That whole section of the Potomac was the site of all sorts of skirmishing. It’s going to be hard to find a point where shots _weren’t_ fired ...
“It’s going to be hard to find a point where shots weren’t fired ...”
True. I found an interesting report put together by Fairfax County:
http://www.fairfaxcounty.gov/parks/resource-management/downloads/civilwarinventory.pdf
On page 21, it states that during the fall/winter of 1861, there were 61 skirmishes!
And since this was an approach to Washington, it was part of the screening defenses. A map on page 28 shows the northernmost end of this screen (in VA at least) was a few hundred yards east of Lowe’s island.
I have no doubt that locals have passed down stories over the years (likely exaggerated each generation) about this time.