I would exercise him more. If he is tired from all of the exercise and training, he will not be so excited about water. He sounds like a bored dog.
How much exercise does he get per day? How much time training everyday?
How many walks, ball throwing, playing tug,swimming,etc.?
Is he in obedience classes?
A dog that is tired out from activity usually just wants to sleep and does not bother with OC behavior.
Gina