Q: I was in West Virginia for a wedding at a stately old stone mansion. On the property was a wooden structure built over a water spring. I am wondering if the term “watershed” had its origin in this type of wooden shed.
A: A wooden shed over a spring may indeed be described as a water shed, but it isn’t the origin of the English word “watershed,” meaning a high point between two river systems, or a region that drains into a body of water.
The Oxford English Dictionary suggests that the English term may have been influenced by wasserscheide, an equivalent word that has been in use in Germany since the 14th century. In the earliest published references in English, the term has the sense of a high point.
The first reference in the OED is from an 1803 collection of essays published by the Highland Society of Scotland: “This is a very high inland tract, being the water-shed of the country between the two seas.” (I’ve modified the citation a bit, based on the original text.)
Here’s another early OED citation, from Darwin’s The Voyage of the Beagle (1845): “The line of Water-shed which divides the inland streams from those on the coast, has a height of 3000 feet.”
The first OED citation for the use of “watershed” in a more general sense (“whole gathering ground of a river system”) is from an 1874 book on ornithology: “The Missouri Region, in its broadest sense, as embracing the whole watershed of that great river and its tributaries.”
Again, I’m sorry to disappoint you. Your suggestion is interesting, but it doesn’t hold water.