and review to implement the best available technology for this aspect of criteria 
assessment. 
4. High-Density Temporal Data. As currently formulated, criteria assessment 
for most of the Bay’s open waters are based on “snapshots” in time of the 
spatial extent of criteria exceedance estimated through interpolation. Data 
collected for use in interpolation span several days given the large area being 
sampled. New technologies should soon be capable of producing high-density 
data in both space and time. Interpolation should accommodate data collected 
densely in space. It is unclear, however, how the CFD process will accommo¬ 
date data that are densely clustered in time. Further work is needed to evaluate 
methods to fully utilize the temporally intensive data currently being collected. 
5. Implementation and Review. As a rule of thumb, the best test of any new 
procedure is putting it to work with stakeholder involvement. Through its 
Criteria Assessment Protocols Workgroup, the Chesapeake Bay Program has 
already established a forum for resolving the details of CFD implementation. 
At appropriate intervals in this process, however, the Chesapeake Bay Program 
should seek independent scientific and technical review of the implementation 
status of the assessment methodology. 
LITERATURE CITED 
Helsel, D.R. and R.M. Hirsch.1992. Statistical Methods in Water Resources. Studies in Envi¬ 
ronmental Science #49. Elsevier Science Publishers, Amsterdam, Netherlands. 552 pp. 
Scientific and Technical Advisory Committee (STAC). 2006. The Cumulative Frequency 
Diagram Method for Determining Water Quality Attainment: Report of the Chesapeake Bay 
Program STAC Panel to Review of Chesapeake Bay Analytical Tools. STAC Publication 06- 
003. 9 October 2006. Chesapeake Bay Program Scientific and Technical Advisory 
Committee. Chesapeake Research Consortium, Edgewater, MD. 
U.S. Environmental Protection Agency (U.S. EPA). 1997. Guidelines for Preparation of the 
Comprehensive State Water Quality Assessments (305(b) reports) and Electronic Updates. 
Assessment and Watershed Protection Division, Office of Wetlands, Oceans and Watersheds, 
Office of Water, U.S. Environmental Protection Agency, Washington, D.C. 
U.S. Environmental Protection Agency. 2003a. Ambient Water Quality Criteria for Dissolved 
Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries. 
EPA 903-R-03-002. Region III Chesapeake Bay Program Office, Annapolis, MD. 
U.S. Environmental Protection Agency. 2003b. Technical Support Document for Chesapeake 
Bay Designated Uses and Attainability. EPA 903-R-03-004. Region III Chesapeake Bay 
Program Office Annapolis, MD. 
Weisberg, S.B., J.A. Ranasinghe, D.M. Dauer, L.C. Schaffner, R.J. Diaz, and J.B. Frithsen. 
1997. An estuarine benthic index of biotic integrity (B-IBI) for Chesapeake Bay. Estuaries 
20:149-158. 
Refinements to the Chesapeake Bay Water Quality Criteria Assessment Methodology 
