Douglas differs from some of the TVA reservoirs in that the landowner owns to the water's edge. There is not a "high water" section that is public land. TVA only has an "easement" to cover the land with water. The landowner still owns the land under the water.
So, yes, she was correct if you were within her property boundaries. If it is privately owned land, you would need the landowner's permission to be out on the land, even at the water's edge.