I have a3 1/2 month old pup, Burley of Salmon River, and I've been working on exposing him to water.  The breeder had the litter wading in a slough before he came to me.  Our weather was cold throughout May and much of June, so swimming conditions were not ideal.  I got Burley to wade in shallow ponds and streams; I put a small wading pool in the back yard, but I couldn't get him to actually swim.  I tried tossing sticks, dummies and even a ruffed grouse compliments of a road kill.  He wasn't fearful of the water, but reluctant get his feet off the bottom to swim.  At a training day in Michigan, Jim Seibel suggested that I try wading across a stream without making any fuss or calling and that pup would likely follow.  As luck would have it, there's a small river close to our home and I found a spot about 15 feet wide that was slow moving and belly-deep on me. It worked like a charm.  My older dog Brinker, swam across, I waded, and before I had made it to the other side, Burley was swiming with gusto!  After a couple minutes, I crossed back and Burley followed without hesitating.  I repeated the process a couple more days and now Burley is having a great time swimming after dummies and enjoying the water.