SECTION II 



ADTJLT FISH V.CRIt.UTf STUDIES - 1946 



Float Experimento As part of the prof,ram of studies to determina 

 the extent of iriortality of fishes in the Col-ombia Hiver belaw Boi.ae-/ille 

 Dam in 1946, it was considered advisable to learn the directioi-i anc 

 iriflnence of wind drift dvirin^ the peak of the fall run of salmon 

 passing Bonneville. We believe that this infonnation vrauld enable u^ 

 to determine the speed at which the river carried floating dead fish 

 dov^ns tream. To obtain such data, 100 wooden flDats were oonstj-jc ted 

 that would be subjected to approximately the SFjne degree of wind, wave, 

 and current action as floating dead fish (Figures 6 and 7). 



The body of each float was of wood, 2 inches thick, 4 inches deep, 

 24 inches long, and painted bright yellow. Holes were bored in the 

 underside of each, and two railroad spikes were inserted, one on each 

 side of the center and 12 inches apart. Two 8-penny spikes were aliiO 

 driven partway into the underside, one on each side of the center and 18 

 inches apart, to balance the floats and to keep them partially sabmergedo 

 Each float v/as fitted with a red and white flag, tied to an 18 inch wire 

 rod mast. Fifty floats had the red half of the flag on top, aud the 

 other 50 had the white half on top. The flags, three inches wide and 

 ten inches long, offered very little resistance to the wind. 



Since there is always a marked difference in the rate of flow of 

 water between the spillv;ay channel and the powerhouse channel daring the 

 low-water period of August and September, it was decided to release EG 

 floats in each channel. Accordingly, at 1:00 a.m. on August 28, 50 floats 

 with white=top flags were released in the powerhouse channel. At the time 

 of release of the red-top floats in the spillway section, all spill-^fey 

 gates had been c losed, resulting in nearly dead water in this channel, and 

 we decided to use only the floats with v/hite- top flags in detenr.-Jnin^- the 

 rate of river flow. Nineteen of the red-top floats went aground on chi 

 end of Bradford Island. At 4s00 a.m., spillway gates v/ere opened, and 

 as a result, sufficient current developed in the channel to take tnt 31 

 floats released after that time downstream to the confluence ■■£' the ~'r. 

 channels. Water was flowing through the powerhouse channel at about 

 92,000 cubic feet per second during the experiment (Appendix, Table 1/. 



Two observers left the dam in a boat at 5:00 a.m. August 28, to 

 follow the floats downstream. They saw floats distributed along tnair 

 route for the first seven miles below the dan^ The "Sandy'» arrived at 

 Cape Horn, 13 miles below Bonneville, at 6:30 a.m., where the observers 

 remained to record the time the floats passed. The first float passed 

 Cape Horn at 9:05 aorti.. Table 4 is a record of the day's observations. 



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