Closely related to our waterways are the roads--many of them major interstate freeways--that cross those waterways on bridges, and in some cases on dams. Destroying any one of these--especially interstate--bridges could have devastating long-term effects on the entire region.
This website lists many of the roads that cross the Columbia river in the Pacific Northwest. https://en.m.wikipedia.org/wiki/List_of_crossings_of_the_Columbia_River