I brought this point up to someone here about a year ago.. and was told that “border security is more important than some cows getting a drink”.
The stupid burned so hot that I felt it on this end, so I didn’t pursue the matter.
The thing with the cows/water needs is that it is dog simple to solve. It is basic irrigation that happens every day throughout the world. Simple water diversion.
Ultimately there is no need for it to be either/or. We can have both.
That said, if it ever came down to it, we just take the River, DMZ the thing and if we feel generous, let them have some of the water.
Not that THAT would ever happen.