• The relationship between habitat assessment scores and bioassessment scores 

 suggests that neither water quality nor habitat degradation limited biotic health at 

 McCloud station. However, both habitat degradation, and, to a lesser extent, 

 diminished water quality combined to impair integrity at Johnstone station. Figure 

 3 illustrates these relationships. The point representing McCloud station lies high 

 in the upper right quadrant of the graph, where its high habitat assessment score is 

 coupled with a high bioassessment score. In contrast, the point representing 

 Johnstone station lies slightly below a line describing the expected relationship 

 between habitat and biotic health when water quality is unimpaired. 



Figure 3. Total bioassessment scores plotted against habitat assessment scores for two sites on Shields 

 River, August 2000. The red line describes the hypothetical relationship expected when water quality is 

 good and biotic health is determined predominantly by habitat quality (Barbour and Stribling 1991). 



100 

 90 

 80 

 70 

 60 

 50 

 40 

 30 

 20 

 10 



TT 



10 



20 



— I — 

 30 



i 



40 50 60 



Habitat assessment score 



70 



80 



90 



-McCloud station O Johnstone station 



