Duf field (1981) estimated the economic value of 

 recreation on the upper Clark Fork and its tributaries. His 

 study used the recreational use survey by Hagmann (1979) and 

 traffic surveys on Rock Creek by the Lolo National Forest. 

 The dollar values of these visits were estimated using the 

 travel cost method. The study results indicated a substan- 

 tial annual use value for instream uses of the upper Clark 

 Fork ranging between a low of $500,000 and a high of $1.4 

 million per year in 1979. 



MACROINVERTEBRATES 



Biological surveys of fishes, macroinvertebrates, and 

 periphyton (attached algae) have been conducted in the Clark 

 Fork Basin by numerous investigators during the past several 

 decades. Aquatic macroinvertebrates have been the most 

 frequently studied as bioindicators of water quality. 

 McGuire (1988) summarized the results of past macroinver- 

 tebrate studies on the Clark Fork to identify trends and 

 information needs. The following summary is from McGuire 's 

 report . 



Silver Bow Creek to Milltown Dam 



Macroinvertebrate studies initiated in the late 1950s 

 provide starting points for both long-term trend monitoring 

 in specific river reaches and evaluations of conditions 

 throughout the Clark Fork drainage. The early studies by 

 Spindler (1959) and Averett (1961) allowed gross comparisons 

 of environmental conditions throughout the drainage. They 

 found macroinvertebrates absent from Silver Bow Creek and 

 only sparse insect populations in the upper Clark Fork. 

 Dipterans (presumably midges and/or black flies) predomi- 

 nated throughout the drainage, while caddisflies, mayflies, 

 stoneflies, and beetles were virtually absent above the 

 confluence of the Little Blackfoot River. 



No additional information is available for the upper 

 Clark Fork until Shinn's (1970) qualitative study of 12 

 sites from Silver Bow Creek to below the Frenchtown Mill 

 (now owned by Stone Container Corp.). Shinn documented 

 degradation in much of his study area, and his data indicated 

 that environmental conditions in the Clark Fork had not 

 changed significantly during the 1960s. Like Averett and 

 Spindler, Shinn found no aquatic insects in Silver Bow Creek 

 and few species in the Clark Fork from the Warm Springs Ponds 

 to Deer Lodge. He found twice as many macroinvertebrate 

 species at Garrison than at Deer Lodge, and attributed this 

 increase to dilution provided by the Little Blackfoot River. 

 From the confluence of the Little Blackfoot River to Milltown 



2-24 



