This is what the dam looks like when it's all intact. Granted, the wooden extension is not the most confidence inspiring construction I've ever seen. When the water's really high, it flows over the top of the extension (Duh).
In any case, here's what the dam looked like once I got to it this morning. Lots of lumber floating down into the Hudson I'd say. This isn't the first time this has happened. The "before" photo above was made prior to the last time it got washed out. The wooden extension was then rebuilt. When it's fully functional, no water goes underneath the wooden part.