WATER FLOW THROUGH A SALMON SPAWNING 

 RIFFLE IN SOUTHEASTERN ALASKA 



by 



William L. Sheridan 



Senior Fisheries Biologist 



Fisheries Research Institute 



University of Washington 



Seattle, Wash. 



ABSTRACT 



The following characteristics were studied in a small salmon stream in South- 

 eastern Alaska from 1956 through 1959: (1) dissolved oxygen content of ground 

 water, (2) variation of dissolved oxygen with depth in streambed, (3) temperature of 

 ground water, (4) extent of ground-water seepage, (5) interchange of flowing stream 

 water and water of streambed gravels, and (6) flow of water in the gravel of stream- 

 bank and gravel bar. 



Ground water was generally low in dissolved oxygen content, and dissolved 

 oxygen levels decreased with depth in streambed. Because of these and other points 

 discussed in this paper, I conclude that the main source of intragravel water of high 

 oxygen content is the flowing stream. 



INTRODUCTION 



In 1956 the Fisheries Research Institute 

 started a study of the effects of logging on the 

 productivity of pink salmon (Oncorhynchus 

 gorbuscha) streams in Alaska, and work has 

 been conducted on four streams in the Hollis 

 area of Kasaan Bay in Southeastern Alaska 

 (fig. 1). The general plan of research was to 

 define normal conditions in the stream be- 

 fore logging, to measure any changes that 

 might accompany logging operations, and to 

 define limits within which environmental 

 changes could occur and yet permit survival 

 of salmon eggs and larvae. The Fisheries 

 Research Institute, in cooperation with the 

 U.S. Forest Service, performed the work 

 under a contract awarded by the Bureau of 

 Commercial Fisheries utilizing Saltonstall- 

 Kennedy funds. 



Note.- -William L. Sheridan presently employed with 

 Alaska Department of Fish and Game, Kitoi Bay Research 

 Station, Afognak Island, Alaska. 



Part of this research involves the mechanics 

 of waterflow within the gravel of a spawning 

 riffle in Indian Creek, one of the study streams. 

 Knowledge of the nature of waterflow through 

 spawning gravels is basic to our study of effects 

 of logging because survival of salmon eggs 

 and larvae depends to a large extent upon 

 water quality (Royce, 1959). 



The investigation included: (1) determining 

 dissolved oxygen content of ground water, 

 (2) measuring variation of dissolved oxygen 

 with depth in streambed, (3) measuring 

 ground-water temperatures, (4) determining 

 extent of ground-water seepage, (5) demon- 

 strating the existence of interchange of flow- 

 ing stream water and water of the streambed 

 gravel, and (6) studying flow characteristics 

 of water in the gravel of streambanks and 

 gravel bars. 



The object of this paper is to present and 

 discuss parts of the Indian Creek study. 



