Hardy Dam (or Hardy Hydroelectric Plant) is an earth-filled embankment dam and powerplant complex on the Muskegon River in Big Prairie Township, Newaygo County, Michigan. At the time of its completion, it was the largest earthen dam in North America east of the Mississippi. Its impoundment forms a lake with over 50 miles of shoreline. The dam impounds a reservoir with a surface area of 4,000 acres (1,618 ha) and its power plant has an installed capacity of 31.5 MW.