Why would it have water in it today?
In order for the Upper to "flow" the level of the reservoir (Spada Lake) has to raise so fast that the dam folks cannot keep up and the water pours out of an overflow.
http://www.ioffer.com/i/spada-lake-morning-glory-spillway-sultan-wa-vintage-pc-13164461That said... I think it would be runnable when the Sultan is absolutely pumping from rain... As long as you put in at the diversion, where the canyon has picked up water. To have any water at the upper putinn, that big hole must be flowing... which seldom happens.