Safeguarding drinking water for 7 million people and avoiding the relocation of 550,000 residents, this pioneering project in a dense urban core created China’s first ecological reservoir adapted to local conditions. Through isolation, connectivity, and ecological restoration, it effectively addressed non-point source pollution while restoring habitats. Leveraging Jiuwei Lake Wetland construction and adjusting a first-class water source protection zone into a quasi-protection zone, it integrated land development with reservoir improvement, unlocked land value, and set a globally model.