Existing approaches for performing environmental restoration either involve problem diagnosis and assessment with little implementation or ad hoc construction with little forethought. Environmental assessment is an important aspect of stewardship that leads to the diagnosis and prioritization of problems requiring restoration. It should come before and inform restoration. Projects that are built ad hoc have been widely reported to fail due to a lack of recognition of key natural processes. By contrast, other creative human endeavors make extensive use of the science of design. Among other concepts, it is inherent in the design process to generate many alternatives, as open-ended problems always have multiple correct solutions. For environmental restoration, such alternatives can be created by integrating widely accepted concepts from hydrology, civil engineering, aquatic biology, riparian ecology, and geomorphology. Then the specifics of each alternative should be analyzed for their relative performance using predictive computer models and other analytical tools. A river restoration approach that makes use of a comprehensive science-based design process has been developed to address the specific problem of fish spawning habitat enhancement. The approach was used in summer 2001 and 2002. In the latter case, science-based design was used at multiple spatial scales. At the reach scale, designs aimed to elevate the bed and increase slopes over constructed riffles. At the sub-reach scale, designs incorporated a complex assemblage of geomorphic units including broad riffles (to encourage divergent flow and gravel deposition at high discharge), small pools (whose widths were constricted by bars to encourage convergent flow and scour at high discharge) and boulder complexes. After thorough analysis and evaluation, the best performing project was selected by a multidisciplinary design team according to habitat and geomorphic goals and then built. A long-term monitoring program to quantify outcomes and assess sustainability is going on. Lessons from this effort will be presented.
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