84 FISH AND GAME COMMISSION 



The stream clearance program of the Bureau of Fish Conservation, 

 which in the main previously had been confined to District 1, was ex- 

 panded considerably during the biennium. A general stream clearance 

 program was started in the northern part of District 5 during the sum- 

 mer of 1950 and the crew doing this work is being equipped with equip- 

 ment as rapidly as funds permit. The most important project of this 

 crew during its first season consisted of the removal of the dam on the 

 Elk River at Falk, Humboldt County. This dam was built in 1883 and 

 some of the logs were four feet in diameter and 25 feet long. In the 

 entire State, seven dams were removed, 11 barriers were reduced, and 

 seven log jams were removed during the biennium. 



IMPROVEMENT DEVICES 



Structures such as deflectors in streams and brush shelters in lakes 

 have not been generally built in California, since considerable doubt has 

 existed that such devices produce economically justifiable results. How- 

 ever, some counties appropriated funds from their share of fish and 

 game fine moneys for stream improvement and our personnel cooperated 

 with sportsmen's groups and other local interests in designing, install- 

 ing, and testing small rock and masonry dams in streams with low 

 summer flows. For example, a series of 57 such dams was built in Holy 

 Jim Creek, Orange County, principally to create pool areas. Advice was 

 also furnished to the Corps of Engineers, Department of the Army, re- 

 garding utilization of existing trees to create brush shelters in proposed 

 large reservoirs. 



AQUATIC WEED CONTROL 



Aquatic weeds do not form a problem in the great majority of 

 California fishing waters. However, members of the biological staff were 

 called upon for advice and assistance in a number of troublesome in- 

 stances, especially in Southern California. At Twin Lakes near Mam- 

 moth, Mono County, personnel of District 7 applied 900 pounds of 

 sodium arsenite to dense plant masses choking areas which were untreated 

 in tlie initial control work during the fall of 1947. 



WILDLIFE CONSERVATION BOARD STREAM AND LAKE 

 IMPROVEMENT PROJECTS 



In addition to the work described above, some stream and lake 

 improvement was initiated or completed with funds allocated by the 

 Wildlife Conservation Board, including two barrier dams and two flow 

 iiiMiiiteiiance dams at the outlets of lakes. For further information, 

 ri'tVr to the section on Wildlife Conservation Board Projects. 



CHEMICAL TREATMENT AND REHABILITATION OF LAKES 



During the biennium approximately 1,755 acres in total lake area 

 and over 70 miles of tributary streams w^ere chemically treated to elim- 

 inatf rough fish wliich had so overrun these waters that sport fishing 

 was practically destroyed in them and were then restocked with game 

 fish. Some of the waters treated were reservoirs which had been drawn 

 down far below their maximum and normal levels, so in effect a much 



