were not collected in this study. It is only assumed that these two modifica- 

 tions would greatly Improve the IFG model for use on Montana's trout rivers. 



Non-Field Method 



The final monthly flow recommendations listed in Table 2 for the five 

 study reaches are expressed as percentages of the mean and median annual 

 flows of record. These percentages are summarized in Table 4. 



Table 4. Summary of the final flow recommendations for the low flow months 

 for five reaches of the Madison, Beaverhead, Gallatin and Big Hole 

 Rivers expressed as percentages of the mean and median annual flows 

 of record. 



Recommendations for a Median Water Year 



Ave. (Standard Deviation) 



% of Mean Annual Flows 54 26-51 39.2 (8.2) 



% of Median Annual Flows 54 45-83 57.7 (11.0) 



No general rules of thumb are evident when the percentages and standard 

 deviations listed in Table 4 are examined. However, general rules are sug- 

 gested when the recommendations for the two Madison reaches are removed and 

 expressed as percentages of the mean annual flows. The recommendations for 

 the two Madison reaches range from 46 to 51% of the mean annual flows and 

 average 48.5% with a standard deviation of 2.6%. The recommendations for the 

 remaining three reaches range from 26 to 35% of the mean annual flows and 

 average 32.8% with a standard deviation of 2.6%. The Madison River, which 

 generally lacks pool development and is considerably wider and shallower than 

 the other rivers of the study area, requires a greater percentage of the mean 

 annual flow. This is expected if one considers the morphological differences 

 between the rivers. 



CONCLUSIONS 



Single Transect Met hod 



The wetted perimeter-discharge curve for a single riffle cross-section 

 provided acceptable flow recommendations for adult trout in the five study 

 reaches. Single, well defined inflection points were generally present on the 

 curves and were easily Interpreted. In addition to providing reliable recom- 

 mendations, the single transect method is also the most time and cost efficient 

 of the three field methods. 



