In California, as in most states, the right to riparian water follows the rule of title or deed. The proof of a water right involves a specific burden of proof found in the chain of title back to the original ownership or patent. Riparian rights water cannot be stored for a period of 30 days or longer. An unused riparian right can be lost to downstream appropriative rights. Once a riparian water right is lost, it is lost forever.
Appropriative water is water that can be diverted for use on non-riparian land.
Non-riparian land is any land not adjacent to a natural watercourse. Pre-1914 appropriative rights predicate a permitting system and required a simple posting to describe intent and scope of water use, diversion or construction of diversion facilities. A pre-1914 right also carries certain prescriptive characteristics. If the appropriated water has gone unused for a period of time exceeding five years, the right is lost. A proven and documented pre-1914 appropriative water right carries priority over a post 1914 water right.