From approximately 1916 to 1958, Wilson T. Carmack of Harmony Grove operated his primary watercress ponds at Fountain Rock and was known as Maryland's largest watercress grower. Watercress farming was his only career, and for many years it supported a family of five. Because watercress contains high levels of vitamins A, B, and C as well as several minerals, upscale restaurants and grocery stores in Washington and Philadelphia maintained strong demand for greens from Frederick County. Working alone, Carmack delivered thousands of bunches to those cities, while little was sold locally. During the spring peak season, he harvested and sold 3,000 bunches each week. The crop was packed in barrels with alternating layers of greens and crushed ice and sold for 2 1/2 to 5 cents per bunch. Watercress thrives only in limestone spring water such as that found abundantly at Fountain Rock, and the large operation ended with Carmack's death in 1959.