INTRODUCTION 



This report describes the design and operation of models I, II, and V. No 

 report has been prepared on model III — the differences in design between it and 

 model II were not great enough to warrant a separate report. Models IV and VI have 

 been tested, and reports describing their features and operation are being prepared. 



The basic design for model I was taken from that developed by the Fish- 

 eries Research Board of Canada during an investigation with traveling cables and a 

 chain. BCF experiments on model I indicated a need to eliminate the drag created 

 by the screen as it returned upstream through the water. This change was accom- 

 plished in model II by raising the screen clear of the water on its return upstream. 



Model III, installed and tested within the Maxwell Canal (Hermiston, 

 Oreg.) during 1966, had some improvements over model II, particularly in design 

 of the carriage, track, and drive systems. 



The step from model III to IV was significant from the standpoint of 

 design and size of structure — the carriage and track systems were drastically 

 changed, and the screen had to be made larger and stronger to handle flows that 

 were 10 times greater than those handled by model III, 



Model V represented a complete change in design and incorporated such 

 features as a cable-suspension support structure, cantilevered screen panels to 

 resist water forces, and replaceable panels in lieu of continuous screen belting. 



iv 



