482 U. S. BUREAU OF l-ISHEEIES 



Because of high water and bad weather conditions, which made it 

 ahnost impossible to catch the migrating fish, it was possible to tag 

 only 50 steelheads during the winter of 1930-31. One of those 

 tagged fish was recovered in July, 1931, in the upper portion of 

 the Rogue River. 



Another attempt is being made to tag these fish during the winter 

 of 1931-32 ; and until some recoveries are made from that tagging the 

 question of" whether or not two separate populations of steelheads 

 inhabit the Rogue River can not be definitely answered. 



CONSERVATION OF FISH BY MEANS OF SCREENS AND LADDERS 



The activities of the bureau's engineers, Shirley Baker and U. B. 

 Gilroy, in perfecting fish screens and ladders for the conservation 

 of the runs of anadromous and migratory fishes in the rivers of the 

 Pacific Northwest during 1931 included (1) the construction of a 

 revolving mechanical fish screen on the Jocko Canal, Mont.; (2) the 

 preparation of, design, and specifications of a revolving mechanical 

 fish screen for the Sun River Slope Canal in Montana; (3) continued 

 operation of mechanical and electric screens on Government diver- 

 sions in the State of Washington ; (4) assistance rendered the State 

 Commissions of Maine, Oregon, Nevada, and Utah regarding fish 

 screen and ladder problems; and (5) the designing of fishways for 

 Sunbeam Dam, Idaho, and Anan Creek, Alaska, and various other 

 inspections and engineering services on major hydroelectric projects 

 in the Pacific Northwest. 



MECHANICAL FISH SCREENS 



The revolving mechanical screen recommended and used by the 

 bureau follows the design developed by the Oregon State Commis- 

 sion in 1921, and since that time adopted by the State of Washington. 

 This type was first installed in Ahtanum Canal by the bureau in 

 1929 and described in previous reports. It continues to be the most 

 satisfactory and reliable type of which we have knowledge, and 

 properly installed is positive in its action. The device is not patented. 



Jocko Canal screen. — This year to prevent the serious loss of fish 

 on the Flathead project of the United States Indian Irrigation Serv- 

 ice in Montana and to encourage the adoption of this type of mechan- 

 ical screen in that State the bureau installed such a screen on the 

 Jocko Canal. This canal has a capacity of 300 second-feet. The 

 installation consists of three sections of revolving screen cylinders, 

 each being 4i/2 feet in diameter and having a width of 10 feet. 



The point of installation is 6 miles downstream at the outlet oi 

 the lower of two small lakes through which water, diverted into the 

 canal from Jocko River, is passed. The purpose of the installation 

 is to prevent rainbow trout from leaving the lakes, and thus it is 

 hoped to accumulate an attractive supply of fish in those waters. 



8un River slope screen. — In the proposed Sun River slope screen 

 we have the most ambitious attempt yet made in the application of 

 the revolving mechanical screen. The capacity of this canal is 1,435 

 second-feet. On this project water is taken from Sun River at a 

 diversion dam in a narrow canyon and transported by canal to 

 Pishkun Reservoir. From the reservoir the water is conveyed to the 



