Garden Creek. Aside from minor natural stress and a single abnormal diatom valve, the 

 upper site on Garden Creek had excellent biological integrity (Table 4). The lower site on 

 Garden Creek supported an elevated number of motile diatoms for a mountain stream, indicating 

 minor impairment from sedimentation. A few teratological diatom valves were also counted at 

 this site. The two sites on Garden Creek shared over 40 percent of their diatom assemblages, 

 which indicates that only minor environmental change occurred between them. 



Mormon Creek. An elevated number of motile diatoms indicate moderate impairment 

 from sedimentation in Mormon Creek. A depressed pollution index also indicates minor 

 impairment from organic loading. A relatively large number of teratological diatoms suggests 

 that this site may have elevated concentrations of heavy metals. 



North Fork Greenhorn Creek. Over 13 percent of the diatoms at this site were 

 abnormal (Table 4), which suggests severe impairment from heavy metals. The number of 

 motile diatoms here was also elevated, indicating minor impairment from sedimentation. The 

 pollution index was near the threshold for minor impairment and the dominant species here 

 (Synedra ulna) is tolerant of organic loading (PTC = 2). 



West Fork Ruby River. A large number of motile diatoms indicate moderate 

 impairment from sedimentation at this site. The pollution index was also depressed, indicating 

 minor impairment from organic loading. No teratological diatom cells were counted at this site. 



Modal Categories 



Several ecological attributes assigned by Stevenson and Van Dam et al. (1994) were 

 selected from the diatom reports in the appendix and modal categories of these attributes were 

 extracted to characterize water quality tendencies in streams of the Ruby River TMDL planning 

 area (Table 5). The largest category of diatoms at most sites was "not motile", but highly motile 

 diatoms comprised the largest category in California Creek near mouth, Hawkeye Creek, and the 

 West Fork of the Ruby River. These three sites also had the highest sedimentation indexes. 



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