Import MODPATH Main Data File The Import MODPATH Main Data File command displays a Windows Open dialog box. Only files with a dat extension are displayed. The main MODPATH data file contains information on the top and bottom elevations of model layers that standard MODFLOW import packages lack. Graphic Groundwater ignores redundant data. In other words, Graphic Groundwater will not read data normally contained in a MODFLOW input file. Consult Chapter 4 for additional information on this command.