C-470 & Santa Fe
The level needs to be at 320 to be ok, although you can surf it at 210. Don't expect much even at 320 with regard to flat spins or side surfing, at 320 you can front surf and back surf all day long.
At higher levels(if the Denver water gods so release) 500 to 1200 cfs it gets very interesting down there. The wave gets very pronounced and pushy with a lot of turbulance in the trough, kinda like Smelter at 500. You'll bounce a lot in it. Since the slot is narrow, take care with flipping in it. You might end up with a headache. I did it once a few years ago and the level was insane at 1500+ and I got the ride of my life on it. 8 ft wave, with a beautiful glassed trough.
Three better drops are about 1/4 mile above Hudson Gardens, again, these are manmade and watch for rocks when upside down.
The gauge to really give you a good view on the flow is Above Union Ave or At Union Ave. then you might look to the Below Chatfield gauge too