There's a lock gate between lake lothing (salt) and Oulton Broad.
Most of the time, the gates are shut but there's about a 20cm gap between the gate ends.
As the place is tidal, the gap allows salt and fresh to mix twice a day.
Incidentally, Sid Huggins once caught a codling on double red maggot at the Beauchamp Arms on the River Yare, followed by a bream and a hybrid.
No more kisses Dave, Wols jealous!