The lowest dam is Bonneville. From there, the river flows unimpeded to the Pacific near Astoria OR.
The great American river flowing into the Pacific, the Columbia originates in ice fields in the Rocky Mountains near the border between British Columbia and Alberta in Canada. It flows north for a distance, and then turns south. The [wa:grandcod] in eastern Washington creates [wa:fdrlake], which backs water all the way to Canada. Below the Grand Coulee are many more dams, which have tamed the floods and made the river navigable. They also provide irrigation that has expanded agriculture on the "dry side" of the Cascades.
The lowest dam is Bonneville. From there, the river flows unimpeded to the Pacific near [or:astoria] OR.
The two most important tributaries are the [id:snakeriv] and the [or:willamri].
