Well,
The River has spoken: A before and after.
This was after the first night of high water. One hive lost overnight and we saved the two short hives shown. The tall one was lost in the night that was coming.
This morning...
I lost two hives from the perch shown below on the first night of flooding...You can see the size of the 'debris' floating by, and this trunk is on the very edge of the floodplain in the shallowest water (our home is behind me taking this picture, and about 30 feet above this spot).
Jumpstarting the hives after water ruined the brood nest:
Another thing learned. I texted tec and asked for advice about the two hives we did save. The bees were definitely stressed after two nights out in the rain and clinging to the top cover. They just didn't go into the hives at their new location shown here.
Tec recommended I freeze the brood frames to keep SHB under control. So I took the brood frames out and replaced them with foundation. I had supers with mostly drawn comb and they were placed on each of the hives. The bottom boards were literally covered in dead larvae and dead bees, with SHB crawling in the muck. The water soaked Brood frames were full of SHB too. No wonder they didn't want to go back in the hive! Tec also recommended feeding them. I put sugar water with some Honey Bee Healthy and electrolytes in a top feeder on both hives. One hive would fill a five frame NUC and the other fills about a super and a half (probably a stronger queen pheromone, they were equal before the flood).
I'll probably rob some brood frames from stronger hives to get them going again.
Thanks to all for your support and kind words! We will not be placing any hives in the floodplain again...well maybe, a mating NUC that can go under my arm...