By Dr. Robert Thorson

Sometimes it’s the footnotes to a larger text that catch the most attention. So it was when I suggested in an offhand aside during a speech last month that we get rid of the word “watershed” — a word that’s been confusing environmental scientists for the last century. For at least one member of my audience at the annual meeting of the Massachusetts Woodland Institute in Wilbraham, Mass., this thought was a revelation.

“What a great idea!” the man exclaimed as we talked after my speech. He was a professional forester with decades of outdoor work experience, one of dozens at the meeting. Now he could think about his landscape in a new and fundamental way.

Getting rid of “watershed,” however, won’t be easy. This word is codified in our legal system, jargonized in our bureaucracies, taught in college courses and part of my daily work vocabulary. Nevertheless, I want it hauled to the unmarked graveyard where disused words are buried and forgotten.

The federal Environmental Protection Agency defines watershed as an “area of land where all of the water that is under it or drains off of it goes into the same place.” More technically, the U.S. Geological Survey considers it an ” area of land that drains all the streams and rainfall to a common outlet such as the outflow of a reservoir, mouth of a bay or any point along a stream channel.”

Both definitions are fine, except for several annoying problems.

First, if you looked up the word in a Merriam-Webster’s dictionary, for the first entry you would find the opposite meaning — that a watershed is not an area, but a line between areas. Quoting its first definition, it’s the “line of hills or mountains from which rivers drain: a ridge between two rivers.” This usage conforms with the ultimate authority of the Oxford English Dictionary, which defines it as “the line separating the waters flowing into different rivers or river basins: a narrow, elevated tract of ground between two drainage areas. This usage derives from “wasserscheide,” the German precedent dating back to the 14th century.

This usage is completely consistent with media-speak, in which a watershed is a line separating old and new ways of thinking.

My main problem with watershed is its exclusive emphasis on liquid water. Subconsciously, it suggests that water is the only thing being shed from a natural drainage area. What about the sands flowing down to create our beaches? The common clay flowing down to create marine habitat? The dissolved minerals flowing to make the sea salty? The organic nutrients that yield our food? In this context, water is the vehicle of change, not the change itself.

Streams are the means by which the residues of our soils are flushed back to the sea so they might again be recycled back into rock. For every drop of rain falling down from above, there is also an increment of rock rising up from below. The landscapes we live on derive from this duality. Natural watersheds are, in fact, rock-sheds controlled from below.

And what about the word “shed.” It’s a verb synonymous with “discard.” Like the fur of a dog, the shell of a crab, an unwanted spouse or snow from a hillside. The connotation is unmistakably negative. Used this way, our watersheds are places where the land sheds its unwanted water like the gabled roof of a backyard shed.

“Words are the channels through which thought flows,” wrote Aldous Huxley in one of my favorite quotes. Communicating correctly requires using the right words.

Hence I suggest that we shed the word watershed and adopt its synonym “catchment” — a land area that catches everything arriving from above and below, including water that falls, the rock that rises, the ecology and anthropology that come in from all sides. Happily, the connotation is positive, as in “Good Catch!” Catchments are the natural places where the stuff we care about is integrated with humankind.