Can users who have linked attributes to EPA Reach File Version 3 (RF3) move those attributes to NHD?
In the process of building the NHD from RF3 and DLG3 (Digital Line Graph Version 3), the rules for delineating reaches were changed in some significant ways. For example, RF3 has reaches on the shorelines of wide rivers and lakes, while NHD has reaches on artificial paths that run through wide rivers and lakes. Another example is, RF3 did not have waterbody reaches and NHD does. Consequently the spatial representation of an RF3 reach will not equal the spatial representation of an NHD reach in some cases. However, a large number of RF3 reaches are 1-1 with NHD reaches. For example, almost all of the single line stream confluence-to-confluence reaches in RF3 have the same spatial extent in NHD. (The coordinates in NHD are more accurate/precise than those in RF3 and you will generally see a slight shift in the line work between RF3 and NHD.) It is important to know that even the reaches that are 1-1 between RF3 and NHD will have new reach codes. The reach code in RF3 was CU+Segment+Marke
