fishway (fishwa)

An arrangement for enabling a fish to ascend a fall or a dam. In the pool fishways the water falls through small vertical heights, the velocity being retarded by means of rocks and boulders or by falling into pools whence it is allowed to fall again through a slight vertical distance to be again retarded, and so on to the bottom. In the deflected - current fishways the current is retarded by being made to travel through a distance equal to many times the perpendicular descent, being frequently interrupted by objects so placed in its course as to cause a change in its direction. In the coun ter-current fishways the water is delivered down the incline without acceleration of velocity. This is accomplished by compelling the water to travel in a constrained path. Also called fish - ladder.