Abstract: The difficulty of getting through the "last mile" is relatively common in the implementation of grassroots policies, which also exists in the water environment governance with the river chief system, reflected in the operational situation of "policy makers are keen but executors are indifferent", the policy making and implementing means of "one size fits all", the "unshakable interest groups" in grassroots governance, the strategic execution driven by responsibility avoidance, and the embarrassment of technology empowering grassroots policy implementation. From the perspective of "poor power and heavy responsibility", the factors such as the low governance power and the river chief system as a temporary agency, the task setting of "passive acceptance" and "the transfer of power", and the dissolution and counterbalancing function of informal relations on bureaucratic power lead to "the pony pulls the cart"; while the contradiction between layer upon layer compacting tasks and the overburden at the grassroots, the helplessness of fast-changing policies and vertical coordination, and the mechanism of weak incentives and strong accountability lead to "the cart drags the pony". The "poor power and heavy responsibility" in the grassroots water control reflects the dynamic game between vertical bureaucracy and flat governance. How to resolve the contradiction between authority system and effective governance remains to be further explored.