This is the front section . The gray part gets lowered to the river
bottom and sucks up mud and muck and pumps it on shore to a holding
area . Environmentalists always try to stop dredging because they say
that the pumped up mud pollutes the land where it winds up . Rightly
or wrongly the Army Corps of Engineers always over rules them and the
dredging goes on .

Missing here is the actual cutting head which is like a round ball
with nasty teeth . Probably out being rebuilt as it take a beating
grinding up the river bottom .