Switching subjects, I want to talk about dead pigs floating into Shanghai. While I don't know all of the details, this is a nice example of the Tragedy of the Commons and the Law of Unintended Consequences and the connection between agricultural regulation and city quality of life. How could there be over 6000 dead pigs in the Huangpu River?
"The surge in the dumping of dead pigs, believed to be from farms upriver in Zhejiang Province, followed police campaigns to curb the illicit trade of pork products harvested from diseased pigs."
So, as the rural police addressed the nasty pork problem (and its threat to the food supply's quality), the owners of the dead pigs disposed of the bodies in a Mafia Style by dumping them in the river and they flowed down to the mega city causing challenges there. Since the river is public property, this was a rational (but socially inefficient) solution for the farm owners.