segment-periods are visible as red lines. The biologically-based reference curve generated 
from the 100 th percentile of “Scenario A” violations at each time step is visible as a yellow 
line. 
space 
Figure A-l. Scenario B - illustrates the impact of maintaining the sample size criterion of n 
>_10 while relaxing the standard deviation criterion from a maximum of 1.0 to a maximum of 
1.2 
The shape of the CB5MH 1999-2001 curve (light blue line in Figure A-l) raises the question 
of whether increasing the uncertainty of the screening criteria resulted in erroneous 
classification of this segment-period as healthy. In particular, the location of the top half of 
this curve in CFD space that is dominated by degraded curves decreases confidence in the 
accuracy of its classification. The addition of this curve, particularly in combination with the 
methodology of taking the 100 th percentile of each curve at each point in time, would 
increase the potential for the resulting biologically-based reference curve to allow rates of 
hypoxia that result in degradation of the benthic community. 
In the case of Scenario C, the standard deviation is kept consistent with the recommended 
screening criteria but the sample size criterion is relaxed from 10 to 8. This relaxation of the 
recommended criteria results in the classification of 3 additional segments as “healthy.” The 
CFD curves for these additional segments are shown as light blue curves in Figure A-2. 
While two of the additional curves (CB6PH 1998-2000 and CB6PH 2000-2002) fall within 
the cloud of violation rates deemed “acceptable,” one curve (CB3MH 1996-1998) once again 
extends into the cloud of data dominated by CFDs associated with degraded segment-periods 
(Figure A-2). As described earlier, this raises the concern that relaxation of the criteria has 
resulted in the inaccurate classification of a degraded segment-period as healthy. 
