REPORT OF BOARD OF FISH AND GAME COMMISSIONERS. 43 



<iutomatic' self-eleaiiiug parallel bar screens that can be installed suc- 

 cessfully in any of the canals no matter how wide or deep they are. 



Practical experiments have been made by Superintendent Requa at the 

 Sisson Hatchery and he now has in operation there, two working models 

 of self-cleaning rotary screens. He himself is the inventor of one, and 

 he is entitled to the credit of making the best rotary screen that has 

 ■ever been devised. Its most important feature is its absolute simplicity 

 and inexpensiveness. It is so constructed that any farmer could make 

 one in his work shop in half a day. I have neither the time nor the 

 space to take up more fully the minute details of this screen. It is my 

 intention to circulate information on this subject by separate folders. 



This screen is designed for use in ii-rigating ditches, canals, or pipes 

 taking water from streams, reservoirs, or other bodies of water. 



The purpose of this invention is to provide a fish screen of simple con- 

 struction, • equipped with an automatic regulating device which will 

 luaintain a mean water level on the face of the screen under variable 

 heads of water. The driving apparatus, including a crank shaft, pawl 

 and racliet members, is designed for construction without special tools 

 i.'nd at a nominal cost. 



It may be well to add here that the regulation insisted upon requires 

 that streams inhabited by trout, salmon, shad, and striped bass require 

 screens with openings not greater than one fourth of an inch. In 

 streams frequented by black bass, Sacramento perch and California 

 ' ' pike, ' ' and where there are no salmon, shad, trout, or striped bass to 

 protect, an opening of one half an inch square is permissible. 



I have found that the reluctance in screening is more with the engin- 

 eers, superintendents or water masters, than the directors or real owners 

 in land companies. Notice has been served to all water users that the 

 law will be enforced. When a reasonable length of time has elapsed and 

 no intention is shown to comply with the law, I shall request your hon- 

 orable Board to instruct the Commission's attorney to begin proceedings 

 to compel the obstinate ones to comply with the law. 



In our study of the "ladder" question we are finding that most of 

 the opposition to the construction of efficient fish "ladders" is not on 

 account of the expense entailed in construction. In many instances, 

 and particularly is it the case with large power companies, non-com- 

 pliance is because they do not want to allow sufficient water to pass 

 through the ladders to make them operative, so as to support and pre- 

 serve the fish life in the streams below the plants. Several companies 

 were public spirited and made it a rule to allow sufficient water to pass 

 through their dams to keep the fish in good condition during the 

 period of the minimum flow of water in the streams. 



This work of the inspection and installing of ' ' ladders ' ' and screens 

 will be most energetically pursued in the future, and I believe that 

 another year will see satisfactory progress in this line. 



