Our dog used to do that. We tied a rubbish bag full if water (can't remember if dh put something in it that smelled like vinegar..) on the line, when he went to eat it it burst and covered him in water and he never did it again - and he's a waterholic so I'm surprised it did work at all.
:yeahthat:
This is what i was going to post - you can do the same thing for digging dogs, just bury the balloon. Citrus is meant to be a deterrent too, so you could add a citrus smell in the water
Good luck!