This is the original Los Angeles aqueduct, bringing water from the Owens Valley all the way down to LA. This one was built of iron and in the 1970's another, smaller aqueduct was built of steel to handle the additional needs of LA's thirsty lawns and the agricultural lands between Owens Valley and the city. The water needs to be pumped in some places, but to get over the hill in this picture gravity is sufficient (with a siphoning affect).