6 
present information in parallel with these objectives and it is a useful geographic 
pointer for data management. 
The Chesapeake Bay Program Segmentation Scheme: Revisions, decisions and 
rationales 1983-2003 (U.S. EPA 2004b, 2005) contains the following maps and 
tables used to document changes to the segmentation scheme from 1983 through 
2003 as well as provide the jurisdictions with detailed documentation on the 
geographical delineation of each segment’s boundaries: 
• Maps for the 1983, 1997 and 2003 segmentation schemes; 
• Statistics on the perimeter, surface area and volume of each Chesapeake Bay 
Program segment; 
• Narrative descriptions of each of the coordinates bounding each Chesapeake 
Bay Program segment; and 
• Maps of all the Chesapeake Bay Water Quality Monitoring Program stations 
displayed by segment by Maryland, Virginia and the District of Columbia. 
A concise history of the original 1983 segmentation scheme, and the 1997 and 2003 
revised segmentation schemes is published in Chapter 3 of the U.S. EPA (2004a) 
Technical Support Document for identification of Chesapeake Designated Uses and 
Attainability, 2004 Addendum. A detailed history of segmentation schemes is 
provided in the Chesapeake Bay Program Segment Scheme document at 
http://www.chesapeakebay.net/pubs/segmentscheme.pdf and the summary docu¬ 
ments of U.S. EPA 2004b, 2005. 
2008 CHESAPEAKE BAY AND TIDAL TRIBUTARIES 
92-SEGMENT SCHEME 
The 92-segment scheme for the Chesapeake Bay and its tidal tributaries used for 
dissolved oxygen and water clarity assessments in the 2008 303d/305b listing efforts 
of the four Bay tidal jurisdictions is documented here. The 92-segment scheme was 
derived from: 1) the 2003 published 78-segment scheme with the addition of juris¬ 
dictional boundary lines imposed to create 89 segments; then 2) includes only the 
split segments agreed upon for the tidal James and Potomac rivers. The result of the 
State partners’ decisions on the Chesapeake Bay water quality criteria assessment 
framework is the 92-segment scheme (Figure II-1), a subset of the 2003 104-segment 
scheme that defined boundaries of split segments published in U.S. EPA 2004b. 
Table II-1 is a complementary reference table that lists the 92 segments definitions 
according to their application across the 25 year history of Chesapeake Bay segment 
schemes. 
chapter ii 
2008 92-Segment Scheme for the Chesapeake Bay Water Quality Criteria 
