Figure 2. — Test area, drained to show 

 horizontal (left) and vertical (right) 

 orifices at the shallow setting. 

 Centerllne of each orifice is 3 

 feet below water surface. Struc- 

 tures on each side of orifice panels 

 are screened to prevent entry of 

 fish. Introductory pool is in fore- 

 ground. 



Figure 4. — Vertical and horizontal 

 orifices at deep setting (centerllne 

 of each orifice is 9 feet below 

 water surface). 



Figure 3. — Removing panel from 

 guide slots to change position of 

 orifice. 



Figure 5. — Test condition for com- 

 paring responses of salmon to 

 vertical orifices at deep (left) and 

 shallow (right) settings. 



