Ever seen Falcon or Amistad Reservoir? How do you build a fence across a lake?
How did they build that highway just north of New Orleans across 22 miles of water??
It is NOT impossible.
How do you build a fence across a lake?
You know the border patrols hands are tied to stop them...read the Border Patrols site which explains they cannot interfer with those crossings and why. Take away those restrictions and let the Border patrol do their job