Chesapeake Bay SAV data were mapped from aerial photography, primarily at a scale of 1:24,000, for the
following regions: western shore, Va. only - 1971 & 1974; lower Bay, Va.
only - 1980 & 1981; upper Bay, selected sections, 1979; Baywide, 1978, 1984
- 1987, and 1989 - 2006. Each area of SAV was classified into one of four
density classes by the percentage of cover as determined from the aerial
photography (methodology is described in each annual report - e.g. see
Orth et al., 2007). The SAV beds are stored
as ArcInfo GIS coverages using the quality control procedures documented
in the individual metadata files. Data were collected by the Virginia
Institute of Marine Science and can be attributed by including a reference
to the associated annual SAV distribution and abundance report.
The SAV data files are in uncompressed ArcInfo (ESRI, Redlands, CA)
export format. They have been compressed using pkzip compression to form .zip
files for use on IBM-compatible personal computers and also compressed using
unix standard compression to form .tar.Z files for use on unix platforms. Each
file contains both the .e00 ARC/INFO export file and also a .txt metadata file.
Please consult the metadata file to determine if a particular dataset will
satisfy your needs.