Lake Diane is a 400 acre all sports lake located in southern Hillsdale County. This large, man-made reservoir was created by the construction of a dam on a tributary to Clark Fork Creek.

Two natural lakes located on the tributary, Goforth and Hagerman, were inundated when the reservoir was created as part of a real estate venture in 1966.

The Lake Diane community has grown into a thriving community consisting of approximately 70% second homes and 30% full time residents.