Due consideration must also be given 

 to the fact that our experimental subjects 

 were diverted from a large 1:16 slope fish- 

 way approximately 35 feet wide into a narrow 

 by-pass fishway 6 feet wide having a 1:8 

 slope. From this point they entered a large 

 collection pool and were then released to 

 enter a 1:16 slope test fishway of a 6-foot 

 width. We assumed that performance in the 

 test fishway was independent of the changing 

 entry conditions. 



Plans for succeeding experiments call 

 for reduction in fishway width and a change 

 in weir crest design. By decreasing the 

 present fishway width to 4 feet we expect to 

 reduce the total fish requirement necessary 

 to measure capacity. The change in weir 

 crest is intended to eliminate the unstable 

 hydraulic condition which developed in the 

 recent tests due to use of a 7 1/2-inch 

 square-crested weir. 



S UNWARY 



Initial experiments were undertaken to 

 measure the capacity (maximum number of fish 

 passed per unit time) in an overfall-type 

 fishway which was 6 feet wide and consisted 

 of 6 pools, each 16 feet long (weir center 

 to weir center) with an average depth of 6.3 

 feet. There was a 1-foot rise between pools 

 and approximately 0.8-foot head on the weirs 

 which were square crested cUid 7 1/2 inches 

 thick. The calculated dischcirge was 15.9 

 c.f.s. 



The following is a summary of opera- 

 tions and observations made in the 1956 

 capacity tests: 



1. Eight tests in which releases 

 varied in magnitude from 70 to 

 2886 fish in a 1-hour period were 

 conducted from May 22 through 

 September 7, 1956. 



2. In numbers, the Icirgest release 

 during a 1-hour period totalled 

 2886 fish. Estimated average 

 weight of fish in this test was 

 3 pounds. The total estimated 

 weight of all fish in the test was 

 8658 pounds. 



3. In a test adjudged to be the larg- 

 est release in terms of gross 

 weight, 1515 fish, averaging an 



estimated 13 pounds per fish, 

 entered the test fishway in a 1- 

 hour period. The total estimated 

 weight of fish in this release was 

 19,700 pounds. 



4. A maximum entry rate of 350 fish 

 per minute was observed in the 

 test in which fish averaged appro- 

 ximately 3 pounds in weight. This 

 high entry level could not be sus- 

 tained, possibly because of rapid 

 depletion of the original supply 

 of fish. 



5. Maximum entry in the test in which 

 fish averaged 13 pounds, was 75 

 fish per minute. For a period of 

 17 minutes (minute 6 through 22) 

 the entry ranged from 40 to 60 

 fish per minute, averaging 51 fish 

 per minute. This was the only 

 tried among the eight conducted in 

 which a sustained entry was observ- 

 ed, suggesting that a limiting 

 level may have been reached. 



6. Among the eight trials, the median 

 elapsed passcige time required to 

 ascend the 6-pool test fishway 

 ranged from 12 to 35 minutes. 



7. During some tests the action of 

 fish in the fishway appeared to 

 cause the flow pattern to cheuige 

 from plunging to streaming. The 

 change in flow markedly deterred 

 fish passage. While the delays 

 in passage were temporary, there 

 is evidence that the overall pas- 

 sage time in the fishway was 

 materially affected, possibly 

 slowed as much as 5 minutes or 

 longer . 



8. Numbers present each minute in a 

 given pool were obtained for the 

 three lower pools (55, 56, and 57) 

 in the season's final test when 

 the estimated average weight was 

 13 pounds per fish. A maximum 

 residence of 239 fish was observed 

 in each of the two lower pools. 

 Maximum residence in the third 

 pool was 189 fish. The maximum 

 number present in the 6-pool fish- 

 way was 948 fish. Residence in 

 the first pool (55) remained at a 

 high level while residence in 



17 



