Fla_deadheader,
From what I've been told at some of the talks, they are thinking the river will be silty for years... it depends on the amount of floods we have in those first few years. Overall, they are thinking the silt and gravel will fill back in on the lower parts of the river, which has been reduced to cobble-sized rocks or bigger over the years... there is hardly any gravel on the river below the lower dam. I believe they plan on removing the upper dam first.
They are predicting the gravel bars out by the entrance to the sea will grow, and Ediz Hook, which is a five? mile long sand spit a couple of miles east of the river mouth... will stop eroding, which it has been for about a hundred years... though it's been fortified with large rip-rap a number of times.