Evaluation of an Innovative Fish Ladder Design to Address Issues of Perched Culverts

This study evaluates the design of a new fish ladder for impassable perched culverts. The fish ladder and associated baffles were evaluated through the use of a 3-dimensional computational fluid dynamics model (Flow-3D). The new design termed the Duguay-Hannaford baffle consists of a lower and a higher passageway to accommodate fish passage over a wide range of seasonal flow rates. The numerical simulations were evaluated for barrier velocities, turbulence and maximum vertical drop between pools. Numerical results show that velocities at the passageways respect critical swim speeds for a wide range of fish species of socioeconomic importance to North America. The volumetric dissipative power is lower than maximum values suggested for salmonid species. The presence of adequate hydraulic refuge zones was also assessed. The Hannaford fish ladder shows promise as an easily transportable and effective solution to the problem of aquatic habitat fragmentation caused by perched culverts on remote and difficult to access terrain.