I've done Elk Falls but in drier conditions; the river was calm enough that there were fly fisherman in the river downstream closer to town. I recall that it was a very nice run.
Thought it would be a nice run (although a bit fiddly at the moment because part of the track further downstream has been rerouted for a redevelopment of the power station). I was staying on the other side of town so a bit far afield for that.