I seem to recall reading something a long time ago with respect to the Reed Sea the possibility of sand bars - water on both sides at low tide, completely submerged at high tide (or stormy weather).
I've seen this at some beaches in southern ME - it's actually dangerous walking the beach at night during the shift form low to high tide. You're walking on a sand bank (without realizing it), walk a certain distance, turn around to head back and it's all water in back of you now.
I don't recall if the Read Sea is actually just a fresh water lake or if a tidal lake.