Nearing the top of the stairway in yesterday's photo, this is the view off to the east. I don't think this is a blocked stream or anything, just a low area whose drainage was obstructed by the advancing wall of obsidian. I suspect that the water input is mostly from percolation through and out of the flow itself. As far as outflow, I think there must be a lip somewhere down there at the far end; there definitely seems to be an upper end to the water level in this pond- this is about it. However, when it's particularly dry, I think this can get pretty low. 2011, though, was a very cool and late summer.