Figure 4. - -View of electrode line showing deflection of electrodes from vertical 



position caused by water velocity at medium high -water stage of river. 



The Entiat weir has been in operation 

 since 1953. In the first season of operation the 

 entire runs of chinook (Oncorhynchus 

 tshawytscha) and sockeye (O. nerka) salmon 

 were diverted into the holding ponds and none 

 were successful in passing through the electric- 

 al field. In the years of operation since 1953 

 portions of the chinook and sockeye runs have 

 been allowed to pass upstream . The weir has 

 been under close observation throughout all 

 periods of its operation and at no time have 

 adult salmon been observed passing through the 

 electrical field. This type of electrical weir 

 has proved entirely practicable for the diversion 

 of adult salmon when certain specific operating 



conditions are met. 



FACTORS INFLUENCING EFFICIENT 

 OPERATION 



An alternating current, 60 cycle, electric- 

 al field can either kill or severely injure adult 

 salmon under certain conditions. When a salmon 

 penetrates an electrical field with a minimum bar- 

 rier strength of 0.5 volts per inch and remains 

 within the field more than three minutes it be- 

 comes immobilized. Once immobilized, 

 respiration gradually slows until the fish dies. 

 If the fish is removed from the field within three 

 minutes no apparent damage is sustained. The 



