Abstract: To ensure the safety of drinking water for residents, it is particularly important to understand the water environment characteristics and potential pollution risks of drinking water sources.Taking two drinking water source sections(Qingyun Water Plant and Chaoyang Water Plant) and their upstream and downstream sections in Nanchang City(West Lake section) of the Ganjiang River as the research subjects, the water environment status of each section was investigated and analyzed, and the pollution attenuation and diffusion process in the upstream of the water source area was deduced.According to GB3838—2022Surface Water Environmental Quality Standards, the water quality safety level of the drinking water source was judged.By analyzing the phosphorus release rate and phosphorus form characteristics of sediment in water bodies, we evaluated the pollution risk of endogenous phosphorus release in drinking water sources.The results showed that:(1) The water quality of the key sections on Ganjiang River(West Lake section) was Class Ⅱ water, and the chemical oxygen demand(COD) of the section of Qingyun Water Plant exceeded the Class Ⅱ water standard in June2022.(2) Qianhu Electric Discharge Station, a large-scale sewage outlet upstream of the drinking water source, would downgrade the water quality according to simulation results.(3) The total phosphorus(TP) content in sediments of the Ganjiang River(West Lake section) was generally in a state of mild to moderate pollution.The main form of phosphorus in sediments was iron aluminum-bound inorganic phosphorus(Fe/Al-Pi),followed by moderately active organic phosphorus(MA-Po) and calcium-bound inorganic phosphorus(Ca-Pi),with average proportions of32.56%,20.72%,and19.4%,and average contents of123.17,78.36,and73.38mg/kg, respectively.The organic matter(OM) content exhibited a significant correlation with the TP content(R=0.873,P≤0.05),and Fe/Al-Pi content(R=0.949,P≤0.05).(4) The section of Qingyun Water Plant had the highest phosphorus release rate(vP),indicating a high risk of phosphorus release.It is recommended to continuously monitor the water quality at upstream and downstream sections of the drinking water source, and closely monitor the TP index change of the Qingyun Water Plant section; regularly inspect and trace the water drained from the Qianhu Electric Discharge Station to avoid mixing of rainwater and sewage or the direct discharge of wastewater into the river; strengthen the standardized construction and management of riverside drinking water source protection areas, and reduce the impact of human activities on the water environment.The research results can provide certain references for scientifically ensuring the safety of urban drinking water.