Water transfer is becoming a popular method for solving the problems of water quality deterioration and water level drawdown in lakes.However,the principle of choosing water sources for water transfer projects has mainly been based on the effects on water quality,which neglects the influence in the variation of phytoplankton community and the risk of algal blooms.In this study,algal growth potential (AGP) test was applied to predict changes in the phytoplankton community caused by water transfer projects.The feasibility of proposed water transfer sources (Baqing River and Jinsha River) was assessed through the changes in both water quality and phytoplankton community in Chenghai Lake,Southwest China.The results showed that the concentration of total nitrogen (TN) and total phosphorus (TP) in Chenghai Lake could be decreased to 0.52 mg/L and 0.02 mg/L respectively with the simulated water transfer source of Jinsha River.The algal cell density could be reduced by 60％,and the phytoplankton community would become relatively stable with theJinsha River water transfer project,and the dominant species of Anabaena cylindrica evolved into Anabaenopsis arnoldii due to the species competition.However,the risk of algal blooms would be increased after the Baqing River water transfer project even with the improved water quality.Algae gained faster proliferation with the same dominant species in water transfer source.Therefore,water transfer projects should be assessed from not only the variation of water quality but also the risk of algal blooms.