Assessment of fish habitat impairment in U.S. reservoirs

Reservoirs constitute an essential component of the freshwater resources in the U.S.  However, they also represent a substantial alteration to the natural river ecosystem, posing unique challenges to fisheries managers.  A nationwide management strategy is needed, but cannot proceed until the current condition of reservoirs has been assessed.  Therefore, we are developing a science-based classification system for reservoirs (≥ 100 ha) in the contiguous U.S.  In combination with a decision support system that accounts for economic and sociologic factors, this system will serve as a tool for guiding and prioritizing fisheries management activities.  Reservoir condition will be described by integrating environmental descriptors (e.g., physiographic, hydrologic), habitat impairment metrics (e.g., habitat availability, water quality, flow regime), and fish community characteristics.  Environmental descriptors are being compiled from existing datasets, while impairment and fish community descriptors are being collected via an online survey of fisheries managers.  When completed, the survey is expected to include approximately 5,000 reservoirs from all states of the contiguous U.S.  Preliminary analyses suggest various key impairment factors that vary geographically across the U.S. and that can direct a classification system based on impairment extent and type.