Hydraulic evaluation and improvement of the Dunnville Dam fishway

The Ontario Ministry of Natural Resources and the Grand River Conservation Authority would like to see more walleye using the Dunnville Dam fishway. Monitoring and raidotelemetry studies have indicated that the two resting pools within the fishway may create hydraulic barriers to fish passage through the fishway. This research involved a field investigation and physical scale model study in order to identify potential hydraulic barriers and test modifications to remove them. The field investigation showed directional velocity cues in the lower pool that would lead fish away from the pool exit. This pattern of flow was confirmed in the physical scale model study. The upper resting pool was determined to have no hydraulic barriers to fish movement. After testing several modifications to the lower pool, it is recommended that a full solid surface deflector with its bottom edge at 1 m above the pool bottom and traversing the width of the pool be installed to remove hydraulic barriers.