Nearly a decade has passed since the last vestiges of the oyster farm were dredged from the soft, silty bottom of Drakes Estero. During a year-long cleanup led by the National Park Service, nearly 7,000 wooden posts and 500 tons of weathered racks were hauled away with the aid of a hydraulic excavator mounted on a barge. An additional 60 tons of oyster shells and debris were cleared, and every visible trace of the operation—its…