CourseThe Columbia begins its journey in the southern in British Columbia (BC). – above – and the adjoining form the river's . The trench is a broad, deep, and long between the and the in BC. For its first , the Columbia flows northwest along the trench through Windermere Lake and the town of , a region known in British Columbia as the , then northwest to Golden and into . Rounding the northern end of the , the river turns sharply south through a region known as the Big Bend Country, passing through and the . Revelstoke, the Big Bend, and the Columbia Valley combined are referred to in BC parlance as the . Below the Arrow Lakes, the Columbia passes the cities of Castlegar, located at the Columbia's with the , and , two major population centers of the region. The joins the Columbia about north of the US–Canada border. The Columbia enters flowing south and turning to the west at the confluence. It marks the southern and eastern borders of the and the western border of the . The river turns south after the confluence, then southeasterly near the confluence with the in central Washington. This C‑shaped segment of the river is also known as the "Big Bend". During the Missoula Floods 10,000 to 15,000 years ago, much of the floodwater took a more direct route south, forming the ancient river bed known as the . After the floods, the river found its present course, and the Grand Coulee was left dry. The construction of the in the mid-20th century impounded the river, forming Lake Roosevelt, from which water was pumped into the dry , forming the of . The river flows past , a prominent concert venue in the Northwest, then through Priest Rapids Dam, and then through the . Entirely within the reservation is , the only US stretch of the river that is completely free-flowing, unimpeded by dams and not a tidal . The and join the Columbia in the Tri‑Cities population center. The Columbia makes a sharp bend to the west at the Washington–Oregon border. The river defines that border for the final of its journey. The Deschutes River joins the Columbia near . Between The Dalles and , the river cuts through the , forming the dramatic . No other rivers except for the Klamath and completely breach the Cascades—the other rivers that flow through the range also originate in or very near the mountains. The headwaters and upper course of the Pit River are on the ; downstream the Pit cuts a canyon through the southern reaches of the Cascades. In contrast, the Columbia cuts through the range nearly a thousand miles from its source in the Rocky Mountains. The gorge is known for its strong and steady winds, scenic beauty, and its role as an important transportation link. The river continues west, bending sharply to the north-northwest near Portland and , at the confluence. Here the river slows considerably, dropping sediment that might otherwise form a . Near and the confluence, the river turns west again. The Columbia empties into the Pacific Ocean just west of , over the , a shifting that makes the river's mouth one of the most hazardous stretches of water to navigate in the world. Because of the danger and the many shipwrecks near the mouth, it acquired a reputation as the "Graveyard of Ships". The Columbia drains an area of about . Its drainage basin covers nearly all of , large portions of British Columbia, Oregon, and Washington, ultimately all of west of the , and small portions of , , and ; the total area is similar to the size of France. Roughly of the river's length and 85 percent of its drainage basin are in the US. The Columbia is the twelfth-longest river and has the sixth-largest drainage basin in the United States. In Canada, where the Columbia flows for and drains , the river ranks 23rd in length, and the Canadian part of its basin ranks 13th in size among Canadian basins. The Columbia shares its name with nearby places, such as British Columbia, as well as with landforms and bodies of water.
DischargeWith an average flow at the mouth of about , the Columbia is the largest river by discharge flowing into the Pacific from the Americas and is the fourth-largest by volume in the US. The average flow where the river crosses the international border between Canada and the United States is from a drainage basin of . This amounts to about 15 percent of the entire Columbia watershed. The Columbia's highest recorded flow, measured at The Dalles, was in June 1894, before the river was dammed. The lowest flow recorded at The Dalles was on April 16, 1968, and was caused by the initial closure of the , upstream. The Dalles is about from the mouth; the river at this point drains about or about 91 percent of the total watershed. Flow rates on the Columbia are affected by many large upstream reservoirs, many diversions for irrigation, and, on the lower stretches, reverse flow from the s of the Pacific Ocean. The observes water levels at six s and issues tide forecasts for twenty-two additional locations along the river between the entrance at the North Jetty and the base of , the head of tide.
GeologyWhen the ing of , due to the process of , pushed North America away from Europe and Africa and into the Panthalassic Ocean (ancestor to the modern Pacific Ocean), the Pacific Northwest was not part of the continent. As the North American continent moved westward, the under its western margin. As the plate subducted, it carried along s which were accreted to the North American continent, resulting in the creation of the Pacific Northwest between 150 and 90 million years ago. The general outline of the Columbia Basin was not complete until between 60 and 40 million years ago, but it lay under a large inland sea later subject to uplift. Between 50 and 20 million years ago, from the through the eras, tremendous volcanic eruptions frequently modified much of the landscape traversed by the Columbia. The lower reaches of the ancestral river passed through a valley near where later arose. Carrying sediments from erosion and erupting volcanoes, it built a thick delta that underlies the foothills on the east side of the Coast Range near in northwestern Oregon. Between 17 million and 6 million years ago, huge outpourings of lava covered the and forced the lower Columbia into its present course. The modern Cascade Range began to uplift 5 to 4 million years ago. Cutting through the uplifting mountains, the Columbia River significantly deepened the Columbia River Gorge. The river and its drainage basin experienced some of the world's greatest known catastrophic floods toward the end of the last . The periodic rupturing of ice dams at resulted in the Missoula Floods, with discharges exceeding the combined flow of all the other rivers in the world, dozens of times over thousands of years. The exact number of floods is unknown, but geologists have documented at least 40; evidence suggests that they occurred between about 19,000 and 13,000 years ago. The floodwaters rushed across eastern Washington, creating the , which are a complex network of dry canyon-like channels, or coulees that are often braided and sharply gouged into the basalt rock underlying the region's deep topsoil. Numerous flat-topped s with rich soil stand high above the chaotic scablands. Constrictions at several places caused the floodwaters to pool into large temporary lakes, such as , in which sediments were deposited. Water depths have been estimated at at and over modern Portland, Oregon. Sediments were also deposited when the floodwaters slowed in the broad flats of the Quincy, Othello, and Pasco Basins. The floods' periodic inundation of the lower Columbia River Plateau deposited rich sediments; 21st-century farmers in the Willamette Valley "plow fields of fertile Montana soil and clays from Washington's Palouse". Over the last several thousand years a series of large landslides have occurred on the north side of the Columbia River Gorge, sending massive amounts of debris south from Table Mountain (Skamania County, Washington), Table Mountain and Greenleaf Peak into the gorge near the present site of Bonneville Dam. The most recent and significant is known as the Bonneville Slide, which formed a massive earthen dam, filling of the river's length. Various studies have placed the date of the Bonneville Slide anywhere between 1060 and 1760 AD; the idea that the landslide debris present today was formed by more than one slide is relatively recent and may explain the large range of estimates. It has been suggested that if the later dates are accurate there may be a link with the 1700 Cascadia earthquake. The pile of debris resulting from the Bonneville Slide blocked the river until rising water finally washed away the sediment. It is not known how long it took the river to break through the barrier; estimates range from several months to several years. Much of the landslide's debris remained, forcing the river about south of its previous channel and forming the Cascade Rapids. In 1938, the construction of Bonneville Dam inundated the rapids as well as the remaining trees that could be used to refine the estimated date of the landslide. In 1980, the 1980 eruption of Mount St. Helens, eruption of Mount St. Helens deposited large amounts of sediment in the lower Columbia, temporarily reducing the depth of the shipping channel by .
Indigenous peoplesHumans have inhabited the Columbia's watershed for more than 15,000 years, with a transition to a sedentary lifestyle based mainly on salmon starting about 3,500 years ago. In 1962, archaeologists found evidence of human activity dating back 11,230 years at the Marmes Rockshelter, near the confluence of the Palouse River, Palouse and Snake rivers in eastern Washington. In 1996 the skeletal remains of a 9,000-year-old prehistoric man (dubbed Kennewick Man) were found near Kennewick, Washington. The discovery rekindled debate in the scientific community over the origins of human habitation in North America and sparked a protracted controversy over whether the scientific or Native Americans in the United States, Native American community was entitled to possess and/or study the remains. Many different Native Americans and First Nations peoples have a historical and continuing presence on the Columbia. South of the Canada–US border, the Colville (tribe), Colville, Spokane (tribe), Spokane, Coeur d'Alene Tribe, Coeur d'Alene, Yakama, Nez Perce people, Nez Perce, Cayuse people, Cayuse, Palus (tribe), Palus, Umatilla (tribe), Umatilla, Cowlitz (tribe), Cowlitz, and the Confederated Tribes of Warm Springs live along the US stretch. Along the upper Snake River and Salmon River (Idaho), Salmon River, the Shoshone Bannock (tribe), Bannock tribes are present. The Sinixt or Lakes people lived on the lower stretch of the Canadian portion, while above that the Shuswap people (Secwepemc in their own language) reckon the whole of the upper Columbia east to the Rockies as part of their territory. The Canadian portion of the Columbia Basin outlines the traditional homelands of the Canadian Kootenay–Ktunaxa. The Chinookan, Chinook tribe, which is not federally recognized tribes, federally recognized, who live near the lower Columbia River, call it ' or ' in the Upper Chinook language, Upper Chinook (Kiksht) language, and it is ''Nch’i-Wàna'' or ''Nchi wana'' to the Sahaptin language, Sahaptin (Ichishkíin Sɨ́nwit)-speaking peoples of its middle course in present-day Washington. The river is known as ' by the Sinixt people, who live in the area of the Arrow Lakes in the river's upper reaches in Canada. All three terms essentially mean "the big river". Oral histories describe the formation and destruction of the Bridge of the Gods (geologic event), Bridge of the Gods, a land bridge that connected the Oregon and Washington sides of the river in the Columbia River Gorge. The bridge, which aligns with geological records of the Bonneville Slide, was described in some stories as the result of a battle between gods, represented by Mount Adams (Washington), Mount Adams and , in their competition for the affection of a goddess, represented by Mount St. Helens. Native American stories about the bridge differ in their details but agree in general that the bridge permitted increased interaction between tribes on the north and south sides of the river. Horses, originally acquired from Santa Fe de Nuevo México, Spanish New Mexico, spread widely via native trade networks, reaching the Shoshone of the Snake River Plain by 1700. The Nez Perce, Cayuse, and Confederated Salish and Kootenai Tribes of the Flathead Nation, Flathead people acquired their first horses around 1730. Along with horses came aspects of the emerging Plains Indian, plains culture, such as equestrian and horse training skills, greatly increased mobility, hunting efficiency, trade over long distances, intensified warfare, the linking of wealth and prestige to horses and war, and the rise of large and powerful tribal confederacies. The Nez Perce and Cayuse kept large herds and made annual long-distance trips to the Great Plains for bison hunting, adopted the plains culture to a significant degree, and became the main conduit through which horses and the plains culture diffused into the Columbia River region. Other peoples acquired horses and aspects of the plains culture unevenly. The Yakama, Umatilla, Palus, Spokane, and Coeur d'Alene maintained sizable herds of horses and adopted some of the plains cultural characteristics, but fishing and fish-related economies remained important. Less affected groups included the Molala people, Molala, Klickitat (tribe), Klickitat, Wenatchi, Okanagan, and Sinkiuse-Columbia peoples, who owned small numbers of horses and adopted few plains culture features. Some groups remained essentially unaffected, such as the Sanpoil (tribe), Sanpoil and Nespelem (tribe), Nespelem people, whose culture remained centered on fishing. Natives of the region encountered foreigners at several times and places during the 18th and 19th centuries. European and American vessels explored the coastal area around the mouth of the river in the late 18th century, trading with local natives. The contact would prove devastating to the Indian tribes; a large portion of their population was wiped out by a smallpox epidemic. Canadian explorer Alexander Mackenzie (explorer), Alexander Mackenzie crossed what is now interior British Columbia in 1793. From 1805 to 1807, the Lewis and Clark Expedition entered the Oregon Country along the Clearwater River (Idaho), Clearwater and Snake rivers, and encountered numerous small settlements of natives. Their records recount tales of hospitable traders who were not above stealing small items from the visitors. They also noted brass teakettles, a British musket, and other artifacts that had been obtained in trade with coastal tribes. From the earliest contact with westerners, the natives of the mid- and lower Columbia were not tribal, but instead congregated in social units no larger than a village, and more often at a family level; these units would shift with the season as people moved about, following the salmon catch up and down the river's tributaries. Sparked by the 1847 Whitman Massacre, a number of violent battles were fought between American settlers and the region's natives. The subsequent Indian Wars, especially the Yakima War, decimated the native population and removed much land from native control. As years progressed, the right of natives to fish along the Columbia became the central issue of contention with the states, commercial fishers, and private property owners. The US Supreme Court upheld fishing rights in landmark cases in 1905 and 1918, as well as the 1974 case ''United States v. Washington'', commonly called the Boldt Decision. Fish were central to the culture of the region's natives, both as sustenance and as part of their religious beliefs. Natives drew fish from the Columbia at several major sites, which also served as trading posts. Celilo Falls, located east of the modern city of The Dalles, was a vital hub for trade and the interaction of different cultural groups, being used for fishing and trading for 11,000 years. Prior to contact with westerners, villages along this stretch may have at times had a population as great as 10,000. The site drew traders from as far away as the Great Plains. The Cascades Rapids of the Columbia River Gorge, and Kettle Falls and Priest Rapids in eastern Washington, were also major fishing and trading sites. In prehistoric times the Columbia's salmon and steelhead runs numbered an estimated annual average of 10 to 16 million fish. In comparison, the largest run since 1938 was in 1986, with 3.2 million fish entering the Columbia. The annual catch by natives has been estimated at . The most important and productive native fishing site was located at Celilo Falls, which was perhaps the most productive inland fishing site in North America. The falls were located at the border between Chinookan- and Sahaptian-speaking peoples and served as the center of an extensive trading network across the Pacific Plateau. Celilo was the oldest continuously inhabited community on the North American continent. Salmon canneries established by white settlers beginning in 1866 had a strong negative impact on the salmon population, and in 1908 US President Theodore Roosevelt observed that the salmon runs were but a fraction of what they had been 25 years prior. As river development continued in the 20th century, each of these major fishing sites was flooded by a dam, beginning with Cascades Rapids in 1938. The development was accompanied by extensive negotiations between natives and US government agencies. The Confederated Tribes of Warm Springs, a coalition of various tribes, adopted a constitution and incorporated after the 1938 completion of the Bonneville Dam flooded Cascades Rapids; Still, in the 1930s, there were natives who lived along the river and fished year round, moving along with the fish's migration patterns throughout the seasons. The Yakama were slower to do so, organizing a formal government in 1944. In the 21st century, the Yakama, Nez Perce, Umatilla, and Warm Springs tribes all have treaty fishing rights along the Columbia and its tributaries. In 1957 Celilo Falls was submerged by the construction of The Dalles Dam, and the native fishing community was displaced. The affected tribes received a $26.8 million settlement for the loss of Celilo and other fishing sites submerged by The Dalles Dam. The Confederated Tribes of Warm Springs used part of its $4 million settlement to establish the Kah-Nee-Ta High Desert Resort and Casino, Kah-Nee-Ta resort south of Mount Hood.
New waves of explorersSome historians believe that Japanese or Chinese vessels blown off course reached the Northwest Coast long before Europeans—possibly as early as 219 Before Common Era, BCE. Historian Derek Hayes claims that "It is a near certainty that Japanese or Chinese people arrived on the northwest coast long before any European." It is unknown whether they landed near the Columbia. Evidence exists that Spanish castaways reached the shore in 1679 and traded with the Clatsop; if these were the first Europeans to see the Columbia, they failed to send word home to Spain. In the 18th century, there was strong interest in discovering a Northwest Passage that would permit navigation between the Atlantic (or inland North America) and the Pacific Ocean. Many ships in the area, especially those under Spanish and British command, searched the northwest coast for a large river that might connect to Hudson Bay or the Missouri River. The first documented European discovery of the Columbia River was that of , who in 1775 sighted the river's mouth. On the advice of his officers, he did not explore it, as he was short-staffed and the current was strong. He considered it a bay, and called it '':wikt:ensenada, Ensenada de Asunción'' (''Assumption of Mary, Assumption Cove''). Later Spanish maps, based on his sighting, showed a river, labeled ''Río de San Roque'' (''The Saint Roch River''), or an entrance, called ''Entrada de Hezeta'', named for Bruno de Hezeta, who sailed the region. Following Hezeta's reports, British maritime fur trader Captain John Meares searched for the river in 1788 but concluded that it did not exist. He named Cape Disappointment (Washington), Cape Disappointment for the non-existent river, not realizing the cape marks the northern edge of the river's mouth. What happened next would form the basis for decades of both cooperation and dispute between British and American exploration of, and ownership claim to, the region. Royal Navy commander George Vancouver sailed past the mouth in April 1792 and observed a change in the water's color, but he accepted Meares' report and continued on his journey northward. Later that month, Vancouver encountered the American captain Robert Gray (sea-captain), Robert Gray at the Strait of Juan de Fuca. Gray reported that he had seen the entrance to the Columbia and had spent nine days trying but failing to enter. On May 12, 1792, Gray returned south and crossed the Columbia Bar, becoming Gray sails the Columbia River, the first known explorer of European descent to enter the river. Gray's fur trading mission had been financed by Boston, Oregon, Boston merchants, who outfitted him with a private vessel named ''Columbia Rediviva''; he named the river after the ship on May 18. Gray spent nine days trading near the mouth of the Columbia, then left without having gone beyond upstream. The farthest point reached was Grays Bay at the mouth of Grays River (Washington), Grays River. Gray's discovery of the Columbia River was later used by the United States to support its claim to the Oregon Country, which was also claimed by Russian Empire, Russia, Kingdom of Great Britain, Great Britain, Spain and other nations. In October 1792, Vancouver sent Lieutenant , his second-in-command, up the river. Broughton got as far as the Sandy River (Oregon), Sandy River at the western end of the Columbia River Gorge, about upstream, sighting and naming Mount Hood. Broughton formally claimed the river, its drainage basin, and the nearby coast for Britain. In contrast, Gray had not made any formal claims on behalf of the United States. Because the Columbia was at the same latitude as the headwaters of the Missouri River, there was some speculation that Gray and Vancouver had discovered the long-sought Northwest Passage. A 1798 British map showed a dotted line connecting the Columbia with the Missouri. When the American explorers Meriwether Lewis and William Clark (explorer), William Clark charted the vast, unmapped lands of the American West in their Lewis and Clark expedition, overland expedition (1803–05), they found no passage between the rivers. After crossing the , Lewis and Clark built dugout canoes and paddled down the Snake River, reaching the Columbia near the present-day Tri-Cities, Washington. They explored a few miles upriver, as far as Bateman Island, before heading down the Columbia, concluding their journey at the river's mouth and establishing Fort Clatsop, a short-lived establishment that was occupied for less than three months. Canadian explorer David Thompson (explorer), David Thompson, of the North West Company, spent the winter of 1807–08 at Kootanae House near the source of the Columbia at present-day Invermere, British Columbia. Over the next few years he explored much of the river and its northern tributaries. In 1811 he traveled down the Columbia to the Pacific Ocean, arriving at the mouth just after John Jacob Astor's Pacific Fur Company had founded Astoria. On his return to the north, Thompson explored the one remaining part of the river he had not yet seen, becoming the first Euro-descended person to travel the entire length of the river. In 1825, the Hudson's Bay Company (HBC) established Fort Vancouver on the bank of the Columbia, in what is now Vancouver, Washington, as the headquarters of the company's Columbia District, which encompassed everything west of the Rocky Mountains, north of California, and south of Russian-claimed Alaska. Factor (agent), Chief Factor John McLoughlin, a physician who had been in the fur trade since 1804, was appointed superintendent of the Columbia District. The HBC reoriented its Columbia District operations toward the Pacific Ocean via the Columbia, which became the region's main trunk route. In the early 1840s Americans began to colonize the Oregon country in large numbers via the Oregon Trail, despite the HBC's efforts to discourage American settlement in the region. For many the final leg of the journey involved travel down the lower Columbia River to Fort Vancouver. This part of the Oregon Trail, the treacherous stretch from The Dalles to below the Cascades, could not be traversed by horses or wagons (only watercraft, at great risk). This prompted the 1846 construction of the Barlow Road. In the Treaty of 1818 the United States and Britain agreed that both nations were to enjoy equal rights in Oregon Country for 10 years. By 1828, when the so-called "joint occupation" was renewed for an indefinite period, it seemed probable that the lower Columbia River would in time become the border between the two nations. For years the Hudson's Bay Company successfully maintained control of the Columbia River and American attempts to gain a foothold were fended off. In the 1830s, American religious missions were established at several locations in the lower Columbia River region. In the 1840s a mass migration of American settlers undermined British control. The Hudson's Bay Company tried to maintain dominance by shifting from the fur trade, which was in decline, to exporting other goods such as salmon and lumber. Colonization schemes were attempted, but failed to match the scale of American settlement. Americans generally settled south of the Columbia, mainly in the Willamette Valley. The Hudson's Bay Company tried to establish settlements north of the river, but nearly all the British colonists moved south to the Willamette Valley. The hope that the British colonists might dilute the American presence in the valley failed in the face of the overwhelming number of American settlers. These developments rekindled the issue of "joint occupation" and the Oregon boundary dispute, boundary dispute. While some British interests, especially the Hudson's Bay Company, fought for a boundary along the Columbia River, the Oregon Treaty of 1846 set the boundary at the 49th parallel. As part of the treaty, the British retained all areas north of the line while the U.S. acquired the south. The Columbia River became much of the border between the U.S. territories of Oregon Territory, Oregon and Washington Territory, Washington. became a U.S. state in 1859, while later entered into the Union in 1889. By the turn of the 20th century, the difficulty of navigating the Columbia was seen as an impediment to the economic development of the Inland Empire (Pacific Northwest), Inland Empire region east of the Cascades. The dredging and dam building that followed would permanently alter the river, disrupting its natural flow but also providing electricity, , navigability and other benefits to the region.
NavigationAmerican captain Robert Gray and British captain George Vancouver, who explored the river in 1792, proved that it was possible to cross the Columbia Bar. Many of the challenges associated with that feat remain today; even with modern engineering alterations to the mouth of the river, the strong currents and shifting sandbar make it dangerous to pass between the river and the Pacific Ocean. The use of steamboats along the river, beginning with the British ''Beaver (steamship), Beaver'' in 1836 and followed by American vessels in 1850, contributed to the rapid settlement and economic development of the region. Steamboats operated in several distinct stretches of the river: on its lower reaches, from the Pacific Ocean to Cascades Rapids; from the Cascades to the Dalles-Celilo Falls; from Celilo to Priests Rapids; Steamboats of Columbia River, Wenatchee Reach, on the Wenatchee Reach of eastern Washington; Steamboats of the Arrow Lakes, on British Columbia's Arrow Lakes; and Steamboats of the Willamette River, on tributaries like the Willamette, the Snake and Kootenay Lake. The boats, initially powered by burning wood, carried passengers and freight throughout the region for many years. Early railroads served to connect steamboat lines interrupted by waterfalls on the river's lower reaches. In the 1880s, railroads maintained by companies such as the Oregon Railroad and Navigation Company began to supplement steamboat operations as the major transportation links along the river.
Opening the passage to LewistonAs early as 1881, industrialists proposed altering the natural channel of the Columbia to improve navigation. Changes to the river over the years have included the construction of jetty, jetties at the river's mouth, , and the construction of canals and lock (water transport), navigation locks. Today, ocean freighters can travel upriver as far as Portland and Vancouver, and barges can reach as far inland as Lewiston, Idaho. The shifting Columbia Bar makes passage between the river and the Pacific Ocean difficult and dangerous, and numerous rapids along the river hinder navigation. ''Pacific Graveyard,'' a 1964 book by James A. Gibbs, describes the many shipwrecks near the mouth of the Columbia. Jetties, first constructed in 1886, extend the river's channel into the ocean. Strong currents and the shifting sandbar remain a threat to ships entering the river and necessitate continuous maintenance of the jetties. In 1891 the Columbia was dredged to enhance shipping. The channel between the ocean and Portland and Vancouver was deepened from to . ''The Columbian'' called for the channel to be deepened to as early as 1905, but that depth was not attained until 1976. Cascade Locks and Canal were first constructed in 1896 around the Cascades Rapids, enabling boats to travel safely through the Columbia River Gorge. The Celilo Canal, bypassing Celilo Falls, opened to river traffic in 1915. In the mid-20th century, the construction of dams along the length of the river submerged the rapids beneath a series of reservoirs. An extensive system of locks allowed ships and barges to pass easily from one reservoir to the next. A Snake River#Dams, navigation channel reaching to Lewiston, Idaho, along the Columbia and Snake rivers, was completed in 1975. Among the main commodities are wheat and other grains, mainly for export. As of 2016, the Columbia ranked third, behind the Mississippi River, Mississippi and Paraná River, Paraná rivers, among the world's largest export corridors for grain. The 1980 eruption of Mount St. Helens caused mudslides in the area, which reduced the Columbia's depth by for a stretch, disrupting Portland's economy.
Deeper shipping channelEfforts to maintain and improve the navigation channel have continued to the present day. In 1990 a new round of studies examined the possibility of further dredging on the lower Columbia. The plans were controversial from the start because of economic and environmental concerns. In 1999, Congress authorized deepening the channel between Portland and Astoria from , which will make it possible for large container and grain ships to reach Portland and Vancouver. The project has met opposition because of concerns about stirring up toxic sediment on the riverbed. Portland-based Northwest Environmental Advocates brought a lawsuit against the Army Corps of Engineers, but it was rejected by the United States Court of Appeals for the Ninth Circuit, Ninth U.S. Circuit Court of Appeals in August 2006. The project includes measures to mitigate environmental damage; for instance, the United States Army Corps of Engineers, US Army Corps of Engineers must restore 12 times the area of wetland damaged by the project. In early 2006, the Corps spilled of hydraulic oil into the Columbia, drawing further criticism from environmental organizations. Work on the project began in 2005 and concluded in 2010. The project's cost is estimated at $150 million. The federal government is paying 65 percent, Oregon and Washington are paying $27 million each, and six local ports are also contributing to the cost.
DamsIn 1902, the United States Bureau of Reclamation was established to aid in the economic development of arid Western United States, western states. One of its major undertakings was building Grand Coulee Dam to provide irrigation for the of the Columbia Basin Project in central Washington. With the onset of World War II, the focus of dam construction shifted to production of hydroelectricity. Irrigation efforts resumed after the war. River development occurred within the structure of the 1909 International Boundary Waters Treaty between the US and Canada. The United States Congress passed the Rivers and Harbors Act#List of later acts, Rivers and Harbors Act of 1925, which directed the Army Corps of Engineers and the Federal Power Commission to explore the development of the nation's rivers. This prompted agencies to conduct the first formal financial analysis of hydroelectric development; the reports produced by various agencies were presented in House Document 308. Those reports, and subsequent related reports, are referred to as 308 Reports. In the late 1920s, political forces in the Northwestern United States generally favored private development of hydroelectric dams along the Columbia. But the overwhelming victories of gubernatorial candidate George W. Joseph in the Oregon gubernatorial election, 1930, 1930 Republican primary, and later his law partner Julius Meier, were understood to demonstrate strong public support for public ownership of dams. In 1933, President Franklin D. Roosevelt signed a bill that enabled the construction of the Bonneville and Grand Coulee dams as public works projects. The legislation was attributed to the efforts of Oregon Senator Charles McNary, Washington Senator Clarence Dill, and Oregon Congressman Charles Martin (Oregon politician), Charles Martin, among others. In 1948 floods swept through the Columbia watershed, destroying Vanport, Oregon, Vanport, then the second largest city in Oregon, and impacting cities as far north as Trail, British Columbia. The flooding prompted the United States Congress to pass the Flood Control Act of 1950, authorizing the federal development of additional dams and other flood control mechanisms. By that time local communities had become wary of federal hydroelectric projects, and sought local control of new developments; a public utility district in Grant County, Washington, ultimately began construction of the dam at Priest Rapids. In the 1960s, the United States and Canada signed the Columbia River Treaty, which focused on flood control and the maximization of downstream power generation. Canada agreed to build dams and provide reservoir storage, and the United States agreed to deliver to Canada one-half of the increase in US downstream power benefits as estimated five years in advance. Canada's obligation was met by building three dams (two on the Columbia, and one on the Duncan River (British Columbia), Duncan River), the last of which was completed in 1973. Today the main stem of the Columbia River has 14 dams, of which three are in Canada and 11 in the US. Four mainstem dams and four lower Snake River dams contain navigation locks to allow ship and barge passage from the ocean as far as Lewiston, Idaho. The river system as a whole has more than 400 dams for hydroelectricity and irrigation. The dams address a variety of demands, including flood control, navigation, stream flow regulation, storage and delivery of stored waters, land reclamation, reclamation of public lands and Indian reservations, and the generation of hydroelectric power. The larger US dams are owned and operated by the federal government (some by the Army Corps of Engineers and some by the Bureau of Reclamation), while the smaller dams are operated by public utility districts, and private power companies. The federally operated system is known as the Federal Columbia River Power System, which includes 31 dams on the Columbia and its List of tributaries of the Columbia River, tributaries. The system has altered the seasonal flow of the river in order to meet higher electricity demands during the winter. At the beginning of the 20th century, roughly 75 percent of the Columbia's flow occurred in the summer, between April and September. By 1980, the summer proportion had been lowered to about 50 percent, essentially eliminating the seasonal pattern. The installation of dams dramatically altered the landscape and ecosystem of the river. At one time, the Columbia was one of the top -producing river systems in the world. Previously active fishing sites, such as Celilo Falls in the eastern Columbia River Gorge, have exhibited a sharp decline in fishing along the Columbia in the last century, and salmon populations have been dramatically reduced. Fish ladders have been installed at some dam sites to help the fish journey to spawning waters. Chief Joseph Dam has no fish ladders and completely blocks fish migration to the upper half of the Columbia River system.
IrrigationThe Bureau of Reclamation's Columbia Basin Project focused on the generally dry region of central Washington known as the Columbia Basin, which features rich loess soil. Several groups developed competing proposals, and in 1933, President Franklin D. Roosevelt authorized the Columbia Basin Project. The Grand Coulee Dam was the project's central component; upon completion, it pumped water up from the Columbia to fill the formerly dry Grand Coulee, forming Banks Lake. By 1935, the intended height of the dam was increased from a range between to , a height that would extend the lake impounded by the dam all the way to the Canada–US border; the project had grown from a local New Deal relief measure to a major national project. The project's initial purpose was irrigation, but the onset of World War II created a high demand for electricity, mainly for aluminum production and for the development of s at the Hanford Site. Irrigation began in 1951. The project provides water to more than of fertile but arid land in central Washington, transforming the region into a major agricultural center. Important crops include orchard fruit, potatoes, alfalfa, mentha, mint, beans, beets, and wine grapes. Since 1750, the Columbia has experienced six multi-year droughts. The longest, lasting 12 years in the mid‑19th century, reduced the river's flow to 20 percent below average. Scientists have expressed concern that a similar drought would have grave consequences in a region so dependent on the Columbia. In 1992–1993, a lesser drought affected farmers, hydroelectric power producers, shippers, and wildlife managers. Many farmers in central Washington build dams on their property for irrigation and to control frost on their crops. The Washington Department of Ecology, using new techniques involving aerial photographs, estimated there may be as many as a hundred such dams in the area, most of which are illegal. Six such dams have failed in recent years, causing hundreds of thousands of dollars of damage to crops and public roads. Fourteen farms in the area have gone through the permitting process to build such dams legally.
HydroelectricityThe Columbia's heavy flow and large elevation drop over a short distance, , give it tremendous capacity for hydroelectricity generation. In comparison, the Mississippi River, Mississippi drops less than . The Columbia alone possesses one-third of the United States's hydroelectric potential. In 2012, the river and its tributaries accounted for 29 Gigawatt, GW of hydroelectric generating capacity, contributing 44 percent of the total hydroelectric generation in the nation. The largest of the 150 hydroelectric projects, the Grand Coulee Dam and the Chief Joseph Dam, are also the largest in the United States. As of 2017, Grand Coulee is the fifth largest hydroelectric plant in the world. Inexpensive hydropower supported the location of a large aluminum industry in the region, because its Aluminium production, reduction from bauxite requires large amounts of electricity. Until 2000, the Northwestern United States produced up to 17 percent of the world's aluminum and 40 percent of the aluminum produced in the United States. The commoditization of power in the early 21st century, coupled with drought that reduced the generation capacity of the river, damaged the industry and by 2001, Columbia River aluminum producers had idled 80 percent of its production capacity. By 2003, the entire United States produced only 15 percent of the world's aluminum, and many smelters along the Columbia had gone dormant or out of business. Power remains relatively inexpensive along the Columbia, and since the mid-2000 several global enterprises have moved server farm operations into the area to avail themselves of cheap power. Downriver of Grand Coulee, each dam's reservoir is closely regulated by the Bonneville Power Administration (BPA), the U.S. Army Corps of Engineers, and various Washington public utility districts to ensure flow, flood control, and power generation objectives are met. Increasingly, hydro-power operations are required to meet standards under the US Endangered Species Act and other agreements to manage operations to minimize impacts on salmon and other fish, and some conservation and fishing groups support removing four dams on the lower Snake River, the largest tributary of the Columbia. In 1941, the BPA hired Oklahoma folksinger Woody Guthrie to write songs for a documentary film promoting the benefits of hydropower. In the month he spent traveling the region Guthrie wrote The Columbia River Collection, 26 songs, which have become an important part of the cultural history of the region.
Ecology and environment
Fish migrationThe Columbia supports several species of fish that migrate between the Pacific Ocean and fresh water tributaries of the river. Sockeye salmon, Coho salmon, Coho and Chinook salmon, Chinook (also known as "king") salmon, and Rainbow trout, steelhead, all of the genus ''Oncorhynchus'', are ocean fish that migrate up the rivers at the end of their life cycles to spawn. White sturgeon, which take 15 to 25 years to mature, typically migrate between the ocean and the upstream habitat several times during their lives. Salmon populations declined dramatically after the establishment of salmon cannery, canneries in 1867. In 1879 it was reported that 545,450 salmon, with an average weight of were caught (in a recent season) and mainly canned for export to England. A can weighing could be sold for penny (British pre-decimal coin), 8d or 9d. By 1908, there was widespread concern about the decline of salmon and sturgeon. In that year, the people of Oregon passed two laws under their newly instituted program of Oregon System, citizens' initiatives limiting fishing on the Columbia and other rivers. Then in 1948, another initiative banned the use of seine fishing, seine nets (devices already used by Native Americans, and refined by later settlers) altogether. Dams interrupt the migration of anadromous fish. Salmon and steelhead return to the streams in which they were born to spawn; where dams prevent their return, entire populations of salmon die. Some of the Columbia and Snake River dams employ fish ladders, which are effective to varying degrees at allowing these fish to travel upstream. Another problem exists for the juvenile salmon headed downstream to the ocean. Previously, this journey would have taken two to three weeks. With river currents slowed by the dams, and the Columbia converted from wild river to a series of slackwater pools, the journey can take several months, which increases the mortality rate. In some cases, the Army Corps of Engineers transports juvenile fish downstream by truck or river barge. The Chief Joseph Dam and several dams on the Columbia's tributaries entirely block migration, and there are no migrating fish on the river above these dams. Sturgeon have different migration habits and can survive without ever visiting the ocean. In many upstream areas cut off from the ocean by dams, sturgeon simply live upstream of the dam. Not all fish have suffered from the modifications to the river; the northern pikeminnow (formerly known as the ''squawfish'') thrives in the warmer, slower water created by the dams. Research in the mid-1980s found that juvenile salmon were suffering substantially from the predatory pikeminnow, and in 1990, in the interest of protecting salmon, a "bounty" program was established to reward anglers for catching pikeminnow. In 1994, the salmon catch was smaller than usual in the rivers of Oregon, Washington, and British Columbia, causing concern among commercial fishermen, government agencies, and tribal leaders. US government intervention, to which the states of Alaska, Idaho, and Oregon objected, included an 11-day closure of an Alaska fishery. In April 1994 the U.S. Regional Fishery Management Councils, Pacific Fisheries Management Council unanimously approved the strictest regulations in 18 years, banning all commercial salmon fishing for that year from Cape Falcon, Oregon, Cape Falcon north to the Canada–US border. In the winter of 1994, the return of coho salmon far exceeded expectations, which was attributed in part to the fishing ban. Also in 1994, United States Secretary of the Interior Bruce Babbitt first proposed the removal of several Pacific Northwest dams because of their impact on salmon spawning. The Northwest Power and Conservation Council, Northwest Power Planning Council approved a plan that provided more water for fish and less for electricity, irrigation, and transportation. Environmental advocates have called for the removal of certain dams in the Columbia system in the years since. Of the 227 major dams in the Columbia River drainage basin, the four Washington dams on the lower Snake River are often identified for removal, for example in an ongoing lawsuit concerning a Presidency of George W. Bush, Bush administration plan for salmon recovery. These dams and reservoirs limit the recovery of upriver salmon runs to Idaho's Salmon and Clearwater rivers. Historically, the Snake produced over 1.5 million spring and summer Chinook salmon, a number that has dwindled to several thousand in recent years. Idaho Power, Idaho Power Company's Hells Canyon dams have no fish ladders (and do not pass juvenile salmon downstream), and thus allow no steelhead or salmon to migrate above Hells Canyon. In 2007, the destruction of the Bull Run Hydroelectric Project, Marmot Dam on the Sandy River was the first dam removal in the system. Other Columbia Basin dams that have been removed include Condit Hydroelectric Project, Condit Dam on Washington's White Salmon River, and the Milltown Dam on the Clark Fork (river), Clark Fork in Montana.
PollutionIn southeastern Washington, a stretch of the river passes through the , established in 1943 as part of the Manhattan Project. The site served as a plutonium production complex, with nine nuclear reactors and related facilities along the banks of the river. From 1944 to 1971, pump systems drew cooling water from the river and, after treating this water for use by the reactors, returned it to the river. Before being released back into the river, the used water was held in large tanks known as retention basins for up to six hours. Longer-lived isotopes were not affected by this retention, and several becquerel, terabecquerels entered the river every day. By 1957, the eight plutonium production reactors at Hanford dumped a daily average of 50,000 Curie (unit), curies of radioactive material into the Columbia. These releases were kept secret by the federal government until the release of declassified documents in the late 1980s. Radiation was measured downstream as far west as the Washington and Oregon coasts. The nuclear reactors were decommissioned at the end of the Cold War, and the Hanford site is the focus of one of the world's largest environmental remediation, environmental cleanup, managed by the United States Department of Energy, Department of Energy under the oversight of the Washington Department of Ecology and the United States Environmental Protection Agency, Environmental Protection Agency. Nearby aquifers contain an estimated 270 billion US gallons (1 billion m3) of groundwater contaminated by high-level nuclear waste that has leaked out of Hanford's underground storage tanks. , 1 million US gallons (3,785 m3) of highly radioactive waste is traveling through groundwater toward the Columbia River. This waste is expected to reach the river in 12 to 50 years if cleanup does not proceed on schedule. In addition to concerns about nuclear waste, numerous other pollutants are found in the river. These include chemical pesticides, bacteria, arsenic, dioxins, and polychlorinated biphenyls (PCB). Studies have also found significant levels of toxins in fish and the waters they inhabit within the basin. Accumulation of toxins in fish threatens the survival of fish species, and human consumption of these fish can lead to health problems. Water quality is also an important factor in the survival of other wildlife and plants that grow in the Columbia River drainage basin. The states, Indian tribes, and federal government are all engaged in efforts to restore and improve the water, land, and air quality of the Columbia River drainage basin and have committed to work together to enhance and accomplish critical ecosystem restoration efforts. A number of cleanup efforts are currently underway, including Superfund projects at Portland Harbor, Hanford, and Lake Roosevelt. Timber industry activity further contaminates river water, for example in the increased sediment runoff that results from clearcutting, clearcuts. The Northwest Forest Plan, a piece of federal legislation from 1994, mandated that timber companies consider the environmental impacts of their practices on rivers like the Columbia. On July 1, 2003, Christopher Swain of Portland, Oregon, became the first person to swim the Columbia River's entire length, in an effort to raise public awareness about the river's environmental health.
Nutrient cycleBoth natural and Human impact on the environment, anthropogenic processes are involved in the nutrient cycle, cycling of nutrients in the Columbia River basin. Natural processes in the system include Estuary, estuarine mixing of fresh and ocean waters, and climate variability patterns such as the Pacific Decadal Oscillation and the El Niño–Southern Oscillation, El Nino Southern Oscillation (both climatic cycles that affect the amount of regional snowpack and river discharge). Natural sources of nutrients in the Columbia River include weathering, leaf litter, carcasses, runoff from its Tributary, tributaries, and Estuarine water circulation, ocean estuary exchange. Major anthropogenic impacts to nutrients in the basin are due to fertilizers from agriculture, sewage systems, logging, and the construction of dams. Nutrients dynamics vary in the river basin from the River source, headwaters to the main river and dams, to finally reaching the Columbia River Estuary, Columbia River estuary and ocean. Upstream in the headwaters, salmon runs are the main source of nutrients. Dams along the river impact nutrient cycling by increasing Residence time (fluid dynamics), residence time of nutrients, and reducing the transport of silicate to the estuary, which directly impacts diatoms, a type of phytoplankton. The dams are also a barrier to salmon migration, and can increase the amount of methane locally produced. The Columbia River estuary exports high rates of nutrients into the Pacific Ocean; with the exception of nitrogen, which is delivered into the estuary by ocean upwelling sources.
WatershedMost of the Columbia's drainage basin (which, at , is about the size of France) lies roughly between the Rocky Mountains on the east and the Cascade Mountains on the west. In the United States and Canada the term watershed is often used to mean drainage basin. The term ''Columbia Basin'' is used to refer not only to the entire drainage basin but also to subsets of the river's full watershed, such as the relatively flat and unforested area in eastern Washington bounded by the Cascades, the Rocky Mountains, and the Blue Mountains. Within the watershed are diverse landforms including mountains, arid plateaus, river valleys, rolling uplands, and deep gorges. Grand Teton National Park lies in the watershed, as well as parts of Yellowstone National Park, Glacier National Park (U.S.), Glacier National Park, Mount Rainier National Park, and North Cascades National Park. Canadian National Parks in the watershed include Kootenay National Park, Yoho National Park, Glacier National Park (Canada), Glacier National Park, and Mount Revelstoke National Park. Hells Canyon, the deepest gorge in North America, and the Columbia Gorge are in the watershed. Vegetation varies widely, ranging from Tsuga heterophylla, western hemlock and Thuja plicata, western redcedar in the moist regions to sagebrush in the arid regions. The watershed provides habitat for 609 known fish and wildlife species, including the bull trout, bald eagle, gray wolf, grizzly bear, and Canada lynx. The World Wide Fund for Nature (WWF) divides the waters of the Columbia and its tributaries into three freshwater ecoregions, naming them Columbia Glaciated, Columbia Unglaciated, and Upper Snake. The Columbia Glaciated ecoregion, making up about a third of the total watershed, lies in the north and was covered with ice sheets during the Pleistocene. The ecoregion includes the mainstem Columbia north of the Snake River and tributaries such as the Yakima, Okanagan, Pend Oreille, Clark Fork, and Kootenay rivers. The effects of glacier, glaciation include a number of large lakes and a relatively low diversity of freshwater fish. The Upper Snake ecoregion is defined as the Snake River watershed above Shoshone Falls, which totally blocks fish migration. This region has 14 species of fish, many of which are endemism, endemic. The Columbia Unglaciated ecoregion makes up the rest of the watershed. It includes the mainstem Columbia below the Snake River and tributaries such as the Salmon, John Day, Deschutes, and lower Snake Rivers. Of the three ecoregions it is the richest in terms of freshwater species diversity. There are 35 species of fish, of which four are endemic. There are also high levels of mollusk endemism. In 2016, over eight million people lived within the Columbia's drainage basin. Of this total about 3.5 million people lived in Oregon, 2.1 million in Washington, 1.7 million in Idaho, half a million in British Columbia, and 0.4 million in Montana. Population in the watershed has been rising for many decades and is projected to rise to about 10 million by 2030. The highest population densities are found west of the Cascade Mountains along the Interstate 5, I-5 corridor, especially in the Portland-Vancouver urban area. High densities are also found around Spokane, Washington, and Boise, Idaho. Although much of the watershed is rural and sparsely populated, areas with recreational and scenic values are growing rapidly. The central Oregon county of Deschutes County, Oregon, Deschutes is the fastest-growing in the state. Populations have also been growing just east of the Cascades in central Washington around the city of Yakima, Washington, Yakima and the Tri-Cities area. Projections for the coming decades assume growth throughout the watershed, including the interior. The Canadian part of the Okanagan subbasin is also growing rapidly. Climate varies greatly from place to place within the watershed. Elevation ranges from sea level at the river mouth to more than in the mountains, and temperatures vary with elevation. The highest peak is Mount Rainier, at . High elevations have cold winters and short cool summers; interior regions are subject to great temperature variability and severe droughts. Over some of the watershed, especially west of the Cascade Mountains, precipitation maximums occur in winter, when Pacific storms come ashore. Atmospheric conditions block the flow of moisture in summer, which is generally dry except for occasional thunderstorms in the interior. In some of the eastern parts of the watershed, especially shrub-steppe regions with Continental climate patterns, precipitation maximums occur in early summer. Annual precipitation varies from more than a year in the Cascades to less than in the interior. Much of the watershed gets less than a year. Several major North American drainage basins and many minor ones share a common border with the Columbia River's drainage basin. To the east, in northern Wyoming and Montana, the Continental Divide separates the Columbia watershed from the Mississippi-Missouri watershed, which empties into the Gulf of Mexico. To the northeast, mostly along the southern border between British Columbia and Alberta, the Continental Divide separates the Columbia watershed from the Nelson River, Nelson-Lake Winnipeg-Saskatchewan River, Saskatchewan watershed, which empties into Hudson Bay. The Mississippi and Nelson watersheds are separated by the Laurentian Divide, which meets the Continental Divide at Triple Divide Peak (Montana), Triple Divide Peak near the headwaters of the Columbia's Flathead River tributary. This point marks the meeting of three of North America's main drainage patterns, to the Pacific Ocean, to Hudson Bay, and to the Atlantic Ocean via the Gulf of Mexico. Further north along the Continental Divide, a short portion of the combined Continental and Laurentian divides separate the Columbia watershed from the MacKenzie River, MacKenzie-Slave River, Slave-Athabasca River, Athabasca watershed, which empties into the Arctic Ocean. The Nelson and Mackenzie watersheds are separated by a divide between streams flowing to the Arctic Ocean and those of the List of Hudson Bay rivers, Hudson Bay watershed. This divide meets the Continental Divide at Snow Dome (Canada), Snow Dome (also known as Dome), near the northernmost bend of the Columbia River. To the southeast, in western Wyoming, another divide separates the Columbia watershed from the Colorado River, Colorado–Green River (Colorado River), Green watershed, which empties into the Gulf of California. The Columbia, Colorado, and Mississippi watersheds meet at Three Waters Mountain in the Wind River Range of . To the south, in Oregon, Nevada, Utah, Idaho, and Wyoming, the Columbia watershed is divided from the Great Basin, whose several watersheds are endorheic basin, endorheic, not emptying into any ocean but rather drying up or sinking into sumps. Great Basin watersheds that share a border with the Columbia watershed include Harney Basin, Humboldt River, and Great Salt Lake. The associated triple divide points are Commissary Ridge North, Wyoming, and Sproats Meadow Northwest, Oregon. To the north, mostly in British Columbia, the Columbia watershed borders the Fraser River watershed. To the west and southwest the Columbia watershed borders a number of smaller watersheds that drain to the Pacific Ocean, such as the Klamath River in Oregon and California and the Puget Sound Basin in Washington.
Major tributariesThe Columbia receives more than 60 significant tributary, tributaries. The four largest that empty directly into the Columbia (measured either by discharge (hydrology), discharge or by size of watershed) are the Snake River (mostly in Idaho), the Willamette River (in northwest Oregon), the Kootenay River (mostly in British Columbia), and the Pend Oreille River (mostly in northern Washington and Idaho, also known as the lower part of the Clark Fork). Each of these four averages more than and drains an area of more than . The Snake is by far the largest tributary. Its watershed of is larger than the state of Idaho. Its discharge is roughly a third of the Columbia's at the rivers' confluence but compared to the Columbia upstream of the confluence the Snake is longer (113%) and has a larger drainage basin (104%). The Pend Oreille River system (including its main tributaries, the Clark Fork and Flathead rivers) is also similar in size to the Columbia at their confluence. Compared to the Columbia River above the two rivers' confluence, the Pend Oreille-Clark-Flathead is nearly as long (about 86%), its basin about three-fourths as large (76%), and its discharge over a third (37%).Calculated mainly with data from:
See also* Columbia Park (Kennewick, Washington), a recreational area * Columbia River Estuary * Columbia River Maritime Museum, Astoria, Oregon * Empire Builder, an Amtrak rail line that follows the river from Portland to Pasco, Washington * Estella Mine, an abandoned mine with a view of the Columbia River Valley * Historic Columbia River Highway, a scenic highway on the Oregon side * List of crossings of the Columbia River * List of dams in the Columbia River watershed * List of longest rivers of Canada * List of longest rivers of the United States (by main stem) * List of longest streams of Oregon * Lists of ecoregions in List of ecoregions in North America (CEC), North America and List of ecoregions in Oregon, Oregon * Lists of rivers of List of rivers of British Columbia, British Columbia, List of rivers of Oregon, Oregon, and List of rivers of Washington, Washington * Okanagan Trail, a historic trail that followed the Columbia and Okanagan rivers * Robert Gray's Columbia River expedition
Sources* * * * * * * * * * * * * * * * * * * * * * * * * * (see s:en:The Columbia River: Its History, Its Myths, Its Scenery, Its Commerce, here for full online transcription) * * * * * * * * * * * * * * * * * * *