previous estimate made in early September 1973 (Spence 1975). A 2,455-foot section was 

 electrofished with a Smith-Root Type VI backpack shocker. The marking run was made on 

 September 25 and the recapture run on October 2, 1975. 



Stream Sedi ment and Ta ilings Analyses 



One sample of sediment that had washed downstream from the tailings dam was collected and 

 sent to the Montana Bureau of Mines and Geology, Butte, for metals analysis. This sample was 

 arbitrarily collected at a deposition zone in the Blackfoot River upstream from Shoue Gulch on 

 June 23, 1975. Approximately two liters of a sediment/water mixture were collected from the 

 upper 2-3 inches of deposited material. Laboratory results are compared with a sediment sample 

 collected at Pop's Place in 1973. 



Two samples of the mine tailings behind the dam were collected by the Anaconda Company on 

 July 10, 1975 and analyzed in their laboratory in Tucson, Arizona. Results of those analyses are 

 given later in this report. 



RESULTS 



Water Quality 



Analytical results of individual water quality samples taken at the sites shown in Table 1 are 

 given in Appendix B. 



Bottom Fauna 



Results of the bottom fauna collected at two stations (Pop's Place and Flesher) in October 1971 

 and November 1972 (before dam failure) and in October 1975 (after dam failure) are tabulated in 

 Table 3. 



The most noticeable differences were at the Flesher station, particularly within genera which 

 contained large numbers of individuals before dam failure and much fewer after failure. For 

 example, in the order Plecoptera, the genus Alloperla contained only 67 individuals in 1 975 

 compared to 243 in 1971 and 336 in 1972. Similarly, the genus Bgetis, in the order 

 Ephemeroptera, contained six individuals in 1975 compared to 157 in 1971 and 81 in 1972. On 

 the other hand, some genera occurred in 1975 which had not been found in 1971 or 1972. 

 Overall, there was a marked reduction in numbers within individual genera in 1975 compared to 

 those present in 1971 and 1972. The number of genera decreased by 65.3% at Pop's Place and 

 65.2% at Flesher. Total numbers were 86.2% less at Pop's Place and 92.4% less at Flesher. 

 Numbers per square foot decreased 92.5% at Pop's Place and 86.7% at Flesher. The above 

 percentages were calculated using the average of 1971 and 1972 data. 



