I don't like the excuses that things are harder to solve in the US because it's so big, diverse or whatever. If anything I think it should be easier in the US because it can solve a lot of problems without having to think about what the impact on neighboring countries is. As far as water goes, the US has pretty much all types of climate zones under its control so it could divert water or move agriculture to more favorable locations. A small country like Israel doesn't have access to water rich areas but the US has.

The only reason why the US can't solve problems is because it's dysfunctional and people prefer to fight each other and not accept facts they don't like.