Fig. 1. — A typical section of the North Fork of the 

 North Fork Sun River, 



The North and South Forks of the North Fork Sun River are medium- 

 altitude streams (about 1|,730 feet m.sdo at their confluence); each 

 has an abundance of pools and riffles and a width of about 60 feet in 

 the lower reaches. Records indicate a marked similarity in the flow 

 of the two streams. In 1951 the combined flow at their confluence 

 reached the maximum in May, v/hen the average flow for the month was 

 li,253 second- feet. The minimuin monthly flow of 30ii second- feet occurred 

 in Marcho Ihese two streams drain an area of about 1,000 square miles. 

 The principal tributaries are Moose Creek on the North Fork and the 

 West Fork on the South Fork, but there are many other named and un- 

 named tributaries in the drainage „ Beaver dams are found on many of 

 the smaller creeks. Although the river below the junction of the two 

 forks has been considerably modified by water-development projects, 

 the tributary streams that originate the North Fork Sun River are 

 essentially in a natural state. The upper slopes of the headwater 

 valleys are characterized by stands of lodgepole pine, Douglas-fir, 

 and spruce. Both streams lie within the Le^d.s and Clark National 

 Forest. A part of the South Fork and all of the North Fork are within 

 the Bob Marshall Wilderness Area. Tnis headwater area can be reached 

 by boat through Gibson Reservoir, or by hiking or horseback. The 

 North Fork may be reached also by trails entering the area from the 

 headwaters of the Tfeton River at the Ear Movintain Ranger Station, and 



