

FIG. 3 Photo of 10-transducer sonic array and recorder. 



20 40 60 80 100 120 140 



NUMBER OF FISH 



FIG. 4 Numbers of fish detected (at 0.33 m intervals) by sonic 

 gear during 75 hr of operation at Columbia River beaches 

 near Prescott, Oregon. 



beaches netted 37 juvenile chinook, 21 crappie, 17 

 perch, 16 stickleback, 9 flounder, 2 peamouth chub 

 and a whitefish. This indicates that the "sounder" 

 results can be approximately quantified for species 

 composition with a minimum beach seining effort. 

 We feel this method of determining vertical fish 

 distribution will eliminate some of the problems 

 associated with gill netting. 



CAS SATURATION LEVELS AT PRESCOTT, 

 OREGON— 1971-1974 



Since January 1971 approximately 1,000 

 Columbia River water samples have been analyzed 

 for gas content. During this period samples have 

 been taken twice weekly from the Oregon side of 

 the Columbia River (RM 72)*; daily samples were 

 taken when the N 2 level exceeded 110%. The 

 highest level recorded at Prescott was 136.6% 

 N 2 (132.6% total gas saturation) on June 25, 1974. 

 Nitrogen concentrations in the lower Columbia 

 River exceeded the provisional standard (110% 

 N 2 ) each month from November 1973 through 

 August 1974. Additional information was 

 obtained from samples taken weekly on a hori- 

 zontal transect of the river. N 2 saturations on the 

 Washington side of the river are usually higher 

 than on the Oregon side; highest levels are gen- 

 erally recorded from the ship channel. 



The saturation levels at Prescott, Oregon, are 

 influenced by the volume of water being spilled at 

 Bonneville Dam, for example, when weekly aver- 

 age spillway discharges at Bonneville reaches 

 4.247 KCMS (150 KCFS) the N 2 saturation levels at 

 Prescott exceed 115% (Fig. 5). Gas saturation levels 

 during the first 8 months of 1972 and 1974 are 

 comparable (Fig. 6); both being associated with 

 40-yr high-water flows. In 1973 N 2 levels were 

 considerably less than in previous years; outflow 

 was 69% of a 15-yr average. 



The data collected from this sampling pro- 

 gram is tabulated and stored in the Corps of Engi- 

 neers, North Pacific Divisions' ADP system. 



SPILL DISCHARGE 



FEB MAR APR MAY JUN JUL AUG 



FIG. 5 Weekly averages of Bonneville "spill" and percent N 2 

 saturation at Prescott, Oregon. 



•River mile (RM), rather than river kilometer, is used in this 

 report because most current references do not include the 

 metric equivalent. 



Research at Prescott 15 



