Data of studies of 2013-2019 were used to assess the current environmental-geochemical conditions of surface water and groundwater in the basin of the Ganjiang River, the largest tributary of Poyang Lake (China). The main objects of studies were the Ganjiang River, its tributaries-the rivers of Jinjiang and Yuanshui, groundwater of quaternary deposits in the valleys of the Ganjiang River and its tributaries, and the domestic and industrial wastewaters reaching the Jinjiang River. The analysis of the results included estimating the background concentrations of substances; the comparison of the chemistry of surface water and groundwater with the background characteristics and standards for domestic water quality accepted in Russia and China; the estimation of the saturation indices of river water, groundwater, and wastewater by some minerals and organomineral complexes; correlation and regression analyses aimed at revealing relationships between geochemical characteristics. In addition, the anthropogenic effect on the state of the Jinjiang River and groundwater in the Ganjiang River basin was evaluated by solving the diffusion equation and the transport equation, respectively. The conditions of water objects were found to be unsatisfactory because of the high concentrations of several toxic trace elements in individual river segments and groundwater; however, in general over many-year aspect, it satisfies drinking water quality standards introduced in China (by the total proportions between the actual and allowable concentrations). The state of the studied groundwater was poorer than that of surface water. This is due to the higher self-purification capacity of surface water in the region because of precipitation of poorly soluble compounds, coprecipitation of some trace elements on particles of river load and bottom sediments, and more intense water exchange.