  H10560/94--OPR-K171-MI-94; FOUND AN UNIDENTIFIED OBSTRUCTION IN LAT. 29/44/37.19N, LONG. 093/20/32.30W (NAD83).  A DIVE INVESTIGATION WAS NOT ATTEMPTED DUE TO TRAFFIC, WEATHER, CURRENTS, AND LOW VISIBILITY.  THE LEAST DEPTH OF 6.5 METERS MLLW AND THE P