Import MODFLOW Packages The Import MODFLOW Packages command displays six additional commands (Drain, General Head Boundary, River, Well, Evapotranspiration, and Recharge) all designed to import MODFLOW data files. The files must be in text format and in the standard input format for the respective package. Each command displays a Windows Open dialog box. Only files with a relevant extension are displayed. For example, if you would like to import the MODFLOW drain package, the extension is drn (ghb for General Head Boundary; riv for River, wel for Well, evt for Evapotranspiration, and rch for Recharge). Importing adds cell stresses to the existing cell stresses in the model and replaces existing data on recharge and evapotranspiration. Consult Chapter 4 for additional information on these commands.