RedactedNarrative: Unit 1 was attempting to dock as they were experiencing engine trouble.  While attempting to restart the motor Unit 1 drifted into a standing tree on the edge of the lake.  When the starboard bow of the boat collided with the tree it dislodged the top portion of the tree.  The broken section of the tree landed on a female passenger near the bow of the boat knocking her unconscious.  EMS was then contacted and she was transported to the hospital where she succumbed to her injuries.  The operator was arrested for BUI.