This book presents the results of an interdisciplinary project that examined how law, policy and ecological dynamics influence the governance of regional scale water based social-ecological systems in the United States and Australia. The volume explores the obstacles and opportunities for governance that is capable of management, adaptation, and transformation in these regional social-ecological systems as they respond to accelerating environmental change. With the onset of the Anthropocene, global and regional changes in biophysical inputs to these systems will challenge their capacity to respond while maintaining functions of water supply, flood control, hydropower production, water quality, and biodiversity. Governance lies at the heart of the capacity of these systems to meet these challenges. Assessment of water basins in the United States and Australia indicates that state-centric governance of these complex and dynamic social-environmental systems is evolving to a more complex, diverse, and complex array of public and private arrangements.