Water management policies are established to administer a limited resource. They are all based on the answer to the question: How much water is available in this area (a hydrologic basin or smaller region)? Typically all management policies allow a fraction of the available water to be extracted for human needs, and much of the discussion centers on determining the "right" fraction (yield) that can be allowed, either under sustainable development or resource mining policies. Although the terms of that debate cannot be changed, a different perspective can lead to better understanding of the system, and hence to better policies. That perspective arises from the fact that natural systems can never be perfectly known, so that all answers to the above question (and the policies based upon them) are subject to uncertainty. Fortunately, uncertainty can be evaluated and policies adopted that minimize the risk of undesirable consequences, such as depleting an aquifer or mining it at a rate faster than desired. Actions can be taken at any time under risk-based yield management policies that take into account all relevant uncertainties.