and the disappearance of Nostoc, may indicate warmer water at 

 LMC-7 than at UMC-1. 



DIATOMS 



All but one of the major diatom species in Mizpah Creek were 

 either very tolerant or somewhat tolerant of organic pollution 

 (Table 5). The only sensitive species- -Cocconeis placentula- -was 

 much more abundant at the upstream site (UMC-1) . 



Very tolerant species, especially Navicula circumtexta and 

 Navicula veneta, were much more abundant at LMC-7, resulting in a 

 very small pollution index (1.36) at this site. These taxa, 

 along with Nitzschia reversa, also indicate an increase in 

 dissolved solids between UMC-1 and LMC-7. 



Over 80% of the diatom species at LMC-7 were motile and 

 adapted to living on unstable substrates. This resulted in a 

 very high siltation index, even for a prairie stream. LMC-7 also 

 had borderline values for diatom species diversity, percent 

 dominant species, and percent abnormal cells (Table 5) . 



Diatom association metrics indicated good to excellent water 

 quality and biological integrity at UMC-1. This site proved to 

 be a suitable reference site for use in Protocol II. UMC-1 also 

 supported a significant percentage of diatoms in the family 

 Epithemiaceae, indicating that nitrogen was probably the limiting 

 nutrient here. The two sites had less than a third of their 

 diatom associations in common, indicating that a significant 

 amount of environmental change occurred between them. 



