  H09881/80--OPR-K104-MI-80;  LOCATED AN OBSTRUCTION RISING APPROXIMATELY 4 FEET OFF THE BOTTOM WITH A LEAST DEPTH OF 89 FEET MLLW BY ECHOSOUNDER IN LAT. 28/36/43.45N, LONG 095/10/11.71W (NAD27).  THE OBSTRUCTION WAS NOT DIVER INVESTIGATED.  (ENTERED 4/0