This report summarizes the methods and results for mapping submerged aquatic vegetation in Lake
Gaston, with a particular focus on hydrilla. Hydroacoustic data were collected along the entire
littoral zone of the lake. In addition, 867 physical sampling points were collected for species
information.

All of the data in this report were collected between October 16-31, 2007.

The results estimate a total of 1,438 acres of submerged vegetation (29% of the main littoral zone).
Of that total, 1,235 acres were estimated as containing hydrilla (86%). Of the submerged
vegetation beds containing hydrilla, 75% were classified as hydrilla monocultures.
Physical sampling for species characteristics took place at 867 sites, 468 of which had hydrilla
presence (54%). No plants were found at 230 sites (26.5%).

Maps, tables, and statistics of the results are included within the summary report and the Appendix.
The results of this study provide significantly different acreage estimates than the previous lakewide
submerged vegetation studies at the lake (Smart, R.M., et al., 2007, "Lake Gaston Aquatic
Plant Management Strategy Development: Interim Summary Report," U.S. Army ERDC, Vicksburg,
MS). However, drawing direct comparisons between overall SAV and hydrilla bed calculations
between the reports is risky for two reasons: (1) management acres and strategies have adapted in
recent years, which directly affects the aquatic plant population in the lake; and (2) significantly
different methods were used to collect and interpret field data between this report and previous
reports. In that regard, applying a consistent mapping methodology annually will begin to track
changes and better enable year-to-year comparisons of the lake's submerged vegetation and hydrilla
populations within just a few short years.

Sincerely,

Doug Henderson
Commercial Manager
ReMetrix LLC