Back in the day I used to fish a Lea valley pit that involved a long walk along a canal towpath to access it. We used to visit the lake in the close season to bait up and plumb swims and the canal bank was clean.
By about June 20th the towpath would be filthy - and it was obviously all anglers’ litter.
why can’t clubs/water owners ban those that leave litter ? Reading club has a rule to the effect that ANY litter in your peg means a ban - So people pick up any litter before they start fishing. Simple. But it requires good bailiffing.
I had a party of four guys come to my lakes for a long weekend a few years ago. The day after they left I found a bag of litter hidden under a bush adjacent to one of the swims they had been fishing. They won’t be coming back.