Extensive field checking was done on many of the quads. The coverage windex, same location, includes attributes for the completion status of each quad or sub-quad areas. The spec for maximum error for any control point is 50 feet, which is slightly exceeded in some cases. Regardless of specifications, the actual linework may have larger displacement error in some locations where position control was very limited. The main source of positional error, in general, is from due to the difficulty of delineating wetland boundaries in transitional areas.
Classification is based on species recognition by interpreters, resulting in high thematic accuracy.
Accuracy is greater for classes such as water and cypress, and can be less for certain mixed classes that intergrade. For example, Hardwood Swamp can be confused with Hydric Hammock in transitional areas. Accuracy varies for different locations, dates, and interpreters. Drained wetlands are mapped as uplands if wetlands vegetation is not present, or if land is farmed or developed. Managed forests in hydric areas may be mapped as Forested Depression - Pine or as uplands.