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.
Indeed, even a putz like me could dope out several ways to handle it.
I tend to bring it up when folks seem to think it's just a matter of building a nice wall.
It ain't that simple. Not impossible, but a wall won't get it by itself.
That's OUR water and we ain't giving it up.