Daniel P. Muller
Published: 1999
Total Pages: 6
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The value-based process (Jackson et al., 1989) for protecting instream flows has been used successfully by the U.S. Bureau of Land Management for more than 10 years. Over the last decade, the methodology has evolved significantly as it has been applied to increasingly complex river systems. In the original process, which was somewhat linear, hydrologic characterization was an early step and development of a flow-protection strategy was a late step, and the focus was primarily on resource values and their flow dependency. The procedure has evolved into a trichotomous process in which legal/institutional analyses and hydrologic characterization occur concurrently with and frequently overshadow the assessment of flow-dependent resources. For complex river systems, the legal/institutional analysis usually includes historical analysis of water management in the basin, a geographical description of projects and facilities controlling streamflows, a review of operating principles and other institutional constraints, development of potential flow scenarios, and identification of other management opportunities. Similarly, hydrologic characterization may include detailed ground-water and geomorphological investigations to support assessment of flow-dependent resources, and extensive historical analysis to support the legal/institutional framework. Thus, whereas the resource assessment identifies flows needed to support resource values, the legal/institutional analysis and hydrologic characterization identify both the physical and institutional limits that will influence management decisions.