Most of the 102 streams tributary to the Madison (shown on 

 the U, S. Forest Service map) are short and many are dry except during 

 the time of snow melt„ Some that are not naturally intermittent are 

 completely dewatered during the summer by irrigators , Tributaries 

 which are important as nursery streams includes Grayling, Duck, Cabin, 

 Beaver, O'Dell, Jack, North Meadow, Jourdain, South Meadow, and Cherry 

 Creeks, and the South Fork and West Fork of the Madison „ These 

 streams have minimum flows of about 25 second-feet„ The West Fork of 

 the Madison has extensive beaver dams near its mouth which prevent 

 free movement of fish except during periods of high water „ 



Diversions of water from the river are common below Bear 

 Trap Canyon 5 upstream from Bear Trap there are only three direct 

 diversions,, The latter are above Varney Bridge, Less than 10 second- 

 feet is removed by the smaller of the three. The larger one, West 

 Madison Canal, removes about 150 second-feet. A fish screen had been 

 provided for the West Madison Canal, but it was not in operation dur- 

 ing the period of study (1951) and a considerable number of fish went 

 into the canal and were presumably lost. No specific investigations 

 were conducted during this study to determine the extent of fish 

 losses in irrigation canals arising from the Madison, but limited 

 observations conducted on the West Madison Canal in September 19U8, 

 following an inadvertent closure, disclosed a loss of more than 

 lh s 000 trout in the first 3 miles of the canal. Total population in 

 this 15-mile canal prior to closure was estimated to exceed U0,000 

 fish. 



Algae and other low forms of aquatic vegetation were common 

 in certain stretches of the river, especially in the lower reaches,, 

 Qnergent aquatic vegetation was sparse. The vegetation of the valley 

 is characteristic of the inner mountain region of the Rockies, About 

 two-thirds of the total drainage area outside of Yellowstone National 

 Park is included in national forests and in most areas is well timbered 

 with conifers. In addition, many tracts of private land are covered 

 with coniferous forests. These forests serve to protect the water- 

 shed from sudden snow melts and flash floods. Forest cover contributes 

 to the uniform flows and thus benefits the fishery. Trees and brush 

 on the banks of the river consist of alder, willows* and cottonwood, 

 however much of the river bank and valley floor is free of woody 

 vegetation. 



Bottom fauna was abundant on the rubble and boulders through- 

 out the course of the river. Nymphs of mayflies, midges, and stone 

 flies were the most abundant forms, The largest stone fly in the 

 United States, locally called the salmon fly ( Fteronarcys californica ) , 

 was abundant in most areas and was used extensively as bait 



Madison Reservoir (Fig, h) located at the head of Bear Trap 

 Canyon (see map), was built for power production by the Montana Power 



