GREEN BAY, WI (AP) -

A Milwaukee family has sold an island off of Door County to the Nature Conservatory, to ensure that it is protected.

Fred Luber is former chairman and chief executive of Super Steel Products. He and his family sold 94 percent of St. Martin Island to the conservancy for $1.5 million -- about 60 percent of its fair market value.

The Green Bay Press-Gazette reports the island will soon belong to the U.S. Fish & Wildlife Service's Green Bay National Wildlife Refuge.

The remaining 6 percent of the island is owned by another private landowner and the Little Traverse Bay Bands of Odawa Indians. The conservancy has contacted both about preservation.

The island is technically in Michigan waters. The conservancy's Wisconsin and Michigan programs partnered up to acquire it.