The card text made me think it counted water creatures in play, rather than drawn by this card, until I read your explanation. The card itself seems balancecd to me, and while not overpowered, does have some use, as it provides a way to potentially gain card advantage (in water decks) or get another chance to draw something useful (in any deck). For instance, if you are flooded with cards you can't use for some reason, you can play this and replace them with 3 others.