The system was final tested by lifting a chinook salmon redd egg pocket in the 

 Poverty Flat spawning area of the South Fork Salmon River in October 1978. A sample 

 30 by 54 by 17 inches deep (0.76 by 1.37 by 0.43 m) , weighing about 1,990 lb (900 kg), 

 was lifted from the redd. Twelve tanks containing 600 lb (272 kg) of C0 2 were used to 

 provide 75 minutes of freezing time which completely froze the sample at a river temper- 

 ature of 37°F (3°C). The ratio of C0 2 consumed to substrate lifted was about 0.35 

 lb to 1 lb (0.34 kg to 1 kg) dry sample. This value is better than the estimate of 

 0.37 lb/lb (0.37 kg C0 2 /kg) . 



The four corners of the sample area were marked with the outer corner probes 

 (fig. 9 and 10). The ice anchors were driven into the sample and the wings spread so 

 they were at least 9 inches (23 cm) below the channel surface. They were also angled 

 inward to eliminate bending force during lifting of the sample. 



Figure 9. --Probes being 

 driven into the chinook 

 salmon redd. 



Probes and Caps 



The probes were driven into the streambed with a slide hammer (fig. 9) and two 

 suffered minor damage. To avoid damage a hardened steel shaft can first be driven to 

 the desired depth, withdrawn, and the probe placed in the remaining hole. The corner 

 probes defined the 18 by 32-inch (0.45 by 0.81 m) sample. The remaining probes were 

 placed within the rectangle at 6-inch (15.2 cm) intervals to a depth of 12 inches 

 (30.4 mm). During probe installation the CO2 tank frames were set up and the tanks 

 connected together. Aluminum tanks were used which weighed 50 lb (23 kg) empty instead 

 of steel tanks that weigh 100 lb (45 kg) empty. The tanks, hoses, and connections 

 were checked for leaks by closing the valve on the end of the hose and opening one 

 tank valve to apply pressure. The tank valve was then closed until ready to operate. 

 Before installation of the probe caps, probes were checked with a dry dipstick for 

 water that may have leaked in through" cracks or tears. 



The caps with throttle valves were placed on the four upstream probes and the 

 caps with pressure gages and relief valves were placed on the four downstream probes. 

 After the caps were in place, the plastic tubing was connected between the probes. 

 The nylon tubing was pushed straight in the receiving couplet as far as it would go, 

 carefully avoiding any kinks. The tubing connected the outlet on one probe to the 

 inlet of the next downstream probe. The inlet connection was always next to the cap 

 bolt retaining pin. 



12 



