Not sure a river will prevent a fence. Not even a bit.
Just have to place it far enough away, and reinforce the construction where necessary.
I don’t believe there is snow-melt flooding on the Rio Grande, though that could also be a consideration. Though it is just a challenge.
Start the shovels. Get started. :D
“Not sure a river will prevent a fence. Not even a bit.”
Which side of the river to you plan on building this fence.