I think it's too weak. The 'can't attack for one turn' means that you lose a turn of attacks in exchange for +1/+1 to your water creatures. It does synergize with flooding in theory, but in practice it is fairly rare for there to ever be more than 1 row of creatures in play, unless there is a dedicated deck for it. (boneyard, firefly queen, pharaoh, etc)
I do realize that the 'can't attack for 1 turn' was probably built to make it useful against Shard of Sacrifice, but nobody is going to use this card for that when there are upped sundials; unless they play water, upped sundial does the job better.