FORTY-FIRST BIENNIAL REPORT 83 



TEST WATERS 



Although much useful information can be obtained from creel cen- 

 suses of the type previously described, it is usually difficult to contact 

 all anglers throughout the season and so obtain information on total 

 yields from different lots of planted fish. 8uch information must be 

 obtained at "test" waters: streams and lakes where studies can be made 

 under controlled conditions. 



The major test lake studied during the biennium was Castle Lake 

 in Siskiyou County. A summary of results obtained there and at other 

 lakes in California will be published in a forthcoming issue of California 

 Fish and Game. 



fStudies at Rush Creek Test Stream in Mono County and Sacramento 

 River Test Stream in Siskiyou County, initiated in 1947 and 1948, 

 respectively, were continued during the biennium. 



STREAM AND LAKE IMPROVEMENT 



FISH SCREENS 



The stream improvement headquarters at Yreka, Siskiyou County, 

 continued as the center of fisli screen activities conducted by the Bureau 

 of Fish Conservation. This has been supplemented by a small screen 

 maintenance shop in Weaverville, to service installations in Trinity 

 C'Ounty. 



The Yreka shoji instaHed screens mainly in the Klamatii and Trinity 

 drainages, but also constructed a few screens for use in other parts of 

 the State. 



Perhaps the outstanding achievement of the Yreka shop has been 

 the creation and development of a new type of fish screen known as 

 the "perforated plate screen." This type of screen is fully described 

 in an article in the October, 1950, issue of California Fish and Game. 

 It has now been thoroughly tested and is widely recognized as the best 

 type which has ever been devised for irrigation diversions. Screens of 

 this type are now being installed in all diversions in Bureau of Fish 

 Conservation District 1. 



An office building for use by the fish screen foreman and the local 

 biologist was constructed at the Yreka headquarters during the biennium. 



FISHWAYS 



Existing fishways in District 1 were maintained by personnel from 

 the Yreka headquarters and the Weaverville shop, and plans were drawn 

 for three new fishways which will be constructed in the near future. 

 Tests were made of fishway models of a new type, which may be useful 

 at certain obstructions. Repairs and minor alterations were also made 

 to a few fishways by other personnel of the Bureau. 



BARRIER REMOVAL 



The removal of abandoned dams to permit salmon and steelhead to 

 reach important spawning areas has progressed very satisfactorily in 

 tributaries of the Klamath and Trinity Rivers, with five dams removed 

 during the biennium. In addition, two log jam barriers were removed 

 from these tributaries. 



