Taking a strong dog to Michigan state parks
The state is generous with shoreline for leashed dogs, with a few firm exceptions.

The leash rule
The DNR pets in parks page says dogs are welcome in state parks, campgrounds, state forest campgrounds, harbors and designated trails, except designated swim beaches, endangered species habitat and other posted areas. Pets must always be on a six-foot leash and under immediate control.
Shoreline and water
The same page allows pets along the shoreline except buoyed swim areas and signed habitat, and says the six-foot leash applies even in the water. The DNR bulletin on bringing pets to state parks adds that in general pets are allowed in state parks, park campgrounds and state forest campgrounds on a leash not over six feet at all times, with exceptions such as state buildings.

The dog is the test
A guard-type dog on a crowded shoreline needs to settle quickly. Ask any professional to show that skill outside of a training field.
Interested in protection dogs in Michigan?
Send your ZIP code and what you need the dog for. A professional who works in your area can get in touch.
Ask for a referral