Ensuring fish passage

Culverts in wetland areas are the main passage for fish and other aquatic animals. A number of considerations apply if culverts are used as fish passages:

  • The flow velocity through the culvert should not be greater than the swimming capabilities of the fish. The swimming capacities of species vary and are often unknown. It may be useful to apply a very gentle slope through the culverts so as not to interfere with fish movement.
  • The outlet of the culvert should not have a vertical drop that makes it difficult for fish to swim or leap out.
  • The water level in the culvert should be minimum, at least during the fish movement season. Shallow water in the culvert will enable fish to cross.
  • There should be no debris or sediment accumulation in the culvert that causes physical blockage or increased turbulence that might prevent fish from moving across the culvert.