I see that some folks feel quite strongly about this. Is that because in the US they actually take it seriously and so the ethic has been adopted? There was a time when drinking and driving wasn't such a social taboo, either. Is it because if I pay, you should pay too?
I'm not exactly enamored with the quality of the harbor's water either, but while the idea of floating turds IS repugnant, I am a lot more concerned about the toxic buildup in the sediments from industry. That's the stuff that gives you seals with two heads. Not to mention people.
Not surprisingly the harbor authority recently announced "troubling" levels of E. coli in the water, but from what I understand from my microbiologist bro, in most cases it's harmless, but it's a MARKER for fecal contamination, which gets the health authorities scared fast. In fresh water it can lead to all kinds of plagues and stuff, but saltwater? What is the worry other than we don't like floating in sewers?
The thing about most ethics and morals, they only work if a good, solid segment of society also follow them. If you're the only guy adhering to a value, and paying all the consequences while everyone else ignores it and reaps the reward, you might feel good about yourself, and you might even be a model fellow, but you also just might be an twit.