cha pter 
2008 92-Segment Scheme 
for the Chesapeake Bay 
Water Quality Criteria 
BACKGROUND 
For 25 years, the Chesapeake Bay Program partners have used various versions of a 
basic segmentation scheme to organize the collection, analysis and presentation of 
environmental data. The Chesapeake Bay Program Segmentation Scheme: Revi¬ 
sions, decisions and rationales provided documentation on the spatial segmentation 
scheme of the Chesapeake Bay and its tidal tributaries and the later revisions and 
changes over the last 25 years (U.S. EPA 2004b, 2005). This chapter provides 
concise information on the historical 1983, 1997, 2003 segmentation schemes and 
illustrates the recommended 2008 92-segment scheme for assessing Chesapeake Bay 
water quality criteria. 
CHESAPEAKE BAY PROGRAM 
SEGMENTATION SCHEMES 
Segmentation is the compartmentalization of the estuary into subunits based on 
selected criteria. The Chesapeake Bay ecosystem is diverse and complex, and the 
physical and chemical factors which vary throughout the Bay determine the biolog¬ 
ical communities and affect the kind and extent of their response to pollution stress. 
These same factors also influence their response to restoration and remediation. For 
diagnosing anthropogenic impacts, segmentation is a way to group regions having 
similar natural characteristics so that differences in water quality and biological 
communities among similar segments can be identified and their source elucidated. 
For management purposes, segmentation is a way to group similar regions to define 
a range of water quality and resource objectives, target implementation of specific 
actions and monitor responses. It provides a meaningful way to summarize and 
chapter ii 
2008 92-Segment Scheme for the Chesapeake Bay Water Quality Criteria 
