Before the pool was plastered the dogs would go into the deep and and spalsh around in the dirty water. Now that the water is clean they don't want anything to do with it. Since they knew how to get in and out of the pool before it was filled, maybe they will remember that.
I can't take that chance, but it would be reassuring if I put them in the deep end and they immediately swim to the shallow end (tanning shelf/exit).

PS. Aren't retrievers born water dogs? I'm surprised you can keep yours out of the water.