Medina Lake was constructed in 1912 as an irrigation reservoir, and its 26-mile gravity-flow canal system delivers water to 34,000 acres of farmland through earthen canals. Wooden trestles and flumes, including several in these hills, once carried water across the deepest ravines. One of them has been replaced by a siphon, and the trestle pictured is the only one still standing, though it is no longer in use.