Grassy Island became a dumping ground for the U.S. Army Corps of Engineers since 1961 -- the same year Congress declared it part of the Detroit International Wildlife Refuge, the Detroit News said.
The newspaper said the 72-acre island near Wyandotte, Mich., is so polluted "federal officials have posted signs warning against setting foot on it."
While it currently contains high levels of lead, PCBs and arsenic, state and federal officials say the island could someday be a tourist attraction.
The U.S. Fish and Wildlife Service have allotted $1 million to study what it would take to restore the island.
Supporters say the island shows signs of hope, with shrubs and trees taking root over the iron, bacteria, oils and other metals that once killed off the plants. Deer and waterfowl also have returned to the island, the newspaper said.