Instream Flow Recommendations 



^, ^ Standing Crop and Flow Relationshj.ps V •' _ 



The standing crop and flow data generated a range of mini- 

 mum instream flow recommendations for each of the five reaches. 

 Flows less than the lower limit are judged undesirable since 

 they appear to lead to substantial reductions of the standing 

 crop of adult fish or the standing crop of a particular group 

 of fish, such as trophy-size trout. This lower limit will be 

 referred to as the absolute minimum instream flow recommenda- 

 tion. Flows equal to or greater than the upper limit supported 

 the highest standing crops. This upper limit will be referred 

 to as the most desirable minimum instream flow recommendation. 

 The flows needed to sustain optimum standing crops will prob- 

 ably exceed the most desirable minimum. The flows between the 

 absolute and most desirable minimums are assumed to sustain 

 intermediate or normal population levels. These minimums are 

 listed by reach in Table 15. The life stage and species of ^"; 

 fish for which each minimum was derived are also given. „-,,,:^ ' 



Table 15. Siimmary of the minimum instream flow recommendations 

 derived from the fish population and flow data col- 

 lected in five reaches of the Madison, Beaverhead, 

 Gallatin and Big Hole rivers. The life stage and 

 ': ,. species of fish for which each recommendation ap- 

 plies are also listed. 



Reach 

 Madison (#1) 



Madison (#3) 



■■ r 



Beaverhead (#2) 

 Gallatin{#2) 

 Big Hole(#l) 



Life Stage 



and Species --;■,. 



adult brown trout 

 adult rainbow trout 



juv. brown trout 

 adult brown trout 

 adult rainbow trout 



adult brown trout 

 juv. rainbow trout 

 adult rainbow trout 



adult brown trout 

 adult rainbow trout 

 adult mtn. whitefish 



adult brown trout • 

 adult rainbow trout 



Instream Flow 

 Recommendations (cfs) 



400 

 400 



a - applies to age IV and older brown trout, 

 b - applies to age III+ rainbow trout, 

 c - applies to age IV+ and older (trophy-size) 

 d - the optimum flow lies within this range. 



rainbow trout. 



49 



