The Columbia River contains class five rapids.
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 Columbia River multiannual average discharge: == Geology ==When the rifting of Pangaea, due to the process of plate tectonics, 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

