of this methodology, each Chesapeake Bay Program segment (see Figure VI-1 and 
Table VI-4) has an underwater bay grass restoration goal acreage, with the exception 
of those segments documented as underwater bay grass no-grow zones along their 
entire shoreline, with the total acreage summed up from all segments equaling 
185,000 acres. 
In adopting and implementing their water quality standards for protecting the 
shallow-water bay grass designated use, states may: 1) adopt the segment-specific 
underwater bay grass restoration goal acreages that make up the baywide 185,000 
restoration goal; or 2) adopt a lower initial Chesapeake Bay Program segment- 
specific underwater bay grass acreage, below the established goal acreage for a 
segment, and use their upcoming triennial reviews of state water quality standards to 
continually evaluate and appropriately increase the segment-specific acreages 
towards the ultimate underwater bay grass restoration goal acreage. If states choose 
to adopt a lower initial segment-specific acreage, at a minimum they must adopt an 
underwater bay grass acreage for that Chesapeake Bay Program segment equal to or 
greater than the existing use underwater bay grasses acreage defined as either the 
single best year of composite acreage of underwater bay grasses mapped through the 
baywide underwater bay grasses aerial survey since 1975. The Chesapeake Bay 
Program segment-specific acreages that, added together, make up the baywide 
185,000 restoration goal are documented in the Technical Support Document for the 
Identification of Chesapeake Bay Designated Uses and Attainability along with the 
segment-specific existing use underwater bay grasses acreages (U.S. EPA 2003). 
Achieving the Chesapeake Bay Program segment-specific underwater bay grass 
restoration acreages should be measured as the single best year of acreage as 
observed through the most recent three years of data from the Chesapeake Bay 
underwater bay grasses aerial survey. All mapped acreages of underwater bay 
grasses in a segment should be counted towards achievement of each segment- 
specific restoration goal regardless of the depth. Chesapeake Bay segment level 
acreages of underwater bay grasses are published annually and can be accessed 
through the Chesapeake Bay Program’s web site at http://www.chesapeakebay. 
net/data, or directly through the Virginia Institute of Marine Science’s “Bay Grass in 
Chesapeake Bay and Delmarva Peninsula Coastal Bays” web site at http://www. 
vims.edu/bio/sav/index.html. 
Assessing Water Clarity Criteria Attainment at an Established Applica¬ 
tion Depth. The recommended method for assessing water clarity criteria 
attainment is, first, to interpolate monthly values of to obtain a K d value for each 
interpolator cell, then to calculate PLW for each cell using the interpolated value of 
IQ and the Chesapeake Bay Program segment-specific shallow-water bay grass 
designated use boundary depth (see U.S. EPA 2003 for a full listing of the recom¬ 
mended shallow-water bay grass designated use boundary depths). Note that for 
statistical reasons, the interpolations are performed using a log transformation of the 
light values (logfK^). The resulting interpolated cell values are converted back to 
their untransformed status for the PLW calculation. 
chapter vi • Recommended Implementation Procedures 
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