One of the problems of effective groundwater management (assuming you consider groundwater as a more or less common pool resource) is the tendency of individual users to maximize their use in the near-term lest their neighbor(s) beat them to the gains - most often referred to as "the race to the well". The prior appropriation system of water rights was supposed to address this condition (and many others) by preventing new appropriations whenever they were likely to impair those that already existed. Thus protected, there is no pressing need to maximize one's gains immediately - at least not because you're afraid your neighbor will get to your expected benefits first.
However, in an overappropriated prior appropriation system, the race to the well mentality is rekindled - and becomes stronger the more the overappropriation level is. Of course the question is: What are the ways this problem can be addressed? One way is to administer the system by eliminating junior water rights until you're back to sustainable withdrawal levels. Another way is to recognize the finite timeframe of the current use and convert all existing water rights (from annual authorized quantities) to absolute quantities based on their share of the pool and how long you want the pool to last. In actuality this resembles an appropriation correlative rights system.
Administering the system will achieve groundwater sustainability, and relieve the need to maximize individual profits before your neighbor does, but it will also never allow the water remaining in storage to be utilized at all. The only water available is the long-term annual recharge. Converting all water rights to absolute quantities can allow the system to achieve stabilization at any pre-chosen level - thus allowing the use of as much or as little of the storage as the governing body chooses.
In cases where the junior water users are the most efficient, the administration approach leaves only the least efficient users left in the system. The other approach allows everyone to continue pumping to some extent. Moreover, converting all water rights to an absolute total appropriation allows one to save his or her remaining water right for whatever reasons; makes any potential water market more vibrant, allows users to adopt as aggressive of a conservation strategy they choose, and can even incorporate the senior/junior priority system by the relative weighting of all conversions based on priority. The proposal can also be staged in to encourage and reward early conservation by individual uses or groups of users. With all these features, it virtually eliminates any need to use your water early (while it doesn't prevent it), and can actually create advantages for saving your water for later use or marketing. Maybe we'll discuss this more in a later post.