I've had a similar (but MUCH smaller) vortex on my big pond. Last spring we had 100 year rains, and my 18" culvert was completely covered, plus around maybe 10" over the top. It drew one heck of a vortex for probably a day or so. I did not feel comfortable until after the water was back below the top of the culvert and it was draining normally.
Didn't someone post a video of one down south somewhere where trees were actually getting sucked into it? I believe Eric might have posted it and it was due to a sink hole?
That's what happens when you're using one of the super braids on your rod and you get hung up on the bottom. Instead of breaking the line, you pull the plug out of the pond.
You don't have to worry about that. I have to. Seriously This (yes, THIS ONE) event happened like ~ 50 km from my pond last spring (this video was quite famous in my country last year). We had great flood and different things happened
What is really happening there? Is it going into a drain under the water, or is it a sinkhole that formed? Wish they showed the outlet, if it was a pipe. Awful big chunks disappearing. Seems as if it was a pipe, those chunks would eventually plug it.
Jodi and I visited that area in January. Interesting fact is that that lake was freshwater before it drained and now is saltwater because it drew water from Lake Vermilion/GOM to refill.