Table 2. Mean chemical and physical properties of the Beaver- 

 head River in the summer of 1972 at sites 0.25, 

 6.0, 15.0 and 2 7.0 miles below Clark Canyon Dam 

 (data from Smith, 1973) . 



0.25 



Site (miles) 

 1 13 — 



27 



Turbidity (JTU) 4 4 



Conductivity (umhos @ 25 C) 565 572 



pH 8.1 8.2 



Dissolved Oxygen (ppm) 9.6 9.7 



Total Alkalinity (ppm CaC03) 19 8 199 , 



Total Hardness (ppm CaCOj) 220 230 



Ammonia (ppm NH3-N .14 .08 



Nitrate (ppm NO3-N) .057 .110 



Nitrite (ppm NO2-N) .015 .018 



Orthophosphate (ppm PO^"-^) .11 .10 



7 



555 

 8.2 

 9.3 



190 



216 



.05 



5 



617 

 8.1 

 10.0 

 218 

 252 



.02 



.089 .285 

 .015 .006 

 .08 .05 



Reach #2 encompasses a 16-mile sect 

 East Bench Diversion Dam at Barretts (ri 

 Canyon Dam (river mile 80) . The average 

 83 ft. The streambed primarily consists 

 Si±»merged and overhanging willows and un 

 much of the trout cover in this reach, 

 one or two channels consisting primarily 

 Brown trout, rainbow trout, mountain whi 

 sucker, longnose sucker, mottled sculpin 

 inhabit this reach. 



ion of river between the 

 ver mile 64) and Clark 

 channel width is about 

 of cobble and gravel, 

 dercut banks provide 

 Flow is confined to 



of riffle-pool areas, 

 tefish, burbot, white 

 , and longnose dace 



The flows in reach #2 are completely regulated by Clark 

 Canyon Dam. From October through March, Clark Canyon Reser- 

 voir stores water for the upcoming irrigation season. Releases 

 into the river are minimal during this period. Irrigation re- 

 leases occur from April through September. The diversion of 

 irrigation water begins 16 miles below the dam. The major impact 

 of the reservoir on the flow regime in reach #2 was to extend 

 the high water period an additional four months from April 

 through September. This extension occurs at the expense of 

 October through March flows. 



14 



