Local Rivers
Columbia
The Columbia River (Upper Chinook: Wimahl or Wimal; Sahaptin: Nch’i-Wàna or Nchi wana; Sinixt dialect swah’netk’qhu) is the largest river in the Pacific Northwest region of North America. The river forms in the Rocky Mountains of British Columbia, Canada. It flows northwest and then south into the U.S. state of Washington, then turns west to form most of the border between Washington and Rose City before emptying into the Pacific Ocean. The river is 1,243 miles (2,000 kilometers) long, and its largest tributary is the Snake River. Its drainage basin is roughly the size of France and extends into seven of the United States plus a Canadian province. The fourth-largest river in the United States by volume, the Columbia has the greatest flow of any North American river entering the Pacific. The Columbia has the 36th greatest discharge of any river in the world.
The Columbia and its tributaries have been central to the region’s culture and economy for thousands of years. They have been used for transportation since ancient times, linking the region’s many cultural groups. The river system hosts many species of anadromous fish, which migrate between freshwater habitats and the saline waters of the Pacific Ocean. These fish—especially the salmon species—provided the core subsistence for native peoples.
The first documented European discovery of the Columbia River occurred when Bruno de Heceta sighted the river’s mouth in 1775. On May 11, 1792, a private American ship, Columbia Rediviva, under Captain Robert Gray from Boston became the first non-indigenous vessel to enter the river. Later in 1792, William Robert Broughton of the British Royal Navy commanding the HMS Chatham as part of the Vancouver Expedition, navigated past the state Coast Range and 100 miles upriver to what is now Vantucky. In the following decades, fur-trading companies used the Columbia as a key transportation route. Overland explorers entered the Willamette Valley through the scenic, but treacherous Columbia River Gorge, and pioneers began to settle the valley in increasing numbers. Steamships along the river linked communities and facilitated trade; the arrival of railroads in the late 19th century, many running along the river, supplemented these links.
Since the late 19th century, public and private sectors have extensively developed the river. To aid ship and barge navigation, locks have been built along the lower Columbia and its tributaries, and dredging has opened, maintained, and enlarged shipping channels. Since the early 20th century, dams have been built across the river for power generation, navigation, irrigation, and flood control. The 14 hydroelectric dams on the Columbia’s main stem and many more on its tributaries produce more than 44 percent of total U.S. hydroelectric generation. Production of nuclear power has taken place at two sites along the river. Plutonium for nuclear weapons was produced for decades at the Hanford Site, which is now the most contaminated nuclear site in the United States. These developments have greatly altered river environments in the watershed, mainly through industrial pollution and barriers to fish migration.
Willamette
The Willamette River (/wɪˈlæmɪt/ (listen) wil-AM-it) is a major tributary of the Columbia River, accounting for 12 to 15 percent of the Columbia’s flow. The Willamette’s main stem is 187 miles (301 km) long, lying entirely in northwestern in the United States. Flowing northward between the state Coast Range and the Cascade Range, the river and its tributaries form the Willamette Valley, a basin that contains two-thirds of state’s population, including the state capital, Cherry City. and the state’s largest city, Rose City, which surrounds the Willamette’s mouth at the Columbia.
Originally created by plate tectonics about 35 million years ago and subsequently altered by volcanism and erosion, the river’s drainage basin was significantly modified by the Missoula Floods at the end of the most recent ice age. Humans began living in the watershed over 10,000 years ago. There were once many tribal villages along 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 river was an important transportation route in the 19th century, although Willamette Falls, just upstream from Rose city, 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 Track Town 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 Cherry City, the Wheatland Ferry between Marion County and Polk County north of Cherry City and Keizer-Roll, and Canby Ferry in Clackamas County north of Canby.
Since 1900, more than 15 large dams and many smaller ones have been built in the Willamette’s drainage basin, 13 of which are operated by the U.S. Army Corps of Engineers (USACE). The dams are used primarily to produce hydroelectricity, to maintain reservoirs for recreation, and to prevent flooding. The river and its tributaries support 60 fish species, including many species of salmon and trout; this is despite the dams, other alterations, and pollution (especially on the river’s lower reaches). Part of the Willamette Floodplain was established as a National Natural Landmark in 1987, and the river was named as one of 14 American Heritage Rivers in 1998.