Discussion Forum—A Way with Words, a fun radio show and podcast about language

I just listened to your “watershed” episode and disagree with your explanation. (I'll admit the OED gives your explanation as its first definition, but I think that current (engineering/technical) usage is more along the lines of the second definition, as I explain below.)

The ridge line you describe is more properly called a “divide” as in “Continental Divide.” The watershed is all the land that drains (or sheds) water into a particular river or basin. The Continental Divide separates the Missouri River watershed from the Snake River watershed and the Great Basin, much of which is the Great Salt Lake watershed.

I live in the Hominy Creek (an 1860's map at the Missouri Geological Survey says Harmony Creek) watershed which is part of the Pomme de Terre watershed, part of the Osage River watershed, part of the Missouri River watershed, and, finally, part of the Mississippi River watershed. My 5-mile-away farm is on the other side of a divide that stretches about 30 miles from Indian Point at the Pomme de Terre lake. It is in the Brush Creek watershed, part of the Lindley Creek watershed, part of the Pomme de Terre watershed, etc.

I think the “watershed moment in history” has the connotation of an unstoppable collection of events which will result in a great change. So too is a flood in a watershed. The people of Fargo are sandbagging their town against the Red River because there is an unstoppable collection of snow and heavy rain (none of which causing a flood on its own) in its watershed. Their sandbagging is a great change for their city trying to avoid a greater change which would result if the flooding cannot be contained.

Emmett

P.S. What? No math?