USGS Lake Tahoe Data Clearinghouse U.S. Geological Survey Lake Tahoe Data Clearinghouse The National Map Geography Western Geographic Science Center

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.

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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.

DLG of Basin Lake Tahoe.

The following DLG data are stored in three different file formats, each contain the same information:

  • footer image. Spatial Data Transfer Standard (SDTS) format -- files ending in .sdts
  • ARC/INFO export format -- files ending in .e00
  • Shapefile format -- files ending in .shp





Human-made features

DLG Metadata.

Click on the above image to view a more detailed image and the legend.

USGS stream-flow data can be downloaded at footer image.


Digital Data


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