It’s confusing because much of the media is referring to the “main” concrete flume spillway as the “emergency” spillway.
But as I understand it, there is another earthen spillway running roughly parallel to the main concrete one. I guess that one is higher than the main concrete one. I would assume that one would be the emergency or auxiliary one, but the media makes it really confusing.
I agree that most of the writing has been rather poor. You are right that the main spillway (concrete lined) is lower than the emergency one. The main one has the gates that can be opened and throttled to control outlet flow. The emergency weir just does what it does when the water overflows the top. I’m amazed that the emergency spillway just flows over earth! That’s what the environmentalists were complaining about a decade ago — that too much dirt would be washed into the river if it were used.