Although the rate of siltation in Madison Reservoir has 

 never been measured, it is considered to be low. Nevertheless, the 

 water of the reservoir becomes quite turbid at times due to wave 

 action. Surface water temperatures as recorded in 1950 ranged 

 from I4O F. to 7k° F., with an average of about 58°. 



Hebgen Reservoir (see map and Fig. 5) was built in 1915, 

 also by the Montana Power Company. Irregular in shape, it is about 

 18 miles long by about 2-1/2 miles wide. It has a surface area of 

 13,h00 acres and a maximum depth of 70 feet. There are about 65 

 miles of shoreline. 



Fig. 5. Hebgen Reservoir, surrounded by mountains and forests, 

 is not only a beautiful spot but is productive of fish, 

 Hebgen Dam is located around the bend to the left. 

 (Photo by L. E. Hiner). 



A number of small streams enter Hebgen Reservoir, the most 

 important of which are the South Fork of the Madison and Duck and 

 Grayling Creeks. These streams are used extensively by spawning 

 fish. Other streams that may accommodate some spawning are Cherry, 

 Rumbaugh, Watkins, and Trapper Creeks. Gravel shoal areas appear as 

 narrow bands along the north and west shores. Although these 

 appear to be suitable for trout spawning, their value for this is 

 limited by fluctuations in water level. 



