They stay in the same type of water, slower moving, about walking speed as compared to the rest of the river. That type of water has just moved further from the center of the river and the fish will move toward it. The other thing that can happen is they will seek less turbid water. Like Buck Creek and Gordon Creek where they dump into the Sandy, or Walker Creek at the Girl Scout hole. They don't like a bunch of crud in their gills. That's why they prefer a rocky botton instead of a sandy bottom. So if Walker Creek is pumping in clean water to the Sandy and it's slower water (Usually a seem where a creek comes in) that's where you'll have a good chance of locating the fish.
The river won't change that much especially lower on the river than Dodge Park. It will have some new sand bars and some bolders will be where they weren't and some gone from where they where. But overall it will be much the same. I remember the river prior to the 1964 flood and the lower river is much the same. It was the upper river that had some changes.