Hydraulic and Biological Evaluation and Monitoring of Non-Traditional Fish Passage Structures

Non-traditional fish passageways are built in support of stream and ecosystem restoration with goal of passing higher numbers and a broader range of species than traditional structures.  However, no standardized methods of evaluation or monitoring currently exist. We propose that structures be evaluated and monitored at three levels: structurally, hydraulically, and biologically, to ensure effective initial and long-term performance. Physical evaluation and monitoring involves field verification of structural design compared to the original design. Hydraulic monitoring requires flow depth, point-velocity, total flow, and qualitative flow (i.e., documentation of flow patterns) measurements, and comparison of field data to hydraulics estimated by pre-construction hydrograph, HEC-RAS, or CFD models. Biological monitoring can be performed qualitatively with underwater video, or quantitatively with variety of telemetry methods, such as PIT and radio and acoustic tagging, to assess both the overall passage efficiency and the time required for fish to pass the fishway or restored river reach.  Biological monitoring of nontraditional structures poses unique challenges with respect to scale and configuration of the structures.  The relative cost, effort, and information benefit of these evaluation and monitoring methods are discussed.