Iron mining and smelting once took place along the upper reaches of Popolopen Creek. The Forest of Dean Mine produced iron ore from the Revolutionary era into the twentieth century, and operated a narrow gauge railroad along the creek as far as the eastern slopes of Popolopen Torne. The mine site has been submerged by Stilwell Lake. Queensboro Furnace, located just above the outlet of Queensboro Brook into the creek, smelted iron during the late eighteenth century. The remains of the furnace have been preserved, as part of the grounds of the West Point Military Reservation.