In this example, the best predictions overall were obtained in JMSPH and the worse 
predictions for JMSMH. As chlorophyll a assessments expand across the tidal 
waters, additional environmental parameter(s) may need to be used to increase the 
accuracy of estimates similar to the way K d and turbidity relationships turned to 
additive multivariate models. 
An additional consideration is that field data are interpolated without respect to land 
barriers, which can result in station data having undue influence on distant grid cells. 
The use of DATAFLOW data cruise-track points minimizes this because of the high 
density of “nearest neighbors.” However, it becomes an issue of concern when 
cruise-track points are not available in the search radius and the segment of interest 
has meandering portions (such as JMSTFU). Interpolating with barriers is not an 
option for the Bay Interpolator at this time, but ArcGIS Geostatistical Analyst for 
example provides a limited form of this functionality. 
LITERATURE CITED 
COMAR 26.08.02.03-3 C (10)). Chlorophyll a narrative criteria. 
Thomann, R. V. and J. A. Mueller. 1987. Principles of Surface Water Quality 
Modeling and Control. Harper & Row, Publ., Inc., New York, NY. 
U.S. Environmental Protection Agency. 1997. Technical Guidance Manual for 
Developing Total Maximum Daily Loads, Book 2, Part 1. EPA# 823-B-97-002. 
Office of Water, Washington, DC. 
U.S. Environmental Protection Agency. 2003. Ambient Water Quality Criteria for 
Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its 
Tidal Tributaries. April 2003. EPA 903-R-03-002. Region III Chesapeake Bay 
Program Office, Annapolis, MD. 
U.S. Environmental Protection Agency. 2004. Ambient Water Quality Criteria for 
Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its 
Tidal Tributaries - 2004 Addendum. October 2004. EPA 903-R-03-002. Region III 
Chesapeake Bay Program Office, Annapolis, MD. 
U.S. Environmental Protection Agency. 2007a. Ambient Water Quality Criteria for 
Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its 
Tidal Tributaries - 2007 Addendum. July 2007. EPA 903-R-07-003. Region III 
Chesapeake Bay Program Office, Annapolis, MD. 
U.S. Environmental Protection Agency. 2007b. Ambient Water Quality Criteria for 
Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its 
Tidal Tributaries - 2007 Chlorophyll Criteria Addendum. November 2007. EPA 903- 
R-07-005. Region III Chesapeake Bay Program Office, Annapolis, MD. 
Virginia Department of Environmental Quality (VA DEQ). 2007. Water Quality 
Assessment Guidance Manual for Y2008 303(d)/305(b) Integrative Water Quality 
Report. Water Quality Division, Office of Water Quality Programs, Virginia Depart¬ 
ment of Environmental Quality, Richmond, VA. 
chapter v 
Chlorophyll a Criteria Assessment Procedures 
