Fish Screens

Fish screens physically exclude fish from pipe, canals, or other structures that collect water from their habitat. To serve its purpose the screen must have holes small enough to prevent fish from passing through the screen, or becoming stuck in the holes, while allowing enough water to pass to serve its purpose.

Water current passing through the screen must be slow enough that the fish can avoid it and not be stuck against the screen.  There should also be flow along the face of the screen which guides fish away from the screen and to an exit that leads back to the river.  Dead ends where fish cannot find their way back to the river are almost as bad as no screen at all.

Screens are often angled to the incoming current to guide fish along the face of the screen to an exit at the downstream end which returns them to the river.  Some screens are mounted on drums that are turned by paddlewheels.  As these screens turn, they pass by a brush that removes debris.