Just because Labrador Retrievers love water doesn't mean you should disregard water safety. Water safety for Labrador Retrievers is a lot like water safety for kids.
Introduce your Lab puppy to a small pond as soon as she seems interested in water. Use gentle, loving care (think about how you might teach a child to swim). A good time to introduce litters to the water (assuming the weather isn't too cold) is when they're about 6 or 7 weeks old, and they all wind up swimming at that age. Find a natural body of water where you can wade in and wade out. Let your puppy follow you at his own pace.
If your Lab is reluctant, return another day and let your pup see how much fun you're having in the water, or bring along another dog who is a veteran swimmer. With a little patience, your pup will get his feet wet, so to speak.
Once your Lab, gets the hang of things, you'll want to keep the following in mind.
Make sure the water in which your Lab will swim is clean enough for you to enter. Also avoid places with heavy currents, where your Lab could be swept out to sea or down a river. If you consider the water safe enough for you or your children, it should be safe enough for your Lab.
Don't let your Lab overexert himself or become chilled. Remember, Labs are like children and can't be trusted to use good judgment when doing fun activities. They can get carried away having a good time and trying to please you. It's up to you to say when enough is enough.
Always supervise your Lab when he's in a swimming pool, and be very sure he knows how to get back out. A bad swimming pool experience can traumatize a puppy and make him afraid of all water.
If your puppy falls in the pool when you aren't watching and doesn't know how to get back out again, he could drown.