I'm a great admirer of people and initiatives like this:
www.trashpaddler.com/
But I must admit I'm not such a hero myself. I meet a lot of trash in the rivers: bikes, washing machines, full garbage bags, ... But I often find that stuff either too gross to take on board, or it's just too large, or too much, or lying too deep, or ... I can always find some excuse, also because I'm there to paddle, not to collect garbage. I often take out simple items and throw them on land, hoping that the real garbage man will pick them up some day.
How do you deal with trash in the waters?