Human waste is quite infectious, as any traveller south of the border will attest. Rain water or other water sources washing over the waste will tend to carry a bit of the bacterial load with it. The waste of one person trickling into the local groundwater by such means isn't much of a threat; the wastes of a hundred such people can kill the weak, elderly and small children, and it can leave a region with a nasty reputation. Thus, population density is a big factor in whether and to what extend your area needs rules on the disposal of human wastes.

"Robbins’s claim fails because the Hobbs Act does not apply when the National Government is the intended beneficiary of the allegedly extortionate acts."