J-1 
appendix 
Chesapeake Bay Estuarine 
Benthic Communities 
Assessment Protocol for 
Maryland and Virginia 
305b/303d Integrated Reports 
Maryland (Department of the Environment, Department of Natural Resources), 
Virginia (Department of Environmental Quality) and U.S. EPA (Region 3 Water 
Protection Division and Chesapeake Bay Program Office) reached agreement on the 
protocol to assess Chesapeake Bay benthic community health. This appendix docu¬ 
mented the assessment protocol supporting the States evaluation of Chesapeake Bay 
benthic community data as part of their 305b/303d Integrated Reports. This assess¬ 
ment protocol builds directly on the more detailed assessment methods 
recommended by Llanso et al. 2005 (see Appendix K). 
The overall decision protocol is shown in Figure J-1. Phase I consists of the evalu¬ 
ation of the sample size ( i.e ., number of B-IBI scores) available from the waterbody 
segment during the five-year assessment window. If the sample size satisfies the 
requirements of the statistical method (N > 10), a formal assessment of status (i.e. 
impaired vs. supports aquatic life use) is determined utilizing the “percent degraded 
area” statistical methodology (Phase II). If the sample size requirement is not met 
an impairment assessment based solely on these analyses is not possible. Results for 
segments with insufficient sample size should still be examined for possible use in 
conjunction with other assessment data of the 305b/303d reporting process. 
Phase II consists of the impairment assessment of aquatic life use attainment based 
on a comparison of Benthic Index of Biotic Integrity (B-IBI) scores and can only be 
performed when the number of B-IBI scores within a specified waterbody segment 
is sufficient to meet the sample size requirement of the approved statistical method 
(N > 10). Phase II can result in one of two possible outcomes: (1) the segment is not 
impaired for Aquatic Life use due to benthic community status (note that the 
segment may still be impaired for aquatic life use due to failure of other aquatic life 
use criteria), or (2) the segment fails to support aquatic life use due to benthic 
community status and is assessed as impaired. Best professional judgment can be 
appendix J 
Bay Estuarine Benthic Communities Assessment Protocol for Maryland and Virginia 
