The inflow and outflow of Lake Taihu have changed over the years due to various measures. Data from 1986 to 2017 shows a significant increase in annual total inflow and outflow. The increase in inflow is mainly from Jiangsu Province, while Zhejiang Province saw a smaller change. Wangyu River had the highest inflow increase rate. These changes have raised the water levels in Lake Taihu, with little impact on the maximum water level. The impact of hydrological engineering on the lake's water flow is becoming more important.