That reservoir is about a half mile from me, so theoretically, I would be drinking that water, BUT, the thing is about 500'x500'x50'.... I can't imagine that I would get that badly hurt by one errant sperm that might have been let loose in the thing that might just get to me.
But these are pretty rude people.
BTW, there is an ordinance on the books here in Portland that was passed three or four years ago that it is violation of city code to have sex on picnic tables in city parks. A similarly simian couple had a tryst on one next to a school picnic, and when the cops came to arrest them, they found out there was no law against it, so now there is.