to observe the action of salmon in the Bonneville fish ladders as the 

 fish passed through the submerged orifices in the weirs » Such obser- 

 vations, it was believed, would determine whether or not the injuries 

 observed at the counting stations and at the hatcheries could have 

 been sustained in the ladders. Consequently, the Corps of Enpiaeers 

 built a submersible operation chamber for the purpose (Figure 5)o 



The chamber was made of an 8-foot section of galvanized-iron 

 culvert pipe, three feet in diameter. The lower end was welded 

 to a steel plate, s/S inch thick and seven feet square. The pipe 

 and its base were strengthened by having four steel-rod stays of 

 7/8 inch diameter fastened to the upper ring of the pipe and the 

 plate bass to which it v/as welded. A 4 inch vertical flange was 

 welded to each of the four sides of the base plate, forming an open 

 box to hold the iron weights used in submerging the lower part of 

 the chamber. About 3,200 pounds of cast-iron weights were necessary 

 to overcome buoyancy. Two watertight glass observation ports were 

 built into the walls of the chamber. One of the ports was 12 inches 

 and the other 24 inches from the floor. The glass por^s were made of 

 clear plate glass, 3/I6 of an inch thick and about 12 inches square. 

 The device was provided with a cover to exclude light from above. 



On September 5, 1946, the observation chamber was lowered into the 

 fish ladder in the first pool below the Bradford Island counting station, 

 From the chamber, large numbers of chinook salmon and steelhead trout 

 were observed passing through the submerged orifice m the lower weir 

 of the pool. The velocity of the -water passing through the opening was 

 about five feet per second. 



The following statement was taken from office memorancVjim of 

 October 8, 1946, subject *'Fishway Observation," by Mr. F. L. Abbott, 

 Superintendent of Fishways at Bonneville Dam. (Copy of memorandum 

 and letter of transmittal included in Appendix l) "Fish do at times, 

 rub the top and sides of orifices, but several different observers 

 agree that they saw no fish passing through which, in their opinion, 

 rubbed hard enough to be injured. From my own personal observation, 

 I am not prepared to say definitely that fish are not in some instances 

 injured." 



Two 200 foot reels of 16 mm., motion picture film showing the 

 actions of the fish while passing through the submerged o-ifice were 

 taken, and these are kept at Bonneville Dam in the office of bhe U. S. 

 Corps of Engineers. 



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