The Willamette River ( ) is a major

tributary A tributary, or affluent, is a stream or river that flows into a larger stream or 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 drain the surrounding drainage ...

of the

Columbia River The Columbia River (Upper Chinook: ' or '; Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, C ...

, accounting for 12 to 15 percent of the Columbia's flow. The Willamette's

main stem In hydrology, a mainstem (or trunk) is "the primary downstream segment of a river, as contrasted to its tributaries". Water enters the mainstem from the river's drainage basin, the land area through which the mainstem and its tributaries flow.. A ...

is long, lying entirely in northwestern

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

in the United States. Flowing northward between the

Oregon Coast Range The Oregon Coast Range, often called simply the Coast Range and sometimes the Pacific Coast Range, is a mountain range, in the Pacific Coast Ranges physiographic region, in the U.S. state of Oregon along the Pacific Ocean. This north-south ru ...

and the

Cascade Range The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...

, the river and its tributaries form the

Willamette Valley The Willamette Valley ( ) is a long valley in Oregon, in the Pacific Northwest region of the United States. The Willamette River flows the entire length of the valley and is surrounded by mountains on three sides: the Cascade Range to the east, ...

, a basin that contains two-thirds of Oregon's population, including the state capital, Salem, and the state's largest city,

Portland Portland most commonly refers to: * Portland, Oregon, the largest city in the state of Oregon, in the Pacific Northwest region of the United States * Portland, Maine, the largest city in the state of Maine, in the New England region of the northeas ...

, which surrounds the Willamette's mouth at the Columbia. Originally created by

plate tectonics Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...

about 35 million years ago and subsequently altered by

volcanism Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called ...

and erosion, the river's

drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, t ...

was significantly modified by the

Missoula Floods The Missoula floods (also known as the Spokane floods or the Bretz floods or Bretz's floods) were cataclysmic glacial lake outburst floods that swept periodically across eastern Washington and down the Columbia River Gorge at the end of the las ...

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 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 Oregon Trail was a east–west, large-wheeled wagon route and Westward Expansion Trails, emigrant trail in the United States that connected the Missouri River to valleys in Oregon. The eastern part of the Oregon Trail spanned part of what ...

. The river was an important transportation route in the 19th century, although

Willamette Falls The Willamette Falls is a natural waterfall on the Willamette River between Oregon City, Oregon, Oregon City and West Linn, Oregon, in the United States. It is the largest waterfall in the Northwestern United States by volume, and the seventeen ...

, 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 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 The Wheatland Ferry is a cable ferry that connects Marion County and Yamhill County across the Willamette River in the U.S. state of Oregon. The ferry travels approximately across the river, depending on the height of the river, and is powere ...

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 , colors = , anniversaries = 16 June (Organization Day) , battles = , battles_label = Wars , website = , commander1 = ...

(USACE). The dams are used primarily to produce

hydroelectricity Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other Renewabl ...

, to maintain reservoirs for recreation, and to prevent flooding. The river and its tributaries support 60 fish species, including many species of

salmon Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...

and

trout Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salmoni ...

; this is despite the dams, other alterations, and pollution (especially on the river's lower reaches). Part of the

Willamette Floodplain The Willamette Floodplain consists of of natural grassland, near the Willamette River, that was made a National Natural Landmark in May 1987. The floodplain is within the William L. Finley National Wildlife Refuge and located about south of ...

was established as a

National Natural Landmark The National Natural Landmarks (NNL) Program recognizes and encourages the conservation of outstanding examples of the natural history of the United States. It is the only national natural areas program that identifies and recognizes the best ...

in 1987, and the river was named as one of 14

American Heritage Rivers American Heritage Rivers were designated by the United States Environmental Protection Agency in the 1990s to receive special attention (coordinating efforts of multiple governmental entities) to further three objectives: natural resource and envir ...

in 1998.

Course

The upper tributaries of the Willamette originate in the mountains south and southeast of

Eugene, Oregon Eugene ( ) is a city in the U.S. state of Oregon. It is located at the southern end of the Willamette Valley, near the confluence of the McKenzie and Willamette rivers, about east of the Oregon Coast. As of the 2020 United States Census, Eu ...

. Formed by the confluence of the

Middle Fork Willamette River The Middle Fork Willamette River is one of several forks that unite to form the Willamette River in the western part of the U.S. state of Oregon. It is approximately long, draining an area of the Cascade Range southeast of Eugene, which is at t ...

and the

Coast Fork Willamette River The Coast Fork Willamette River is one of two forks that unite to form the Willamette River in western Oregon in the United States. It is about long, draining an area of the mountains at the south end of the Willamette Valley south of Eugene. Co ...

near Springfield, the

Willamette meanders generally north for to the

. The river's two most significant course deviations occur at Newberg, where it turns sharply east, and about downstream from Newberg, where it turns north again. Near its mouth north of downtown

, the river splits into two channels that flow around

Sauvie Island Sauvie Island, in the U.S. state of Oregon, originally Wapato Island or Wappatoo Island, is the largest island along the Columbia River, at , and one of the largest river islands in the United States. It lies approximately ten miles northwest o ...

. Used for navigation purposes, these channels are managed by the

U.S. federal government The federal government of the United States (U.S. federal government or U.S. government) is the national government of the United States, a federal republic located primarily in North America, composed of 50 states, a city within a fed ...

. The main channel, which is the primary navigational conduit for Portland's harbor and riverside industrial areas, is deep and varies in width from , although the river broadens to in some of its lower reaches. This channel enters the Columbia about from the Columbia's mouth on the Pacific Ocean. The smaller Multnomah Channel, a

distributary A distributary, or a distributary channel, is a stream that branches off and flows away from a main stream channel. Distributaries are a common feature of river deltas. The phenomenon is known as river bifurcation. The opposite of a distributar ...

, is long, about wide, and deep. It ends about farther downstream on the Columbia, near St. Helens in Columbia County. Relevant map quadrangles include Eugene East, Coburg, Junction City, Harrisburg, Peoria, Riverside, Lewisburg, Albany, Monmouth, Salem West, Mission Bottom, Dayton, St. Paul, Newberg, Sherwood, Canby, Lake Oswego, Portland, Linnton, Sauvie Island, and Saint Helens. Proposals have been made for deepening the Multnomah Channel to in conjunction with roughly of tandem-maintained navigation on 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. Multnomah Channel (Multnomah County, Oregon scenic images) (mulDA0081a)

Multnomah Channel (Multnomah County, Oregon scenic images) (mulDA0081a)

Interstate 5 Interstate 5 (I-5) is the main north–south Interstate Highway on the West Coast of the United States, running largely parallel to the Pacific coast of the contiguous U.S. from Mexico to Canada. It travels through the states of Californi ...

and three branches of

Oregon Route 99 Oregon Route 99 is a state highway that runs between the southern border of Oregon, and the city of Junction City. Oregon Route 99 was formed from parts of the former U.S. Route 99; it shares much of its route with I-5, but much of it is also ...

are 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 Harrisburg is the capital city of the Pennsylvania, Commonwealth of Pennsylvania, United States, and the county seat of Dauphin County, Pennsylvania, Dauphin County. With a population of 50,135 as of the 2021 census, Harrisburg is the List of c ...

in Linn County; Corvallis in Benton County; Albany in Linn and Benton counties;

Independence Independence is a condition of a person, nation, country, or state in which residents and population, or some portion thereof, exercise self-government, and usually sovereignty, over its territory. The opposite of independence is the statu ...

Polk County Polk County is the name of twelve counties in the United States, all except two named after president of the United States James Knox Polk: * Polk County, Arkansas * Polk County, Florida * Polk County, Georgia * Polk County, Iowa * Polk Count ...

; Salem in Marion County; Newberg in

Yamhill County Yamhill County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the population was 107,722. The county seat is McMinnville. Yamhill County was named after the Yamhelas, members of the Kalapuya Tribe. Yamhill Cou ...

; Oregon City,

West Linn West Linn is a city in Clackamas County, Oregon, United States. A southern suburb within the Portland metropolitan area, West Linn developed on the site of the former Linn City, which was named after U.S. Senator Lewis F. Linn of Ste. Genevie ...

, Milwaukie, and

Lake Oswego Lake Oswego () is a city in the U.S. state of Oregon, primarily in Clackamas County, with small portions extending into neighboring Multnomah and Washington counties. Located about south of Portland and surrounding the Oswego Lake, the town w ...

Clackamas County Clackamas County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the population was 421,401, making it Oregon's third-most populous county. Its county seat is Oregon City. The county was named after the Native ...

; and Portland in Multnomah and

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

counties. Significant tributaries from source to mouth include the Middle and Coast forks and the McKenzie, Long Tom, Marys, Calapooia, Santiam, Luckiamute, Yamhill, Molalla, Tualatin, and Clackamas rivers. Beginning at above sea level, the main stem descends between source and mouth, or about 2.3 feet per mile (0.4 m per km). Source and mouth elevation derived from

Google Earth Google Earth is a computer program that renders a 3D computer graphics, 3D representation of Earth based primarily on satellite imagery. The program maps the Earth by superimposition, superimposing satellite images, aerial photography, and geog ...

search using GNIS source and mouth coordinates. The gradient is slightly steeper from the source to Albany than it is from Albany to Oregon City.Benke, ''et al.'', p. 617 At

, between West Linn and Oregon City, the river plunges about . 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 .

Discharge

With an average flow at the mouth of about , 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 in August to more than in December. Oregon_Route_34_1717

The

U.S. Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and ...

(USGS) operates five stream gauges along the river, at Harrisburg, Corvallis, Albany, Salem, and Portland. The average discharge at the lowermost gauge, near the Morrison Bridge in Portland, was between 1972 and 2013. Located at

river mile A river mile is a measure of distance in miles along a river from its mouth. River mile numbers begin at zero and increase further upstream. The corresponding metric unit using kilometers is the river kilometer. They are analogous to vehicle roa ...

(RM) 12.8 or river kilometer (RK) 20.6, the gauge measures the flow from an area of , roughly 97 percent of the Willamette basin. The highest flow recorded at this station was on February 9, 1996, during the Willamette Valley Flood of 1996, and the minimum was on July 10, 1978. The highest recorded flow of for the Willamette at a different gauge in Portland occurred during a flood in 1861. This and many other large flows preceded the

Flood Control Act of 1936 The Flood Control Act of 1936, , (FCA 1936) was an Act of the United States Congress signed into law by President Franklin Delano Roosevelt on 22 June 1936. The river below Willamette Falls, from the mouth, is affected by semidiurnal tides, and gauges have detected reverse flows (backwards river flows) below

Ross Island Ross Island is an island formed by four volcanoes in the Ross Sea near the continent of Antarctica, off the coast of Victoria Land in McMurdo Sound. Ross Island lies within the boundaries of Ross Dependency, an area of Antarctica claimed by New ...

at RM 15 (RK 24). The

National Weather Service The National Weather Service (NWS) is an Government agency, agency of the Federal government of the United States, United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weathe ...

issues tide forecasts for the river at the

Morrison Bridge The Morrison Bridge is a bascule bridge that spans the Willamette River in Portland, Oregon. Completed in 1958, it is the third bridge at approximately the same site to carry that name. It is one of the most heavily used bridges in Portland. It ...

Geology

The Willamette River basin was created primarily by

and

and was altered by erosion and sedimentation, including deposits from enormous glacial floods as recent as 13,000 years ago.Wallick, ''et al.'', pp. 495–97 The oldest rocks beneath the Willamette Valley are the

Siletz River Volcanics The Siletz River Volcanics, located in the Oregon Coast Range, United States, are a sequence of basaltic pillow lavas that make up part of Siletzia.subducted Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

by the

Farallon Plate The Farallon Plate was an ancient oceanic plate. It formed one of the three main plates of Panthalassa, alongside the Phoenix Plate and Izanagi Plate, which were connected by a triple junction. The Farallon Plate began subducting under the west ...

beneath the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...

, creating the

forearc Forearc is a plate tectonic term referring to a region between an oceanic trench, also known as a subduction zone, and the associated volcanic arc. Forearc regions are present along a convergent margins and eponymously form 'in front of' the vol ...

basin that would later become the Willamette Valley.Benke, ''et al.'', p. 616 The valley was initially part of the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...

, 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 Uplift may refer to: Science * Geologic uplift, a geological process ** Tectonic uplift, a geological process * Stellar uplift, the theoretical prospect of moving a stellar mass * Uplift mountains * Llano Uplift * Nemaha Uplift Business * Uplif ...

formed the Coast Range and separated the basin from the Pacific Ocean.

Basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

s of the

Columbia River Basalt Group The Columbia River Basalt Group is the youngest, smallest and one of the best-preserved continental flood basalt province on Earth, covering over mainly eastern Oregon and Washington, western Idaho, and part of northern Nevada. The basalt grou ...

, from eruptions primarily in

eastern Oregon Eastern Oregon is the eastern part of the U.S. state of Oregon. It is not an officially recognized geographic entity; thus, the boundaries of the region vary according to context. It is sometimes understood to include only the eight easternmost ...

, flowed across large parts of the northern half of the basin about 15 million years ago. They covered the

Tualatin Mountains The Tualatin Mountains (also known as the West Hills or Southwest Hills of Portland) are a range on the western border of Multnomah County, Oregon, United States. A spur of the Northern Oregon Coast Range, they separate the Tualatin Basin of Was ...

(West Hills), most of the

Tualatin Valley The Tualatin Valley is a farming and suburban region southwest of Portland, Oregon in the United States. The valley is formed by the meandering Tualatin River, a tributary of the Willamette River at the northwest corner of the Willamette Valley, ...

, and the slopes of hills further south, with up to of

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

. Later depositions covered the basalt with up to of silt in the Portland and Tualatin basins. During the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

, 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 river A braided river, or braided channel, consists of a network of river channels separated by small, often temporary, islands called braid bars or, in English usage, ''aits'' or ''eyots''. Braided streams tend to occur in rivers with high sediment l ...

s created

alluvial fan An alluvial fan is an accumulation of sediments that fans outwards from a concentrated source of sediments, such as a narrow canyon emerging from an escarpment. They are characteristic of mountainous terrain in arid to semiarid climates, but a ...

s spreading down from the east. Erratic rock Oregon

Between about 15,500 and 13,000 years ago, the

—a series of large outpourings originating at

Glacial Lake Missoula Lake Missoula was a prehistoric proglacial lake in western Montana that existed periodically at the end of the last ice age between 15,000 and 13,000 years ago. The lake measured about and contained about of water, half the volume of Lake Mic ...

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 in the Portland region, each flood created a temporary lake,

Lake Allison Lake Allison was a temporary lake in the Willamette Valley of Oregon, formed periodically by the Missoula Floods from 15,000 to 13,000 BC. The lake is the main cause of the rich and fertile soil that now characterizes the Willamette Valley. Histo ...

, that stretched from Lake Oswego to near Eugene.Orr (1999), pp. 212–13 The ancestral Tualatin Valley, part of the Willamette basin, flooded as well; water depths ranged from at Lake Oswego to as far upstream (west) as Forest Grove. Flood deposits of silt and clay, ranging in thickness from in the north to about in 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 erratic A glacial erratic is glacially deposited rock differing from the type of rock native to the area in which it rests. Erratics, which take their name from the Latin word ' ("to wander"), are carried by glacial ice, often over distances of hundre ...

s 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 in diameter.Orr (1999), p. 214 Before being partly chipped away and removed, the largest of these originally weighed about . 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.Orr (1999), pp. 215–19 In 1993, the Scotts Mills earthquake—the largest recent earthquake in the valley, measuring 5.6 on the

Richter scale The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 ...

—was centered near Scotts Mills, about south of Portland. It caused $30 million in damage, including harm to 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 The Cascadia subduction zone is a convergent plate boundary that stretches from northern Vancouver Island in Canada to Northern California in the United States. It is a very long, sloping subduction zone where the Explorer, Juan de Fuca, a ...

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 the Willamette Valley especially vulnerable to damage from strong earthquakes.

Watershed

The Willamette River drains a region of , 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 long and wide. Elevations within the watershed range from at Mount Jefferson in the Cascade Range to at the mouth on the Columbia River. Watersheds bordering the Willamette River basin are those of the

Little Deschutes River The Little Deschutes River is a tributary of the Deschutes River in the central part of the U.S. state of Oregon. It is about long, with a drainage basin of . It drains a rural area on the east side of the Cascade Range south of Bend. The Littl ...

to the southeast, the

Deschutes River Deschutes River may refer to: *Deschutes River (Oregon) The Deschutes River in central Oregon is a major tributary of the Columbia River. The river provides much of the drainage on the eastern side of the Cascade Range in Oregon, gathering many ...

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 Alsea are a Native American tribe of Western Oregon. They are (since 1856), confederated with other Tribes on the Siletz Reservation, Oregon, and are members of the Confederated Tribes of Siletz. Their origin story says that the Yaquina, Al ...

, the Yaquina, the

Siletz The Siletz (pronounced SIGH-lets) were the southernmost of several divisions of the Tillamook people speaking a distinct dialect; the other dialect-divisions were: ''Salmon River'' on the river of that name, ''Nestucca'' on Little and Nestucca ...

, 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 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 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 The Bureau of Land Management (BLM) is an agency within the United States Department of the Interior responsible for administering federal lands. Headquartered in Washington DC, and with oversight over , it governs one eighth of the country's la ...

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 of roads criss-cross the watershed.Benke, ''et al.'', pp. 616–17 In 1987, the

U.S. Secretary of the Interior The United States secretary of the interior is the head of the United States Department of the Interior. The secretary and the Department of the Interior are responsible for the management and conservation of most federal land along with natural ...

designated of the watershed in Benton County as a

. This area is the

, the largest remaining unplowed native grassland in the North Pacific geologic province, which encompasses most of the Pacific Northwest coast.

History

First inhabitants

For at least 10,000 years, a variety of indigenous peoples populated the Willamette Valley. These included the

Kalapuya The Kalapuya are a Native American people, which had eight independent groups speaking three mutually intelligible dialects. The Kalapuya tribes' traditional homelands were the Willamette Valley of present-day western Oregon in the United Sta ...

, 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 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 Molala (also Molale, Molalla, Molele) are a people of the Plateau culture area in the Oregon Cascades and central Oregon, United States. They are one of the Confederated Tribes of the Grand Ronde Community of Oregon, with 141 of the 882 member ...

. The name ''Willamette'' is of indigenous origin, deriving from the French pronunciation of the name of a Clackamas Native American village.Bright, p. 567 However, Native American languages in Oregon were very similar, so the name may also be derived from Kalapuya dialects. Wilhamut

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, the Clackamas' tribal population was roughly 1,800. The

U.S. Census Bureau The United States Census Bureau (USCB), officially the Bureau of the Census, is a principal agency of the U.S. Federal Statistical System, responsible for producing data about the American people and economy. The Census Bureau is part of the ...

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 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 Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...

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 the Native Americans. Upper-river tribes caught

steelhead Steelhead, or occasionally steelhead trout, is the common name of the anadromous form of the coastal rainbow trout or redband trout (O. m. gairdneri). Steelhead are native to cold-water tributaries of the Pacific basin in Northeast Asia and ...

and salmon, often by building

weir A weir or low head dam is a barrier across the width of a river that alters the flow characteristics of water and usually results in a change in the height of the river level. Weirs are also used to control the flow of water for outlets of l ...

s across tributary streams. Tribes of the northern Willamette Valley practiced a generally settled lifestyle. The Chinooks lived in great wooden lodges,Ruby and Brown, p. 16 practiced

slavery Slavery and enslavement are both the state and the condition of being a slave—someone forbidden to quit one's service for an enslaver, and who is treated by the enslaver as property. Slavery typically involves slaves being made to perf ...

, and had a well-defined

caste Caste is a form of social stratification characterised by endogamy, hereditary transmission of a style of life which often includes an occupation, ritual status in a hierarchy, and customary social interaction and exclusion based on cultura ...

system. People of the south were more nomadic, traveling from place to place with the seasons. They were known for the controlled burning of woodlands to create meadows for hunting and plant gathering (especially camas).

Fur trade

The Willamette River first appears in the records of outsiders in 1792, when it was seen by British Lieutenant

William Robert Broughton William Robert Broughton (22 March 176214 March 1821) was a British naval officer in the late 18th century. As a lieutenant in the Royal Navy, he commanded HMS ''Chatham'' as part of the Vancouver Expedition, a voyage of exploration through th ...

of the

Vancouver Expedition The Vancouver Expedition (1791–1795) was a four-and-a-half-year voyage of exploration and diplomacy, commanded by Captain George Vancouver of the Royal Navy. The British expedition circumnavigated the globe and made contact with five continen ...

, led by George Vancouver. From the 18th to the mid-19th century, much of the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...

and most of its rivers were involved in the

fur trade The fur trade is a worldwide industry dealing in the acquisition and sale of animal fur. Since the establishment of a world fur market in the early modern period, furs of boreal, polar and cold temperate mammalian animals have been the mos ...

, in which fur trappers (mostly French-Canadians working for the

Hudson's Bay Company The Hudson's Bay Company (HBC; french: Compagnie de la Baie d'Hudson) is a Canadian retail business group. A fur trading business for much of its existence, HBC now owns and operates retail stores in Canada. The company's namesake business div ...

and the

North West Company The North West Company was a fur trading business headquartered in Montreal from 1779 to 1821. It competed with increasing success against the Hudson's Bay Company in what is present-day Western Canada and Northwestern Ontario. With great weal ...

, which later merged) hunted for

beaver Beavers are large, semiaquatic rodents in the genus ''Castor'' native to the temperate Northern Hemisphere. There are two extant species: the North American beaver (''Castor canadensis'') and the Eurasian beaver (''C. fiber''). Beavers ar ...

and

sea otter The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of the weasel family, but among the small ...

on rivers, streams, and coastlines. The pelts of these animals commanded substantial prices in either the United States, Canada or eastern Asia, because of their "thick, luxurious and water-repellent" qualities. Fur traders heavily exploited the Willamette River and its tributaries. During this period, the

Siskiyou Trail The Siskiyou Trail stretched from California's Central Valley to Oregon's Willamette Valley; modern-day Interstate 5 follows this pioneer path. Originally based on existing Native American foot trails winding their way through river valleys, t ...

(or California-Oregon Trail) was created. This trading path, over long, stretched from the mouth of the Willamette River near present-day Portland south through the Willamette Valley, crossing the Cascades and the

Siskiyou Mountains The Siskiyou Mountains are a coastal subrange of the Klamath Mountains, and located in northwestern California and southwestern Oregon in the United States. They extend in an arc for approximately from east of Crescent City, California, northea ...

, and south through the

Sacramento Valley , photo =Sacramento Riverfront.jpg , photo_caption= Sacramento , map_image=Map california central valley.jpg , map_caption= The Central Valley of California , location = California, United States , coordinates = , boundaries = Sierra Nevada (ea ...

San Francisco San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...

19th-century development

In 1805, the

Lewis and Clark Expedition The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select gro ...

traveled thousands of miles across central North America in an attempt to map and explore the

Louisiana Territory The Territory of Louisiana or Louisiana Territory was an organized incorporated territory of the United States that existed from July 4, 1805, until June 4, 1812, when it was renamed the Missouri Territory. The territory was formed out of the ...

of the United States and the Oregon Country, which were then occupied mainly by Native Americans and settlers from Great Britain. As the expedition traveled down and back up the Columbia River, it missed the mouth of the Willamette, one of the Columbia's largest tributaries. It was only after receiving directions from natives along the Sandy River that the explorers learned about their oversight.

William Clark William Clark (August 1, 1770 – September 1, 1838) was an American explorer, soldier, Indian agent, and territorial governor. A native of Virginia, he grew up in pre-statehood Kentucky before later settling in what became the state of Misso ...

returned down the Columbia and entered the Willamette River in April 1806. The

United States Exploring Expedition The United States Exploring Expedition of 1838–1842 was an exploring and surveying expedition of the Pacific Ocean and surrounding lands conducted by the United States. The original appointed commanding officer was Commodore Thomas ap Catesby ...

passed through the Willamette Valley in 1841 while traveling along the Siskiyou Trail. The expedition members noted extensive salmon fishing by natives at Willamette Falls, much like that at

Celilo Falls Celilo Falls (Wyam, meaning "echo of falling water" or "sound of water upon the rocks," in several native languages) was a tribal fishing area on the Columbia River, just east of the Cascade Mountains, on what is today the border between the U.S. ...

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 the

eastern United States The Eastern United States, commonly referred to as the American East, Eastern America, or simply the East, is the region of the United States to the east of the Mississippi River. In some cases the term may refer to a smaller area or the East C ...

, mainly the

Upland South The Upland South and Upper South are two overlapping cultural and geographic subregions in the inland part of the Southern and lower Midwestern United States. They differ from the Deep South and Atlantic coastal plain by terrain, history, econom ...

borderlands of Missouri, Iowa, and the Ohio Valley. Many of these emigrants followed the

, a trail across western North America that began at

Independence, Missouri Independence is the fifth-largest city in Missouri and the county seat of Jackson County, Missouri, Jackson County. Independence is a satellite city of Kansas City, Missouri, and is the largest suburb on the Missouri side of the Kansas City metro ...

, 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 the next 25 years, some 500,000 settlers traveled the Oregon Trail, braving the rapids of the

Snake Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...

and Columbia Rivers to reach the Willamette Valley. Oregon City and Willamette Falls, 1867

Starting in the 1820s, Oregon City developed near Willamette Falls. It was incorporated in 1844, becoming the first city west of the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico in ...

to have that distinction. John McLoughlin, a Hudson's Bay Company (HBC) official, was one of the major contributors to the founding of the town in 1829. McLoughlin attempted to persuade the British government (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

paper mill A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags, and other ingredients. Prior to the invention and adoption of the Fourdrinier machine and other types of paper machine that use an endless belt, ...

s that were run by the water power of Willamette Falls, but the falls formed an impassable barrier to river navigation.

Linn City Linn City was a community in Clackamas County, Oregon, United States, that existed from 1843-1861 and was destroyed in the Great Flood of 1862. The former site of Linn City was incorporated into the city of West Linn. History Robert Moore founded ...

(originally Robins Nest) 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,

steamboat A steamboat is a boat that is marine propulsion, propelled primarily by marine steam engine, steam power, typically driving propellers or Paddle steamer, paddlewheels. Steamboats sometimes use the ship prefix, prefix designation SS, S.S. or S/S ...

s began to ply the Willamette, despite the fact that they could not pass Willamette Falls. As a result, navigation on the Willamette River was divided into two stretches: the 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

portage Portage or portaging (Canada: ; ) is the practice of carrying water craft or cargo over land, either around an obstacle in a river, or between two bodies of water. A path where items are regularly carried between bodies of water is also called a ...

d. This led to competition for business among steam portage companies. In 1873, the construction of the

Willamette Falls Locks The Willamette Falls Locks are a lock system on the Willamette River in the U.S. state of Oregon. Opened in 1873 and closed since 2011, they allowed boat traffic on the Willamette to navigate beyond Willamette Falls and the T.W. Sullivan Dam. ...

bypassed the falls and allowed easy navigation between the upper and lower river. Each lock chamber measured long and 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, 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 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 The Coast Indian Reservation is a former Indian reservation in the U.S. state of Oregon, established in 1855. It was gradually reduced in size and in the 21st century is known as the present-day Siletz Reservation. History The Coast Reservation wa ...

. In 1855,

Joel Palmer General Joel Palmer (October 4, 1810 – June 9, 1881) was an American pioneer of the Oregon Territory in the Pacific Northwest region of North America. He was born in Canada, and spent his early years in New York and Pennsylvania before serving ...

, 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 the government to a part of the Coast Reservation that later became the

Grande Ronde Reservation The Grand Ronde Community is an Indian reservation located on several non-contiguous sections of land in southwestern Yamhill County and northwestern Polk County, Oregon, United States, about east of Lincoln City, near the community of Grand ...

. Between 1879 and 1885, the Willamette River was charted by Cleveland S. Rockwell, a topographical engineer and cartographer for the

U.S. Coast and Geodetic Survey The National Geodetic Survey (NGS) is a United States federal agency that defines and manages a national coordinate system, providing the foundation for transportation and communication; mapping and charting; and a large number of applications ...

. Rockwell surveyed the lower Willamette from the foot of

through Portland to the Columbia River and then downstream on the Columbia to

Bachelor Island The Elizabeth Islands are a chain of small islands extending southwest from the southern coast of Cape Cod, Massachusetts in the United States. They are located at the outer edge of Buzzards Bay, north of Martha's Vineyard, from which they are ...

. 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 , colors = , anniversaries = 16 June (Organization Day) , battles = , battles_label = Wars , website = , commander1 = ...

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 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.

20th and 21st centuries

Conveyor belt for Big Pipe project - Portland, Oregon

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 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 the 1960s, Oregon Governor

Tom McCall Thomas Lawson McCall (March 22, 1913 January 8, 1983) was an American statesman, politician and journalist in the state of Oregon. A Republican, he was the state's thirtieth governor from 1967 to 1975. A native of Massachusetts, McCall grew up t ...

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 The Willamette River Greenway is a cooperative state and local government effort to maintain and enhance the scenic, recreational, historic, natural and agricultural qualities of the Willamette River and its adjacent lands. A number of trails exi ...

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 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 American Heritage Rivers were designated by the United States Environmental Protection Agency in the 1990s to receive special attention (coordinating efforts of multiple governmental entities) to further three objectives: natural resource and envir ...

by U.S. President

Bill Clinton William Jefferson Clinton ( né Blythe III; born August 19, 1946) is an American politician who served as the 42nd president of the United States from 1993 to 2001. He previously served as governor of Arkansas from 1979 to 1981 and agai ...

. 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 the non-profit

Willamette Riverkeeper Willamette Riverkeeper is a non profit organization formed in 1996 in order to protect and restore the Willamette River's water quality and habitat. Willamette River The Willamette River runs through a large stretch of Oregon's Willamette Vall ...

organization designated the full length of the river as the Willamette River Water Trail. Four years later, the

National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational propertie ...

added the Willamette water trail—expanded to 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 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 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 from Eugene to the river mouth in 25 days.

Dams and bridges

Dams

There are more than 20 major dams on the Willamette's tributaries, as well as a complex series of levees, dikes, and channels to control the river's flow. The only dam on the Willamette's main stem is the

Dam, a low

-type structure at Willamette Falls that diverts water into the headraces of the adjacent mills and 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 the 1940s through the 1960s and are operated by the

United States Army Corps of Engineers , colors = , anniversaries = 16 June (Organization Day) , battles = , battles_label = Wars , website = , commander1 = ...

(USACE). Of those 13, 11 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 the water stored in the reservoirs is used for irrigation. USACE Detroit Dam Oregon

Cougar Dam Cougar Dam is a tall rockfill hydroelectric dam in the U.S. state of Oregon. It has a gated concrete spillway and a powerhouse with two turbines totaling 25 megawatts of electric power. The dam impounds the South Fork McKenzie River about east ...

on the

South Fork McKenzie River The South Fork McKenzie River is a tributary, about long, of the McKenzie River in the U.S. state of Oregon. It begins at about above sea level near Mink Lake in the Three Sisters Wilderness of the Cascade Range. Flowing northwest within Lan ...

and

Detroit Dam Detroit Dam is a gravity dam on the North Santiam River between Linn County and Marion County, Oregon. It is located in the Cascades, about west of the city of Detroit. It was constructed between 1949 and 1953 by the United States Army Corps o ...

on the

North Santiam River The North Santiam River is a tributary of the Santiam River in western Oregon in the United States. It drains of the Cascade Range on the eastern side of the Willamette Valley east of Salem. It rises in the high Cascades in eastern Linn count ...

are the two tallest dams in the Willamette River basin. Detroit Dam is high and stores of water. Lookout Point Dam on the

, forming Lookout Point Lake, has the largest water storage capacity, at . The other 11 dams are Big Cliff on the North Santiam River; Green Peter and Foster on the

Santiam River The Santiam River is a tributary of the Willamette River, about long, in western Oregon in the United States. Through its two principal tributaries, the North Santiam and the South Santiam rivers, it drains a large area of the Cascade Range a ...

; Cougar on the

; 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 the

, and Dorena on the Row River. Due to these tall dams,

Chinook salmon The Chinook salmon (''Oncorhynchus tshawytscha'') is the largest and most valuable species of Pacific salmon in North America, as well as the largest in the genus '' Oncorhynchus''. Its common name is derived from the Chinookan peoples. Other ...

and

are blocked from roughly half of their historic habitat and

spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...

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 a plan to improve fish passage and 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 the

Clackamas River The Clackamas River is an approximately tributary of the Willamette River in northwestern Oregon, in the United States. Draining an area of about , the Clackamas flows through mostly forested and rugged mountainous terrain in its upper reaches, a ...

are owned by

Portland General Electric Portland General Electric (PGE) is a Fortune 1000 public utility based in Portland, Oregon. It distributes electricity to customers in parts of Multnomah, Clackamas, Marion, Yamhill, Washington, and Polk counties - 44% of the inhabitants ...

. These include the River Mill Hydroelectric Project, the Oak Grove project, and the dam at

Timothy Lake Timothy Lake is a lake about southeast of Portland, Oregon, United States. It is in proximity to Clear Lake and an impoundment of the Oak Grove Fork Clackamas River. The compacted-earth Timothy Lake Dam was built by Portland General Electric ...

Bridges

The 50 or so crossings of the Willamette River include many historic structures, such as the Van Buren Street Bridge, a

swing bridge A swing bridge (or swing span bridge) is a movable bridge that has as its primary structural support a vertical locating pin and support ring, usually at or near to its center of gravity, about which the swing span (turning span) can then pi ...

. Built in 1913, it carries

Oregon Route 34 Oregon Route 34 is a state highway in the U.S. state of Oregon that runs between the city of Waldport on the Oregon Coast and the city of Lebanon in the western part of the state. OR 34 traverses the Alsea Highway No. 27 from Waldpo ...

(Corvallis–Lebanon Highway) over the river upstream of RM 131 (RK 211) in Corvallis. The machinery to operate the swing span was removed in the 1950s. The

Oregon City Bridge The Oregon City Bridge, also known as the Arch Bridge, is a steel through arch bridge spanning the Willamette River between Oregon City and West Linn, Oregon, United States. Completed in 1922, it is listed on the National Register of Historic P ...

, built in 1922, replaced a suspension span constructed at the site in 1888. It carries

Oregon Route 43 Oregon Route 43 is an Oregon state highway that runs between the cities of Oregon City and Portland, mostly along the western flank of the Willamette River. While it is technically known by the Oregon Department of Transportation as the Osweg ...

over the river at about RM 26 (RK 42) between Oregon City and

. The

Ross Island Bridge The Ross Island Bridge is a cantilever truss bridge that spans the Willamette River in Portland, Oregon. It carries U.S. Route 26 (Mount Hood Highway) across the river between southwest and southeast Portland. The bridge opened in 1926 and was ...

carries U.S. Route 26 (

Mount Hood Highway The Mount Hood Highway No. 26 (see Oregon highways and routes) is the Oregon Department of Transportation's designation for a highway from Portland east around the south side of Mount Hood and north via Bennett Pass to Hood River. It is marked ...

) over the river at RM 14 (RK 23). It is one of 10 highway bridges crossing the river in Portland. The bridge is the only cantilevered deck truss in Oregon. SteelBridgePano1

Tilikum Crossing Tilikum Crossing, Bridge of the People is a cable-stayed bridge across the Willamette River in Portland, Oregon, United States. It was designed by TriMet, the Portland metropolitan area's regional transit authority, for its MAX Orange Line lig ...

is a

cable-stayed bridge A cable-stayed bridge has one or more ''towers'' (or ''pylons''), from which cables support the bridge deck. A distinctive feature are the cables or stays, which run directly from the tower to the deck, normally forming a fan-like pattern o ...

that carries public transit, bicycles, and pedestrians, but no cars or trucks, over the river. It opened for general use on September 12, 2015, becoming the first new bridge built across the river in the

Portland metropolitan area The Portland metropolitan area is a metro area in the U.S. states of Oregon and Washington centered on the principal city of Portland, Oregon. The U.S. Office of Management and Budget (OMB) identifies it as the Portland–Vancouver–Hillsboro, ...

since 1973. Further downstream is the oldest remaining highway structure over the Willamette, the

Hawthorne Bridge The Hawthorne Bridge is a truss bridge with a vertical lift that spans the Willamette River in Portland, Oregon, joining Hawthorne Boulevard and Madison Street. It is the oldest vertical-lift bridge in operation in the United States and the o ...

, built in 1910. It is the oldest vertical-lift bridge in operation in the United States and the oldest highway bridge in Portland. It is also the busiest bicycle and

transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1979 film), a 1979 Israeli film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the world * ''Transit'' (2006 film), a 2006 ...

bridge in Oregon, with over 8,000 cyclists and 800

TriMet TriMet, formally known as the Tri-County Metropolitan Transportation District of Oregon, is a public agency that operates mass transit in a region that spans most of the Portland metropolitan area in the U.S. state of Oregon. Created in 1969 ...

buses (carrying about 17,400 riders) daily.

Another historic structure, the

Steel Bridge The Steel Bridge is a through truss, double-deck vertical-lift bridge across the Willamette River in Portland, Oregon, United States, opened in 1912. Its lower deck carries railroad and bicycle/pedestrian traffic, while the upper deck carries r ...

, further downstream, was "the largest telescoping bridge in the world at the time of its opening" in 1912.Smith, ''et al.'', p. 208 It carries trains on its lower deck, MAX (Metropolitan Area Express) light-rail trains and motorized vehicles on its upper deck, and foot and bicycle traffic on a cantilevered walkway attached to the lower deck. When small ships must pass under the bridge, its double vertical-lift span can raise a lower railway deck without disturbing traffic on the upper deck. Operators can raise both decks as high as above the water. The Steel Bridge is "believed to be the world's only double-lift span that can raise its lower deck independently of the upper deck." The Broadway Bridge, slightly downstream of the Steel Bridge, was the world's longest double-leaf bascule drawbridge at the time of its construction in 1913.Smith, ''et al.'', p. 116 Further downstream, the St. Johns Bridge, a steel suspension bridge built in 1931, replaced the last of the Willamette River

ferries A ferry is a ship, watercraft or amphibious vehicle used to carry passengers, and sometimes vehicles and cargo, across a body of water. A passenger ferry with many stops, such as in Venice, Italy, is sometimes called a water bus or water tax ...

in Portland.Smith, ''et al.'', p. 113 At about RM 6 (RK 10), it carries the U.S. Route 30 Bypass. The bridge has two Gothic towers supporting the span. The adjacent park and neighborhood of Cathedral Park are named after the

Gothic Cathedral Gothic cathedrals and churches are religious buildings created in Europe between the mid-12th century and the beginning of the 16th century. The cathedrals are notable particularly for their great height and their extensive use of stained glass t ...

-like appearance of the bridge towers. It is the tallest bridge in Portland, with tall towers and a navigational clearance.

Flooding

Due to the volume and seasonality of precipitation in western Oregon, the Willamette River has often flooded. Heavy rains and mountain snows are common in winter, and snowpack in the Cascade Range can rapidly melt during warmer winter storms. The greatest Willamette River flood in recorded history began in 1861, well before the construction of dams in the watershed. Rainstorms and warm temperatures in December 1861 combined with a well-above-average snowpack in the Cascades created the largest Willamette River flood in recorded history. An observer of the flood wrote, "The whole Willamette valley was a sheet of water". From Eugene to Portland, thousands of acres of farmland were washed away, and many towns in the valley were damaged or destroyed. The "

Great Flood A flood myth or a deluge myth is a myth in which a great flood, usually sent by a deity or deities, destroys civilization, often in an act of divine retribution. Parallels are often drawn between the flood waters of these myths and the primaeval ...

", as it is sometimes called, was massively destructive to human development because most of that development was located on the river's floodplain, which provided rich soils and ready access to water transportation. The 1861 flood peaked at —more than the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...

usually discharges in the 21st century—and inundated some of land. This flood destroyed the town of

. When the flood ended on December 14, only three homes remained standing in Linn City. No one died in the Linn City flood, but the destruction was too significant for the town to recover, and it was abandoned. Today the city of

stands about where Linn City once was. Significant flooding recurred in the winter of early 1890, when the river rapidly rose and crested. Portland's main street was completely submerged, communication over the Cascades was cut off, and many rail lines were forced to shut down. Another major flood occurred on the Willamette in 1894, and although it too caused much damage, it was not as large as that of 1861. Aerial view of vanport flooded

Throughout the 1940s the Willamette continued to flood its valley. It washed out five bridges in Lane County in December 1942, caused seven deaths in Portland and evacuations in Eugene in January 1943, flooded Corvallis in November 1946, contributed to the destruction of Vanport City and the death of about 15 of its residents in May 1948, and nearly flooded parts of Salem in December 1948. Although the Willamette was, by the mid-20th century, heavily engineered and controlled by a complex system of dams, channels, and barriers, it experienced severe floods through the end of the century. Storms caused a major flood that swelled the Willamette and other rivers in the Pacific Northwest from December 1964 through January 1965, submerging nearly of land. Before dawn on December 21, 1964, the Willamette reached , which was higher than the seawall on its banks in Portland. By this time, about 15 people had died as a result of the flooding, and about 8,000 had been forced to evacuate their homes. On December 24, 1964, President

Lyndon B. Johnson Lyndon Baines Johnson (; August 27, 1908January 22, 1973), often referred to by his initials LBJ, was an American politician who served as the 36th president of the United States from 1963 to 1969. He had previously served as the 37th vice ...

ordered federal aid for the flooded areas, as the Willamette continued to rise. In the next couple of days, the river receded, but on December 27, it was at , which was still nearly above the flood stage. The river continued to pose flood threats through January 1965, and more stormy weather occurred along the Pacific Coast. In February 1996, heavy warm rains driven by a subtropical

jet stream Jet streams are fast flowing, narrow, meandering thermal wind, air currents in the Atmosphere of Earth, atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are west ...

fell on a deep snowpack in the Willamette watershed. These conditions, similar to those that caused the 1861 flood, caused some of the costliest flooding in the river's recorded history. An

Associated Press The Associated Press (AP) is an American non-profit news agency headquartered in New York City. Founded in 1846, it operates as a cooperative, unincorporated association. It produces news reports that are distributed to its members, U.S. newspa ...

journalist reported, "The river crested at one town after another—at Corvallis 3½ feet above flood stage, Oregon City 18 feet above, Portland 10.5 feet above—much like a meal moving through a boa constrictor." The flood was serious enough to interrupt the progress of Oregon's growing economy, but the inundated acreage was smaller than in 1964—only about . About 450 concrete flood-protection walls in Portland that had been constructed during the February flood, each weighing about , were removed in April 1996. In October, they were replaced by a larger steel wall that cost the city about $300,000. The new wall had removable steel plates designed to better prevent future flooding.

Pollution

Since as early as 1869, with the introduction of a federally funded "snag puller" designed to keep the waterway clear, human habitation has affected the

ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

of the river basin. Domestic and industrial waste from the cities built up along the river "essentially urnedthe main-stem river into an open sewer by the 1920s." The construction of large federal dams on the Willamette's tributaries between 1941 and 1969 damaged the spawning grounds for spring

and

. A 1927 City Club of Portland report labeled the waterway "filthy and ugly" and identified the City of Portland as the worst offender. The Oregon Anti-Stream Pollution League brought a pollution-abatement measure before the 39th Oregon Legislative Assembly in 1937. The bill passed, but Governor Charles Martin vetoed it. The

Izaak Walton League The Izaak Walton League is an American environmental organization founded in 1922 that promotes natural resource protection and outdoor recreation. The organization was founded in Chicago, Illinois, by a group of sportsmen who wished to protect fi ...

and the Oregon affiliate of the

National Wildlife Federation The National Wildlife Federation (NWF) is the United States' largest private, nonprofit conservation education and advocacy organization, with over six million members and supporters, and 51 state and territorial affiliated organizations (includin ...

countered the governor's veto with a ballot initiative, which passed in November 1938. Governor

, shortly after he was elected in 1966, ordered water quality tests on the Willamette, conducted his own research on the water quality, and became head of the

Oregon State Sanitary Authority The Oregon State Sanitary Authority (OSSA) was the first agency in the U.S. state of Oregon that was charged with protecting the environment. In 1938, Oregon voters, by a three-to-one margin, approved an initiative to regulate water pollution and t ...

. McCall learned that the river was heavily polluted in Portland. In a television documentary, ''Pollution in Paradise'', he said, "The Willamette River was actually cleaner when the Oregon Sanitary Authority was created in 1938 than it was in 1962."Williams, p. 131 He then discouraged tourism in the state and made it harder for companies to qualify for a permit to operate near the river. He also regulated how much those companies could pollute and closed plants that did not meet state pollution standards.Williams, p. 132 Despite earlier cleanup efforts, state studies in the 1990s identified a wide variety of pollutants in the river bottom, including heavy metals,

polychlorinated biphenyl Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1979 and internationally by t ...

s (PCBs), and

pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...

s along the lower of the river, in Portland. As a result, this section of the river was designated a

Superfund Superfund is a United States federal environmental remediation program established by the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA). The program is administered by the United States Environmental Pro ...

site in 2000, involving the

U.S. Environmental Protection Agency The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...

(EPA) in cleanup of the river bottom. The area to be addressed stretches from the Fremont Bridge almost to the Columbia – spanning nearly 11 river miles. Reducing risk from the pollutants in this stretch will involve removing contaminated sediment from the river bottom and efforts to contain contaminated sediment by placing clean sediment on top (known as "capping"). Pollution has been exacerbated by combined sewer overflows, which the city has greatly reduced through its Big Pipe Project. Farther upstream, the pressing environmental issues have mainly been variations in pH and dissolved oxygen. The Willamette is nevertheless clean enough to be used by cities such as Corvallis and Wilsonville for drinking water. Since pollution concerns are primarily along the lower river, the Willamette in general scores relatively high on the Oregon Water Quality Index (OWQI), which is compiled by the

Oregon Department of Environmental Quality The Oregon Department of Environmental Quality (DEQ) is the chief regulatory agency of the government of the U.S. state of Oregon responsible for protecting and enhancing the state's natural resources and managing sanitary and toxic waste disposal ...

(DEQ). The DEQ considers index scores of less than 60 to be very poor; the other categories are 60–79 (poor); 80–84 (fair); 85–89 (good), and 90–100 (excellent). The Willamette River's water quality is rated excellent near the source, though it gradually declines to fair near the mouth. Between 1998 and 2007, the average score for the upper Willamette at Springfield (RM 185, RK 298) was 93. At Salem (RM 84, RK 135), the score was 89, and good scores continued down to the Hawthorne Bridge in Portland (RM 13, RK 21) at 85. Scores were in the "fair" category farther downstream; the least favorable reading was 81 at the Swan Island Channel midpoint (RM 0.5, RK 0.8). By comparison, sites on the

Winchuck River The Winchuck River (Tolowa: duu-sr-xuu-shi taa-ghin-li~') is a short coastal stream that runs through the Rogue River–Siskiyou National Forest to the Pacific Ocean in the U.S. states of Oregon and California. Flowing generally west from its origi ...

, the Clackamas, and the North Santiam all scored 95, and a site at a pump station on Klamath Strait Drain between

Upper Klamath Lake Upper Klamath Lake (sometimes called Klamath Lake) ( Klamath: ?ews, "lake" ) is a large, shallow freshwater lake east of the Cascade Range in south-central Oregon in the United States. The largest body of fresh water by surface area in Oregon, it ...

and

Lower Klamath Lake Lower Klamath Lake is a lake in Siskiyou County, California. At one time it was connected to Upper Klamath Lake. It currently is used to hold overflow water for Klamath Project irrigation uses. The lake is in Northern California, near the borde ...

recorded the lowest score in Oregon at 19.Oregon Water Quality Index, pp. 7–10

Flora and fauna

Over the past 150 years, a significant change for the Willamette River has been the loss of its floodplain forests, which covered an estimated 89 percent of a band along each river bank in 1850. By 1990, only 37 percent of this zone was forested; the rest had been converted to farm fields or cleared for urban or suburban uses. The remaining forests close to the river include stands of

black cottonwood ''Populus trichocarpa'', the black cottonwood, western balsam-poplar or California poplar, is a deciduous broadleaf tree species native to western North America. It is used for timber, and is notable as a model organism in plant biology. ...

Oregon ash ''Fraxinus latifolia'', the Oregon ash, is a member of the ash genus '' Fraxinus'', native to western North America. Description ''Fraxinus latifolia'' is a medium-sized deciduous tree that can grow to heights of in height, with a trunk diame ...

willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...

, and

bigleaf maple ''Acer macrophyllum'', the bigleaf maple or Oregon maple, is a large deciduous tree in the genus '' Acer''. It is native to western North America, mostly near the Pacific coast, from southernmost Alaska to southern California. Some stands are al ...

.Benke, ''et al.'', p. 619 The central valley—a former perennial grass prairie interspersed with oak,

Douglas fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three va ...

ponderosa pine ''Pinus ponderosa'', commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is the ...

, and other trees—is devoted almost entirely to farming. Douglas fir,

western hemlock ''Tsuga heterophylla'', the western hemlock or western hemlock-spruce, is a species of hemlock native to the west coast of North America, with its northwestern limit on the Kenai Peninsula, Alaska, and its southeastern limit in northern Sonoma ...

, and

western red cedar ''Thuja plicata'' is an evergreen coniferous tree in the cypress family Cupressaceae, native to western North America. Its common name is western redcedar (western red cedar in the UK), and it is also called Pacific redcedar, giant arborvitae ...

dominate the forest on the Coast Range side of the basin. Forests to the east in the Cascade Range are predominantly Douglas fir,

Pacific silver fir ''Abies amabilis'', commonly known as the Pacific silver fir, is a fir native to the Pacific Northwest of North America, occurring in the Pacific Coast Ranges and the Cascade Range. It is also commonly referred to as the white fir, red fir, l ...

, western hemlock, and western red cedar. Fish in the Willamette basin include 31 native species, among them cutthroat,

bull A bull is an intact (i.e., not castrated) adult male of the species ''Bos taurus'' (cattle). More muscular and aggressive than the females of the same species (i.e., cows), bulls have long been an important symbol in many religions, includin ...

, and

rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributaries of the Pacific Ocean in Asia and North America. The steelhead (sometimes called "steelhead trout") is an anadromous (sea-run) form of the coasta ...

, several species of

sucker Sucker may refer to: General use * Lollipop or sucker, a type of confection * Sucker (slang), a slang term for a very gullible person * Hard candy ** Cough drop ** Mint (candy) Biology * Sucker (botany), a term for a shoot that arises undergro ...

minnow Minnow is the common name for a number of species of small freshwater fish, belonging to several genera of the families Cyprinidae and Leuciscidae. They are also known in Ireland as pinkeens. Smaller fish in the subfamily Leusciscidae are c ...

, sculpin, and

lamprey Lampreys (sometimes inaccurately called lamprey eels) are an ancient extant lineage of jawless fish of the order Petromyzontiformes , placed in the superclass Cyclostomata. The adult lamprey may be characterized by a toothed, funnel-like s ...

, as well as

sturgeon Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretace ...

, stickleback, and others. Among the 29 non-native species in the basin, there are

brook A brook is a small river or natural stream of fresh water. It may also refer to: Computing *Brook, a programming language for GPU programming based on C *Brook+, an explicit data-parallel C compiler *BrookGPU, a framework for GPGPU programming ...

brown Brown is a color. It can be considered a composite color, but it is mainly a darker shade of orange. In the CMYK color model used in printing or painting, brown is usually made by combining the colors orange and black. In the RGB color model us ...

, and

lake trout The lake trout (''Salvelinus namaycush'') is a freshwater char living mainly in lakes in northern North America. Other names for it include mackinaw, namaycush, lake char (or charr), touladi, togue, and grey trout. In Lake Superior, it can also ...

, largemouth and smallmouth bass,

walleye The walleye (''Sander vitreus'', synonym ''Stizostedion vitreum''), also called the yellow pike or yellow pickerel, is a freshwater perciform fish native to most of Canada and to the Northern United States. It is a North American close relat ...

carp Carp are various species of oily freshwater fish from the family Cyprinidae, a very large group of fish native to Europe and Asia. While carp is consumed in many parts of the world, they are generally considered an invasive species in parts of ...

, bluegill, and others. In addition to fish, the basin supports 18 species of amphibians, such as the

Pacific giant salamander The Pacific giant salamanders (frequently stylized as Giant Pacific Salamanders or GPS) are members of the genus ''Dicamptodon''. They are large salamanders endemic to the Pacific Northwest in North America. They are included in the family Ambyst ...

Beaver Beavers are large, semiaquatic rodents in the genus ''Castor'' native to the temperate Northern Hemisphere. There are two extant species: the North American beaver (''Castor canadensis'') and the Eurasian beaver (''C. fiber''). Beavers ar ...

and river otter are among 69 mammal species living in the watershed, also frequented by 154 bird species, such as the

American dipper The American dipper (''Cinclus mexicanus''), also known as a water ouzel, is a stocky dark grey bird with a head sometimes tinged with brown, and white feathers on the eyelids that cause the eyes to flash white as the bird blinks. It is long, ...

osprey The osprey (''Pandion haliaetus''), , also called sea hawk, river hawk, and fish hawk, is a diurnal, fish-eating bird of prey with a cosmopolitan range. It is a large raptor reaching more than in length and across the wings. It is brown o ...

, and

harlequin duck The harlequin duck (''Histrionicus histrionicus'') is a small sea duck. It takes its name from Harlequin (French ''Arlequin'', Italian ''Arlecchino''), a colourfully dressed character in Commedia dell'arte. The species name comes from the Latin ...

Garter snake Garter snake is a common name for generally harmless, small to medium-sized snakes belonging to the genus ''Thamnophis'' in the family Colubridae. Native to North and Central America, species in the genus ''Thamnophis'' can be found from the ...

s are among the 15 species of reptiles found in the basin. Species diversity is greatest along the lower river and its tributaries. Threatened, endangered, or sensitive species include spring Chinook salmon, winter steelhead,

chum salmon The chum salmon (''Oncorhynchus keta''), also known as dog salmon or keta salmon, is a species of anadromous salmonid fish from the genus '' Oncorhynchus'' (Pacific salmon) native to the coastal rivers of the North Pacific and the Beringian A ...

Coho salmon The coho salmon (''Oncorhynchus kisutch;'' Karuk: achvuun) is a species of anadromous fish in the salmon family (biology), family and one of the five Pacific salmon species. Coho salmon are also known as silver salmon or "silvers". The scientif ...

and

Oregon chub The Oregon chub (''Oregonichthys crameri'') is a species of ray-finned fish in the family Cyprinidae. It is endemic to Oregon in the United States. From 1993 to 2015 it was a federally listed threatened species. This chub is native to the drain ...

.Benke, ''et al.'', pp. 620–21 In the central valley, several projects have been done to restore and protect wetlands in order to provide habitat for

bald eagle The bald eagle (''Haliaeetus leucocephalus'') is a bird of prey found in North America. A sea eagle, it has two known subspecies and forms a species pair with the white-tailed eagle (''Haliaeetus albicilla''), which occupies the same niche as ...

Fender's blue butterfly Fender's blue butterfly (''Icaricia icarioides fenderi'') is an endangered subspecies of Boisduval's blue (''Icaricia icarioides)'' endemic to the Willamette Valley of northwestern Oregon, United States. Thpotential rangeof the butterfly extend ...

(of which 6,000 remain), Oregon chub,

Bradshaw's desert parsley ''Lomatium bradshawii'', also known as Bradshaw's desert parsley, is an endangered perennial herb native to Oregon and Washington, United States. ''Lomatium bradshawii'' was thought to be extinct until 1979, when it was rediscovered by a Univers ...

, a variety of Willamette fleabane, and Kincaid's lupine. In the early 21st century, osprey populations are increasing along the river, possibly because of a ban on the pesticide

DDT Dichlorodiphenyltrichloroethane, commonly known as DDT, is a colorless, tasteless, and almost odorless crystalline chemical compound, an organochloride. Originally developed as an insecticide, it became infamous for its environmental impacts. ...

and on the birds' ability to use power poles for nesting.Benke, ''et al.'', p. 621 Beaver populations, presumed to be much lower than historic levels, are increasing throughout the basin.

References

Works cited

* �
"Oregon Water Quality Index Summary Report, Water Years 1998–2007"
(PDF), May 2008. Oregon Department of Environmental Quality. Retrieved April 10, 2011. * Benke, Arthur C., ed., and Cushing, Colbert E., ed.; Stanford, Jack A.; Gregory, Stanley V.; Hauer, Richard F.; Snyder, Eric B. (2005). "Chapter 13: Columbia River Basin" in ''Rivers of North America''. Burlington, Massachusetts: Elsevier Academic Press. . . * Bright, William (2004). ''Native American Placenames of the United States''. Norman, Oklahoma: University of Oklahoma Press. . . * Campbell, Lyle (1997). ''American Indian Languages''. New York, New York: Oxford University Press. . . * Deur, Douglas; Turner, Nancy J. (2005). ''Keeping it Living: Traditions of Plant Use and Cultivation on the Northwest Coast of North America''. Seattle: University of Washington Press. . . * Edwards, G. Thomas; Schwantes, Carlos A. (1986). ''Experiences in a Promised Land: Essays in Pacific Northwest History''. Seattle: University of Washington Press. . . * Engeman, Richard H. (2009). ''The Oregon Companion: A Historical Gazetteer of the Useful, the Curious, and the Arcane''. Portland, Oregon: Timber Press. . . * Gulick, Bill (2004). ''Steamboats on Northwest Rivers''. Caldwell, Idaho: Caxton Press. . . * Holman, Frederick Van Voorhies (1907). ''Dr. John McLoughlin, the Father of Oregon''. Cleveland, Ohio: A. H. Clark Company. . . * Laenen, Antonius; Dunnette, David A. (1997). ''River Quality: Dynamics and Restoration''. Boca Raton, Florida: CRC Press. . . * Loy, Willam G.; Allan, Stuart Allan; Buckley, Aileen R.; Meecham, James E. (2001)

976 Year 976 ( CMLXXVI) was a leap year starting on Saturday (link will display the full calendar) of the Julian calendar. Events By place Byzantine Empire * January 10 – Emperor John I Tzimiskes dies at Constantinople, after re ...

''Atlas of Oregon'' (2nd ed.). Eugene, Oregon: University of Oregon Press. . . * Mackie, Richard Somerset (1997). ''Trading Beyond the Mountains: the British Fur Trade on the Pacific, 1793–1843''. Vancouver: UBC Press. . . * McArthur, Lewis A.; McArthur, Lewis L. (2003)

928 Year 928 (Roman numerals, CMXXVIII) was a leap year starting on Tuesday (link will display the full calendar) of the Julian calendar. Events By place Europe * King Rudolph of France, Rudolph I loses the support of Herbert II, Count of ...

''Oregon Geographic Names'' (7th ed.). Portland, Oregon: Oregon Historical Society Press. . . * * Orr, Elizabeth L.; Orr, William N. (1999). ''Geology of Oregon'' (5th ed.). Dubuque, Iowa: Kendall/Hunt Publishing Company. . . * Orr, Elizabeth L.; Orr, William N. (2012). ''Oregon Geology'' (6th ed.). Corvallis, Oregon: Oregon State University Press. . . * * Samson, Karl (2010). ''Frommer's Oregon''. Hoboken, New Jersey: Wiley-Blackwell. . . * Smith, Dwight A.; Norman, James B.; Dykman, Pieter T. (1989)

986 Year 986 ( CMLXXXVI) was a common year starting on Friday (link will display the full calendar) of the Julian calendar. Events By place Byzantine Empire * August 17 – Battle of the Gates of Trajan: Emperor Basil II leads a Byz ...

''Historic Highway Bridges of Oregon'' (2nd ed.). Portland, Oregon: Oregon Historical Society Press. . . * Snipp, C. Matthew (1989). ''American Indians: The First of This Land''. New York, New York: Russell Sage Foundation. . . * Stenzel, Franz (1972). ''Cleveland Rockwell: Scientist and Artist, 1837–1907''. Portland, Oregon: Oregon Historical Society. . . * * * * * * * Wortman, Sharon Wood; Wortman, Ed.; Norman, James B. (2006). ''The Portland Bridge Book'' (3rd ed.). Portland, Oregon: Urban Adventure Press. . .

External links

City of Portland River Renaissance Strategy

Guiding the Willamette
eb archive ''Think Out Loud'' radio program on

Oregon Public Broadcasting Oregon Public Broadcasting (OPB) is the primary television and radio public broadcasting network for most of the U.S. state of Oregon as well as southern Washington. OPB consists of five full-power television stations, dozens of VHF or UHF tra ...

, April 1, 2009
Historic river channels between Albany and Monmouth
nbsp;– Oregon Department of Geology and Mineral Industries

lidar Lidar (, also LIDAR, or LiDAR; sometimes LADAR) is a method for determining ranges (variable distance) by targeting an object or a surface with a laser and measuring the time for the reflected light to return to the receiver. It can also be ...

Course

Discharge

Geology

Watershed

History

First inhabitants

Fur trade

19th-century development

20th and 21st centuries

Dams and bridges

Dams

Bridges

Flooding

Pollution

Flora and fauna

See also

References

Works cited

External links