[TowerTalk] Vertical in pond

[Jim WB5OXQ inb Waco, TX]

Would there be much if any advantage to mounting a hf vertical on a mast in the center of a small fresh water pond.  The pond is aproximately 80' in dameter and 10' deep in the center.  I see coastal broadcast stations putting their towers over the ocean but that is salt water.
What about the middle of a metal roof building 80X120?  Roof is not flat rather slopes away from the center gradually.  I have a 10' mast in the center on a roof tripod that used to support a tv antenna.
WB5OXQ