Yeah, you can't tell from the picture but there's a channel there that it flows into.
Nope, rock has not been placed yet, you can see one of my piles right next to the water. I plan on extending the outlet end of the siphon so I have more room on (nearly) level ground to make it easier getting around it with my tractor. Then the rock will go in. For now, I've let the grass get tall and thick in the downstream channel to protect against the erosion and so far it's ok.
I was fortunate, but am hearing reports of other emergency spillways that were damaged and one dam that was topped. It sounds like that dam survived, but I have not seen it yet.