One of these days I will book some time off for these river clean up events.
But for myself I always carry a small plastic bag and so far this year I've pulled out enough line to spool one reel from Furry creek, Squamish and Ambleside, a small stack of Tim's cups and several gooey ziplock bags (Part of my wants to find these people and just wrap the bag around their face and suffocate them in old smelly Borax, Procure and eggs.) This year I haven't seen a TON of garbage yet but that doesn't include Stave which can be REALLY bad.
I'll never get what makes people think that throwing garbage on the ground is alright, from it being either cultural or just indifferent thinking/ beliefs, I'll never understand it but if these people want areas like Furry Creek shut down to fishing then they are helping to contribute to the reasons why as some of the people who live in that area do complain about garbage that is left behind like cups, plastic bags and line.
A big personal pet peeve is idiots who snag and cut their mainline cause they are using braid or even heavy mono. Seriously?!?! cutting and leaving like 40+ feet of line in the river to possibly snag around another anglers legs or even kill animals like the beaver a friend posted a while ago, heavy mono wrapped around it's legs and cut through into the flesh and most likely died a slow death.