NWI Frequently Asked Questions Tuesday, May 21, 2002
What is NWI data?

The National Wetlands Inventory is digital data describing wetland and upland
habitats in the coastal or near Gulf Coast areas of Louisiana in 1988.

Who created the NWI data for Louisiana?
The USGS National Wetlands Research Center (NWRC) created the NWI data for Louisiana by digitizing 343 1:24,000 NWI maps.. For information specific to NWI data for Louisiana, visit http://sdms.nwrc.gov/pub/la/newla88.html.
How can I view the NWI data? Each NWI quadrangle is an ArcView shapefile. Any program that can read shapefiles can view the NWI data. You can also see the NWI data in a raster format online by using Atlas's Rasterviewer by setting its background to "NWI Data."
Can the NWI data be used with a GIS? Yes! The shapefile format is the native format for ESRI ArcView. Also, Intergraph Geomedia coordinate system files (.csf) have been added so that the shapefiles can register with existing data.
What is the projection of the NWI data? The shapefiles are in UTM zone 15 or 16 north, North American Datum 1983, ground units of meters. Each downloadable Winzip file from Atlas will have information as to whether the shapefile is in zone 15 or zone 16. (Any data east of 90 degrees west longitude is in zone 16; otherwise, the UTM zone will be 15.)
What do the categories of the NWI data mean? See a description of each category in "nwrc_nwi_legend.txt". (On the NWRC site, this file is called "nwrc-nwi.leg".) This file is found in each downloadable Winzip file. The categories are listed in the legend under the map when NWI data is displayed as the background for Atlas's Rasterviewer.
What are the limits of the usage of the NWI data?

For more information about the limit of the NWI data, read the "Use_Constraints" in the metadata file lac88.txt. This file has also been included with each Winzip archive file.

Where can I get more information about GAP data? One way to get more information is to visit the NWI page on the NWRC site http://sdms.nwrc.gov/pub/la/newla88.html and click on the metadata link. Another way is to review the NWI FAQ file by clicking on lac88.txt. This file has also been included with every downloadable Winzip archive file.