Wilson T. Carmack of Harmony Grove was known as Maryland's largest watercress grower, having his primary ponds at Fountain Rock from approximately 1916 to 1958. With a sole career of watercress farming, he supported a family of five for many years.
Watercress contains a high content of vitamins A, B, C, and several minerals, therefore, upscale metropolitan restaurants and grocery stores in Washington and Philadelphia sustained a healthy demand for these greens from Frederick county. Working by himself, Carmack delivered thousands of bunches to these cities, though little was sold locally. During the spring peak season, he harvested and sold 3,000 bunches weekly. The watercress was packed in barrels with alternating layers of greens and crushed ice and sold for 2 ½ to 5 cents per bunch.
The plant thrives only in limestone spring water such as abounds at Fountain Rock. This large operation ceased production with the death of Mr. Carmack in 1959.