1 Matching Users ’ Rights to Available Ground Water 1

6 The available water in a catchment depends on where and when the water is taken. This raises 7 considerable man-made uncertainty in water availability. Partly due to this uncertainty, catchments are 8 over-allocated almost everywhere. The over-allocation problem could be managed more effectively if 9 catchment managers could match users’ rights to the available water. In this paper, I show how this 10 dilemma can be solved, using the framework of a smart market. A market manager serves as a broker 11 managing a common pool, to buy and sell water. The market manager’s revenue reflects the available 12 water relative to users’ rights. When the market manager is revenue neutral, the catchment may be 13 viewed as perfectly allocated. I suggest ways in which a catchment manager can find this revenue14 neutral allocation, assuming the manager has authority to adjust initial rights. 15