: The boat dock is downstream of/from the dam.
Hi Brandon,
The way I see it, the sleeplessness arises from the word downstream in your example, rather than from the "of/from" dilemma. I can hardly think of another word that would accept the two "prepositions" equally interchangeably. This is due to the fact that a stream moves in nature, while on the map it is just a blue band. So when showing the way to a tourist on the street, I would say downstream from, while in a report with attached map I would use of.