The South-to-North Water Diversion Project (SNWDP) of China is the largest water diversion project in the world to divert water from the Yangtze River to alleviate the pressure of water scarcity in northern China. The eastern route of the SNWDP pumps water from the Lower Yangtze River near Yangzhou, Jiangsu, passes the Beijing-Hangzhou Grand Canal and a series of storage lakes, and finally provides water for provinces of Shangdong and Tianjin. We monitored water quality, plankton, macroinvertebrates, aquatic plants, and fishes in two storage lakes-Gaoyou and Dongping since April 2016 and wanted to detect the effects of the water diversion on lake ecosystems.
The current study showed: (1) water depth increased and varied in the studied lakes; (2) the monitored water quality parameters such as nutrient (nitrate, total ammonia nitrogen, phosphate), total suspended solids (TSS), and conductivity showed seasonal variations in both lakes; (3) heavy metals such as Pb, Zn and Mn showed significantly higher concentrations in summer in both lakes; (4) the abundance of resident fishes (e.g., Culter oxycephaloides Kreyenberg et Pappenheim, Chanodichtys oxycephalus Bleeker, Abbottina rivularis) was reduced while lake-river migration fishes (e.g., Mylopharyngodon piceus, Ctenopharyngodon idellus) were increased in both lakes; and (5) the estuary fish Taenioides cirratus was also observed in the Gaoyou Lake. The operation of the eastern route SNWDP could change the structure and function of the associated lakes significantly and needs more attention in the future.