There is no date on your story so I assume it is the
time frame of the Ca. gold rush, 1850's ?
If so, and if the gold was buried close enough to
the river to have flooded back then, better bring
your diving gear, Lake Sakakawea is 60+ feet deep
in that area. When Garrison Dam was finished in
1953, and the reservoir began to fill, like with any
huge dam, untold amounts of historic relics, artifacts,
and culture were buried underwater, forever in terms
of our short lives. But hey, I have plenty of electricity
to run the computer!