Not sure what your referring too as gravel beds, but the one the locals call the gravel bed is in approx 26' of water and 4 miles NE of the Toledo water intake

move your cursor so its located at Lat.41.752 Lon.83.225 in the link below and you will see the area called the gravel bed

http://marina.geowake.com/map/index....fullscreenexit