National Wetlands Inventory Data Acquisition and Processing

Although the National Wetlands Inventory is contained within the U.S. Fish and Wildlife Service, NWI data sets are compiled within the U.S. Geological Survey, from their topographic quadrangles and aerial photographs, and stored within their archives. Most of the wetlands of the United States have been mapped by the Inventory, but not all of the resulting maps have been digitized and stored as digital information. The USGS maintains a status report on their web site which shows the areas that have been mapped and that have been digitized; the areas are digitized when an entity is willing to pay to have it done.

The U.S. Fish and Wildlife Service National Wetlands Inventory homepage directs the viewer to several data sources:

• National Wetlands Inventory

In areas which did not have the NWI information to combine with the TM imagery to run the Coastal Marsh Project (CMP) model, the results are not trustworthy and are noted as such. The CMP downloaded the digitized coverages from the NWI ftp site and uncompressed them as the directions indicate.