Annals of Arid Zone 45(3&4): 399-423, 2006

Water resources management is one of the most important challenges to today's society. Functionally intact and biologically complex freshwater ecosystems provide many economically valuable commodities and services to society (ecosystem services), beyond simply direct water supply. Besides being an integral part of the ecosystem, water is also a social and economic good. It is therefore critical that efforts intended to be sustainable fully consider the health, integrity, and function of aquatic ecosystems and that the environmental value of these ecosystems be recognized when making economic and social decisions on water allocation and use. Sustainable development is the centerpiece and key to water resource quantity and quality management, as well as national security, economic health, and societal wellbeing. Considering a sustainability approach anchors a system of evaluative concepts by organizing our scientific information and our important judgments (core values) to correspond to a world that unfolds on multiple temporal scales. Sustaining water resources requires a multi-dimensional way of thinking about the connections or inter-dependencies among natural, social, and economic systems in the use of water to achieve economic vitality while enhancing/preserving ecological integrity, social well-being, and security for all. Traditionally, water quality improvements have focused on specific sources of pollution. While this approach may be successful in addressing a detailed problem, it often fails to address the more subtle and chronic problems that contribute to a watershed's decline. Because watersheds are defined by natural hydrology, they represent the most logical basis for managing water resources. Besides the environmental pay-off, watershed approaches can have the added benefit of saving time and money. Because acting sustainably requires simultaneous multi-dimensional thinking thinking that covers both temporal and spatial scales for the different sector concerns of economy, society, and environment to build a viable concept of sustainability, an individual or group must involve themselves in thinking as Leopold described, like a mountain, or a watershed, in order to adequately protect the natural resources in an ecosystem concept that support our socio-economic desires. Watershed thinking evokes dimension and scale in connection with human responsibility, recognition that there are rhythms and dynamics in nature that we do not experience as immediately relevant to us, but which affect our world by changing dynamics we have hitherto taken for granted. Adaptive management is a decision-making processes that effectively integrates both short-term and long-term economic, environmental, and social concerns. It provides a mechanism to evaluate and fully consider all the other principles discussed here, with the guidance of thinking like a watershed. Examples of watershed thinking are presented to fully characterize the vast utility of this approach. Thinking like a watershed, therefore, is thinking about human values as time-sensitive and as produced by specific processes and dynamics that unfold on identifiable scales.