Northwest Fisheries Science Center

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Document Type: Contract Report
Center: NWFSC
Document ID: 7226
Title: Summary report:  biological investigations of horizontal traveling screen model VII
Author/Editor: Earl F. Prentice, Frank J. Ossiander
Publication Year: 1973
Publisher: National Marine Fisheries Service
Contracting Agency: Eugene Water and Electric Board and U.S. Bureau of Reclamation. Eugene, Oregon
Date: 1973

(1)  Biological evaluations of horizontal traveling screen (HTS) model VII were made in a hydraulic flume on the Grande Ronde River near Troy, Oregon, using fingerling and fry chinook salmon.  The triangular-shaped screen array was 27 ft long on the fish guiding leg (upstream face; 32 ft between centers of upstream and downstream turns) and led horizontally at a speed of 1.34 ft/s.  Channel velocities in the flume were approximately 1.0 and 3.0 ft/s, whereas the normal velocity at the screen array (30° to flow) were 0.5 and 1.5 ft/s. 

(2)  Conventional operation of HTS VII indicated that from 97 to 100% of all fingerling and yearling chinook salmon can be safely diverted into a bypass at normal velocities of 0.5 and 1.5 ft/s.

(3)  Fry impinging on the screen suffered no appreciable losses during exposure periods of up to 60 minutes at 0.5 ft/s normal velocity (approach velocity 1.0 ft/s). 

(4)  At a normal velocity of 1.5 ft/s (3.0 ft/s approach velocity), virtually no loss of impinged fry occurred until the fish were exposed on the screen for more than 6 minutes (a screen traveling at 1.34 ft/s would traverse about 480 ft during a 6–minute period). 

(5)  Injuries (hemorraghing) were noted among impinged fry at normal velocities of 1.5 ft/s and greater following prolonged exposure on the screen.  Evidence of oxygen stress was observed among fry impinged on a screen for 15 minutes and longer at a 1.0 ft/s velocity, but no losses of fish occurred until impingement exceeded 30 minutes.  Most of the observed injuries among surviving fry disappeared after 48 h.