Tracks found near a lake by witnesses

The witness reports finding tracks in soft soil at the edge of a freshwater lake in early October 1999, first a single set and then about two weeks later three sets of different sizes. The tracks were where large-leafed underwater plants were growing, and the plants appeared stripped from the water where the tracks were found. The witness photographed and videotaped the tracks and area, but weather destroyed the tracks before a cast could be made, and later visits in November and December found no further sign.