Operator stated that he was outbound listed canal near the mouth and struck something hard on the bottom of the canal.  Deputy inspected the boat in a hoist and found substantial damage. The adjoining DNR Access Site on the canal is currently under construction repairing seawall/breakwall.  Operator claims he may have struck concrete that had fallen into water during construction.  Operator filed report with DNR officials.  No injuries were reported.
Chesterfield                  