63 
unique zone codes, for example, there may be 463 cells that were in attainment for 
cells in 1-2 m of depth, where current and historic SAV are present. 
ACCESS is used to calculate water clarity acres by initially converting cell counts of 
attainment into acreage of attainment inside and outside of current SAV areas for 
each segment. Water clarity acres for the segment are then calculated by the taking 
the annual mean of the monthly acreage. Finally, the annual water clarity acreage is 
compared with the segment goals as defined in DEQ document 9 VAC 25-260 
Virginia Water Quality Standards (2005). 
_I_ 
K d Thresholds: < 1.51 (0-1 m), < ,76(1-2m) 
t 
Figure E-4. The Kd grid is compared to the appropriate «d threshold on a cell by cell basis 
to create the attainment grid. 
Figure E-5. Chesapeake Bay exclusion zones are removed from further analysis. 
appendix e 
Chesapeake Bay Water Clarity Assessment Framework 
