Figure 24. — Dam constructed across creek to divert adult salmon up fishway and 

 into holding ponds. (See also fig. 1.) 



carried away sections of the instal- 

 lation. Identical tripods have been 

 utilized in the Big White Salmon 

 Eiver, tributary to the lower Co- 

 lumbia River. 



Smaller rack installations are the 

 rule and usually can be held in the 

 stream with constant attention and 

 effort through the few weeks of the 

 spawning season. Under favorable 

 circumstances it is possible to rack 

 only a portion of a stream and thus 

 divert part of the run of salmon into 

 holding ponds. At other places, 

 such as Walcott Slough on Hood 

 Canal off Puget Sound, Wash., a 

 permanent trap is installed in a 

 small spring outlet within the reach 

 of tidal rise. Here chum salmon 

 are spawned with utmost conve- 

 nience, as the adults entering the 

 traps are fully mature. This run, 

 incidentally, is hatchery-created 

 and hatchery-maintained. 



In certain streams where the bot- 

 tom and channel are stabilized, con- 

 crete aprons about 15 to 20 feet wide 

 often are placed across the bed of 

 the stream, with appropriate means 

 of anchoring tripods to the apron. 

 Often, too, concrete blocks have been 

 poured at intervals across the apron 

 to replace the tripods. The racks 

 are then laid against the sloping up- 

 stream face of the blocks. Where 

 floods and logs are encountered, such 

 permanent installations are undesir- 

 able because they form a solid foun- 

 dation for a debris dam and 

 resultant flooding of surrounding 

 areas. On the Klickitat River, un- 

 der the Federally financed fisheries 

 program, the Washington Depart- 

 nient of Fisheries has installed a 

 new kind of tripod that is most con- 

 venient and successful in this type 

 of stream with no heavy debris. 

 This installation consists of a con- 



49 



