Arizona Revised Statutes Title 45. Waters § 45-173. Use of natural waterway to carry water of another or for other water projects; dispute over division of waters

A. Although the waters which naturally flow in the natural channel of a stream have been previously appropriated and put to beneficial use by others, the channel may be used to carry water of another or used for the location of an underground storage facility pursuant to chapter 3.1  1 of this title, if such use can be made without diminishing the quantity of water which naturally flows therein the use of which has been appropriated.

B. When the parties interested cannot agree upon the division of the water turned into the natural channel from the water naturally flowing therein, or if it is difficult to ascertain the amount to which each party is entitled, the water superintendent of the district shall make the division.