Lol, they dont need sonar, they can walk the river now, and just look with their eyes. Lots of sediment has accumulated in the river over the last 50 years. I would guess atleast 15 feet of sand in the main course of the river. Not to mention the course of the river has changed significantly over the years. The windy river bends, have been turning into a quite a few long straight stretches. I wish them luck, but it sure seems like a waste of tax dollars, in a tough era.