This book is a first hand investigation into water management in a fast-growing region of the arid American West. It presents three states that adopted the conjunctive management (CJM) of groundwater and surface water to make resources go further in serving people and the environment. CJM has followed a different history, been practiced differently, and produced different outcomes in each state. The authors question why different results have emerged from neighbors trying to solve similar problems with the same policy reform.The first book on conjunctive water management, Common Waters, Diverging Streams describes how CJM came into existence, how it is practiced, and what it does and does not accomplish. A further contribution is its linkages between institutions and policy outcomes. Scholars often declare that institutions matter, but few works provide an explicit study of how policy linkages operate in practice. The authors show how diverging courses in CJM can be explained by state laws and regulations, legal doctrines, the organizations governing and managing water supplies, and the division of authority between levels of government.