the angle of the marketing people.
Last time I was there it was its typical brownish yellowish. It's not "dirty." The color is from tannin and other vegetation "stains" from all the tributaries. Back in the days of, "Arrrrgh! Sail!" water from Lake Drummond, which feeds the Great Dismal Swamp Canal, was much prized for filling the water butts of ships. It's the color of dark tea, but was utterly safe to drink . . no nasty microbes could live in it. Add a little rum and you had a rather tasty cocktail.