Sadly, you are correct "N.A.". Like Scott, Bob G, et al, I spend a lot of time on the Canal and agree with your assessments from what I see there. A few quick points:
* Yes, I have picked up some trash and added it to my own on the occasion of having a spare hand. I also try to be as quiet as possible when parking and using access routes near housing. Though, I'm no saint, I try anyway.
* On the Canal, it's not strictly "fishermen". Though a they are the largest part of the mess and will always end up feeling the inevitable backlash. (fishing line, hooks etc make it seem pretty obvious as to who left the rest of the garbage) One thing I'd like to see there, for example, is a "pooper-scooper" law. Good luck navigating the civilian, pet land mines at night. And NEVER lay your jacket or fishing gear in the grass, yuck!! These same folks with a squatting black lab at the end of a leash hunched over the borders of the walkways will be the ones who sign the petitions, call their representatives and vote to ban fishing access to the canal (or any other applicable site) due to the "mess fishermen make".
I guess this means that we all have to be extra, extra diligent in keeping our passtime's reputation, and recreating areas clean.
-John-