The East Route of the South to North Water Diversion Project (ER-SNWDP) spans the four major river basins of the Yangtze, Huaihe, Yellow and Haihe rivers. The ER-SNWDP connects lakes and reservoirs such as Lake Gaoyou, Lake Hongze, Lake Luoma, Lake Nansi, Lake Dongping and Beidagang Reservoir from south to north through the Beijing-Hangzhou Grand Canal and water conveyance canals, providing water resources for industrial and agricultural development, domestic and ecological use in the eastern part of the Huaihe-Haihe-Yellow River Plain, the Jiaodong region and the Tianjin-Hebei region. The lakes along the ER-SNWDP are key nodes and play an important regulating and storage role for water diversion. Meanwhile, the lakes act as purifiers and important "green kidneys" to improve water quality and ensure the safety of water transmission and supply in the ER-SNWDP. In recent years, under the background of building ecological civilization and maintaining water clear, significant achievements have been made in the management and protection of lakes along the ER-SNWDP, resulting in the improvement of water environment quality. However, under the dual influence of rapid climate change and intensive anthropogenic human activities, water pollution prevention and control, water environment management, and water ecosystem protection and restoration for lakes along the ER-SNWDP still face many serious challenges. This study systematically explores the main ecological services provided by the lakes along the ER-SNWDP in terms of water quantity regulation and purification, drinking water safety, agricultural irrigation and food security, biodiversity conservation, shipping and Grand Canal culture. Several ecological and environmental problems such as water quality deterioration, lake eutrophication, algal blooms and submerged aquatic vegetation degradation have been identified for the lakes along the ER-SNWDP. Protection strategies, including accurate identification of pollution sources, monitoring, early warning and prevention of algal blooms, ecological restoration, multi-department cooperation mechanism are proposed for continuous improvement of water quality and ecosystem integrity, stability and sustainability. All these actions aim to support the national water security strategy of the ER-SNWDP.