The 22 miles of tlie North Fork Sun River (fig. 2), from Diversion 



*'^;te'';- 



Fig, 2. — North Fork Sim River below Diversion Dame 



Dam to its confluence with the Willow Creek Reservoir outlet canal, was 

 included in the census area. The average width of this reach of stream 

 is about 120 feet, and the gradient is about 18 feet per mile. 



Although some of the substantial seepage from Pishkxin Canal enters 

 this section of stream through the few small tributaries, the flow is 

 largely controlled by releases from Diversion Reservoir. D\iring water 

 year 195l> the extremes in flow just below Diversion Dam were 23ii 

 second-feet in February and 3,526 second- feet in Mayo Flows of between 

 3,526 and 1,517 second-feet were maintained during May, Jvine, and July 

 but were dropped to less than 500 second-feet in August, September, 

 October, January, February, and March. Alternate riffles and pools are 

 characteristic of this section of the river. From Diversion Reservoir 

 the river flows through a narrow band of wooded foothills, thence 

 through rolling prairie- type terrain. A fringe of cottonwoods and wil- 

 lows grows along most of the lower river. The upper 3 or It miles is 

 accessible by a graded road, while the rest is accessible in all but 

 the most adverse weather by a network of trails. 



