A typology of hydraulic barriers to salmon migration in a bedrock river

Salmon spend the majority of their life in the ocean, coming into inland rivers for the purpose of spawning. The Fraser River is one of the most productive salmon spawning rivers in the world, and is therefore paramount to understand where hydraulic barriers – reaches of river where fish migration is delayed due to high water velocity – exist. I explore locations in the Fraser River that are apt to be hydraulic barriers based on centerline velocity. Barriers are classified as either 1) plunging flows, where flow is deep with the highest velocities lower in the water column, 2) rapids, where flow is fast and shallow over bedrock steps, or 3) overfalls, where fast flow occurs over a step with a substantial drop in elevation. I find twenty-two sites that are potential hydraulic barriers, providing information on where salmon may be expending more energy and informing future spawning management efforts.