STUDY NUMBER ; 12.1 



ORGANIZATION ; Anaconda Minerals Company/ Chadwick and 

 Associates 



TITLE OF STUDY ; Benthic Invertebrate Studies on the Upper 

 Clark Fork River 



CONTACTS ; Jim Windorski - Anaconda Minerals Co. - 723-4311 



Steve Canton - Chadwick and Associates - (303) 



798-7708 



Loren Bahls - DHES, WQB - 444-2406 



OBJECTIVE: Annually monitor the benthic invertebrate 

 communities in Silver Bow Creek, Mill-Willow Creek and the 

 upper Clark Fork River. 



DURATION ; 1972 - Indefinitely 



CURRENT STATUS ; Benthic invertebrate samples are collected 

 yearly during autumn at eleven stations. Five of these 

 stations are on Silver Bow Creek (from Butte to Opportunity) 

 two are on the Mill-Willow bypass channel (one above the Warm 

 Springs Ponds and one below the confluence with the Pond 2 

 discharge) and three are on the Clark Fork River (at Warm 

 Springs, Deer Lodge and Phosphate). Three separate quantita- 

 tive samples are collected at each station using a modified 

 Hess sampler. Organisms are identified to the lowest 

 practical taxonomic level using available keys. Wet-weight 

 biomass is determined for major groups (i.e. insect orders). 

 Analysis of the invertebrate community includes calculation 

 of the ShannonWeaver Diversity Index. 



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