This freshwater input corresponds to a depth of of water distributed over the area of the sound per year. The freshwater input is highly variable. In a typical year there are several events where the daily rainfall exceeds and the river flow exceeds . The freshwater inflow generates an estuarine circulation in the main channel, with low-salinity water moving outwards at the surface, and higher-salinity water flowing inwards below. The currents in the main channel associated with this circulation are typically , but immediately after a flood event they can be much larger. Fresh water layers have been observed to spread through the Sound at . After each flood event, the freshwater is slowly flushed out of the sound, with a flushing time estimated to be 21 days.