Rock masonry check dams in Coldwater Canyon Creek, Riverside County, stream improvement program. 

 Eight such dams were constructed with county fine money, under supervision of the fisheries biologists 

 in the stream improvement program. Average cost per dam, including labor and materials, was $119.18. 

 These are now providing adequate pool areas where catchable rainbow trout have been planted. Prior 



to this time, suitable trout habitat was lacking. 



Improvement Devices 



Again several counties appropriated funds from their share of fish and 

 game fine moneys for stream improvement. Some of these funds were 

 used to construct small loose rock and masonry dams in Southern Cali- 

 fornia streams, principally to create pool areas. Our personnel cooper- 

 ated with local interests in the design and construction of these dams. 

 Rock masonry projects consisted of 35 dams on Holy Jim and Trabuco 

 Creeks, Orange County, and eight dams on Coldwater Creek, River- 

 side County. Loose rock dams were built as follows : Holy Jim Creek, 

 Orange County, 40-50 dams ; Cucamonga Creek, West Fork, San Ber- 

 nardino County, 45 ; Silverado Creek, Orange County, 50 ; Soldier Creek, 

 Los Angeles County, 30 ; Coldwater Creek, Riverside County, 30 ; Santa 

 Ana River, South Fork, San Bernardino County, 40. 



Aquatic Weed Control 



Although aquatic weeds do not form a problem in the great majority 

 of California fishing waters, members of the biological staff were called 

 upon for advice and assistance in several troublesome instances. At 

 Chubb Lake, Nevada County, personnel of District 3 successfully re- 

 duced heavy growth of aquatic plants by treatment with sodium arsenite 

 during June, 1952. On November 5-9, 1951, Lower, Middle, and Upper 



