I can't help you but I've seen this kind of behaviour before where a dog tries to bite the stream of water coming from a hose. My dad's sheepdog Turbo has been doing it all her life and she's just about 10. But she was never aggressive, she would try and bite it and would then bark at it, then bite, then bark. She never tried to destroy the hose or sprinklers at all and as soon as the water was turned off she would go off and mind her business. It looked like she was just playing and she never looked aggressive at all. If we called her off to do work, she would leave the water alone.
I do hope you can solve it.