Isn't that overkill? I'm assuming there are all sorts of fish and other creatures in the reservoir and they do far more than pee!
Technically, it is overkill.
But, it's likely a perception thing, noting that the populace's opinions have not been heard (apart from the one who urinated into the reservoir being sentenced to community service). I guess he would get a real social media buzz if he posted up, "LOL you're all drinking my pee" if they didn't do anything about it.
In Queensland in the Beattie days, there was a plan to alleviate drinking water concerns by treated recycled water. As soon as the images came up that we were essentially treating waste water, particularly the stuff that comes out of your toilet, no matter what else was said, there was a predominant rejection by communities. (Mind, the "trial" vote for the idea was in Toowoomba, and was 'only' defeated 60-40; rather dubious result overall).
Of course some perceptions stick and others don't. The fact that in Toowoomba, people get their water from old tanks which may have rusted by now on the inside, let alone taken on all the particulate as the water has coursed from where it was captured to the tank, whether this is actually better than treated recycled water, doesn't seem to enter their minds at all.
I remember someone for a news article poured apple juice into a sterilised bed pan - who clearly was told it was apple juice and that the bed pan was sterilised - and then offered to drink from it. No one did.