-ELECTRODES 



Figure 6. — Plot of equlpotentlal lines for a portion of electrical field. No. 4. 



PHYSICAL QUALITY OF WATER 



Temperature 



Measurements of water resistivity and tem- 

 perature were made every 4 hours, with few 

 exceptions, from July 4 to Aug. 1 (table 1). 

 Stream velocities were estimated to be near 

 0.15 m. per second. 



Resistivity 



Water resistivity was measured every 4 

 hours with a conductivity bridge; the sample 

 for each measurement was taken at midchan- 

 nel upstream from the test site (fig. 2), 

 Resistivity readings ranged from 20,000 to 

 46,000 ohm cm, (table 1). 



Conductivity of the water varied from 21 to 45 micro- 

 mhos at 18° C. 



Water temperatures were taken directly 

 from the channel in the same location where 

 the samples for the resistivity measurements 

 were obtained. A standard laboratory ther- 

 mometer was used. Each measurement was 

 recorded concurrently with resistivity. Water 

 temperatures ranged from 15.6 to 25.6° C. 

 (table 1). 



METHOD OF TESTING EFFECTIVENESS 

 OF INSTALLATION 



We adopted the hypothesis that a field in- 

 stallation of this type is not effective in di- 

 verting adult squawfish into traps. To test 



