Just finished reading some other stories, and it looks like the boat underpass at center span has severe shoaling and needs dredging. Problem is that the Obama regime and Congress has so screwed up the military budget (with sequestration) that the Corps of Engineers can no longer afford to carry out its longstanding function of keeping America’s navigable waterways navigable.
Or it could be that the Corps of Engineers and EPA have been too busy trying to regulate every dry depression in the ground that turns into a mud puddle when it rains that they don't have the manpower or money to do what they should be doing.
The Army Corps of Engineers came up with the “migratory molecule” rule, which says that even isolated wetlands fall under federal jurisdiction because there is a theoretical chance that a water molecule from any location may reach a navigable waterway.