I thought the same thing, actually. You should consider it a compliment if you did do it by hand, because it sure looks too good to not have anything to do with a semi-transparent layer.
Actually, it looks good no matter what. The water reminds me of an early shader demo I saw for some graphics card in a relatively old game magazine, where they used, like, normal maps and reflection or whatever on real time water. And it looked almost exactly like that. And I remember thinking "Wow, that sure looks.. not at all like water... unless those characters are half an inch tall and those enormous waves are actually just ripples.."
But yours is to scale and is looking very good!
