Nothing against a barrage as such but I have an interest in the impact of silting in this area.
By comparison with old photographs and maps, it is evident that this part of the Fylde coast has been topographically altered due to heavy silting.
As a couple of examples, silting has enabled significant land reclamation on the southern bank of the Ribble estuary and old photographs show vessels moored up at the St. Anne's pier-end (not possible now due to the loss of draught).
Anecdotally, the outer basin of Preston dock is also becoming badly silted.
The real problem is the vast quantities of materials that come down the Ribble. A barrage would lead to the water movement being rapidly arrested with the attendant deposition of same.
Not to say a barrage wouldn't work for electricity generation but only for a limited timescale before the loss of upstream volume rendered the operation uneconomic.
Dredging would be an act of futility as it is very expensive and generally only used for the maintenance of discrete channels for navigation.