On August 25, 2014, U.S. Supreme Court Justice Antonin Scalia came to Idaho to participate in the final document signing ceremony for the completion of the Snake River Basin Adjudication (SRBA). The SRBA is a nearly 27-year lawsuit that identified, quantified and qualified all water rights on the Snake River.
That means that for each water right, the court, among other things determined: (i) the owner; (ii) the amount, location and period of beneficial use; and (iii) the priority date of the water right. This was a huge undertaking that requires additional litigation to resolve a number of remaining issues. You can read about the SRBA here. http://www.srba.state.id.us/SRBA1.HTM.