BASINS 4.0 -- March 2007 If this computer has an earlier (beta) version of BASINS 4: Any previous version of BASINS 4 should be uninstalled before proceeding. If this computer has BASINS 3.1 installed: Adding BASINS 4 will replace some of the files used by BASINS 3.1. Both should still function properly, but if BASINS 4 is removed, then BASINS 3.1 will need to be re-installed.