Table 4. Percent abundance of major diatom species' and values of selected diatom association metrics for 

 periphyton samples collected from Lake Creek in 2003. Underlined values indicate minor stress; 

 bold values indicate moderate stress; underlined and bold values indicate severe stress; all 

 otfier values indicate no stress and full support of aquatic life uses when compared to criteria for 

 plains streams in Table 2. 



Species/Metric 



PTC Lake Creek above county road 



M12LAKEC01 



Lake Creek above Hevron Road 

 M12LAKEC02 



Cocconeis placentula 

 Cymbella excise 

 Gomphonema minutum 

 Navlcula capitatoradiata 

 Navicula erifuga 

 Navicula gregaria 

 Navicula lanceolata 

 Navicula reichardtiana 

 Navicula veneta 

 Nitzschia dissipate 

 Nitzschia inconspicua 

 Nitzschia palea 

 Nitzsctiia pusilla 

 Rhoicosphenia abbreviate 



Number of Species Counted 

 Shannon Species Diversity 

 Pollution Index 

 Siltation Index 

 Disturbance Index 

 Percent Dominant Species 

 Percent Abnormal Cells 

 Similarity Index'' 



3 

 3 

 3 

 2 

 2 

 2 

 2 

 2 

 1 

 3 

 2 

 1 

 1 

 3 



6.79 

 0.95 

 1.58 

 12.01 

 2.05 

 6.16 

 7.11 

 3.16 

 7.11 

 4.58 

 1.42 

 5.37 



4.11 



59 

 4.99 

 2.15 

 72.99 



1.58 

 12.01 

 0.00 



0.77 

 4.95 

 15.63 

 3.87 

 4.49 

 2.79 



5.42 

 0.31 

 30.34 

 0.93 

 5.57 

 2.17 



48 

 3.97 

 2.16 



63.16 

 2.32 



30.34 

 0.00 



33.97 



'a major diatom species accounts for 3.0% or more of the cells at one or more stations in a sample set. 

 ^(Organic) Pollution Tolerance Class (Lange-Bertalot 1979): 1 = most tolerant; 2 = tolerant; 3 = sensitive. 

 ^Percent Community Similarity (Whittaker 1952) when compared to the diatom assemblage at the adjacent 

 upstream station 



