ELECTRODES 



Table 2. — Sequence in which different water velocities were 

 tested during four test periods 



Figure 8. — Electrical field created by one pulse at one 

 specific location on the left side of the electrode array. 

 (Lines connect points of equal potential; numbers 

 show percentage of the applied voltage. ) 



canal. Water temperature was taken three times 

 daily (6 : 00 a.m., 2 : 00 p.m., and 10 : 00 p.m.) with 

 a standard mercury thermometer. The average 

 water temperature was 14.4° C (range 11.1 to 

 20.0° C). Turbidity and resistivity were also 

 measured three times daily. Turbidity averaged 

 15.6 parts per million silica dioxide (range 10.0 to 

 26.0 p.p.m.), and the average water resistivity was 

 5,535 olim cm. (range 4,290 to 7,400 ohm cm.). 



To minimize the escape of fish from the array 

 trap, the catch was removed every 2 hours (e.g., 

 2 : 00 p.m., 4 : 00 p.m.) . Fish could not escape from 

 the inclined-screen trap ; therefore, it was checked 

 less frequently — at 4-hour intervals (e.g., 4:00 

 p.m., 8:00 p.m.). This schedule was followed 

 throughout the experiment, even during periods of 



Test periods 



Dates (1962) 



Water velocities 



I AprU21-May3.. 



II May 3-May 16... 



UI May 16-May 28.. 



IV May28-June9.. 



M.p.a. 

 0.5 

 .2 



M.p.i. 



0.8 



.5 



.2 



.8 



M.p,8. 



0.2 



.8 



.5 



.2 



maintenance and stoplog manipulation, to ensure 

 that fish were not delayed in their downstream 

 migration. Fish captured in the array trap were 

 transported in an aerated tank to the holding 

 troughs adjacent to the inclined-screen trap where 

 they were counted and identified. Movable parti- 

 tions within the troughs made it possible to count 

 and identify the fish without handling. The fish 

 were released, after the data from each group had 

 been recorded, by removing standpipes from the 

 troughs and allowing the water and fish to drain 

 into the bypass flmne. From the flume, the fish 

 could re-enter the Yakima River. Fish captured 

 in the inclined-screen trap were also identified, 

 counted, and released into the Yakima River. 



EXPERIMENTAL PROCEDURE 



Before beginning each test, we obtained the 

 desired water velocity by manipulating the con- 

 crete stoplogs in the velocity control structure at 

 the entrance to the water-bypass channel and the 

 plywood panels in the velocity control structure in 

 the main canal. This operation required about 8 

 hours. 



Each control test (power off) was started at 

 4 : 00 p.m. The array trap and the inclined-screen 

 trap were cleared of fish before the start of the 

 test and then emptied at regular intervals for the 

 duration. The control test lasted 40 hours (until 

 8 : 00 a.m. on the second day after the experiment 

 .started). The 8 hours following the control test 

 (8:00 a.m. to 4:00 p.m.) were used primarily 

 for maintenance and cleanup. At 4 : 00 p.m., when 

 the maintenance period ended, the electrode array 

 was energized according to preset electrical condi- 

 tions. These conditions were monitored during the 

 entire power-on test by means of a calibrated oscil- 

 loscope. The power-on test lasted 40 hours (until 

 8 : 00 a.m. on the second day after the array was 

 energized) ; the sequential switching equipment 

 was then turned off and the stoplogs and plywood 



FISH-GUIDING EFFICIENCY OF AN ELECTRICAL GUIDING SYSTEM 



315 



