amount of percent fines or Fredle index, but had a significantly lower geometric mean 

 (P=0.037). . . - - 



% Fines (<6.35mni) 



Geometric mean 



Fredle Index 



spring creeks verses existing bull trout spawning sites 



All spring creeks Nevada Spring Kleinschmdt Rock 



0.0004 0.206 0.006 0.002 



0.0004 0.037 0.003 0.002 



0.0001 0.139 0.002 0.002 



Table 15. Summary of statistical analysis (P-value) comparing sediment core metrics of existing 

 bull trout spawning sites to restored spring creeks. 



For the Monture Creek comparison, we found both a lower percentage of fine 

 sediment (<6.35mm) and a larger particle size (i.e. higher geometric mean) below the 

 bridge than above the bridge, however these differences were not significant (% fines P= 

 0.336, geometric mean 



P=0.336, 

 P=0.297). 



Fredle 



Discussion 



The Blackfoot 

 River drains a 



"geologically young" 

 sediment-rich watershed 

 formed of glacial 

 landforms that is highly 

 subject to natural 

 sediment producing 



events such as wildfires 

 and landslides. Within a 

 natural setting, flushing 

 flows through 



vegetatively stable 



channels performs a 

 sorting and cleansing 

 process of stream 

 substrates that permit fish 

 populations to reproduce 

 and flourish. The 



Blackfoot Watershed is 

 however also an area 

 highly prone to 



anthropogenic sediment 

 producing activities from 

 mining, silviculture, 



roads and grazing. A 

 majority of the 36 TMDL 



70 



60 



50 



40 



30 



20 



10 







40 



35 



30 



25 



20 



15 



10 



5 







c 



a) (U 



s ^.Pi^p-^ 





iR'5 B <» -9 <^ o f, 

 §iu m § « > |<^ 

 -J O .2 O 

 n ® 



c 5 I 

 « « « 



lis 





u> -S S -c- -c- -c- £■ 



&3 8 





« I E iiJ 



< 5 -i^ © O X ® 



^ "S *-- 5 « C 



<t E 



U. Q. CD 

 0) 



I 



2 



3 



a: ™ 2 



CD LL 



m 



u 



(0 g 



Figure 57. Percent fine sediment (mean + SD) for particles <6.35mm (top) 

 and <0.84mm (bottom) for 28 Blackfoot River spawning streams. 



0^; 



79 



