Is Newport Park only for residents and property owners of Lake Delton? Or can you use the park if you are a non resident? I am asking as I see only residents and property owners can reserve a shelter.

Anyone can use the Beach, Park, and Shelters. As for the shelters, it's first come first served.

Anyone can go, but you are not guaranteed a shelter. You can bring your own umbrellas/tent/whatever to be safe. Early arrival ups your chance of getting a shelter, if that helps.

We ate lunch there while on vacation. No one said anything to us and there are not any signs posted.