PROTOCOL II 



The index of similarity between the two streams was 36.86 

 (Table 6), indicating that the study stream (Big Dry Creek) 

 shared only about a third of its diatom association with the 

 local reference stream (Little Dry Creek) . Normally, such a low 

 similarly index would indicate that some perturbation had caused 

 the the diatom association of Big Dry Creek to be quite different 

 (from that of Little Dry Creek) and that the stream had been 

 moderately impaired. However, the two streams were sampled at 

 different times of the year. Since the abundance of diatom 

 species is highly seasonal, sampling in different seasons may 

 explain much of the floristic difference between the two streams. 



When compared to metric values for Little Dry Creek, the 

 pollution and siltation indexes for Big Dry Creek indicated only 

 minor impainnent , good biological integrity, and full support of 

 aquatic life uses. The diatom species diversity index was within 

 the range of no impairment and excellent biological integrity 

 when compared to Little Dry Creek. 



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