EFFECT OF FISHWAY SLOPE ON RATE OF 

 PASSAGE OF SALMONiDS"^ 



by 

 Joseph E. Gauley 



U. S. Fish and Wildlife Service 

 Seattle, Washington 



ABSTRACT 



This study on the effect of fishway slope on rate of passage of salmonids 

 was made by comparing passage time of fish in two fishways with different 

 slopes.. It is based mainly on steelhead (Salmo gairdneTi) but includes some 

 Chinook (0 nc orhync hu s tshawytscha) and silver (Oncorhynchus kisutch) salmon. 

 Both fishways were pool -and -overfall type in which 6 feet of elevation 

 was gained. Passage of steelhead in the l:8-slope fishway was in general, 

 as fast as or faster than in the 1:16 -slope fishway. In the 1:8 -slope fishway, 

 the passage time appeared to increase with an increase in rise between 

 pools. In the l:16-slope fishway, the passage tinne of steelhead increased as 

 the season progressed. 



Slope, inasmuch as it determines the 

 length of a fishway, is one of the key 

 features in fishway design. Three slopes 

 have been used for fishways at dams on the 

 Columbia River during the past 25 years 

 but little or no research has been done to 

 determine which is the nnost effective. 

 Rock Island Dam fishways have a 1:10 

 slope, Bonneville and The Dalles Dann a 

 1:16 slope, and McNary Dam a 1:20 slope. 

 A 1:16 slope has apparently come to be 

 accepted as the standard for fishways at 

 major dams on the Colunnbia River. 



Slope is also one of the nnain factors 

 in fishway cost. Construction costs have 

 been increasing steadily in recent years. 

 Bonneville Dam fishways, built in the I930's, 



1 Research financed by the U.S. Army Corps of Engineers as 

 a part of a broad program of Fisheries-Engineering Research 

 for the purpose of providing design criteria for more economical 

 and more efficient fish-passage facilities at Corps projects on 

 the Columbia River. 



cost $7,500,000« but The Dalles Dam fish- 

 ways, completed recently, cost $ 18,200,000.' 

 Fishway costs range from 6 to 16 percent 

 of the total cost of dams on the Columbia 

 and Snake Rivers. 



A study to determine the effect of 

 slope on the passage of salmonids is now 

 in progress at the Fisheries -Engineering 

 Research Laboratory at Bonneville Dam. 

 The objectives of this phase of the study 

 are to determine (a) the effect of slope on 

 the rate of passage of salmonids in fish- 

 ways and (b) other factors that affect rate 

 of passage of salmonids in a fishway. This 

 study is extremely important because slope 



2 Statement by the Fish and Wildlife Service in response to 

 request, dated November 20, 1953, of Senator Styles Bridges, 

 Chairman, Senate Appropriations Committee, for information 

 on the abundance, distribution, and value of the Columbia River 

 fish runs, the effect of dams on these runs, and certain other 

 related information. U.S. Fish and Wildlife Service, Office of 

 Regional Director, Portland, Oregon. 41 pages, mimeographed. 



'U. S. Corps of Engineers. 



