The circles of longitude, meridians, meet at the geographical poles, with the west–east width of a second naturally decreasing as latitude increases. On the Equator at sea level, one longitudinal second measures 30.92 m, a longitudinal minute is 1855 m and a longitudinal degree is 111.3 km. At 30° a longitudinal second is 26.76 m, at Greenwich (51°28′38″N) 19.22 m, and at 60° it

1365-522: Is 15.42 m. On the WGS   84 spheroid, the length in meters of a degree of latitude at latitude ϕ (that is, the number of meters you would have to travel along a north–south line to move 1 degree in latitude, when at latitude ϕ ), is about The returned measure of meters per degree latitude varies continuously with latitude. Similarly, the length in meters of a degree of longitude can be calculated as (Those coefficients can be improved, but as they stand

1470-400: Is Portland, with more than 500,000 residents. Not all of these cities draw water in part or exclusively from the Willamette for their municipal water supply. Other cities in the watershed (but not on the main-stem river) with populations of 20,000 or more are Gresham, Hillsboro, Beaverton, Tigard, McMinnville, Tualatin, Woodburn , and Forest Grove. Sixty-four percent of the watershed

1575-814: Is a major tributary of the Columbia River , accounting for 12 to 15 percent of the Columbia's flow. The Willamette's main stem is 187 miles (301 km) long, lying entirely in northwestern Oregon in the United States. Flowing northward between the Oregon Coast Range and the Cascade Range , the river and its tributaries form the Willamette Valley , a basin that contains two-thirds of Oregon's population, including

1680-521: Is an automobile bridge located in Salem , Oregon , United States . It spans the Willamette River , connecting West Salem and Oregon Route 22 to Salem. It carries vehicle traffic eastbound from Route 22 and directly from Wallace Road. Traffic exits onto Center Street directly, and onto Front Street via an off-ramp, which was built in 1977. Construction of the bridge started in 1917. The bridge

1785-562: Is different from Wikidata Coordinates on Wikidata Infobox mapframe without OSM relation ID on Wikidata All articles with unsourced statements Articles with unsourced statements from December 2008 Pages using the Kartographer extension Geographic coordinate system A geographic coordinate system ( GCS ) is a spherical or geodetic coordinate system for measuring and communicating positions directly on Earth as latitude and longitude . It

1890-456: Is from Albany to Oregon City. At Willamette Falls , between West Linn and Oregon City, the river plunges about 40 feet (12 m). For the rest of its course, the river is extremely low-gradient and is affected by Pacific Ocean tidal effects from the Columbia. The main stem of the Willamette varies in width from about 330 to 660 feet (100 to 200 m). With an average flow at the mouth of about 37,400 cubic feet per second (1,060 m /s),

1995-456: Is known as a graticule . The origin/zero point of this system is located in the Gulf of Guinea about 625 km (390 mi) south of Tema , Ghana , a location often facetiously called Null Island . In order to use the theoretical definitions of latitude, longitude, and height to precisely measure actual locations on the physical earth, a geodetic datum must be used. A horizonal datum

2100-635: Is of indigenous origin, deriving from the French pronunciation of the name of a Clackamas Native American village. However, Native American languages in Oregon were very similar, so the name may also be derived from Kalapuya dialects. Around the year 1850, the Kalapuya numbered between 2,000 and 3,000 and were distributed among several groups. These figures are only speculative; there may have been as few as eight subgroups or as many as 16. In that time period,

2205-577: Is privately owned, while 36 percent is publicly owned. The U.S. Forest Service manages 30 percent of the watershed, the U.S. Bureau of Land Management 5 percent, and the State of Oregon 1 percent. Sixty-eight percent of the watershed is forested; agriculture, concentrated in the Willamette Valley, makes up 19 percent, and urban areas cover 5 percent. More than 81,000 miles (130,000 km) of roads criss-cross

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2310-704: Is the exact distance along a parallel of latitude; getting the distance along the shortest route will be more work, but those two distances are always within 0.6 m of each other if the two points are one degree of longitude apart. Like any series of multiple-digit numbers, latitude-longitude pairs can be challenging to communicate and remember. Therefore, alternative schemes have been developed for encoding GCS coordinates into alphanumeric strings or words: These are not distinct coordinate systems, only alternative methods for expressing latitude and longitude measurements. Willamette River The Willamette River ( / w ɪ ˈ l æ m ɪ t / wil- AM -it )

2415-409: Is the simplest, oldest and most widely used of the various spatial reference systems that are in use, and forms the basis for most others. Although latitude and longitude form a coordinate tuple like a cartesian coordinate system , the geographic coordinate system is not cartesian because the measurements are angles and are not on a planar surface. A full GCS specification, such as those listed in

2520-465: Is used to precisely measure latitude and longitude, while a vertical datum is used to measure elevation or altitude. Both types of datum bind a mathematical model of the shape of the earth (usually a reference ellipsoid for a horizontal datum, and a more precise geoid for a vertical datum) to the earth. Traditionally, this binding was created by a network of control points , surveyed locations at which monuments are installed, and were only accurate for

2625-886: The Clackamas River are owned by Portland General Electric . These include the River Mill Hydroelectric Project , the Oak Grove project, and the dam at Timothy Lake . The 50 or so crossings of the Willamette River include many historic structures, such as the Van Buren Street Bridge , a swing bridge . Built in 1913, it carries Oregon Route 34 (Corvallis–Lebanon Highway) over the river upstream of RM 131 (RK 211) in Corvallis. The machinery to operate

2730-570: The Coast Fork Willamette River , and Dorena on the Row River . Due to these tall dams, Chinook salmon and steelhead are blocked from roughly half of their historic habitat and spawning grounds on the Willamette's major tributaries. Unable to live and reproduce as they once did, they have been "brought to the brink of extinction". Endangered species listings and a subsequent lawsuit by Willamette Riverkeeper led to

2835-750: The EPSG and ISO 19111 standards, also includes a choice of geodetic datum (including an Earth ellipsoid ), as different datums will yield different latitude and longitude values for the same location. The invention of a geographic coordinate system is generally credited to Eratosthenes of Cyrene , who composed his now-lost Geography at the Library of Alexandria in the 3rd century BC. A century later, Hipparchus of Nicaea improved on this system by determining latitude from stellar measurements rather than solar altitude and determining longitude by timings of lunar eclipses , rather than dead reckoning . In

2940-612: The Farallon Plate beneath the North American Plate , creating the forearc basin that would later become the Willamette Valley. The valley was initially part of the continental shelf , rather than a separate inland sea. Many layers of marine deposits formed in the forearc basin and cover the older Siletz River Volcanics. About 20 to 16 million years ago, uplift formed the Coast Range and separated

3045-481: The International Date Line , which diverges from it in several places for political and convenience reasons, including between far eastern Russia and the far western Aleutian Islands . The combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The visual grid on a map formed by lines of latitude and longitude

3150-642: The Missoula Floods —a series of large outpourings originating at Glacial Lake Missoula in Montana—swept down the Columbia River and backfilled the Willamette watershed. Each flood produced "discharges that exceeded the annual discharge of all the present-day rivers of the world combined". Filling the Willamette basin to depths of 400 feet (120 m) in the Portland region, each flood created

3255-626: The Oregon State Capitol in Salem. Evidence suggests that massive quakes of 8 or more on the Richter scale have occurred historically in the Cascadia subduction zone off the Oregon coast, most recently in 1700 CE , and that others as strong as 9 on the Richter scale occur every 500 to 800 years. The basin's high population density, its nearness to this subduction zone, and its loose soils, which tend to amplify shaking, make

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3360-505: The Oregon Trail . The river was an important transportation route in the 19th century, although Willamette Falls , just upstream from Portland, was a major barrier to boat traffic. In the 21st century, major highways follow the river, and roads cross the main stem on approximately 30 different bridges. More than half a dozen bridges not open to motorized vehicles provide separate crossings for bicycles and pedestrians, mostly in

3465-687: The Sandy River did the explorers learn about their oversight. William Clark returned down the Columbia and entered the Willamette River in April 1806. Fur trappers originally working for the Pacific Fur Company (PFC)) and subsequently for the North West Company (NWC) were next to visit the Willamette River and various tributaries. The Siskiyou Trail (or California-Oregon Trail) originally developed by Indigenous people,

3570-857: The Siletz , the Nestucca , the Trask , and the Wilson to the west; the Nehalem and the Clatskanie to the northwest, and the Columbia River to the north. About 2.5 million people lived in the Willamette River basin as of 2010, about 65 percent of the population of Oregon. As of 2009, the basin contained 20 of the 25 most populous cities in Oregon. These cities include Springfield, Eugene, Corvallis, Albany, Salem, Keizer, Newberg, Oregon City, West Linn, Milwaukie, Lake Oswego, and Portland. The largest

3675-415: The U.S. federal government . The main channel, which is the primary navigational conduit for Portland's harbor and riverside industrial areas, is 40 feet (12 m) deep and varies in width from 600 to 1,900 feet (180 to 580 m), although the river broadens to 2,000 feet (610 m) in some of its lower reaches. This channel enters the Columbia about 101 miles (163 km) from the Columbia's mouth on

3780-615: The Willamette River Upstream Independence Street Bridge [REDACTED] Center Street Bridge Downstream Marion Street Bridge Authority control databases : Geographic [REDACTED] Structurae Retrieved from " https://en.wikipedia.org/w/index.php?title=Center_Street_Bridge&oldid=1197545484 " Categories : Bridges completed in 1918 Buildings and structures in Salem, Oregon Bridges over

3885-609: The eastern United States , mainly the Upland South borderlands of Missouri, Iowa, and the Ohio Valley. Many of these emigrants followed the Oregon Trail , a 2,170-mile (3,490 km) trail across western North America that began at Independence, Missouri , and ended at various locations near the mouth of the Willamette River. Although people had been traveling to Oregon since 1836, large-scale migration did not begin until 1843, when nearly 1,000 pioneers headed westward. Over

3990-463: The main stem Willamette meanders generally north for 187 miles (301 km) to the Columbia River . The river's two most significant course deviations occur at Newberg , where it turns sharply east, and about 18 miles (29 km) downstream from Newberg, where it turns north again. Near its mouth north of downtown Portland , the river splits into two channels that flow around Sauvie Island . Used for navigation purposes, these channels are managed by

4095-606: The 1940s through the 1960s and are operated by the United States Army Corps of Engineers (USACE). Of those 13, 9 produce hydropower. Flood-control dams operated by the USACE are estimated to hold up to 27 percent of the Willamette's runoff. They are used to regulate river flows so as to cut peaks off floods and increase low flows in late summer and autumn, and to divert water into deeper, narrower channels to prevent flooding. A relatively small of amount of

4200-453: The 1960s, Oregon Governor Tom McCall led a push for stronger pollution controls on the Willamette. In this, he was encouraged by Robert (Bob) Straub —the state treasurer and future Oregon governor (1975)—who first proposed a Willamette Greenway program during his 1966 gubernatorial campaign against McCall. The Oregon State Legislature established the program in 1967. Through it, state and local governments cooperated in creating or improving

4305-526: The 1st or 2nd century, Marinus of Tyre compiled an extensive gazetteer and mathematically plotted world map using coordinates measured east from a prime meridian at the westernmost known land, designated the Fortunate Isles , off the coast of western Africa around the Canary or Cape Verde Islands , and measured north or south of the island of Rhodes off Asia Minor . Ptolemy credited him with

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4410-825: The Cascade Range to 10 feet (3.0 m) at the mouth on the Columbia River. Watersheds bordering the Willamette River basin are those of the Little Deschutes River to the southeast, the Deschutes River to the east, and the Sandy River to the northeast; the North Umpqua and Umpqua rivers to the south; coastal rivers including (from south to north) the Siuslaw , the Alsea , the Yaquina ,

4515-472: The City of Portland and the State of Oregon to dramatically reduce combined sewer overflows (CSOs) led to Portland's Big Pipe Project . The project, part of a related series of Portland CSO projects completed in late 2011 at a cost of $ 1.44 billion, separates the city's sanitary sewer lines from storm-water inputs that sometimes overwhelmed the combined system during heavy rains. When that occurred, some of

4620-603: The Clackamas' tribal population was roughly 1,800. The U.S. Census Bureau estimated that the Chinook population was nearly 5,000, though not all of the Chinook lived on the Willamette. The Chinook territory encompassed the lower Columbia River valley and significant stretches of the Pacific coast on both the north and the south side of the Columbia's mouth. At times, however, the Chinook territory extended even farther south in

4725-478: The Columbia River. Between the 1850s and the 1960s, channel-straightening and flood control projects, as well as agricultural and urban encroachment, cut the length of the river between the McKenzie River confluence and Harrisburg by 65 percent. Similarly, the river was shortened by 40 percent in the stretch between Harrisburg and Albany. Interstate 5 and three branches of Oregon Route 99 are

4830-554: The Columbia to Bachelor Island . Rockwell's survey was extremely detailed, including 17,782 hydrographic soundings. His work helped open the port of Portland to commerce. In the second half of the 19th century, the USACE dredged channels and built locks and levees in the Willamette's watershed. Although products such as lumber were often transported on an existing network of railroads in Oregon, these advances in navigation helped businesses deliver more goods to Portland, feeding

4935-506: The Earth's surface move relative to each other due to continental plate motion, subsidence, and diurnal Earth tidal movement caused by the Moon and the Sun. This daily movement can be as much as a meter. Continental movement can be up to 10 cm a year, or 10 m in a century. A weather system high-pressure area can cause a sinking of 5 mm . Scandinavia is rising by 1 cm a year as a result of

5040-798: The Eugene area, and several others are exclusively for rail traffic. There are also ferries that convey cars, trucks, motorcycles, bicycles, and pedestrians across the river for a fare and provided river conditions permit. They are the Buena Vista Ferry between Marion County and Polk County south of Independence and Salem, the Wheatland Ferry between Marion County and Polk County north of Salem and Keizer, and Canby Ferry in Clackamas County north of Canby. Since 1900, more than 15 large dams and many smaller ones have been built in

5145-729: The European ED50 , and the British OSGB36 . Given a location, the datum provides the latitude ϕ {\displaystyle \phi } and longitude λ {\displaystyle \lambda } . In the United Kingdom there are three common latitude, longitude, and height systems in use. WGS   84 differs at Greenwich from the one used on published maps OSGB36 by approximately 112   m. The military system ED50 , used by NATO , differs from about 120   m to 180   m. Points on

5250-536: The French Institut national de l'information géographique et forestière —continue to use other meridians for internal purposes. The prime meridian determines the proper Eastern and Western Hemispheres , although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E. This is not to be conflated with

5355-788: The HBC merged with the NWC. In 1825 a new Fort Vancouver headquarters was built on the north shore of the Columbia closer to the Willamette, and Fort George was closed. Alexander Roderick McLeod traveled up the Willamette in 1826 and 1827, to the Umpqua and the Rogue rivers. In 1829 Lucier established a land claim near the Champoeg trading post and started to settle, soon joined by Gervais (1831), Pierre Belleque (1833) and 77 French Canadian settlers by 1836. By 1843, approximately 100 newcomer families lived in

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5460-519: The Middle and Coast forks and the McKenzie , Long Tom , Marys , Calapooia , Santiam , Luckiamute , Yamhill , Molalla , Tualatin , and Clackamas rivers. Beginning at 438 feet (134 m) above sea level, the main stem descends 428 feet (130 m) between source and mouth, or about 2.3 feet per mile (0.4 m per km). The gradient is slightly steeper from the source to Albany than it

5565-486: The Native Americans. Upper-river tribes caught steelhead and salmon, often by building weirs across tributary streams. Tribes of the northern Willamette Valley practiced a generally settled lifestyle. The Chinooks lived in great wooden lodges , practiced slavery , and had a well-defined caste system. People of the south were more nomadic, traveling from place to place with the seasons. They were known for

5670-634: The PFC. Free trappers Registre Bellaire, John Day and Alexander Carson hunted and traded furs during the winter of 1813-14 along the Willamette. About thirty NWC employees were stationed at the Champoeg post, now called the Willamette Trading Post , along with freemen housed in two huts and Kalapuya nearby. Nez Perce and Cayuse warned the NWC to stay out of the Willamette Valley hunting grounds. Skirmishes went on for several years over fishing and hunting grounds contended by several groups. By

5775-462: The Pacific Ocean. The smaller Multnomah Channel , a distributary , is 21 miles (34 km) long, about 600 feet (180 m) wide, and 40 feet (12 m) deep. It ends about 14.5 miles (23.3 km) farther downstream on the Columbia, near St. Helens in Columbia County . Proposals have been made for deepening the Multnomah Channel to 43 feet (13 m) in conjunction with roughly 103.5 miles (166.6 km) of tandem-maintained navigation on

5880-413: The Willamette Falls Locks have been inactive. As commerce and industry flourished on the lower river, most of the original settlers acquired farms in the upper Willamette Valley. By the late 1850s, farmers had begun to grow crops on most of the available fertile land. The settlers increasingly encroached on Native American lands. Skirmishes between natives and settlers in the Umpqua and Rogue valleys to

5985-610: The Willamette River References [ edit ] ^ "Crossing the Willamette" (PDF) . mwvcog.org. Archived from the original (PDF) on May 30, 2004 . Retrieved December 27, 2008 . ^ "History of Bridges" (PDF) . Salem River Crossing. Archived from the original (PDF) on July 27, 2011 . Retrieved December 27, 2008 . ^ Lutz, Dick. "Salem History: Bridges" . salemhistory.net . Retrieved December 27, 2008 . External links [ edit ] Historic images of Center Street Bridge from Salem Public Library Crossings of

6090-467: The Willamette River Transportation in Salem, Oregon Transportation buildings and structures in Polk County, Oregon Transportation buildings and structures in Marion County, Oregon Road bridges in Oregon 1918 establishments in Oregon Steel bridges in the United States Plate girder bridges in the United States Hidden categories: Pages using gadget WikiMiniAtlas Articles with short description Short description

6195-437: The Willamette River was divided into two stretches: the 27-mile (43 km) lower stretch from Portland to Oregon City—which allowed connection with the rest of the Columbia River system—and the upper reach, which encompassed most of the Willamette's length. Any boats whose owners found it absolutely necessary to get past the falls had to be portaged . This led to competition for business among steam portage companies. In 1873,

6300-472: The Willamette Valley especially vulnerable to damage from strong earthquakes. The Willamette River drains a region of 11,478 square miles (29,730 km ), which is 12 percent of the total area of Oregon. Bounded by the Coast Range to the west and the Cascade Range to the east, the river basin is about 180 miles (290 km) long and 100 miles (160 km) wide. Elevations within the watershed range from 10,495 feet (3,199 m) at Mount Jefferson in

6405-434: The Willamette Valley were further divided into groups including the Kalapuyan-speaking Yamhill and Atfalati (Tualatin) (both Northern Kalapuya), Central Kalapuya like the Santiam , Muddy Creek (Chemapho), Long Tom (Chelamela), Calapooia (Tsankupi), Marys River (Chepenafa) and Luckiamute, and the Yoncalla or Southern Kalapuya, as well other tribes such as the Chuchsney-Tufti, Siuslaw and Molala . The name Willamette

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6510-435: The Willamette Valley. The total native population was estimated at 15,000. The indigenous peoples of the Willamette River practiced a variety of life ways. Those on the lower river, slightly closer to the coast, often relied on fishing as their primary economic mainstay. Salmon was the most important fish to Willamette River tribes as well as to the Native Americans of the Columbia River, where white traders traded fish with

6615-417: The Willamette Valley. These included the Kalapuya , the Chinook , and the Clackamas . The territory of the Clackamas encompassed the northeastern portion of the basin, including the Clackamas River (with which their name is shared). Although it is unclear exactly when, the territory of the Chinook once extended across the northern part of the watershed, through the Columbia River valley. Indigenous peoples of

6720-423: The Willamette basin. The highest flow recorded at this station was 420,000 cubic feet per second (11,893 m /s) on February 9, 1996, during the Willamette Valley Flood of 1996 , and the minimum was 4,200 cubic feet per second (120 m /s) on July 10, 1978. The highest recorded flow of 635,000 cubic feet per second (18,000 m /s) for the Willamette at a different gauge in Portland occurred during

6825-428: The Willamette ranks 19th in volume among rivers in the United States and contributes 12 to 15 percent of the total flow of the Columbia River. The Willamette's flow varies considerably season to season, averaging about 8,200 cubic feet per second (230 m /s) in August to more than 79,000 cubic feet per second (2,200 m /s) in December. The U.S. Geological Survey (USGS) operates five stream gauges along

6930-404: The Willamette's drainage basin, 13 of which are operated by the U.S. Army Corps of Engineers (USACE). The dams are used primarily to produce hydroelectricity , to maintain reservoirs for recreation, and to prevent flooding. The river and its tributaries support 60 fish species, including many species of salmon and trout ; this is despite the dams, other alterations, and pollution (especially on

7035-399: The Willamette, continued on until the falls portage (present-day Oregon City ) and finished their journey at a flattening of both banks, the later site of Champoeg . A first trading post was established. By early 1813, William Wallace and John C. Halsey established a second outpost, Wallace House , farther south, north of present-day Salem. By the end of the War of 1812 , the NWC acquired

7140-418: The basalt with up to 1,000 feet (300 m) of silt in the Portland and Tualatin basins. During the Pleistocene , beginning roughly 2.5 million years ago, volcanic activity in the Cascades combined with a cool, moist climate to produce further heavy sedimentation across the basin, and braided rivers created alluvial fans spreading down from the east. Between about 15,500 and 13,000 years ago,

7245-416: The basin from the Pacific Ocean. Basalts of the Columbia River Basalt Group , from eruptions primarily in eastern Oregon , flowed across large parts of the northern half of the basin about 15 million years ago. They covered the Tualatin Mountains (West Hills), most of the Tualatin Valley , and the slopes of hills farther south, with up to 1,000 feet (300 m) of lava . Later deposits covered

7350-464: The center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels , as they are parallel to the Equator and to each other. The North Pole is 90° N; the South Pole is 90° S. The 0° parallel of latitude is designated the Equator , the fundamental plane of all geographic coordinate systems. The Equator divides the globe into Northern and Southern Hemispheres . The longitude λ of

7455-421: The city's first officially recognized public swimming beach, Poet's Beach . There are more than 20 major dams on the Willamette's tributaries, as well as a complex series of levees and channels to control the river's flow. The only dam on the Willamette's main stem is the Willamette Falls Dam, a low weir -type structure at Willamette Falls that diverts water into the headraces of the adjacent mills and

7560-414: The city's growing economy. Trade goods from the Columbia basin north of Portland could also be transported southward on the Willamette due to the deeper channels made at the Willamette's mouth. By the early 20th century, major river-control projects had begun to take place. Levees were constructed along the river in most urban areas, and Portland built concrete walls to protect its downtown sector. In

7665-497: The construction of the Willamette Falls Locks bypassed the falls and allowed easy navigation between the upper and lower river. Each lock chamber measured 210 feet (64 m) long and 40 feet (12 m) wide, and the canal was originally operated manually before it switched to electrical power. Usage of the locks peaked in the 1940s, and by the early 21st century, the lock system was little used. Since 2011,

7770-542: The controlled burning of woodlands to create meadows for hunting and plant gathering (especially camas ). The Willamette River first appeared in written records in 1792, when it was observed by British Lieutenant William Robert Broughton of the Vancouver Expedition , led by George Vancouver . The 1805-1806 Lewis and Clark Expedition originally missed the mouth of the Willamette. On their return journey, only after receiving directions from natives along

7875-649: The default datum used for the Global Positioning System , and the International Terrestrial Reference System and Frame (ITRF), used for estimating continental drift and crustal deformation . The distance to Earth's center can be used both for very deep positions and for positions in space. Local datums chosen by a national cartographical organization include the North American Datum ,

7980-490: The distance they give is correct within a centimeter.) The formulae both return units of meters per degree. An alternative method to estimate the length of a longitudinal degree at latitude ϕ {\displaystyle \phi } is to assume a spherical Earth (to get the width per minute and second, divide by 60 and 3600, respectively): where Earth's average meridional radius M r {\displaystyle \textstyle {M_{r}}\,\!}

8085-447: The following decades, many large dams were built on Cascade Range tributaries of the Willamette. The Army Corps of Engineers operates 13 such dams, which affect flows from about 40 percent of the basin. Most of them do not have fish ladders. With development in and near the river came increased pollution. By the late 1930s, efforts to stem the pollution led to formation of a state sanitary board to oversee modest cleanup efforts. In

8190-475: The founding of the town in 1829. McLoughlin attempted to persuade the HBC (which still held sway over the area) to allow American settlers to live on the land, and provided significant help to American colonization of the area, all against the HBC's orders. Oregon City prospered because of the lumber and grist mills that were run by the water power of Willamette Falls, but the falls formed an impassable barrier to river navigation. Linn City (originally Robins Nest)

8295-474: The full adoption of longitude and latitude, rather than measuring latitude in terms of the length of the midsummer day. Ptolemy's 2nd-century Geography used the same prime meridian but measured latitude from the Equator instead. After their work was translated into Arabic in the 9th century, Al-Khwārizmī 's Book of the Description of the Earth corrected Marinus' and Ptolemy's errors regarding

8400-625: The government to a part of the Coast Reservation that later became the Grande Ronde Reservation . Between 1879 and 1885, the Willamette River was charted by Cleveland S. Rockwell , a topographical engineer and cartographer for the United States Coast and Geodetic Survey . Rockwell surveyed the lower Willamette from the foot of Ross Island through Portland to the Columbia River and then downstream on

8505-657: The largest of these originally weighed about 160 short tons (150 t). The northern part of the watershed is underlain by a network of faults capable of producing earthquakes at any time, and many small quakes have been recorded in the basin since the mid-19th century. In 1993, the Scotts Mills earthquake —the largest recent earthquake in the valley, measuring 5.6 on the Richter scale —was centered near Scotts Mills , about 34 miles (55 km) south of Portland. It caused $ 30 million in damage, including harm to

8610-835: The largest water storage capacity, at 477,700 acre-feet (589,200,000 m ). The other 11 dams are Big Cliff on the North Santiam River; Green Peter and Foster on the Santiam River ; Cougar on the South Fork McKenzie River ; Blue River on the Blue River ; Fern Ridge on the Long Tom River ; Hills Creek and Dexter on the Middle Fork Willamette River; Fall Creek on Fall Creek ; Cottage Grove on

8715-781: The length of the Mediterranean Sea , causing medieval Arabic cartography to use a prime meridian around 10° east of Ptolemy's line. Mathematical cartography resumed in Europe following Maximus Planudes ' recovery of Ptolemy's text a little before 1300; the text was translated into Latin at Florence by Jacopo d'Angelo around 1407. In 1884, the United States hosted the International Meridian Conference , attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt

8820-461: The location has moved, but because the reference system used to measure it has shifted. Because any spatial reference system or map projection is ultimately calculated from latitude and longitude, it is crucial that they clearly state the datum on which they are based. For example, a UTM coordinate based on WGS84 will be different than a UTM coordinate based on NAD27 for the same location. Converting coordinates from one datum to another requires

8925-595: The longitude of the Royal Observatory in Greenwich , England as the zero-reference line. The Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911. The latitude ϕ of a point on Earth's surface is the angle between the equatorial plane and the straight line that passes through that point and through (or close to)

9030-541: The lower river and in the area around its mouth on the Columbia. Indigenous peoples lived throughout the upper reaches of the basin as well. Rich with sediments deposited by flooding and fed by prolific rainfall on the western side of the Cascades, the Willamette Valley is one of the most fertile agricultural regions in North America, and it was thus the destination of many 19th-century pioneers traveling west along

9135-518: The melting of the ice sheets of the last ice age , but neighboring Scotland is rising by only 0.2 cm . These changes are insignificant if a local datum is used, but are statistically significant if a global datum is used. On the GRS   80 or WGS   84 spheroid at sea level at the Equator, one latitudinal second measures 30.715 m , one latitudinal minute is 1843 m and one latitudinal degree

9240-664: The next 25 years, some 500,000 settlers traveled the Oregon Trail, to reach the Willamette Valley. Starting in the 1830s, Oregon City developed near Willamette Falls. It was incorporated in 1844, becoming the first city west of the Rocky Mountains to have that distinction. John McLoughlin , the Hudson's Bay Company (HBC) superintendent of the Columbia District , was one of the major contributors to

9345-637: The non-profit Willamette Riverkeeper organization designated the full length of the river as the Willamette River Water Trail. Four years later, the National Park Service added the Willamette water trail—expanded to 217 miles (349 km) to include some of the major tributaries—to its list of National Water Trails . The water trail system is meant to protect and restore waterways in the United States and enhance recreation on and near them. A 1991 agreement between

9450-479: The raw sewage in the system flowed into the river instead of into the city's wastewater treatment plant. The Big Pipe project and related work reduces CSO volume on the lower river by about 94 percent. In June 2014, Dean Hall became the first person to swim the entire length of the Willamette River. He swam 184 miles (296 km) from Eugene to the river mouth in 25 days. In 2017, Human Access Project partnered with Portland Parks & Recreation to open

9555-540: The river at the Morrison Bridge . The Willamette River basin was created primarily by plate tectonics and volcanism and was altered by erosion and sedimentation, including deposits from enormous glacial floods as recent as 13,000 years ago. The oldest rocks beneath the Willamette Valley are the Siletz River Volcanics . About 35 million years ago, these rocks were subducted by

9660-579: The river's lower reaches). Part of the Willamette Floodplain was established as a National Natural Landmark in 1987, and the river was named as one of 14 American Heritage Rivers in 1998. The upper tributaries of the Willamette originate in the mountains south and southeast of Eugene, Oregon . Formed by the confluence of the Middle Fork Willamette River and the Coast Fork Willamette River near Springfield ,

9765-470: The river, at Harrisburg, Corvallis, Albany, Salem, and Portland. The average discharge at the lowermost gauge, near the Morrison Bridge in Portland, was 33,220 cubic feet per second (941 m /s) between 1972 and 2013. Located at river mile (RM) 12.8 or river kilometer (RK) 20.6, the gauge measures the flow from an area of 11,200 square miles (29,000 km ), roughly 97 percent of

9870-443: The south, settled from this muddy water to form today's valley floor. The floods carried Montana icebergs well into the basin, where they melted and dropped glacial erratics onto the land surface. These rocks, composed of granite and other materials common to central Montana but not to the Willamette Valley, include more than 40 boulders, each at least 3 feet (0.9 m) in diameter. Before being partly chipped away and removed,

9975-583: The southwest of the Willamette River led the Oregon state government to remove the natives by military force. They were first led off their traditional lands to the Willamette Valley, but soon were marched to the Coast Indian Reservation . In 1855, Joel Palmer , an Oregon legislator, negotiated a treaty with the Willamette Valley tribes, who, although unhappy with the treaty, ceded their lands to non-natives. The natives were then relocated by

10080-482: The state capital, Salem , and the state's largest city, Portland , which surrounds the Willamette's mouth at the Columbia. Originally created by plate tectonics about 35 million years ago and subsequently altered by volcanism and erosion, the river's drainage basin was significantly modified by the Missoula Floods at the end of the most recent ice age . Humans began living in the watershed over 10,000 years ago. There were once many tribal villages along

10185-424: The swing span was removed in the 1950s. The Oregon City Bridge , built in 1922, replaced a suspension span constructed at the site in 1888. It carries Oregon Route 43 over the river at about RM 26 (RK 42) between Oregon City and West Linn . The Ross Island Bridge carries U.S. Route 26 ( Mount Hood Highway ) over the river at RM 14 (RK 23). It is one of 10 highway bridges crossing

10290-1065: The two major highways that follow the river for its entire length. Communities along the main stem include Springfield and Eugene in Lane County ; Harrisburg in Linn County ; Corvallis in Benton County ; Albany in Linn and Benton counties; Independence in Polk County ; Salem in Marion County ; Newberg in Yamhill County ; Oregon City , West Linn , Milwaukie , and Lake Oswego in Clackamas County ; and Portland in Multnomah and Washington counties. Significant tributaries from source to mouth include

10395-605: The vicinity of the Willamette on a section referred to as French Prairie . By 1841, members of the United States Exploring Expedition came through the Siskiyou Trail. They noted extensive salmon fishing by natives at Willamette Falls, much like that at Celilo Falls on the Columbia River. In the middle part of the 19th century the Willamette Valley's fertile soils, pleasant climate, and abundant water attracted thousands of settlers from

10500-483: The water stored in the reservoirs is used for irrigation . Cougar Dam on the South Fork McKenzie River and Detroit Dam on the North Santiam River are the two tallest dams in the Willamette River basin. Detroit Dam is 463 feet (141 m) high and stores 455,000 acre-feet (561,000,000 m ) of water. Lookout Point Dam on the Middle Fork Willamette River , forming Lookout Point Lake , has

10605-678: The watershed. In 1987, the U.S. Secretary of the Interior designated 713 acres (289 ha) of the watershed in Benton County as a National Natural Landmark . This area is the Willamette Floodplain , the largest remaining unplowed native grassland in the North Pacific geologic province, which encompasses most of the Pacific Northwest coast. For at least 10,000 years, a variety of indigenous peoples populated

10710-439: The winter of 1818-19, Thomas McKay led a hunting brigade farther south towards the sources of the Willamette River and reached the upper Umpqua River . More violent skirmishes were fought. Most brigade members returned to Fort George (formerly called Fort Astoria ). Louis LaBonté, Joseph Gervais , Étienne Lucier , Louis Kanota, and Louis Pichette (dit DuPré) remained in the Willamette Valley as free trappers. Meanwhile, in 1821

10815-402: Was established across the Willamette from Oregon City. After Portland was incorporated in 1851, quickly growing into Oregon's largest city, Oregon City gradually lost its importance as the economic and political center of the Willamette Valley. Beginning in the 1850s, steamboats began to ply the Willamette, despite the fact that they could not pass Willamette Falls. As a result, navigation on

10920-501: Was officially opened on July 30, 1918, to two-way vehicle traffic. It was later switched to eastbound-only when the westbound-only Marion Street Bridge opened in 1954. Center Street Bridge replaced the steel bridge that had been built in 1891, and was reconstructed in 1983 after the completion of a widening project from two to four lanes on the Marion Street Bridge. See also [ edit ] List of crossings of

11025-545: Was used to reach farther south. This trail, over 600 miles (970 km) long, stretched from the mouth of the Willamette River near present-day Portland south through the Willamette Valley, crossing the Siskiyou Mountains , and south through the Sacramento Valley to San Francisco . In 1812, William Henry and Alfred Seton paddled up from Fort Astoria (PFC) on the Columbia River into the mouth of

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