My guys have been drinking it their whole lives and have never had a problem with it. I try to avoid having them drink mud puddle water especially in town where it could contain gas, oil or antifreeze.
My only concern is here out west Giardia is extremely common in freshwater ponds and streams. Since Giardia is a microscopic parasite the water can appear pristine but can still harbor it.
The good news is that if a dog becomes infected with Giardia it is usually less harmful than human infections because canine intestines are less convoluted than ours. Nevertheless, your dog can become a very poopy pup. The bad news is that humans can pick up the parasite from dogs and become very ill.
It might be worthwhile having the water checked for microscopic parasites. Another thought is that even if your stream is safe Gracie may decide to drink from other streams that she encounters that are not as clean.