Multifunctional aerators were installed in Hiyoshi Dam in Kyoto to oxygenate the deep anaerobic water layer and destroy the thermal stratification in the shallow layer. In August of 2011, field experiments were performed to ascertain the effect of thermocline destruction. In the experiments, the temperature and flow distributions were directly measured near one of the aerators with a high spatial and temporal resolution, and a video camera clearly captured images of water containing sediment that was lifted from the deep layer. Analysis of the data confirmed that the thermocline in the shallow layer was destroyed within an 8-10m radius of the aerator and to a 3m depth in a period of 10minutes, and a horizontal intrusion was present at a depth of 2.7m in the external region. In addition, to assess the performance of the aerator for thermocline destruction, the thermal energy, potential energy and circulation flow rate were also investigated.