594 U. S. BUKEAU OF FISHEraES 



111 1929, 677 steellieads were tagged and 25 were recovered. These 

 recoveries indicate that the summer-run steelheads migrate to the 

 upper readies of the river and into the higher tributaries, and that 

 they are present in these places in a spawning condition as late as 

 March and April following the summer during which they ascended 

 the stream. 



At present the returns from the 1930 operations are by no means 

 complete, and until data are secured on the recovery of winter-run 

 fish no definite conclusions can be made. 



CONSERVING FISH LIFE BY MEANS OF SCREENS AND LADDERS 



The activities of Shirley Baker, engineer, and U. B. Gilroy, assist- 

 ant, in conserving fish life by means of screens and ladders, consisted 

 during 1930 of the following distinct undertakings : 



(1) The continued operation of electric fish screens in the Yakima 

 country, Washington, and in southern Oregon; (2) experimental 

 work leading to the adoption of a simplified and improved type of 

 electric fish screen and specification of this new type for operation 

 during the irrigation season of 1931; (3) cooperative work wdth the 

 power companies comprising experiments conducted at Green River 

 hatchery of the division of fisheries, State of Washington, with a 

 view to using the electric screen to lead upstream migrating salmon 

 to a trap; (4) completion of the installation of the Ahtanum me- 

 chanical fish screen and its operation throughout the irrigation sea- 

 son; (5) the installation of large, concrete fish ladders at the Wapato 

 and Sprague River Dams; (6) inspections and reports on conditions 

 at several major power developments now under construction on 

 important salmon rivers in the Northwest; (7) specification of fish- 

 protective works required at certain hydroelectric power develop- 

 ments; (8) report on several types of mechanical fish screens and 

 recommendations for screening several large water diversions in the 

 State of Montana; (9) participation in the salmon-counting experi- 

 ments conducted at Savage Rapids Dam on the Rogue River, Oreg. ; 

 (10) field work, designs, and reports on improvement to the water- 

 supply system at the Bureau of Fisheries hatchery at Tishomingo, 

 Okla., and for the proposed new hatchery at Butte Falls, Oreg. 



MECHANICAL FISH SCREENS 



From time to time during the course of this investigation we have 

 been asked to examine and report on mechanical fish screens of 

 various types. The variety of designs for such fish screens is very 

 great, but nothing that has Ibeen called to our attention has been found 

 to equal the mechanical revolving screen developed some years ago 

 by the Oregon Game Commission and now approved and installed 

 at a number of sites by that commission, by the Division of Fisheries 

 of the State of Washington, and by our own bureau. A mechanical 

 screen of this type was installed by the bureau in 1929 in the Ahtanum 

 Canal, of the United States Indian Irrigation Service, Yakima, 

 Wash., and is described in the previous report. Observation of the 

 action of the fish at this installation substantiates the conclusion that 

 a submerged orifice type of entrance is superior to an overfall in at- 



