On recent TV show shoots in Bath, Maine, and Essex, Connecticut, the crew of New England Boating encountered several large logs and other debris floating down the Kennebec and Connecticut Rivers. Many of these objects would have done major damage to a lower unit, shaft, prop or rudder if struck at running speed. Worse, in many cases only a tiny piece of the flotsam was visible above the surface, making it hard to discern the size of the underwater hazard.
When boating in and around rivers, be especially cautious of such debris, especially around a very high tide or after heavy rainfall. Both events can dislodge trees and other objects from the banks and send them downstream like so many floating mines.
Also, realize that certain parts of the river tend to accumulate more floating debris due to eddies and variances in current flow, so be particularly cautious in these areas and note them for future reference.
Lastly, take it slow and post a lookout when navigating these waterways.