Digital Line Graph (DLG)
A Digital Line Graph (DLG) is digital vector data representing cartographic information. DLGs contain a wide variety of information depicting geographic features (for example, hypsography, hydrography, boundaries, roads, utility lines, etc). DLGs are derived from hypsographic data (contour lines) using USGS 7.5-minute, 15-minute, 2-arc-second (30- by 60-minute), and 1:2 million-scale topographic quadrangle maps.
For more information about DLGs, please visit 
http://craterlake.wr.usgs.gov/dlg_brief.html.
DLG Download
The following DLG data have been mosaicked together from the18 7.5-minute quadrangles that cover the Lake Tahoe Basin. The mosaicked files are more convenient for looking at areas throughout the basin or areas on the edge of two quadrangles.
DLGs are in UTM NAD27 zone 10 projection. Raw (original) data are in the following projections: data east of 120 degrees longitude are in UTM zone 11 and data west of 120 degrees longitude are in UTM zone 10. It is not possible to combine different projections in Geographic Information System (GIS), therefore, all data have been reprojected into one standard projection, UTM NAD27 zone 10 projection, for the Lake Tahoe Basin.
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The following DLG data are stored in three different file formats, each contain the same information:
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Click on the above image to view a more detailed image and the legend.
USGS stream-flow data can be downloaded at
http://waterdata.usgs.gov/nv/nwis/rt.
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Welcome Digital Data General |
