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Frequently
Asked Questions
- How
can I view NWI maps?
- How
do I know what NWI GIS data is available for a particular area?
- How
can I obtain information on purchasing other NWI products?
- What
projection are the maps?
- How
can I find out what an NWI map code means?
- Where
can I find metadata for NWI quads?
- How do I cite NWI digital data, hard-copy maps, and metadata in publications?
NWI data can be viewed without GIS software on the Wetlands Interactive Mapper. NWI maps for GIS use are available in three formats - Arc Export (.e00), Shapefiles, and personal geodatabases (downloads.htm). They are NOT images (GIFs, JPEG's). GIS software is needed to process NWI digital data into a viewable form. For examples of GIS software go to http://www.esri.com.
How do I know what NWI GIS data is available for an area...
at a glance?
Go to the Regional status maps.if I know the name of the map I want?
NWI digital map data are organized in folders by USGS 1:250,000 map name. To determine which name and corresponding folder you may need, on the Downloads page click on the searchable file, "View and Query NWI digitized data in NAD27." If there is an asterisk before the abbreviated quad name, also check "View and Query List of Updated NWI digitized data in NAD83." In each list, using the browser's toolbar Edit, "Find (on This Page)" feature, enter the map name you are seeking. The first column indicates the 1:250,000 name, plus the quarter quadrant identifier (NE,NW,SE,SW) used for organizing maps. If the digital map data is not located on either list, there are no digital data available. For further assistance, click on the Contact Us at the bottom of the page.
if I don't know the name of the map I want?
Go to the Interactive Wetland Mapper and zoom in (or enter zip code, city, or county in the search box) to the location on the map for the area you are seeking . Use the Legend/Layer List tool to make active the wetlands layer by clicking in the circle before the word Wetlands. Once the wetlands layer is the active layer, use the Identify tool to select a wetlands feature on the map. In the Identify box that is generated, a shortened version of the 1:250,000 and 7.5' map name will appear under Quad Name (ex: washington/alexan). Once you have the quad name, you can follow the instructions above to find the folder for the digital data. If no wetland features are present, the area does not have digital data available. If no digital data is available, check the Status Maps to see if hard-copy maps are available for purchase through a Cooperator-run Distribution Center.
How can I obtain information on purchasing other NWI products?
National Wetlands Inventory maps can be purchased through various Cooperator-Run Distribution Centers. Each Center establishes its own pricing structure, product types and ordering procedures. The Distribution Centers offer paper composites of the NWI maps. Mylar copies and requests for separate NWI overlay copies that do not include the USGS topographic base will no longer be available.
NWI digital quads are projected using the Universal Transverse Mercator (UTM) projection. The units are in meters and the Datum is NAD27 (North American Datum) for the older maps in ARC data, NAD83 for newer ARC data maps created using "heads-up" technologies, and NAD83 for all the Shapefiles data and geodatabases.
How can I find out what an NWI map code means?
To make it easier to find the definition of a wetlands map code, NWI has added to our website the NWI Map Codes Query Form. Definitions provided through this form are based on the attribute classification definitions derived from the Cowardin classification standard. Users can enter a valid wetland classification code and the program will decipher exactly what the code represents. For example, if you're wondering what a PUBHh is, just type it into the NWI Map Codes Query Form, it will give you an explanation. (It's a Palustrine, Unconsolidated Bottom, Permanently Flooded, Diked/Impounded wetland.) The NWI wetland codes are based on the National Wetlands Classification Standards from Cowardin, L.M., V. Carter, F. Golet, and E. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service (Cowardin).
Where can I find metadata for NWI quads?
Standard metadata is available for citation for publication, description of maps, purpose of mapping, constraints on data use, consistency, completeness, scale, contributing data sources, datum, etc. Quad specific metadata can be found in the NWI Maps Database. The search form allows a user to do a search by quad name and all information about the quad will be returned. For a brief description of metadata, go to our metadata page.
How do I cite NWI digital data, hard-copy maps, and metadata in publications?
For NWI digital data downloaded from our website: U. S. Fish and Wildlife Service. publication date. National Wetlands Inventory website. U.S. Department of the Interior, Fish and Wildlife Service, St. Petersburg, FL. http://www.nwi.fws.gov.
For NWI hard-copy maps: U. S. Fish and Wildlife Service. publication date. National Wetlands Inventory map: Map name, State (scale 1:XX,XXX). U.S. Department of the Interior, Washington, D.C.
For NWI maps metadata: U. S. Fish and Wildlife Service. publication date. National Wetlands Inventory metadata. Metadata Standard Version 19940608. U.S. Department of the Interior, Fish and Wildlife Service, St. Petersburg, FL. other/metadata/nwi_meta.txt.