National Wetlands Inventory Case Study

Introduction
The National Wetlands Inventory (NWI) is a program administered by the US Fish and Wildlife Service (USFWS). The program, which was initially put into place in 1974, was tasked with creating and maintaining a nationwide inventory of wetlands and waterbodies in order to provide geospatial maps showing the distribution and extent of wetlands and waterbodies within the U.S. in order to aid planning, management, and wetland conservation efforts.
The NWI maps were never intended to be used as an exceedingly accurate assessment, but were instead intended to be used in identifying general extents and trends in land use, ecological health, and development. However, these maps are often used by both private and governmental entities as an accurate representation of wetland locations and extents, an example of such use illustrated by the attempt of the plaintiffs

wetlands. In order to do this, the NWI developed and utilizes a wetland classification system based on Cowardin et al. (1979). Utilizing this system, image analysts identify and classify wetlands and deepwater habitats from aerial photograph interpretation coupled with field-verification to ensure method accuracy. This information was formally only available as paper maps or transparent overlays, but data is now available through online mapping tools and standardized GIS information.
The NWI is a low-funded program and is not routinely updated. As such, its accuracy within any given area is highly variable.
Objective
The objective of this study is twofold. One – to identify overall accuracy in NWI indicated wetlands and waterbodies utilizing both public and privately gathered data and Two – Identify trends in accuracy so as to provide potential predictive tools for NWI usage depending upon wetland or waterbody type, county, ecoregion, or U.S. Geological Survey (USGS) 7.5 Minute