I don't have a pool (OH I wish I did) but I tried something when staying with a friend who had one. A friend who I'm VERY jealous of. It might work for you.

I got in the the pool and showed Blackjack the Wonder Mutt that it was a safe place. He was interested. I then took his favorite toy in with me, followed by treats, trying to show him that the pool is where all his favorite things were.

He wanted to come in and was acting all nervous and crazy. Whining. Finally, I sat on the steps, mostly out of the pool, and he came over to me. Just like a little kid, he tried one foot in the water, then both, then all four, then finally got in and paddled around. It was 10 minutes of work but SO WORTH IT. We got to swim together!

Good luck!