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Published: 1968

Total Pages: 108

ISBN-13:

Facilities for passing fish upstream over John Day Dam include a powerhouse collection system with fishway entrances at each end and along the downstream face of the powerhouse, and a 24-ft-wide fish ladder with 1-on-10 slope on both sides of the river. The north fish ladder (except entrance section) and a portion of ladder adjacent to the south fish counting station were studied in a 1:10-scale model. A group of four typical diffusion chambers in each ladder was reproduced in a 1:8-scale model. Fishway weirs with 6-ft-long overflow crests at each end of a 12-ft-long nonoverflow section, upstream fins, and 18- by 18-in. orifices at the floor were adopted. Orifice sizes in the regulating sections were adjusted to control discharge and head drops between 19 nonoverflow bulkheads for an 11-ft range in forebay levels. Sloping floors, baffle beams at a constant elevation, and metering orifices sized to provide 60 cfs each were selected for diffusers in sloping portions of the fish ladders. (Modified author abstract).