I probably don't have too much to add, other than that the Columbia River has many dams on it, of course, which help to control the flood events. In those kinds of situations, there is more opportunity to control the water. Here on the Fraser River, there is usually 24 hours or less notice, and you might have a variation of water levels of 10 to 20 feet.
On August 13th, 2020. See this statement in context.