Thus, a detailed on the ground and historical analysis of a single site may result in a revision of the wetland boundaries established through photographic interpretation. In addition, some small wetlands and those obscured by dense forest cover may not be included in this dataset. 7.5 minute quadrangles along the Minnesota border with the exception of Wisconsin contain data from adjacent states. Horizontal Positional Accuracy Horizontal positional accuracy for the digital data is tested by visual comparison of the source with hard copy plots. Enhanced digital data is also snapped to existing quadrangle boundaries and is compared to adjacent files.
Files contain ground planimetric coordinates and wetland attributes.
The determination of scanning versus manual digitizing production method was based on feature density, source map quality, feature symbology, and availability of production systems. The data were checked for position by comparing plots of the digital data to the source material. DLG data was downloaded from NWI ftp server for all of Minnesota. Wetland codes for each 7.5 minute quadrangle were loaded into a statewide NWI code list from which a unique code number was assigned for each wetland type. These data were changed into the correct upper and lower case codes.