Species diversity of the bottom fauna populations before and after dam failure was determined 

 using Shannon- Weaver diversity indices (Shannon and Weaver 1964). Formulae for the indices 

 are given in Appendix A. Appendix A also shows Brillouin diversity indices, which are 

 modifications of Shannon- Weaver (Peilou 1969, quoted in Newell 1976a). 



Live Caged Fish 



Four live cages containing wild cutthroat trout were placed at four locations to measure survival. 

 Cages were placed at the locations listed in Table 2 and shown on Map No. 2 (Page A-72 at the 

 end of this report). Cage No. 4 was a control placed in Shoue Gulch (also known as Shave 

 Gulch), an unaffected tributary entering the Blackfoot River about one mile below the tailings 

 dam. 



Table 2. Live cage data 



Cages were checked daily from July 9-13 and the status offish noted (re. alive and healthy, alive 

 but stressed, dead). Cages were removed after checking them on July 13. 



Fish Populations 



Electrofishing with a Fisher-Shocker, Model FS-101, powered by a 1500 watt alternator, was 

 conducted on July 11, 1975 to determine if a complete kill offish had occurred due to the tailings 

 pollution. Sampling was done in the Blackfoot River at Flesher Pass road crossing at a site 

 previously sampled by Spence (1975). Approximately 900 feet of stream were sampled. Prior to 

 this date, water was too high for adequate sampling efficiency and safety. Sampling was also 

 done on a 600-foot section of the Blackfoot River at Pop's Place on July 18, 1975. 



A second fish sampling program was done in late September at the Flesher road site. This time a 

 fish population estimate was made using the method of Vincent (1974) and was compared with a 



