Rain, rain, and more rain
That whole part of the country is soaked. At my sister-in-laws in Milan, MI, I had to go to a local RV park rather than park in their yard as planned. Even that RV park couldn't use many of their sites because of mud. At Kewanee, near Door County, at least half the sites were unusable because of water.
They had to use tractors to tow some of the units in during the Homecoming, as well. I was able to get to my site without assistance,although I had to keep my 2wd diesel moving all the way.
A local farmer brought 3 tractors; one was a real brute used to move the motorhomes. By a day or two later, everything had dried up enough that I was able to get in and out with no trouble and everyone seemed to leave wthout trouble.
John W. Irwin
2018 Interstate GT, "Sabre-Dog V"