Photograph of a man dumping mining tailings in a tunnel during the construction of the Colorado River Aqueduct, ca.1930. A large rail car can be seen at right and the top section is tipped to the left. Large amounts of dirt and rocks are pouring out the side into a deep tunnel. A man in construction clothes is standing at left and pulling a lever. He is looking towards the viewer and is holding a long hose. Several pipes and wooden braces can be seen on the walls of the tunnel, while a rail road track is visible at right.