Fourteen main-stem dams power nearly half of U.S. hydropower
The Columbia runs 1,243 miles from British Columbia's Rockies to the Pacific, draining a France-sized basin. Fourteen hydroelectric dams on its main stem—plus many more on tributaries—generate more than 44 percent of all U.S. hydropower while salmon still try to commute between river and ocean.
Largest river of the Pacific Northwest, the Columbia rises near Columbia Lake and wetlands in the Rocky Mountain Trench, flows northwest then south into Washington, and turns west to mark most of the Washington–Oregon border. The Snake is its greatest tributary. Indigenous names include Wimahl/Wimal (Upper Chinook) and Nch’i-Wàna (Sahaptin). Anadromous fish, especially salmon, fed Native subsistence for millennia and tied cultures along a shared water highway.
Bruno de Heceta sighted the mouth in 1775; on 11 May 1792 Captain Robert Gray's Columbia Rediviva became the first non-Indigenous ship to enter, lending the river—and later British Columbia—its English name. Broughton's Chatham pushed about a hundred miles inland the same year. Fur traders followed; later locks, dredging, irrigation, flood control, and nuclear work at Hanford reshaped the corridor. Hanford Reach remains the only U.S. main-stem stretch that is fully free-flowing, undammed, and non-tidal.
About 258,000 square miles (670,000 km2) drain toward the Pacific—nearly all of Idaho plus large shares of B.C., Oregon, and Washington. Roughly 745 miles and 85 percent of the basin lie in the United States. Missoula Floods 10–15,000 years ago scoured the Grand Coulee before the river settled its present Big Bend. Through the Columbia River Gorge the river crosses the Cascades lower than any peer, riding famous winds. Downstream of Portland sediment drops instead of building a classic delta—another engineered and geologic compromise on a working river.
Source: Columbia River
