We went end of March last year and hit it just as it was coming down. I believe we took out and it was in the low teens. Wouldn't want to take gear boats down much lower than that and a lot of it was boney in a playboat at that level.
Granted that was the only time I have been down it and this year there is a lot of snow, but there isn't the altitude to hold it unless it is a cold, wet spring in the south.
Good luck - great trip if there is water. Can't imagine what it is like at these flows