Bonneville Dam is liiO miles above the mouth of the river and much 

 of the stream below tht dam is available and suitable for shad spawning 

 purposes. In the natural river before Bonneville Dam was built there was 

 a drop of approximately 26 feet in water surface in the U-mile stretch 

 between Bonneville and the head of Cascade Rapids « It is not known how 

 many shad migrated past this point before 1938^ but for practical purposes 

 this may have been the upper limit of spawning. The incentive for sur- 

 moimting the dam, therefore, may not be so great for shad as it is for 

 the runs of salmon whose spawning grounds are many miles upstream. Some 

 of the shad that pass the dam are known to ascend at present at least to 

 Celilo Falls which is about 6o rniles above the dam (Oregon Fish Coramissionj 

 19l;8) . 



Year 

 1938 

 1939 

 19liO 

 191^1 

 19l;2 

 191^3 

 19Uh 



Table 1,- Annual shad count at Bonneville Dam 

 Count Year 



5,273 

 a, 803 

 22^230 

 18,675 

 12,859 

 2,8ii8 

 17,103 



19U5 

 19h6 

 19h7 

 19h8 

 19h9 

 1950 



Count 

 9ii,526 

 20,383 



26,oia 



8,U22 



22,579 



7,816 



Time of Passage Compared with Flow and Temperature 



Since variation exists both in the numtersof shad passing the dam 

 each year and in the time of passing, an exainination was made of the water 

 temperature and water flow to determine their relations to number and 

 passage time. A graph for each year was made showing the count of shad 

 by daj'^s, the corresponding water temperature, and the combined rate of 

 flow (c.f.s.) for the powerhouse and spillway. The graphs for 19liO, 19U6, 

 and 1950 are shown in figures 5, 6, and 7 and depict runs that are early, 

 average, and late, respectively. 



