I am not claiming to understand the situation, it was a genuine question.
Obviously as a native american myself the fact that we were genocided and mistreated isnt lost on me.
But they have access to water, ground water. Are you claiming the terms of the treaty was they would have justisdiction of the river? If so please share that and that would be enough info to convince me they have a right to it.
I know nothing about the details of the treaty that gave them the land. My assumption, and perhaps an incorrect one, is they were given a plot of land, that land has ground water on it so it includes access to water. Obviously the genocide was an injustice, where do you feel the resolution agreed upon, however, is not being honored?