L-3 
from the Virginia Mainstem that is characterized as having low levels of contami¬ 
nants and accordingly classified as of no environmental concern (USEPA 1999). 
Our a priori expectation was that all branches of the Elizabeth River would show a 
higher percent area placed into the Contaminant Group compared to the Virginia 
Mainstem. For the Virginia Mainstem the number of sites placed into the Contami¬ 
nant Group represented 11% of the entire stratum. Consistent with our a priori 
expectation, all strata in the Elizabeth River had higher proportions placed into the 
Contaminant Group, ranging from 40-92% (Table 2; Figure 1). These results indi¬ 
cate strong support for the CDT. 
1996-2002 RANDOM DATA FOR CHESAPEAKE BAY 
The second putative data set consisted of random samples collected as part of the 
Maryland and Virginia Benthic Monitoring Program from 1996-2002. All samples 
were analyzed using the CDT function and placed into categories based upon the 
posterior probability of inclusion into the sediment Contaminant Group. The a 
priori expectation was that more samples collected near highly urbanized or indus¬ 
trialized watersheds would be placed into the Contaminant Group. Results are more 
difficult to interpret but the pattern of location of samples placed into the Contami¬ 
nant Group is non-random (Table 3; Figure 2), and can be interpreted to be consistent 
with known patterns of sediment contaminant distributions for the entire Chesapeake 
Bay (e.g. see USEPA 1999). GIS maps show patterns of location that agree well 
with a priori expectations within highly contaminated regions of the Bay such as 
Baltimore Harbor (Figure 3) and the Elizabeth River (Figure 4). The maps were 
made with data placed on a 100 m grid and interpolated using a two-dimensional 
surface fitting algorithm. 
4. REFERENCES 
Conrad, C.F. and C.J. Chisholm-Brause. 2004. Spatial survey of trace metal contaminants 
in the sediments of the Elizabeth River, Virginia. Marine Pollution Bulletin 49:319324. 
Dauer, D.M. 2001. Benthic Biological Monitoring Program of the Elizabeth River Water¬ 
shed (2000). Final Report to the Virginia Department of Environmental Quality, Chesapeake 
Bay Program, 35 pp. plus Appendix. 
Dauer, D.M. 2002. Benthic Biological Monitoring Program of the Elizabeth River Water¬ 
shed (2001) with a study of Paradise Creek. Final Report to the Virginia Department of 
Environmental Quality, Chesapeake Bay Program, 45 pp. 
Dauer, D.M. 2003. Benthic Biological Monitoring Program of the Elizabeth River Water¬ 
shed (2002). Final Report to the Virginia Department of Environmental Quality, Chesapeake 
Bay Program, 56 pp. 
Dauer, D.M. 2004. Benthic Biological Monitoring Program of the Elizabeth River Water¬ 
shed (2003). Final Report to the Virginia Department of Environmental Quality, Chesapeake 
Bay Program, 88 pp. 
Dauer, D.M., M.F. Lane and R.J. Llanso. 2002. Development of Diagnostic Approaches to 
Determine Sources of Anthropogenic Stress Affecting Benthic Community Condition in the 
appendix 1 
Addendum to the Report 
