Maybe ten years ago we frequented a private campground that had no sewer hookups, but a lot of seasonal campers. One small wing-like cluster of seasonal campsites suddenly went vacant, so I asked the campground owner what happened to them.
He had caught them dumping grey water on the ground behind their sites. In a ravine with a small stream that fed directly into the camp fishing lake. Which they had polluted to the extent it was no longer safe to keep your catch. So much for the stocking done earlier in the season.
Of course, he kicked them out of the campground and closed that part of the loop to other campers.