While memories of the U.S. Open are still fresh, it might be a good time to reveal one of the Potomac River’s little-known secrets.

It has to do with golf balls. Those of us who poke around the river’s shores and explore the crevasses in its rocks know that golf balls make up a small but ubiquitous share of its trash load. You see one here, you see one there.

But one spot in the river is paved with golf balls in such numbers that it looks like a golf ball graveyard. I won’t say exactly where it is except that it’s within sight of the American Legion Bridge.

The golf balls lie in a rock hollow between two ledges that are about 20 feet apart. They gleam in the sunlit water, the old ones greenish with algae, new ones shiny white, yellow, and orange. This same spot is also a favored resting place for black walnuts, which look like golf balls that have been shrunk and cured by Jívaro Indians.

A twin mystery. It could very well be the work of our local trickster, the Potomac River. The audience admires its display of slight of hand, but then wants answers: Where do all of these golf balls come from? And why should they be in this one spot?

As for the first question, I would presume that they come from golf courses, not only those bordering the main stem of the river itself, but also ones near streams and creeks. Periodic floods sweep the usual assortment of Potomac trash downstream—Styrofoam cups, old tires, plastic bags and water bottles,  beer cans, children’s toys, golf balls—until it all ends up in the river’s main stem.

As for the question of why so many ended up in this one spot, it might have to do with the river’s tendency to sort things out and put them where they belong. For example, flood waters deposit bigger, heavier stones closer to their mountain sources and carry the smaller, lighter ones further downstream. Where the river empties into a bay or the ocean, the sorting continues, with the sand deposited first, followed by the fine particles of silt.

In the Potomac I’ve seen assemblages of old tires on the river bottom, like stromatolites from the beginning of life on earth. I’ve always thought these were places where the force of the current and the specific gravity of the tires ended in a truce.

I’d imagine it’s similar with the golf balls. A strong current will carry them over the upstream ledge of my golf ball graveyard, but that same ledge slows down the current just enough that the balls drop to the bottom and never make it over the second ledge. That’s my guess. The trickster might know better.

Whichever way, the game of golf now has something even better than a hole in one—a hole for all.