These elevation contours were extracted from USGS 7.5 minute (1:24,000 scale) hypsography DLG data and converted to an ArcView shapefile.
Digital line graph (DLG) data are digital representations of cartographic information. DLG's of map features are converted to digital form from maps and related sources. All DLG data distributed by the USGS are DLG - Level 3 (DLG-3), which means the data contain a full range of attribute codes, have full topological structuring, and have passed certain quality-control checks.
- ''Depth curves'' for lakes are included in this layer.
- Quad tiles were not edgematched, therefore contours do not necessarily line up across tile boundaries.
- Some DLG vectors represent more than one elevation (e.g., a cliff).
- Entire seven county geographic area is covered.