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90-758: Historically, the Pudding River flowed directly into the Willamette River , and aerial photos dating back to 1936 provide evidence of the Willamette River's confluence with the Pudding River mainstem channel. Currently, it flows directly into the Molalla River near River Mile 1 before joining the Willamette River. Anadromous and resident salmonids use the Lower Pudding River main stem and key tributaries that support

180-562: 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

270-400: A new river, to be given its own name, perhaps one already known to 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

360-470: 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

450-404: 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

540-666: A snowpack-limited ridgeline (i.e. no glaciers are present) that forms a critical linkage from the Mount Hood National Forest and Table Rock Wilderness to Silver Falls State Park and the rolling Waldo Hills east of Salem . Peak ridgeline elevations vary from 3,750 to 4,250 feet (1,140 to 1,300 m). After emerging from the Cascade Mountain foothills of the Panther Rock Ridge and its unique forested upper-elevation wetlands and lakes,

630-523: 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

720-467: 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

810-400: 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

900-473: Is despite the dams, other alterations, and pollution (especially on 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

990-512: 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),

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1080-635: 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,

1170-554: Is part of the Molalla River State Park . The upper river offers catch-and-release fishing for wild trout, while the lower river has bass and panfish . Although the Pudding River is not stocked with hatchery fish, coastal cutthroat trout and rainbow trout enter the upper main stem from Drift, Butte, Silver, and Abiqua creeks. Fishing is restricted to artificial flies and lures and is not allowed for winter-run steelhead (anadromous rainbow trout) that spawn in

1260-577: 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

1350-848: 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 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

1440-819: 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

1530-570: 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

1620-612: 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

1710-572: The Middle Fork Willamette River and the Coast Fork Willamette River near Springfield , 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 ,

1800-642: 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

1890-678: 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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1980-687: 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,

2070-857: 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

2160-669: 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

2250-606: 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

2340-453: 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

2430-825: 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 ,

2520-472: 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

2610-603: 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

2700-478: 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

2790-729: The Columbia about 101 miles (163 km) from the Columbia's mouth on 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

Pudding River - Misplaced Pages Continue

2880-554: 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

2970-788: 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

3060-519: 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

3150-486: 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

3240-634: 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

3330-734: 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 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,

3420-541: 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

3510-437: 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,

3600-472: 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

3690-687: 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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3780-435: 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

3870-647: 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

3960-498: 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

4050-428: 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

4140-399: 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

4230-418: 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,

4320-416: 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

4410-409: The basin's ecosystems. About 24 million years ago at the end of the Oligocene , Oregon had started to look how it is today and the Willamette Bay finally became the Willamette Valley by drying up and being raised above sea level, after assuming a shape much like today's Puget Sound . The Pudding River Basin's complex of headwater creeks originates from the western edge of the Cascade Mountains along

4500-421: 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

4590-414: 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

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4680-423: 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,

4770-471: 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

4860-447: 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

4950-475: 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)

5040-411: 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

5130-451: The handedness is from the point of view of an observer facing upstream. For instance, Steer Creek has 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

5220-424: The joining of tributaries. The opposite to a tributary is a distributary , a river or stream that branches off from and flows away from 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

5310-544: The key tributaries of the watershed like ecologically-important Butte Creek converge near Woodburn into the meandering Pudding River. Passing through and within the Pudding River Valley, the numerous subwatersheds of the Pudding Basin represent a vital part of fertile agricultural lands of the Lower Willamette Valley sub-basin. Two forks of the Pudding join between the cities of Silverton and Mt. Angel , at 45°02′11″N 122°50′00″W  /  45.036368°N 122.833275°W  / 45.036368; -122.833275 , as

5400-543: 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

5490-420: 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

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5580-419: 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

5670-482: 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

5760-406: The opposite bank before approaching the confluence. An early tributary 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

5850-476: The perspective of looking downstream, that is, facing the direction the water current of the main stem is going. In 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

5940-479: 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

6030-402: 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

6120-444: The river continues its course northward where it receives Abiqua Creek from the right at about 2 miles (3.2 km) northwest of Silverton. North of Mt. Angel, Butte Creek , which comes down from the Cascade Range foothills past Scotts Mills , empties into the Pudding River at 45°09′39″N 122°46′25″W  /  45.160768°N 122.773569°W  / 45.160768; -122.773569 . The river continues northward past

6210-406: The river in Portland. The 3,700-foot (1,100 m) bridge is the only cantilevered deck truss in Oregon. 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 flow, drain

6300-432: The river into which they feed, they are called forks . These are typically designated by compass direction. For example, 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,

6390-472: The river splits into two channels that flow around Sauvie Island . Used for navigation purposes, these channels are managed by 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

6480-447: 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 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

6570-494: 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 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

6660-470: 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

6750-418: The smaller stream designated the little fork, the larger either retaining its name unmodified, or receives 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

6840-443: 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,

6930-583: 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

7020-432: The streams are seen to diverge by the cardinal direction (north, south, east, or west) in which they proceed upstream, sometimes 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:

7110-547: 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 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

7200-424: 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

7290-463: The town of Aurora . For most of its course, Butte Creek and the Lower Pudding River mainstem defines the boundary between Marion and Clackamas Counties. The Pudding River flows into the Molalla River, at 45°16′57″N 122°43′01″W  /  45.282375°N 122.716856°W  / 45.282375; -122.716856 , just before the Molalla joins the Willamette River in a floodplain that

7380-472: The tributaries. The extreme lower reaches of the river are navigable by boat when the stream flow is sufficient, sometimes as late as June. Willamette River The Willamette River ( / w ɪ ˈ l æ m ɪ t / wil- AM -it ) 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

7470-1065: 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

7560-605: 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

7650-561: 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

7740-678: 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

7830-560: 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 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

7920-439: 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

8010-402: 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

8100-545: 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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