The Leelanau is a plesiosaur like Lake Monster said to live in Lake Leelanau, Leelanau County, Michigan. Local legend says that it appeared after the Lake Leelanau Dam was built. Reports are rare, and have stopped completely. It is likely extinct.
It would appear that is had a small population to begin with at the dam's construction. Reports were probably rare due to a only a small number of animals living there, cut off from the rest of the pod.