Pumping grout against a water flow? Yea, that will work.
I was up on my roof yesterday with some Dow asphalt goop stuff - says it works wet or dry. (Except it is pouring down rain now - I’m not working in THAT!) Anyway - maybe a few million tubes of that stuff might work.
Oh, to be fair, the downstream side of the emergency spillway is dry at the moment, and that is where they are laying the boulders and concrete. I hope they are making good progress and that the rains hold off a bit.
Just looked at the forecast, next rain is coming in Weds. evening and will last through Friday, with a total of about 2.5 inches of rain. Hopefully that won’t over run the top.