the South Fork may be reached by way of a graded road v/hich terminates at 

 the Bench I^rk Ranger Station. Pack trails follow many of the larger trib- 

 utary streams. The K-L Ranch, with facilities at the confluence of the 

 Worth and South Forks and on nearby Arsenic Creek, is open to guests through- 

 out the summer o 



Gibson Reservoir, on the Worth Fork Sim River just below the confluence 

 of the tiTO principal tributary streams, is a storage reservoir » It is about 

 7 miles long and has a maximum width of approximately 1 mile. It has a sur- 

 face area of 1,360 acres at maximum capacity* The maximimi depth is about 

 180 feet; normally about four-fifths of the reservoir is over 30 feet deep. 

 The reservoir is subject to considerable fluctuation of v/ater level. For 

 example, during the past 6 years, the maximum annual fluctuation was 116 

 feet (1949) and the minimiroi T/as 29 feet (1951), In 1951 the water level 

 dropped 28 feet in August, after having risen more or less consistentlyo 



Gibson Reservoir lies within the Lev/is and Clark National Forest, at 

 elevation 4,729 feet. It is surrounded by rocky ridges, partlj^ covered 

 with coniferous grovrbh. It can be reached at the dam by a steep, narrow, 

 rocky road, and is accessible by foot or horseback from a pack trail which 

 skirts the north shore. Boats may be used on the reservoir providing they 

 are at least 14 feet in length and have a beam of 48 inches. 



That part of the Worth Fork Sun River v/hich lies between Gibson Dam 

 and Diversion Reservoir is 3 miles long and about 80 feet wide. Here the 

 river flows through a narrow canyon and is characterized by large, deep 

 pools and' turbulent riffles. The flovr is regulated by discharge from 

 Gibson Dam, During 1951 the flow varied from 234 second-feet in February 

 to 4,060" second-feet in May; during the study period the flavr gradually de- 

 • creased from the 4,060 second-feet in May to 407 second-feet in September, 

 Several streams, the largest of v/hich is Beaver Creek (about 15 feet vj-ide), 

 enter this reach of the river. All streams entering from the north were 

 closed to fishing, and all on the south side were open to fishing. Of 

 those entering from the south, Beaver Creek v/as the most extensively used 

 by fishennen. A forest road extends up Beaver Creek a distance of about 

 2 miles. Large areas of the canyon and adjacent gulches ai'e barren of 

 forest cover because of the rocky terrain and past fires. 



Diversion Reservoir, 3 miles downstream from Gibson Reservoir, is a 

 long, narrow, 100-acre impoundment. Water in this reservoir is maintained 

 at a relatively stable level. Diversion Reservoir is in the same canyon 

 as the river between it and Gibson Reservoir and therefore has a similar 

 setting. It is accessible by a road along the south shore. 



