Something Special or Springs?

A day or two ago I noticed what I would consider to be large circles on the ice on the Wapsipinicon River. Being the curious type, I did some research. Apparently there is a phenomenon where, under the proper conditions, ice circles can form on bodies of slow moving water. That explanation makes sense, but I do not think applies to the circles I am seeing.

https://www.smithsonianmag.com/travel/science-behind-snow-rollers-ice-circles-other-winter-phenomena-180973946/

Each of the ice circles I documented has at least one hole. My best guess is maybe there are numerous spring in the river and these froze as the warmer water rose from the center and spread out symmetrically. Maybe?

If someone knows, please share with me.