What to do when you find a derelict boat?
I don't know, but there are mulitple scenarios of how and where a boat is considered to be derelict. So, there is likely no single solution, and nothing worth while is ever simple. It'll take sustained level of procativity. I believe the techncial term is "nagging."
What will the Coast Guard or DNR do with boats that are merely reported as ...
"may be adrift"
"may be dragging its anchor?"
"suspected of leaking oil/fuel into the water system?"
... what are their obligations on these reports?
I'd LIKE to think that it would start an official event history on that hull, so that it can eventually be seized or hauled away. Maybe I'm being naive, but several reports from different boaters about a problem boat can't be ignored for long. (The squeeky wheel gets replaced.) It is a fact, however, that passive acceptance and complaining to nobody in particular accomplishes little.
“If you nag people enough, work becomes the course of least resistance.”
-Stephen R. Covey