How do water rights figure into this situation?
Water rights are compensable and transferable.
And therefore can be seized by eminent domain.
Years ago (3??) I read an article about these property disputes in Texas along the river. It has been going on for a long time. IIRC - the water rights was the primary thing.
An extra 200 feet or whatever of property along the river for grazing wasn’t a huge deal - it was how do you water the cattle now? If you can’t water them, it makes the other 20,000 acres worthless.
I would think that there would be an engineering solution. Diversion structure upstream to put water into a pipe, etc. But I think that opens up a whole can of worms as soon as you start diverting water with regard to water rights, international law, etc.