TBAR is a known deposit area for junk. I would guess that the flow reversal pushed the money (bag) up beyond TBAR then when it ended (tidal) the river then pushed it back onto TBAR or close by. It may have been washed up or get dredged onto its found position. These events are also called tidal floods.
Now, here you agree with floating objects, but you told Trapper a buoy test wouldn't work? and you need to show reverse flow from the Lewis river down to T-bar to start with, and not from the Hayden island to T-bar area, which again is where another river connects...
For this theory a dredge is still in play, but a submerged object can still get washed up. Rivers have extremely dynamic properties.. some currents flow both ways at different levels, sideways or even from bottom to surface on shorelines. In a flood tide the water level rises, then at normalization it drops. That could deposit a submerged object on a shoreline. We don't know..
IMO, if money was submerged (some bundles still in the bag) then a buoy surface float will have limited value. Unlike a submerged object, surface float is affected by winds.
But, the big problem is the current conditions vs the possible float event pre 1980. The dramatic change invariables can't be replicated.
A money bag with some bundles left in it would be a sail underwater..
Can a test can be developed where we can put a money bag with the equivalent of some bundles of money during a good flow reversal event and track it from the Lewis?? Attach a fishing line with slack?