Vessel was stationary with motor idling.  The injured female was swimming up behind the boat.  As the injured female was stepping onto the ladder a two year old who was sitting on her dad's lap put the engine in reverse by grabbing the throttle.  The father quickly returned the throttle to neutral and shut the engine off.  The injured female then began to scream and had blood in the water all around her.  She was pulled from the water and treated by Dells Delton EMS.
Lake Delton