Good to know. 

What it means Nadir is get lost, we do not want you swimming here, this is our patch.
A dozen or so of us had a swimming spot and when others found it and said 'this is a great place,' we would tell them, 'yes, until the sewage pours into this spot.' It worked every time. Once a couple of newcomers found the place and saw a few 'thurds' floating by. 'There, look,' we said, 'happens all the time.' Off they went. Amazing what a few brown rotting bananas can do.
Covid did away of our little private swimming place. They came in their dozens and kept it up. Nothing lasts forever.