Problem: IHydrologyOp.Fill leaves temporary intermediate grids in the working directory
The IHydrologyOp.Fill method generates output as a temporary grid. This output is deleted from the working directory unless it is saved; however, intermediate temporary grids are left behind in the working directory.
This is a known problem with ArcGIS 8.1.
Solution or Workaround
This issue has been addressed in ArcGIS Version 8.1.2.
In ArcGIS 8.1, use ArcCatalog to delete the intermediate temporary grids.