57 
designated as SAV no-grow zones (see pages 108-110 in U.S. EPA 2003b). In the 39 
segments with SAV no-grow zones, 31 of the segments have such zones extending over 
a portion of the segment (see Table V-l on page 42 in U.S. EPA 2004c). In these 
segments, an area delineated as an SAV no-grow zone should simply be left out of any 
assessment of shallow-water designated-use attainment based on water-clarity acres or 
on a CFD-based assessment of water clarity criteria attainment. 
In the case of the eight segments where the entire shallow-water area was delineated 
as an SAV no-grow zone (see pages 108-110 in U.S. EPA 2003b), the best available 
information indicates the shallow-water bay grass designated use is not appropriate. 
The EPA recommends that this designated use not apply to (or that it be removed 
from) any segment in which the area encompassing the entire 2 meters or less 
shallow-water habitat be delineated as an SAV no-grow zone (Table V-l). 
Table V-l is an updated version of Table IV-3 originally published on pages 62-63 
in the 2003 Technical Support Document for Identification of Chesapeake Bay 
Designated Uses and Attainability (U.S. EPA 2003b). This revised table documents 
the above-described segments that are entirely SAV no-grow zones (where the 
shallow-water bay grass designated use does not apply) or had no previously estab¬ 
lished SAV restoration goal. This table includes a list of all the Chesapeake Bay 
Program segments in the Chesapeake Bay, its tidal tributaries, and its embayments 
(U.S. EPA 2004b, 2005) as well as the sub-segments delineated by Maryland and 
Virginia (U.S. EPA 2004c). 
WATER CLARITY CRITERIA REFERENCE CURVES 
The original 2003 Chesapeake Bay water quality criteria document included biolog¬ 
ical reference curves to assess attainment of the water clarity criteria using the CFD 
methodology (see pages 173-176 and Appendix H in U.S. EPA 2003a). Those refer¬ 
ence curves were developed using data collected as part of the Chesapeake Bay 
Water Quality Monitoring Program in which the monitoring stations are located in 
open, mid-channel areas of Chesapeake Bay, its tidal tributaries, and its embay¬ 
ments. Use of the fixed-station, mid-channel water quality data was necessary even 
though these data are not necessarily representative of the Bay's shallow-water habi¬ 
tats; sufficient data more representative of the shallow-water habitats were not 
available (see Chapter 9 in Batiuk et al. 2000). 
Efforts are underway through the Chesapeake Bay Shallow-water Monitoring 
Program to collect water clarity data for use in generating more appropriate biolog¬ 
ical reference curves. These data are being collected (see Chapter 7 for additional 
detail) in the same way that shallow-water designated use areas will be assessed. The 
resulting biological reference curves will, therefore, be directly comparable to the 
CFD assessment curves (see Chapter 2 for further details). Further refinement of the 
existing published water clarity criteria biological reference curves (e.g., updating 
with more recent mid-channel data, developing four salinity-regime-based curves) is 
chapter v 
Refinements to the Shallow-Water Designated-Use Assessment Procedures 
