Abstract: Basin governance in China is currently transitioning from water quality-oriented control to multi-dimensional coordination,with the Three-Water Coordination (TWC)-the coordinated management of water resources,water quality and aquatic ecosystems-as a framework for advancing basin-scale systemic governance.This study identifies key challenges in basin governance regarding objectives and evaluation systems,governance modes,and implementation pathway,and distil the core elements of TWC across value,institutional and governance dimensions.TWC is proposed as a synergistic paradigm in which water resource cycling and balance provide the foundation,water quality protection and improvement act as safeguards,and ecological health and sustainability constitute the ultimate objective.This framework is characterized by cross-scale integration,whole-process coupling,multi-objective optimization and systemic coherence.The study further demonstrates that identifying the interactions among materials and their environmental effects,along with monitoring and quantifying associated fluxes,provides the scientific basis for implementing TWC,emphasizing the joint regulation of abundance and structure,storage and function,and temporal-spatial consistency.Using the Lake Dianchi Basin,a national priority watershed in China,as a case study,an integrated simulation and dynamic optimization model linking water resources,water quality and ecosystem processes is developed.It enables the construction and projection of a four-tier coordination strategy spanning lake,river network,basin and inter-basin scales,and allows evaluation of its system-wide benefits.The results provide a transferable pathway for operationalizing coordinated water governance and offer actionable insights for sustainability transitions in coupled human-water systems.