Some 200 quads of data are based on USGS quadrangle maps, which vary widely in vintage from the early 19980s to early 1990s. The DNR 24K Streams data layer is integrated with this layer in the sense that streams flowing into and out of lake and river polygons end and begin at coordinate coincident locations along the polygon delineations. No quantitative assessment of attribute acuracy has been conducted, although qualitatively speaking, data from the NWI source are generally considered to be good representation of open water at the mapping scale. Assignment of DOW Numbers, Lake Names, and Alternate Lake Names were made using automated processes from other sources, and can be expected to contain errors. These features have not been checked exhaustively for correctness.
All lines intersect where intended.
NWI habitats that fall entirely within DNR lake polygons have been retained even if they do not meet the selection criteria. No known quantitative studies of horizontal positional accuracy exist for the data. Vertical Positional Accuracy Not Applicable Lineage Data exhibit two separate lineages. Other NWI types were retained if they were completely surrounded by open water types. Data were then restructured into the final design by examining topological relationships between polygons to correctly code them.