  H10728/97--OPR-G309-WH-96; OBSTRUCTION REPORTED WITH A LEAST DEPTH OF 21 FEET IN POSITION 33 53 05.56 N, 078 06 34.32 W (NAD 83). DIVER INVESTIGATION REVEALED THE OBSTRUCTION TO BE A PILE OF CONCRETE BLOCKS. REPORTED AS A DANGER TO NAVIGATION ON JULY 7