This is another BS thing EPA has done in the last few years. They redefined "navigable waterways" to include ditches, many which sit dry most of the year.
I have one that cuts my property in half. It was a ditch when I bought the place. How does the US Government have the right to change the definition after the fact and redefine the rules associated with affected properties? The mere definition of "navigable waterway" applied to a ditch that isn't even 4 feet wide or deep is ludicrous. It is a man made drainage ditch, created for the purpose of drainage. It is not a natural stream.
Ask them what kind of craft can ‘navigate’ your waterway )ditch).
Ask for pictures.