Behaviour inspection of huge dams is a very important procedure for dam failure prevention as early fault detection could reduce potential losses or damages. Traditionally, a behaviour inspection requires a lot of man-power and is not practical in some situations where critical inspection points are not accessible. This paper presents a design and implementation of Supervisory Control and Data Acquisition (SCADA) System applied to Rajjaprabha Dam, Suratthani, Thailand. The system includes 37 water-level sensors, 11 Remote Terminal Units (RTUs), and a weather station. This system is designed to meet requirements such as cost effectiveness, system reliability and low power consumption. The behaviour inspection system has been under field testing and the results have been highly satisfactory.