) 
adopted a bay wide underwater bay grasses restoration goal of 185,000 acres. This 
baywide restoration goal was established “to reflect historic abundance, measured as 
acreage and density from the 1930s to present” ( Chesapeake 2000, Chesapeake 
Executive Council 2000). 
The single best year of underwater bay grasses growth observed in each Chesapeake 
Bay Program segment from the entire available record of aerial photographs (1938- 
2000) was determined by state and federal agency resource managers and 
Chesapeake Bay scientists as the best available data on underwater bay grasses 
occurrence over the long-term. The underwater bay grasses goal acreage was set 
using the single best year acreage out to a Chesapeake Bay Program segment- 
specific application depth determined as summarized in Table VI-6 and described in 
detail in the Technical Support Document for the Identification of Chesapeake Bay 
Designated Uses and Attainability (U.S. EPA 2003). Based on the implementation 
Table VI-6. Methodology for establishing the 185,000 Chesapeake Bay baywide 
underwater grasses restoration goal. 
The baywide underwater bay grasses goal acreage was set using the single best year 
acreage out to an application depth determined as follows: 
1. Bathymetry data and aerial photographs were used to divide the single best year 
underwater bay grasses acreage in each Chesapeake Bay Program segment into three 
depth zones: 0-0.5 meters, 0.5-1.0 meters and 1-2 meters. 
2. The aerial photographs were then used to determine the maximum depth to which the 
underwater bay grass beds grew in each segment with either a minimum abundance or 
minimum persistence. The underwater bay grass goal for a Chesapeake Bay Program 
segment is the portion of the single best year acreage that falls within this determined 
depth range. The decision rules for this were as follows: 
In all segments, the 0-0.5 meter depth interval was designated for shallow-water 
bay grass use. In addition, the shallow-water bay grass use was designated for 
greater depths within a segment if either: 
A) The single best year of underwater bay grasses distribution covered at least 
20 percent of the potential habitat in a deeper zone; or, 
B) The single best year of underwater bay grasses distribution covered at least 
10 percent of the potential habitat in the segment-depth interval, and at least 
three of the four five-year periods of the more recent record (1978-2000) 
show at least 10 percent SAV coverage of potential habitat in the segment- 
depth interval. 
3. The single best year underwater bay grasses distribution acreage of all Chesapeake 
Bay Program segments were clipped at the deeper depth of the segment-depth 
interval, determined above. The resulting underwater bay grass acreages for each 
segment were added, resulting in the total baywide underwater bay grass restoration 
goal of 185,000 acres. 
Source: U.S. Environmental Protection Agency 2003 
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chapter vi 
Recommended Implementation Procedures 
