There’s a significant undermined ice dam at the top of the Tuckerman Ravine headwall, marked in the photo. The rushing water wasn’t audible until I was pretty much on top of it, and a large section of it collapsed quickly when I poked it with my tool. On closer inspection there was <1″ of ice above a small river, but buried beneath a few inches windboard snow.
Ended up downclimbing a bit and going up to climber's right of the large rock (climber's right of the dam), which was totally solid. All in all a great day ice climbing in tux!