Abstract: Detention and retention basins are an important part of China′s flood control systems.Safety construction projects of detention and retention basins involve a wide range of areas and include a variety of point and linear engineering projects.The implementation of these projects may have an adverse impact on water quality of ecologically sensitive areas and drinking water source protection zones.This paper takes the Zhuhu Lake detention and retention basin as an example and uses lake dispersion decay model and lake fully mixed model to simulate the changes of SS and TP concentration during the construction period and operation period, and analyzes their impact on sensitive water environment targets.The results show that the main unfavorable water environment impact from the project would occur during the construction period.The construction-related water activities cause the diffusion of SS exceeding the background value within about300m range and the diffusion of TP exceeding the background value within about210m range, which has a certain impact on water quality of the drinking water source protection zone.During the operation period, the pollutants carried by floodwater affect the water quality of Zhuhu Lake, but the overall water body of Zhuhu Lake can still meet the Class Ⅲ water quality standard.The operation of the detention and retention basin reduces the water environment risk during excessive floods.This study provides a basis for the water environmental protection of the detention and retention basin safety construction project in Poyang Lake and serves as a reference for the environmental protection work of other detention and retention basins.