Freshwater scientists around the world acknowledge a crisis in biodiversity loss and diminished ecosystem function in streams, rivers, wetlands and lakes. One main culprit in this decline is human-caused change in the historical magnitude, frequency and timing of river flows that have supported key ecological processes and native species in diverse aquatic systems. The Ecological Limits of Hydrologic Alteration (ELOHA) framework arose as a response to the recognition that the rate of global hydrologic change was outpacing science's ability to develop environmental flow guidelines one site at a time. A new scientific framework was needed, one to guide the development of environmental flow guidelines at a regional scale. Regional environmental flow management is extremely challenging. Not only are data needs great for underlying hydroecological models, but translation of science into policy and management necessarily occurs in a complex societal context constrained by governance structures, regulatory authorities and competing political interests. A comprehensive and scientifically sound framework was required, yet it had to be flexible enough to accommodate the inevitable "experiments" that will result from its application to real-world settings. This guidebook presents nine case studies in regional environmental flow management in the United States. The successes described in these case studies clearly illustrate that innovative thinking and creative experimentation within the structured ELOHA framework have significantly advanced the development of flow standards at regional scale. The accomplishments are the fruit of the dedicated efforts of innumerable agency, academic and non-government scientists, engineers, water managers, and policy makers, all of whom were willing to think outside the box and take up the challenge of pushing the frontiers of sustainable environmental management of streams and rivers. Their stories are impressive and inspiring! A key contribution of this guidebook is that it distills an excellent synthesis across the case studies and offers valuable insight into transferable lessons learned from individual studies. Importantly, numerous tips and extended discourse are offered on how to adapt the flexible ELOHA framework to streamline and strengthen the scientific process. While a more robust social framework may still be needed to effectively translate science into policy and regulations, the information presented in this guidebook serves as an indispensible resource for all those engaged in protection and management of freshwater ecosystems. The authors of the guidebook are to be commended for their outstanding product, and more generally for their dedication to the cause of science-based freshwater conservation.
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The Nature Conservancy (Arlington, Virginia)
The Nature Conservancy