Are there good spots for the dog to get wet, to lay in water

Absolutely! You can walk around the entire lake so it's really up to you! I would avoid the spots where people are likely to have gone fishing, we have seen quite a few abandoned books and lures - would hate for your puppy to step on one.

Yes, there is a lake.

I've see a few dogs play in the water at the end of the dam

Not really. You could let them get close to the lake.