This isn't Poucha pond where cars tend to fall into.

Tom

I realize that this is late. I experienced a similar situation in the private subdivision lake I fish. Sounded/looked like someone threw a truck tire and wheel asmy in the water.  A couple of days later. I saw the culprit, a VERY large carp. This lake has given up a 35 lb carp a couple of years ago.

I just know it startled me.

Perhaps it WAS a truck landing in the pond.  Have you checked with the state police for any missing persons?

 

Or maybe it was an alien spacecraft.  Has your "backside" been hurting you lately?

 

Probably a carp, a big gar, or a beaver.

Years ago I was fishing a lake system right next to Cleveland Clinic, in Weston Florida.  It was in the heavy grass by the shore, it looked like a tire in the grass stems.  All of a sudden the tire started to move.  It was a snake the size of my knee in thickness. This was before the python warnings, but apparently a pet some nit wit decided to release when it got too big.  It disappeared into the depths.  I walk carefully around these waters from that point on.   I have not seen one since, but I'm sure people are missing pets somewhere along the miles of connected lakes.

If someone else was fishing it could have been a whopper plopper landing.