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.
East of that the local gov'ts want to charge for getting rid of "your" water.