Picture caption: June 29, 1925. Dredge Pump and Hog Box for Diversion Dam Borrow Pit #4
What a Plumbers nightmare. Dredge pump is in shed, the pipe running from center to lower left is the outlet going to the dam. Pipe in lower right is blocked on the end. Then it branches off going up to the hog box, which I assume has a screen to catch large objects, then to the pump. Shed is to keep the electric motor driving the pump dry.