Adjustable 

 weir 



" I I I I I I I I I I I I I I I r I I ITTTT 



Polyethylene 

 porous plate 



Compressed 

 a ir 



Figure 3.— View of gas equilibration device used to reduce con- 

 centration of gas in river water to about 100% of saturation. 

 Water flowing to the tank from perforated pipe is passed over 

 a 46- by 46-cm porous plate, 0.635 cm thick. Compressed air is 

 forced up through the plate and into the flowing water. The 

 quantity of water that can be effectively equilibrated is deter- 

 mined by depth of the water over the plate. 



The control tank was supplied with water at a flow 

 rate of approximately 26 liters/min. Total capacity of 

 the tank was 2,800 liters. Water depth was main- 

 tained at 1 m. It was stocked with 450 subyearling 

 Chinook and 290 yearling coho salmon. 



All tanks were supplied with Columbia River water 

 by a single pump (Fig. 2). The water flow remained 

 constant in each tank throughout the test. 



Gas content of the water varied between the control 

 and test tanks. Gas content of water fed to the control 

 tank was lowered to about 100% of saturation by for- 

 cing air through a gas equilibration device — a porous 

 plate over which the supply water flowed to the tank 

 (Fig. 3). The water in the control tank was then 

 supplied with supplemental oxygen to increase its ox- 

 ygen content to about the same concentration as in 

 the river. Oxygen replenishing was not required in the 

 test tanks. Unaltered Columbia River water was used, 

 and oxygen depletion due to biological demand was 

 not a problem because of the high rate of water flow 

 (75 liters/min) in the tanks. 



The holding tanks were lined with partitioned nets 

 that could be drawn to the water surface to check fish 

 mortality. Daily mortality records were maintained 



throughout the test. Death criterion was cessation of 

 opercular (gill) movement. Size of dead fish and in- 

 cidence of gas-bubble disease symptoms were record- 

 ed. Examples of the external symptoms referred to in 

 this report are shown in Figure 4, e.g., bubbles on the 

 body, fins, lateral line, and in the mouth, in addition 

 to protruding eyes. Besides daily observations, 

 samples of 20 live fish were taken weekly from each 

 tank and examined for external symptoms, after 

 which the fish were returned to the holding tank. 



Procedures to Determine Water Quality 



Water quality samples were taken daily from the 

 Columbia River and intermittently from the control 

 and test tanks. Figure 2 shows the sampling area 

 within the tanks. All samples were taken at the sur- 

 face and are reported as surface values. Following is 

 an outline of data monitored, method of analysis, and 

 units that the data are reported in. 



1. Dissolved oxygen — Winkler method (Welsh 

 1948) and gas chromatograph — mg/liter. 



2. Nitrogen gas — van Slyke and gas chromatograph 

 (Swinnerton et al. 1962)— ml/liter. 



3. Carbon dioxide — Titrimetric phenolphthalein 

 method (American Public Health Association 

 1971)— ppm. 



4. pH — Expanded scale pH meter— pH units. 



5. Turbidity — Hach turbidimeter — Jackson Tur- 

 bidity Units, JTU. 



6. Conductivity meter — micromhos per centimeter, 

 u mho/cm. 



7. Water temperature — Daily continuous record 

 from thermograph in Columbia River in addition to 

 standard laboratory thermometer for river and test 

 tanks — degrees centigrade, °C. 



A summary of the number of days that an analysis 

 was made for each type of water quality datum is 

 given in Table 1. A review of similar data from tests in 

 1971 showed that daily samples would not be required 

 from the tanks if samples were taken daily from the 

 river. These same tests also showed that only one 

 sample per day was needed to monitor the water con- 

 ditions in the river and tanks. To demonstrate this 

 point, particularly with regard to nitrogen concen- 

 trations, we collected samples every 4 h from the 

 Columbia River and the deep test tank for the 24-h 

 period ending 15 June 1972. The results are compiled 

 in Table 2. Although the concentration of nitrogen in 

 the test tank was consistantly lower than in the river, 

 the average difference was only 1.3 percentage points 

 (relative accuracy of the analysis technique is ap- 

 proximately 2%). 



RELATION BETWEEN COLUMBIA 



RIVER WATER AND WATER 



IN TEST TANKS 



The monitored physical and chemical water 



