Big river scientists and teachers will like this new COE gallery of high-resolution photos on the St. Louis District's website. The collection is all about boats and the built-environment, but says it'll be expanded, and many of the images are beautiful aerials like this one of a barge tow heading downstream into St. Louis.
This appears to be Lock 27 at the southern end of the Chain of Rocks Canal on the Mississippi River, one of those COE projects you might be able to see from the Moon.
Update: The COE website is a little disorganized. Here's one of the galleries in case you have trouble with the link above.