[bradleyjg]

Not necessarily. The idiotic prior appropriation system is a matter of state law and takings doctrine are a matter of federal constitutional law. The combination doesn't have a whole lot of case law at the Supreme Court level. It may well be the case that a coordinated change in both federal and state (statutory) law would be enough to work around the takings clause issue.

Even if all else failed it might well be better to bite the rentier tax once than to live with them forever. Remember takings only requires the payment of fair market value, and these water permits have limited alienability.