Abstract: To predict the time scale for the effects of salt release from sediments on estuary reservoir water, a transient diffusional model was developed to describe the profile of salts in the pore water of sediments. The upper boundary condition and the salt diffusion coefficient of this model were optimized to decrease the uncertainty of the simulation results. A comparison of the transient and steady state release of salts from sediments shows that transient release agrees well with the actual process. The result of a transient simulation for salt release illustrates that it takes more than 600 years for saline sediments to affect the fresh overlying water in the Muguandao Estuary Reservoir. This duration is significantly longer than the life span of a reservoir. The result suggests that instead of measures being taken only at the early stage of an estuary reservoir, effective measures such as periodic monitoring of benthic water and discharging of benthic brackish water should be implemented to prevent salinization throughout its life cycle.