An excellent swim program is infant swim resource. The website is www.infantswim.com. It is a survival course vs. a swim course as children under three, per the AMA don't retain the information to actually swim - i.e. breast stroke, etc.
Infant swim teaches the child how to float, roll over, reach for the edge etc. All skills needed if a child would ever accidentally fall into a pool.
My daughter who also loves the water is three and she can float, roll over and she is actually at the age where she is now swimming. She can swim the length of the pool to me by kicking for forward motion, rolling over to back and resting and then resuming the swimming by rolling back over and kicking to get to me.
She has been in this program since she was 22 months and her instructor states she will be ready for swim team next summer when she is four.
I highly recommend this program - especially when Arizona has so many pools and kids get curious. The program is nationwide and you should be able to locate an instructor near your zip code.