Where at any time the Commission has reason to believe that the holder of water right has not, during the preceding two years, made full beneficial use of that right, it may after giving the holder of the right opportunity of making representations to the Commission, by notice in writing addressed to the holder and having regard to the investment in capital works and the long term national interest involved in the undertaking concerned-

(a) terminate the right; or

           (b) limit or modify in such respects as it may specify the right.