The Royal Irrigation Department (RID) has been collecting hydrological data from various streams and rivers for a long time. The data collection process is mainly done by taking notes on paper, which is quite dated and cumbersome. Recently, data are now reported by phone calls and chat applications, but it still takes a lot of time and not convenient to manage. This article presents the semi-automatic hydrological data collection system via smart phone, which was developed to facilitate the data collection process for RID staff. The application supports four kinds of data collection: water level, water quantity, precipitation, and survey location. The water-level page allows collection of both manual reading by sight and automatic reading via Bluetooth. The other three pages support manual measurements only. Evaluation shows that the system can ease the staff operation by reducing the overall data recording time.