Linking Stream Restoration Success with Watershed, Practice and Design Characteristics

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Virginia Tech

In the United States, stream restoration is currently a billion-dollar industry. Though it is commonly used as a method for stream impact mitigation, Total Maximum Daily Load (TMDL) crediting, and stormwater management, there is little scientific knowledge defending stream restoration as an effective tool for addressing these issues. In particular, few studies have been conducted with the goal of providing recommendations for future design improvements.

To improve stream restoration success rates by advising practitioners and stakeholders in site selection and project assessment, a selection of completed Maryland stream restoration projects were assessed at the watershed and project level. Watershed, site, and design characteristics were quantified using ArcGIS, restoration design plans and monitoring reports. Using current literature and expert advice, stream restoration assessment methodologies were developed to assess geomorphic function and design success both in the field and through monitoring reports. Multiple linear regression analysis and related methods were then used to identify correlations and relationships between watershed- and project-level characteristics and stream restoration success. At the watershed scale, land use was most strongly related to functional success, with projects in more natural watersheds exhibiting higher geomorphic function. Design scores correlated negatively with watershed area. At the project level, projects with higher width to depth ratios scored higher on the functional assessment, while particle size was negatively correlated with geomorphic function. Study results suggest stream restoration designs are improving over time, but the ability to determine project success from monitoring remains limited.

Stream Restoration, Restoration Success, Assessment