I think that's just a question of time!
My dog always loved water, but had fear of enter the pool. In first we entered and expected her to jump on the pool, but that didn't happen. So we putted her on arms, entered the pool(with a life jacket for children, but that's a little unconfortable), keeped playing with her and I always letted her to get out when she asked . She got confidence with time, on vacation I went to the pool almost everyday! Later we went for the beach and she loved it!!She runned crazy for the sea!Well, nowdays this is almost a problem, because everytime she sees water she goes into it, one time she entered a water reservoir!!