None supplied. From introduction: The reluctance of shad to pass through the orifice-type regulating sections of the fish ladders has been a serious problem at John Day Dam. During the shad run the pools of the regulating sections have become extremely crowded with fish and many shad have died in the ladders before spawning. The coordinated effort of Engineers and Biologists resulted in the development of a vertical slot fish ladder that effectively passed shad in the laboratory and provided adequate flow regulation in the Corps' model of the John Day fish ladder. The objective of the evaluation study was to ensure that the new vertical slot regulating section would satisfactorily pass shad and all other species of fish that ascend the John Day fish ladders.