How to Design and Maintain Culverts That Allow Fish Passage How do culverts prevent or impede fish migration?
Here is a list of basic considerations that need to be addressed when designing, installing and maintaining the culvert: 1. Fish need to have adequate access to the pipe, e.g. sufficient plunge pool depth for upstream migration, with suitable pool configuration to allow sufficient from to initiate a jump. If fish cannot approach the culvert because of debris accumulation at the outfall, they may not be able to orient their jump to successfully enter the pipe. 2. The outlet of the culvert needs to be low enough to permit fish to enter the pipe, i.e. the perch height should not exceed the leaping capability of the fish. The leaping ability of fish varies with species, life history state, size and condition. A culvert that is passable to coho in the lower reaches of the stream may not be passable further upstream as the condition of the fish deteriorates. 3. There may be a cumulative effect of culverts upon the energy reserves of fish that can limit the extent of upstream migration. While
