Company in 1908. Roughly 3 miles long by 3-3/U miles wide, it has 

 a shoreline of 11-1/2 miles and a surface area of 3,800 acres. 

 It has a maximum depth of 37 feet (at the dam), however it is esti- 

 mated that 75 percent of the reservoir is less than 15 feet in 

 depth. The shoreline is largely gravel. Shoal areas are extensive 

 and appear ideal for spawning. Aquatic plant beds, including coon- 

 tail, water milfoil, and pondweeds, are abundant in the upper part 

 of the reservoir. 



Fig. h* Lower portion of Madison Reservoir. Madison Dam is 

 located about 1-1/2 miles down Bear Trap Canyon, the 

 head of which is evident in the background. (Photo 

 by L. E. Hiner). 



Since a relatively stable water level is maintained at 

 Madison Reservoir by increasing or decreasing releases from Hebgen 

 Reservoir, the use of water for generating electric power ordinarily 

 doe3 not affect the fishery adversely. During the summer of 1950, 

 after several weeks of unusually dry weather, the normal level 

 (U>5k~L feet m.s.l.) of the reservoir was lowered only 20 inches. On 

 unusual occasions the water level has been lowered 8.5 feet. North 

 Meadow Creek with a normal flow of about 25 second-feet, and Jourdain 

 and South Meadow Creeks with somewhat smaller flows, are the only 

 sources of water other than the Madison. All three of these creeks 

 are important nursery streams. 



