The property ends at the waters edge, the border goes down the middle of the river with the exception of a few small places. Plus the river has the ability to change course and has many times in the past, especially down in the valley where there are many old oxbows present.
And there’s boating, fishing, commerce, etc.
My property borders a major stream in Ohio. My deed says my property line goes to the middle of that stream. There are canoers, fishermen, kayakers, and govt officials who would get royally PO’d if I built a fence in the middle of it.
I’ve built a landing, but I wouldn’t dare put a hydro collector out there. The gov’t claims that stream.
I just choose to live with them and do nothing annoying.
Since all of Texas has a river border on the south, it clearly is a national defence issue. A wall down the middle of the rio grande doesn’t make sense, but the river itself is a barrier, so a road along the entire border does make sense.
Being retired military, I know the power of infrared radar. FLIR stations line-of-site along that entire border would work. Not a rabbit can move without flir seeing it.
What procedures to implement would be important and especially in high population areas.
We need those 10000 new agents and guards.