Many hydrological observation stations for rainfall, pan evaporation and stream flow, etc. were installed by the Royal Irrigation Department for agricultural development. Collected data are processed in a mainframe computer and published in the form of a Water Year Book every year. However, many technicians prefer to consult hydrological data such as hydrographs and discharges on an individual basis. In order to promote the effective utilization of hydrological data, it is important that the data be available to the technicians at their station. Therefore, personal computer software for observed hydrological data suitable for the Microsoft Windows operating system was developed by the authors.